Extract hosts file filter into GroupedSelectDropdown and builder

Add shared Models.Ui grouped-select model, IGroupedSelectBuilder, optional
trigger summary API, and GroupedSelectDropdown component. Hosts page uses
HostsFileFilterBuilder and hosts-specific option row styling for full paths.

Remove HostsSourcePathDisplay and file filter menu records in favor of the
builder. Bump version to 0.0.8.

Dockerfile

@@ -2,7 +2,15 @@
 # Both run as root; file permissions work because config dirs are in the container.
 # For dnsmasq on the host, use the self-contained publish (scripts/publish-self-contained.sh)
 # or run the app on the host; see DnsmasqOptions XML doc for permissions and ReloadCommand scope.
+#
+# Dnsmasq install mode for the test harness:
+# - DNSMASQ_VERSION=latest (default): build the latest stable upstream dnsmasq release.
+# - DNSMASQ_VERSION=<version>       : build that exact upstream release (e.g. 2.91).
+# - DNSMASQ_VERSION=distro          : use the distro package from apt.
+#
+# This keeps day-to-day harness use close to upstream while still allowing pinned-version testing.
 
+ARG DNSMASQ_VERSION=
 FROM mcr.microsoft.com/dotnet/aspnet:10.0 AS base
 WORKDIR /app
 EXPOSE 8080
@@ -19,15 +27,37 @@ RUN dotnet build "DnsmasqWebUI.csproj" -c Release -o /app/build
 FROM build AS publish
 RUN dotnet publish "DnsmasqWebUI.csproj" -c Release -o /app/publish /p:UseAppHost=false
 
-FROM base AS app
+FROM base AS final
+ARG DNSMASQ_VERSION=latest
 WORKDIR /app
 ENV ASPNETCORE_URLS=http://+:8080
-COPY --from=publish /app/publish .
+# Install dnsmasq either from the distro package or by building an upstream release.
-
+RUN if [ "$DNSMASQ_VERSION" = "distro" ]; then \
-FROM app AS final
+    apt-get update && apt-get install -y --no-install-recommends dnsmasq procps \
-RUN apt-get update && apt-get install -y --no-install-recommends dnsmasq procps \
+    && rm -rf /var/lib/apt/lists/*; \
-    && rm -rf /var/lib/apt/lists/*
+    else \
-COPY scripts/entrypoint.sh .
+    apt-get update && apt-get install -y --no-install-recommends procps curl build-essential xz-utils ca-certificates \
-COPY scripts/dnsmasq-status.sh .
+    && rm -rf /var/lib/apt/lists/* \
+    && if [ "$DNSMASQ_VERSION" = "latest" ]; then \
+         DNSMASQ_VERSION="$(curl -fsSL https://thekelleys.org.uk/dnsmasq/ | grep -o 'dnsmasq-[0-9][0-9.]*\.tar\.xz' | sed 's/^dnsmasq-//; s/\.tar\.xz$//' | sort -V | tail -n1)"; \
+       fi \
+    && test -n "$DNSMASQ_VERSION" \
+    && echo "Building dnsmasq $DNSMASQ_VERSION from upstream source" \
+    && curl -fsSL "https://thekelleys.org.uk/dnsmasq/dnsmasq-${DNSMASQ_VERSION}.tar.xz" -o /tmp/dnsmasq.tar.xz \
+    && tar -C /tmp -xJf /tmp/dnsmasq.tar.xz \
+    && make -C /tmp/dnsmasq-${DNSMASQ_VERSION} -j"$(nproc)" \
+    && make -C /tmp/dnsmasq-${DNSMASQ_VERSION} install PREFIX=/usr \
+    && rm -rf /tmp/dnsmasq-${DNSMASQ_VERSION} /tmp/dnsmasq.tar.xz \
+    && apt-get purge -y build-essential curl xz-utils \
+    && apt-get autoremove -y --purge \
+    && rm -rf /var/lib/apt/lists/*; \
+    fi
+COPY scripts/entrypoint.sh scripts/dnsmasq-status.sh ./
 RUN chmod +x entrypoint.sh dnsmasq-status.sh
+# curl for HEALTHCHECK (aspnet image has no curl/wget)
+RUN apt-get update && apt-get install -y --no-install-recommends curl && rm -rf /var/lib/apt/lists/*
+# .NET publish last - only this layer invalidates when code changes
+COPY --from=publish /app/publish .
 ENTRYPOINT ["./entrypoint.sh"]
+HEALTHCHECK --interval=30s --timeout=5s --start-period=5s --retries=3 \
+  CMD curl -f -s http://localhost:8080/healthz/ready || exit 1

README.md

@@ -19,6 +19,8 @@ A self-hosted web UI for managing [dnsmasq](https://thekelleys.org.uk/dnsmasq/do
 - **DHCP host entries** (reservations) if you use DHCP; edit in the UI, written into the managed config.
 - **Reload dnsmasq** after config changes (configurable command, e.g. `systemctl reload dnsmasq` or `pkill -HUP -x dnsmasq`).
 - Optional **status** and **recent logs** commands (e.g. systemctl/journalctl or custom scripts) shown on the Dnsmasq page.
+- **Minimum dnsmasq version** check (configurable; e.g. 2.91). The UI can refuse to start or block config save if the detected version is too old. Version is shown on the Dnsmasq page with a link to release notes.
+- **Readiness endpoint** `GET /healthz/ready` for orchestration (Kubernetes, Docker, load balancers). Returns healthy when dnsmasq version meets the minimum and, if configured, dnsmasq is running. The Docker image includes a HEALTHCHECK that uses this endpoint.
 - **Self-contained Linux binaries** per OS/arch (RID); no .NET install required. Can run in Docker or directly on the host.
 
 <!-- SUGGESTED SCREENSHOT: MAIN CONFIG OR CONFIG EDITOR PAGE IN THE BROWSER -->
@@ -163,7 +165,7 @@ COPY entrypoint.sh /entrypoint.sh
 ENTRYPOINT ["/entrypoint.sh"]
 ```
 
-Set `Dnsmasq__MainConfigPath`, `Dnsmasq__ReloadCommand`, and other options via environment variables or an `appsettings.json` in `/app`. Mount your config dir and expose 8080.
+Set `Dnsmasq__MainConfigPath`, `Dnsmasq__ReloadCommand`, and other options via environment variables or an `appsettings.json` in `/app`. Mount your config dir and expose 8080. The image includes a **HEALTHCHECK** that calls `GET /healthz/ready`; orchestration (e.g. Kubernetes readiness probe, or Compose `depends_on: condition: service_healthy`) can use the same endpoint.
 
 **Config summary for containers:**
 
@@ -173,8 +175,11 @@ Set `Dnsmasq__MainConfigPath`, `Dnsmasq__ReloadCommand`, and other options via e
 | `Dnsmasq__MainConfigPath` | `/data/dnsmasq.conf` | Main dnsmasq config path (required) |
 | `Dnsmasq__ReloadCommand` | `pkill -HUP -x dnsmasq` | Run after config changes |
 | `Dnsmasq__StatusShowCommand` | `/app/dnsmasq-status.sh` | Optional status output (e.g. our script in test harness) |
+| `Dnsmasq__MinimumVersion` | `2.91` | Minimum dnsmasq version (optional; default 2.91). Set `Dnsmasq__EnforceMinimumVersion=false` to allow older versions. |
 | `ASPNETCORE_URLS` | `http://+:8080` | Port the app listens on |
 
+**Readiness:** `GET http://localhost:8080/healthz/ready` returns JSON `{"status":"ok"}` when dnsmasq version meets the minimum and (if `StatusCommand` is set) dnsmasq is running. Use this for Kubernetes readiness probes, Docker HEALTHCHECK, or load balancer health checks.
+
 See [Configuration](#configuration) for all options.
 
 <!-- SUGGESTED SCREENSHOT: EXAMPLE DOCKERFILE SNIPPET OR DOCKER RUN COMMAND SHOWING DNSMASQ + APP IN ONE CONTAINER -->
@@ -205,6 +210,9 @@ The app is configured via **appsettings.json**, **environment variables**, and *
 | `StatusCommand` | Optional: check if dnsmasq is running | `pgrep -x dnsmasq` |
 | `StatusShowCommand` | Optional: full status output (e.g. systemctl status) | `systemctl status dnsmasq --no-pager` |
 | `LogsCommand` | Optional: recent logs (e.g. journalctl) | `journalctl -u dnsmasq -n 100 --no-pager` |
+| `VersionCommand` | Command to probe dnsmasq version (used for minimum-version check and UI display) | `dnsmasq --version` |
+| `MinimumVersion` | Minimum dnsmasq version required (e.g. 2.91). Some options need newer dnsmasq. | `2.91` |
+| `EnforceMinimumVersion` | If true, app fails to start when version probe fails or version is below minimum. If false, only save and readiness checks enforce. | `true` |
 
 **Application options** (use `Application__` prefix for env, `Application` section in JSON):
 
@@ -391,7 +399,7 @@ sudo ./scripts/install.sh --uninstall --purge --system
 
 ### scripts/prepare-test-mount.sh
 
-**Purpose:** Prepare the testdata mount and optionally start or stop the Docker test harness (app + dnsmasq + DHCP clients). Syncs a source dir (default: `testdata`) into a mount dir (default: `testdata-mount`), cleans up previous test data, then runs `docker compose -f docker-compose.test.yml up -d` (or only prepares the mount with `--prepare-only`).
+**Purpose:** Prepare the testdata mount and optionally start or stop the Docker test harness (app + dnsmasq + DHCP clients). Syncs a source dir (default: `testdata`) into a mount dir (default: `testdata-mount`), then runs `docker compose -f docker-compose.test.yml up -d` (or only prepares the mount with `--prepare-only`). Fixture sync skips `leases` and app-managed filenames (`zz-dnsmasq-webui.conf`, `zz-dnsmasq-webui.hosts`) so rebuilds keep DHCP state and UI-written files unless you pass `--clear` or `--reset-managed`. By default the script resolves and uses the **latest stable upstream dnsmasq version** when building images; you can pin a specific version (or use the distro package) for compatibility testing.
 
 **Usage:** `./scripts/prepare-test-mount.sh [OPTIONS] [--]`
 
@@ -401,9 +409,12 @@ sudo ./scripts/install.sh --uninstall --purge --system
 |--------|-------------|
 | `--source DIR` | Source to copy from (default: `testdata`). |
 | `--mount DIR` | Target mount directory (default: `testdata-mount`). Compose uses `TESTDATA_MOUNT`; script exports it when you use `--mount`. |
-| `--no-clear` | Do not clear mount dir; only sync over existing contents (e.g. preserve leases between runs). |
+| `--dnsmasq-version V` | Dnsmasq version for the harness image: `latest` (default), `distro`, or an exact upstream version like `2.91`. |
+| `--clear` | Clear the mount dir completely before sync for a clean run. Default: preserve existing contents and sync over them. |
+| `--reset-managed` | After sync, remove `*dnsmasq-webui*.conf` and `*dnsmasq-webui*.hosts` under the mount so the app recreates them; leaves leases and other files. |
 | `--prepare-only` | Only prepare the mount; do not run docker compose. |
 | `--build` | Pass `--build` to docker compose (rebuild images). Default: use existing images. |
+| `--no-cache-build` | Run `docker compose build --pull --no-cache` before start. Use to force a fresh image build and refresh the resolved latest dnsmasq version. |
 | `--no-build` | Do not rebuild (default). |
 | `--recreate` | Pass `--force-recreate` to docker compose. |
 | `--stop` | Stop the harness: `docker compose down` (no prepare, no start). |
@@ -413,18 +424,28 @@ sudo ./scripts/install.sh --uninstall --purge --system
 **Examples:**
 
 ```bash
-# Full run: clear mount, sync testdata, start containers (no rebuild)
+# Default: preserve mount (fixtures sync over; managed conf/hosts and leases kept), start (no image rebuild)
 ./scripts/prepare-test-mount.sh
 
-# Rebuild images then start
+# Rebuild images then start (mount state preserved unless you pass --clear or --reset-managed)
 ./scripts/prepare-test-mount.sh --build
 
+# Force a fresh image build with no Docker build cache
+./scripts/prepare-test-mount.sh --no-cache-build
+
+# Rebuild with a specific dnsmasq version
+./scripts/prepare-test-mount.sh --dnsmasq-version 2.91 --build
+
+# Use the distro package instead of an upstream build
+./scripts/prepare-test-mount.sh --dnsmasq-version distro --build
+
 # Only prepare the mount; start manually later
 ./scripts/prepare-test-mount.sh --prepare-only
-# Then: TESTDATA_MOUNT=./testdata-mount docker compose -f docker-compose.test.yml up -d
+# Then use the version printed by the script, e.g.:
+# TESTDATA_MOUNT=./testdata-mount DNSMASQ_VERSION=<resolved-version> docker compose -f docker-compose.test.yml up -d
 
-# Preserve mount contents, sync over it, start
+# Fresh managed config/hosts after a rebuild (fixtures still synced; leases kept)
-./scripts/prepare-test-mount.sh --no-clear
+./scripts/prepare-test-mount.sh --reset-managed --build
 
 # Stop the harness
 ./scripts/prepare-test-mount.sh --stop
@@ -449,6 +470,21 @@ sudo ./scripts/install.sh --uninstall --purge --system
 
 **Usage:** Set `DNSMASQ_CONF` to the path of the dnsmasq config file inside the container (e.g. `/data/dnsmasq-test.conf`). No CLI arguments.
 
+---
+
+### scripts/extract-option-help.sh
+
+**Purpose:** Fetch the dnsmasq man page HTML and extract per-option help fragments into `src/DnsmasqWebUI/wwwroot/option-help/*.html`. The Effective Config UI loads these when the user clicks an option label (tooltip is from code; full help is from these files). Requires Docker (uses a temporary `python:3-slim` container). When adding new options to the UI, add the option key to the script’s `OPTION_KEYS` list (keep in sync with `EffectiveConfigSections` / `DnsmasqOptionTooltips`), then run this script so help is available for the new option (if it exists in the man page).
+
+**Usage:** `./scripts/extract-option-help.sh [--url URL] [--output-dir DIR]`
+
+| Option | Description |
+|--------|-------------|
+| `--url URL` | Man page URL (default: https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html). |
+| `--output-dir DIR` | Output directory (default: `src/DnsmasqWebUI/wwwroot/option-help`). |
+
+Run from the repo root. Writes one `.html` file per option that appears in the man page OPTIONS section; options in `OPTION_KEYS` but not in the man page are skipped.
+
 <!-- SUGGESTED SCREENSHOT: TERMINAL WITH PREPARE-TEST-MOUNT.SH USAGE OR DOCKER COMPOSE UP OUTPUT -->
 
 ---
@@ -471,10 +507,10 @@ sudo ./scripts/install.sh --uninstall --purge --system
 **Codebase overview:**
 
 - **Entry and config:** `Program.cs` wires the host; configuration (e.g. `Dnsmasq__*`) lives in `Models/Config/` (`DnsmasqOptions`, `ApplicationOptions`, `DnsmasqOptionsValidator`). Options are validated at startup.
-- **Infrastructure:** Under `Infrastructure/`: **Client/** (HTTP API clients and `Abstractions/`), **Services/** and **Services/Abstractions/** (caches, config/hosts/leases services, reload, hosted services), **Parsers/** (dnsmasq config and hosts line parsers), **Helpers/Config/** and **Helpers/Http/** (option keys, encoding, tooltips, JSON options). A **managed** config file and optional managed hosts file are written by the app; the main config must include the managed file (e.g. via a final `conf-file=` line). Caches (`ConfigSetCache`, `HostsCache`) keep in-memory snapshots and refresh on file changes or staleness.
+- **Infrastructure:** Under `Infrastructure/`: **Client/** (HTTP API clients and `Abstractions/`), **Serialization/Parsers/** (Dnsmasq version/compile, DnsmasqConfig conf-line and include parsers, EffectiveConfig syntax helpers), **Services/** (caches, config/hosts/leases services, reload, hosted services; EffectiveConfig has Metadata, Rendering, Editing, Validation, Readonly), **Helpers/Config/** (file encoding for config/hosts), **Helpers/Http/** (HTTP helpers). A **managed** config file and optional managed hosts file are written by the app; the main config must include the managed file (e.g. via a final `conf-file=` line). Caches (`ConfigSetCache`, `HostsCache`) keep in-memory snapshots and refresh on file changes or staleness.
 - **Models:** `Models/Config/` (options, validators, `DnsmasqConfLine`); `Models/Contracts/` (snapshots and DTOs such as `ConfigSetSnapshot`, `HostsSnapshot`, `ManagedConfigContent`, `ProcessRunResult`, `ReloadResult`); `Models/Dnsmasq/` (status, `SaveWithReloadResult`, and `EffectiveConfig/` for effective config and sources); `Models/Client/`, `Models/Dhcp/`, `Models/Hosts/` (UI and API DTOs).
 - **API and UI:** `Controllers/` expose API endpoints; `Components/` contains Blazor Server components for config editor, hosts, DHCP, Dnsmasq status, and app settings. Static assets in `wwwroot/`.
-- **Tests:** `DnsmasqWebUI.Tests` contains unit tests for parsers, config set service, config, and related logic. Run with `dotnet test`.
+- **Tests:** `DnsmasqWebUI.Tests` contains unit tests organised to mirror the main project: `Serialization/Parsers/` (Dnsmasq, DnsmasqConfig), `Services/Dnsmasq/Config/`, `Services/EffectiveConfig/`, `Models/`, and `Helpers/` (TestDataHelper). Run with `dotnet test`.
 
 <!-- SUGGESTED SCREENSHOT: SOLUTION EXPLORER OR FOLDER TREE OF SRC/ -->
 
@@ -499,7 +535,7 @@ Use `appsettings.json` or launch settings to set `Dnsmasq__MainConfigPath` and o
    ```bash
    ./scripts/prepare-test-mount.sh
    ```
-   This clears the mount dir (by default `testdata-mount`), syncs `testdata/` into it, and starts the stack with `docker-compose.test.yml`. Use `--prepare-only` to only prepare the mount, then start compose manually; use `--build` after changing the app or Dockerfile.
+   This syncs `testdata/` into the mount (preserving existing managed config, hosts, and `leases` unless you use `--clear` or `--reset-managed`), then starts the stack with `docker-compose.test.yml`. Use `--prepare-only` to only prepare the mount, then start compose manually; use `--build` after changing the app or Dockerfile.
 
 2. Open the UI (e.g. http://localhost:8080). The app and dnsmasq use the mounted config; you can edit config/hosts in the UI and trigger reload.
 

agents.md

@@ -17,17 +17,21 @@ From the repo root:
 
 This will:
 
-1. Clear `testdata-mount/` (unless you pass `--no-clear`)
+1. Run `docker compose down`, then sync `testdata/` → `testdata-mount/` (preserving mount contents unless you pass `--clear`). Sync skips `leases` and `zz-dnsmasq-webui.conf` / `zz-dnsmasq-webui.hosts` so rebuilds keep DHCP leases and UI-written managed files.
-2. Sync `testdata/` → `testdata-mount/`
+2. Optionally remove managed `*dnsmasq-webui*.conf` / `*dnsmasq-webui*.hosts` in the mount **only** if you pass `--reset-managed`.
-3. Remove any `*dnsmasq-webui*.conf` in the mount so dnsmasq starts clean
+3. Resolve the requested dnsmasq version (`latest` by default) to a concrete value when building images.
-4. Run `docker compose -f docker-compose.test.yml up -d --build`
+4. Run `docker compose -f docker-compose.test.yml up -d` (add `--build` / `--no-cache-build` when you need a rebuild).
 
 - **Quick restart (no image rebuild):** `./scripts/prepare-test-mount.sh --no-build`
+- **Force a fresh image build:** `./scripts/prepare-test-mount.sh --no-cache-build`
+- **Pin dnsmasq version:** `./scripts/prepare-test-mount.sh --dnsmasq-version 2.91 --build`
+- **Use distro package:** `./scripts/prepare-test-mount.sh --dnsmasq-version distro --build`
 - **Prepare mount only (no start):** `./scripts/prepare-test-mount.sh --prepare-only`  
-  Then start manually: `TESTDATA_MOUNT=./testdata-mount docker compose -f docker-compose.test.yml up -d [--build]`
+  Then start manually with the version printed by the script: `TESTDATA_MOUNT=./testdata-mount DNSMASQ_VERSION=<resolved-version> docker compose -f docker-compose.test.yml up -d [--build]`
-- **Preserve mount (e.g. keep leases):** `./scripts/prepare-test-mount.sh --no-clear --no-build`
+- **Preserve mount (e.g. keep leases and managed config):** default; also use `./scripts/prepare-test-mount.sh --no-build` for a quick up without rebuilding images.
+- **Drop managed conf/hosts only (keep leases):** `./scripts/prepare-test-mount.sh --reset-managed` (often combined with `--build`).
 
-App is at **http://localhost:8080**. Main config path in the container is `/data/dnsmasq-test.conf`; managed file is `zz-dnsmasq-webui.conf` in the same directory.
+App is at **http://localhost:8080**. Main config path in the container is `/data/dnsmasq-test.conf`; managed file is `zz-dnsmasq-webui.conf` in the same directory. The app service has a healthcheck (`GET /healthz/ready`); DHCP client services use `depends_on: app: condition: service_healthy` so they start only after the app (and dnsmasq) is ready.
 
 ### Stop the harness
 
@@ -49,6 +53,9 @@ Stops the harness and deletes the contents of `testdata-mount/` so the next run
 
 - `--source DIR` — Source to sync from (default: `testdata`)
 - `--mount DIR` — Mount directory (default: `testdata-mount`). The script exports `TESTDATA_MOUNT=./DIR` when you use `--mount`, so compose uses it.
+- `--dnsmasq-version V` — Dnsmasq version for the harness image: `latest` (default), `distro`, or an exact upstream version like `2.91`.
+- `--reset-managed` — After sync, delete `*dnsmasq-webui*.conf` and `*dnsmasq-webui*.hosts` under the mount so the app recreates them.
+- `--no-cache-build` — Force a fresh image build with `docker compose build --pull --no-cache` before start.
 
 Example: sync from a custom dir and start:
 
@@ -76,5 +83,12 @@ Build only: `dotnet build`
 
 - **testdata/** — Source for the harness mount. Synced to `testdata-mount/` by `prepare-test-mount.sh`. Unit tests read from the copy in the test output dir. See **testdata/README** for the full layout.
 - **testdata/dnsmasq-test.conf** — Harness main config (`/data/dnsmasq-test.conf`). Richer config: multiple `server=`, `addn-hosts=`, `address=`, `listen-address=`, `conf-dir=/data/dnsmasq.d`.
-- **testdata/dnsmasq.d/** — Included configs (01-other.conf, 02-servers.conf, dhcp.conf). App creates `zz-dnsmasq-webui.conf` here when running.
+- **testdata/dnsmasq.d/** — Included configs (01-other.conf, 02-servers.conf, 03-more.conf, dhcp.conf). App creates `zz-dnsmasq-webui.conf` here when running.
 - **testdata/hosts**, **testdata/hosts.extra** — Addn-hosts files so effective config has multiple addn-hosts; UI can show source per path.
+
+## When adding new effective-config options
+
+When adding a new dnsmasq option to the Effective Config UI (new key in `DnsmasqConfKeys`, section, kind map, parser/write behavior, tooltip, etc.):
+
+1. **Option help:** Add the option key (lowercase, e.g. `no-round-robin`) to the `OPTION_KEYS` list in `scripts/extract-option-help.sh` (keep in sync with `EffectiveConfigSections`). Then run `./scripts/extract-option-help.sh` so `wwwroot/option-help/<key>.html` is generated if the option exists in the dnsmasq man page.
+2. **Testdata (optional):** To show the option in the UI when using the harness or testdata, add a line to e.g. `testdata/dnsmasq.d/03-more.conf` and update `testdata/README` if needed.

docker-compose.test.yml

@@ -1,7 +1,8 @@
 # Run the app with real dnsmasq and several DHCP clients so hosts/leases are real.
 # Some clients also make periodic DNS requests so the DNS cache and logs show activity.
-# Prepare mount: ./scripts/prepare-test-mount.sh [--prepare-only | --no-build | --recreate | --source DIR | --mount DIR]
+# Prepare mount: ./scripts/prepare-test-mount.sh [--clear | --reset-managed | --minimal-conf | --prepare-only | ...]
 # Or set TESTDATA_MOUNT to override the data volume (default: ./testdata-mount).
+# Set TEST_DNSMASQ_CONF to override main config path (default: /data/dnsmasq-test.conf; use /data/dnsmasq-test-minimal.conf for minimal).
 #
 # No systemd in container (dnsmasq runs as a process from entrypoint, like most dnsmasq images).
 # StatusShowCommand/LogsCommand use ps so the Service status / Recent logs sections show something
@@ -13,14 +14,24 @@ services:
   app:
     build:
       context: .
+      args:
+        DNSMASQ_VERSION: ${DNSMASQ_VERSION:-latest}
     ports:
       - "8080:8080"
+    healthcheck:
+      test: ["CMD", "curl", "-f", "-s", "http://localhost:8080/healthz/ready"]
+      interval: 30s
+      timeout: 5s
+      start_period: 5s
+      retries: 3
     cap_add:
       - NET_ADMIN
     environment:
-      DNSMASQ_CONF: /data/dnsmasq-test.conf
+      DNSMASQ_CONF: ${TEST_DNSMASQ_CONF:-/data/dnsmasq-test.conf}
-      Dnsmasq__MainConfigPath: /data/dnsmasq-test.conf
+      Dnsmasq__MainConfigPath: ${TEST_DNSMASQ_CONF:-/data/dnsmasq-test.conf}
       Dnsmasq__ManagedFileName: zz-dnsmasq-webui.conf
+      # No systemd in container: restart by killing and re-running dnsmasq (same as entrypoint.sh). Config path must match DNSMASQ_CONF/MainConfigPath.
+      Dnsmasq__RestartCommand: "pkill -x dnsmasq || true; sleep 1; dnsmasq --test --conf-file=${TEST_DNSMASQ_CONF:-/data/dnsmasq-test.conf} && dnsmasq --conf-file=${TEST_DNSMASQ_CONF:-/data/dnsmasq-test.conf}"
       Dnsmasq__ReloadCommand: "pkill -HUP -x dnsmasq"
       Dnsmasq__StatusCommand: "pgrep -x dnsmasq"
       # Simulated systemctl status + real logs (dnsmasq logs to /data/dnsmasq.log via log-facility in dnsmasq-test.conf)
@@ -41,7 +52,8 @@ services:
     networks:
       testnet: {}
     depends_on:
-      - app
+      app:
+        condition: service_healthy
 
   # DHCP + periodic DNS lookups (every 20s) so DNS cache/logs show activity.
   dhcp-client-dns-a:
@@ -60,7 +72,8 @@ services:
     networks:
       testnet: {}
     depends_on:
-      - app
+      app:
+        condition: service_healthy
 
   # DHCP + periodic DNS lookups (every 45s); different interval for variety.
   dhcp-client-dns-b:
@@ -79,7 +92,8 @@ services:
     networks:
       testnet: {}
     depends_on:
-      - app
+      app:
+        condition: service_healthy
 
   # Third DHCP-only client so the leases table has more entries.
   dhcp-client-2:
@@ -88,7 +102,8 @@ services:
     networks:
       testnet: {}
     depends_on:
-      - app
+      app:
+        condition: service_healthy
 
 networks:
   testnet:

scripts/dnsmasq-status.sh

@@ -1,12 +1,22 @@
 #!/bin/sh
 # Simulates "systemctl status dnsmasq" output when run in a container without systemd.
 # Uses ps/pgrep. Memory is RSS. Uptime line omitted; Active line has break after semicolon with continuation indented.
+# When dnsmasq is not running, runs dnsmasq --test to show config/startup errors (use DNSMASQ_CONF for config path).
 
 pid=$(pgrep -x dnsmasq)
 if [ -z "$pid" ]; then
   echo "● dnsmasq.service - dnsmasq - A lightweight DHCP and caching DNS server"
   echo "     Loaded: (container, no systemd)"
   echo "     Active: inactive (dead)"
+  conf="${DNSMASQ_CONF:-/etc/dnsmasq.conf}"
+  if [ -f "$conf" ]; then
+    err=$(dnsmasq --test --conf-file="$conf" 2>&1)
+    if [ -n "$err" ]; then
+      echo ""
+      echo "     Config test (dnsmasq --test):"
+      echo "$err" | sed 's/^/       /'
+    fi
+  fi
   echo ""
   exit 0
 fi

scripts/extract-option-help.sh

@@ -50,7 +50,7 @@ except ImportError:
 OUT_DIR = "/out"
 URL = os.environ.get("URL", "https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html")
 
-# One per line; keep in sync with DnsmasqOptionTooltips / EffectiveConfigSections. server + local = one UI row.
+# One per line; keep in sync with DnsmasqOptionTooltips / EffectiveConfigSections.
 OPTION_KEYS = [
     "no-hosts",
     "addn-hosts",
@@ -122,6 +122,7 @@ OPTION_KEYS = [
     "dhcp-hostsfile",
     "dhcp-optsfile",
     "dhcp-hostsdir",
+    "dhcp-optsdir",
     "dhcp-boot",
     "dhcp-ignore",
     "dhcp-vendorclass",
@@ -171,6 +172,59 @@ OPTION_KEYS = [
     "keep-in-foreground",
     "no-daemon",
     "conntrack",
+    "connmark-allowlist-enable",
+    "no-round-robin",
+    "dns-forward-max",
+    "connmark-allowlist",
+    "do-0x20-encode",
+    "caa-record",
+    "dns-rr",
+    "synth-domain",
+    "auth-zone",
+    "auth-soa",
+    "auth-sec-servers",
+    "auth-peer",
+    "leasequery",
+    "dhcp-generate-names",
+    "dhcp-broadcast",
+    "dhcp-sequential-ip",
+    "dhcp-ignore-clid",
+    "bootp-dynamic",
+    "no-ping",
+    "script-arp",
+    "script-on-renewal",
+    "dhcp-no-override",
+    "dhcp-alternate-port",
+    "dhcp-duid",
+    "dhcp-luascript",
+    "dhcp-scriptuser",
+    "dhcp-relay",
+    "dhcp-circuitid",
+    "dhcp-remoteid",
+    "dhcp-subscrid",
+    "dhcp-proxy",
+    "tag-if",
+    "bridge-interface",
+    "shared-network",
+    "dhcp-pxe-vendor",
+    "dhcp-option-pxe",
+    "dnssec-no-timecheck",
+    "dnssec-debug",
+    "add-cpe-id",
+    "dnssec-timestamp",
+    "dnssec-limits",
+    "dumpfile",
+    "dumpmask",
+    "use-stale-cache",
+    "add-mac",
+    "strip-mac",
+    "add-subnet",
+    "strip-subnet",
+    "umbrella",
+    "quiet-dhcp",
+    "quiet-dhcp6",
+    "quiet-ra",
+    "quiet-tftp",
 ]
 
 long_opt_re = re.compile(r"--([a-z][a-z0-9-]*)(?:=[^,\s]*)?", re.IGNORECASE)

scripts/prepare-test-mount.sh

@@ -3,8 +3,8 @@
 # (app + dnsmasq + DHCP client). See testdata/README.md and docker-compose.test.yml.
 #
 # What this script does:
-#   Start (default): sync source -> mount (preserving existing unless --clear), clean up previous test data,
+#   Start (default): sync source -> mount (preserving existing unless --clear); optional --reset-managed
-#     then docker compose up -d [--build] [--force-recreate].
+#     removes app-written files in the mount. Then docker compose up -d [--build] [--force-recreate].
 #   --stop: docker compose down (stop and remove containers/networks).
 #   --tidy: docker compose down, then clear the mount directory for a clean next run.
 set -e
@@ -15,12 +15,16 @@ COMPOSE_FILE="docker-compose.test.yml"
 
 SOURCE_DIR=""
 MOUNT_DIR=""
+DNSMASQ_VERSION=""
 PREPARE_ONLY=false
 BUILD=false
+NO_CACHE_BUILD=false
 RECREATE=false
 CLEAR=false
+RESET_MANAGED=false
 STOP=false
 TIDY=false
+MINIMAL_CONF=false
 
 usage() {
   echo "Usage: $0 [OPTIONS] [--]"
@@ -30,24 +34,35 @@ usage() {
   echo ""
   echo "Steps (when starting):"
   echo "  1. Optionally clear mount dir (only with --clear), then sync source -> mount."
-  echo "  2. Clean up previous test data (e.g. managed config) so the harness starts clean."
+  echo "      Sync skips app-managed filenames (zz-dnsmasq-webui.conf / .hosts) so rebuilds keep UI state."
+  echo "  2. Optionally remove managed *dnsmasq-webui*.conf / *dnsmasq-webui*.hosts (only with --reset-managed)."
   echo "  3. If not --prepare-only: docker compose -f $COMPOSE_FILE up -d [options]."
   echo ""
   echo "Path options:"
   echo "  --source DIR        Source to copy from (default: testdata)"
   echo "  --mount DIR         Target mount directory (default: testdata-mount)"
   echo "                      Compose uses TESTDATA_MOUNT; script exports it if you use --mount."
+  echo "  --dnsmasq-version V Dnsmasq version for the harness image:"
+  echo "                      latest (default), distro, or an exact upstream version like 2.91."
+  echo "                      Non-default values require --build or --no-cache-build; script fails with --no-build."
   echo ""
   echo "Mount behaviour:"
   echo "  (default)           Preserve mount dir; sync source over existing contents."
   echo "  --clear             Clear mount dir completely before sync. Use for a clean run."
+  echo "  --reset-managed     After sync, delete *dnsmasq-webui*.conf and *dnsmasq-webui*.hosts under the"
+  echo "                      mount so the app recreates managed config/hosts (leases and other files stay)."
   echo ""
   echo "Compose behaviour:"
+  echo "  --minimal-conf     Use minimal dnsmasq config (dnsmasq-test-minimal.conf) so effective"
+  echo "                      config has few readonly options; good for testing reload/restart failure flows."
   echo "  --prepare-only      Only prepare the mount; do not run docker compose."
   echo "                      Use to inspect or edit the mount before starting containers."
   echo "  --build             Pass --build to docker compose (rebuild images before starting)."
   echo "                      Use after changing the app or Dockerfile. Default: use existing images."
+  echo "  --no-cache-build    Rebuild images with --pull --no-cache before starting."
+  echo "                      Use to force a fresh image build and refresh 'latest' dnsmasq."
   echo "  --no-build          Do not rebuild (default). Use existing images for a quick restart."
+  echo "                      With --no-build, 'latest' is not resolved (no network)."
   echo "  --recreate          Pass --force-recreate to docker compose (recreate containers)."
   echo "                      Use to ensure fresh container state and mounts."
   echo ""
@@ -69,9 +84,15 @@ usage() {
   echo "  $0 --recreate"
   echo "                      Sync, then up -d --force-recreate (fresh containers)."
   echo ""
+  echo "  $0 --no-cache-build"
+  echo "                      Force a fresh image build (no Docker build cache), then start containers."
+  echo ""
   echo "  $0 --clear"
   echo "                      Clear mount, sync testdata, start (clean run, no rebuild)."
   echo ""
+  echo "  $0 --reset-managed --build"
+  echo "                      Rebuild images; sync fixtures; drop managed conf/hosts so app writes fresh."
+  echo ""
   echo "  $0 --prepare-only"
   echo "                      Only sync testdata -> testdata-mount; no containers."
   echo "                      Then run: docker compose -f $COMPOSE_FILE up -d [--build]"
@@ -85,6 +106,38 @@ usage() {
   echo ""
   echo "  $0 --tidy"
   echo "                      Stop harness and clear testdata-mount for a clean next run."
+  echo ""
+  echo "  $0 --minimal-conf"
+  echo "                      Use dnsmasq-test-minimal.conf (single file, few options) and start."
+  echo ""
+  echo "  $0 --dnsmasq-version 2.91 --build"
+  echo "                      Rebuild the harness image with dnsmasq 2.91."
+}
+
+fetch_url() {
+  if command -v curl >/dev/null 2>&1; then
+    curl -fsSL "$1"
+    return $?
+  fi
+  if command -v wget >/dev/null 2>&1; then
+    wget -qO- "$1"
+    return $?
+  fi
+  echo "Error: need curl or wget to resolve the latest upstream dnsmasq version." >&2
+  return 1
+}
+
+resolve_dnsmasq_version() {
+  if [ "$DNSMASQ_VERSION" != "latest" ]; then
+    return 0
+  fi
+
+  RESOLVED_VERSION="$(fetch_url "https://thekelleys.org.uk/dnsmasq/" | sed -n 's/.*LATEST_IS_\([0-9][0-9.]*\).*/\1/p' | head -n1)"
+  if [ -z "$RESOLVED_VERSION" ]; then
+    echo "Error: could not resolve the latest upstream dnsmasq version." >&2
+    exit 1
+  fi
+  DNSMASQ_VERSION="$RESOLVED_VERSION"
 }
 
 while [ $# -gt 0 ]; do
@@ -105,10 +158,20 @@ while [ $# -gt 0 ]; do
       MOUNT_DIR="$1"
       shift
       ;;
+    --dnsmasq-version)
+      shift
+      [ $# -gt 0 ] || { echo "Error: --dnsmasq-version requires VERSION" >&2; exit 1; }
+      DNSMASQ_VERSION="$1"
+      shift
+      ;;
     --clear)
       CLEAR=true
       shift
       ;;
+    --reset-managed)
+      RESET_MANAGED=true
+      shift
+      ;;
     --prepare-only)
       PREPARE_ONLY=true
       shift
@@ -117,14 +180,24 @@ while [ $# -gt 0 ]; do
       BUILD=true
       shift
       ;;
+    --no-cache-build)
+      NO_CACHE_BUILD=true
+      BUILD=true
+      shift
+      ;;
     --no-build)
       BUILD=false
+      NO_CACHE_BUILD=false
       shift
       ;;
     --recreate)
       RECREATE=true
       shift
       ;;
+    --minimal-conf)
+      MINIMAL_CONF=true
+      shift
+      ;;
     --stop)
       STOP=true
       shift
@@ -160,6 +233,7 @@ cd "$REPO_ROOT"
 
 : "${SOURCE_DIR:=testdata}"
 : "${MOUNT_DIR:=testdata-mount}"
+: "${DNSMASQ_VERSION:=latest}"
 
 # Stop and/or tidy: no prepare, no start
 if [ "$STOP" = true ] || [ "$TIDY" = true ]; then
@@ -182,6 +256,17 @@ if [ ! -d "$SOURCE_DIR" ]; then
   exit 1
 fi
 
+# Resolve "latest" only when we will build; avoid network when doing a no-build run.
+WILL_BUILD=false
+[ "$BUILD" = true ] || [ "$NO_CACHE_BUILD" = true ] && WILL_BUILD=true
+if [ "$WILL_BUILD" = false ] && [ "$DNSMASQ_VERSION" != "latest" ] && [ "$DNSMASQ_VERSION" != "distro" ]; then
+  echo "Error: --dnsmasq-version $DNSMASQ_VERSION has no effect without --build or --no-cache-build. Add --build or omit --dnsmasq-version for a no-build run." >&2
+  exit 1
+fi
+if [ "$WILL_BUILD" = true ]; then
+  resolve_dnsmasq_version
+fi
+
 # Take the harness down so all containers (including one-shot DHCP clients) are recreated on up.
 echo "Stopping test harness: docker compose -f $COMPOSE_FILE down"
 docker compose -f "$COMPOSE_FILE" down
@@ -193,15 +278,22 @@ if [ "$CLEAR" = true ]; then
   find "$MOUNT_DIR" -mindepth 1 -delete 2>/dev/null || true
 fi
 
+# Exclude sample leases (harness creates real lease file) and app-managed filenames so rebuilds preserve
+# UI-written config/hosts; use --reset-managed or --clear when you want those removed.
 if command -v rsync >/dev/null 2>&1; then
-  rsync -a --exclude='leases' "$SOURCE_DIR/" "$MOUNT_DIR/"
+  rsync -a \
+    --exclude='leases' \
+    --exclude='zz-dnsmasq-webui.conf' \
+    --exclude='zz-dnsmasq-webui.hosts' \
+    "$SOURCE_DIR/" "$MOUNT_DIR/"
 else
-  cp -r "$SOURCE_DIR/." "$MOUNT_DIR/"
+  (cd "$SOURCE_DIR" && tar cf - --exclude=leases --exclude=zz-dnsmasq-webui.conf --exclude=zz-dnsmasq-webui.hosts .) | (cd "$MOUNT_DIR" && tar xf -)
-  rm -f "$MOUNT_DIR/leases"
 fi
 
-# Clean up previous test data (e.g. managed config) so the harness starts clean (app will create zz-dnsmasq-webui.conf on startup).
+if [ "$RESET_MANAGED" = true ]; then
-find "$MOUNT_DIR" -name '*dnsmasq-webui*.conf' -type f -delete 2>/dev/null || true
+  echo "Removing app-managed files (*dnsmasq-webui*.conf / *dnsmasq-webui*.hosts) under $MOUNT_DIR"
+  find "$MOUNT_DIR" \( -name '*dnsmasq-webui*.conf' -o -name '*dnsmasq-webui*.hosts' \) -type f -delete 2>/dev/null || true
+fi
 
 echo "Mount directory ready: $MOUNT_DIR (source: $SOURCE_DIR)."
 
@@ -210,7 +302,16 @@ if [ "$PREPARE_ONLY" = true ]; then
     /*) MOUNT_EXPORT="$MOUNT_DIR" ;;
     *)  MOUNT_EXPORT="./$MOUNT_DIR" ;;
   esac
-  echo "To start the harness: TESTDATA_MOUNT=$MOUNT_EXPORT docker compose -f $COMPOSE_FILE up -d [--build]"
+  START_PREFIX="TESTDATA_MOUNT=$MOUNT_EXPORT DNSMASQ_VERSION=$DNSMASQ_VERSION"
+  if [ "$MINIMAL_CONF" = true ]; then
+    START_PREFIX="$START_PREFIX TEST_DNSMASQ_CONF=/data/dnsmasq-test-minimal.conf"
+  fi
+  if [ "$NO_CACHE_BUILD" = true ]; then
+    START_CMD="$START_PREFIX docker compose -f $COMPOSE_FILE build --pull --no-cache && $START_PREFIX docker compose -f $COMPOSE_FILE up -d"
+  else
+    START_CMD="$START_PREFIX docker compose -f $COMPOSE_FILE up -d [--build]"
+  fi
+  echo "To start the harness: $START_CMD"
   exit 0
 fi
 
@@ -220,8 +321,30 @@ case "$MOUNT_DIR" in
   *)  export TESTDATA_MOUNT="./$MOUNT_DIR" ;;
 esac
 
+export DNSMASQ_VERSION
+
+case "$DNSMASQ_VERSION" in
+  distro)
+    echo "Using distro-packaged dnsmasq for the harness image."
+    ;;
+  *)
+    echo "Using dnsmasq $DNSMASQ_VERSION for the harness image."
+    ;;
+esac
+
+if [ "$MINIMAL_CONF" = true ]; then
+  export TEST_DNSMASQ_CONF="/data/dnsmasq-test-minimal.conf"
+  echo "Using minimal config: $TEST_DNSMASQ_CONF"
+fi
+
+if [ "$NO_CACHE_BUILD" = true ]; then
+  BUILD_CMD="docker compose -f $COMPOSE_FILE build --pull --no-cache"
+  echo "Running: $BUILD_CMD"
+  $BUILD_CMD
+fi
+
 COMPOSE_CMD="docker compose -f $COMPOSE_FILE up -d"
-if [ "$BUILD" = true ]; then
+if [ "$BUILD" = true ] && [ "$NO_CACHE_BUILD" != true ]; then
   COMPOSE_CMD="$COMPOSE_CMD --build"
 fi
 if [ "$RECREATE" = true ]; then

src/DnsmasqWebUI.Tests/ConfigValueSourceTests.cs

@@ -1,59 +0,0 @@
-using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
-
-namespace DnsmasqWebUI.Tests;
-
-/// <summary>
-/// Tests for <see cref="ConfigValueSource"/> and <see cref="ConfigValueSource.GetReadOnlyTooltip"/>.
-/// </summary>
-public class ConfigValueSourceTests
-{
-    [Fact]
-    public void GetReadOnlyTooltip_WhenManaged_ReturnsNull()
-    {
-        var source = new ConfigValueSource("/data/zz-managed.conf", "zz-managed.conf", IsManaged: true, LineNumber: 5);
-        Assert.Null(source.GetReadOnlyTooltip());
-    }
-
-    [Fact]
-    public void GetReadOnlyTooltip_WhenReadOnlyWithoutLineNumber_ReturnsFileNameOnly()
-    {
-        var fileName = "02.conf";
-        var fullPath = $"/etc/dnsmasq.d/{fileName}";
-        var source = new ConfigValueSource(fullPath, fileName, IsManaged: false, LineNumber: null);
-        var tooltip = source.GetReadOnlyTooltip();
-        Assert.NotNull(tooltip);
-        Assert.Contains(fileName, tooltip);
-        Assert.Contains("readonly", tooltip);
-        Assert.Contains(fullPath, tooltip);
-        Assert.DoesNotContain("line", tooltip);
-    }
-
-    [Fact]
-    public void GetReadOnlyTooltip_WhenReadOnlyWithLineNumber_IncludesLineNumber()
-    {
-        var fileName = "02.conf";
-        var fullPath = $"/etc/dnsmasq.d/{fileName}";
-        int? lineNumber = 3;
-        var source = new ConfigValueSource(fullPath, fileName, IsManaged: false, LineNumber: lineNumber);
-        var tooltip = source.GetReadOnlyTooltip();
-        Assert.NotNull(tooltip);
-        Assert.Contains(fileName, tooltip);
-        Assert.Contains($"line {lineNumber}", tooltip);
-        Assert.Contains("readonly", tooltip);
-        Assert.Contains(fullPath, tooltip);
-    }
-
-    [Fact]
-    public void IsReadOnly_WhenManaged_IsFalse()
-    {
-        var source = new ConfigValueSource("/data/zz.conf", "zz.conf", IsManaged: true);
-        Assert.False(source.IsReadOnly);
-    }
-
-    [Fact]
-    public void IsReadOnly_WhenNotManaged_IsTrue()
-    {
-        var source = new ConfigValueSource("/etc/dnsmasq.conf", "dnsmasq.conf", IsManaged: false);
-        Assert.True(source.IsReadOnly);
-    }
-}

src/DnsmasqWebUI.Tests/Helpers/OptionCoverageData.cs

@@ -0,0 +1,100 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+
+namespace DnsmasqWebUI.Tests.Helpers;
+
+/// <summary>
+/// Sample config line per option for consistent parser coverage. When adding new options to the app,
+/// add an entry here so the option-coverage test continues to exercise every option.
+/// </summary>
+public static class OptionCoverageData
+{
+    /// <summary>Option key and a minimal valid config line (without newline).</summary>
+    public static IReadOnlyList<(string OptionKey, string ConfigLine)> GetParserCoverageEntries()
+    {
+        return new (string, string)[]
+        {
+            // LastWins
+            (DnsmasqConfKeys.Port, "port=53"),
+            (DnsmasqConfKeys.CacheSize, "cache-size=500"),
+            (DnsmasqConfKeys.LocalTtl, "local-ttl=300"),
+            (DnsmasqConfKeys.MxTarget, "mx-target=mail.example.com"),
+            (DnsmasqConfKeys.DhcpLeasefile, "dhcp-leasefile=/var/lib/dnsmasq.leases"),
+            (DnsmasqConfKeys.DhcpLeaseMax, "dhcp-lease-max=1000"),
+            (DnsmasqConfKeys.Hostsdir, "hostsdir=/etc/dnsmasq.d"),
+            (DnsmasqConfKeys.PidFile, "pid-file=/run/dnsmasq.pid"),
+            (DnsmasqConfKeys.User, "user=nobody"),
+            (DnsmasqConfKeys.TftpRoot, "tftp-root=/var/lib/tftpboot"),
+            // Flag
+            (DnsmasqConfKeys.NoHosts, "no-hosts"),
+            (DnsmasqConfKeys.ExpandHosts, "expand-hosts"),
+            (DnsmasqConfKeys.BogusPriv, "bogus-priv"),
+            (DnsmasqConfKeys.NoResolv, "no-resolv"),
+            (DnsmasqConfKeys.DomainNeeded, "domain-needed"),
+            (DnsmasqConfKeys.StrictOrder, "strict-order"),
+            (DnsmasqConfKeys.AllServers, "all-servers"),
+            (DnsmasqConfKeys.BindInterfaces, "bind-interfaces"),
+            (DnsmasqConfKeys.DhcpAuthoritative, "dhcp-authoritative"),
+            (DnsmasqConfKeys.EnableTftp, "enable-tftp"),
+            (DnsmasqConfKeys.Dnssec, "dnssec"),
+            (DnsmasqConfKeys.Conntrack, "conntrack"),
+            (DnsmasqConfKeys.Do0x20Encode, "do-0x20-encode"),
+            (DnsmasqConfKeys.No0x20Encode, "no-0x20-encode"),
+            // Multi - resolver / DNS
+            (DnsmasqConfKeys.Server, "server=1.1.1.1"),
+            (DnsmasqConfKeys.Local, "local=/lan/"),
+            (DnsmasqConfKeys.RevServer, "rev-server=192.168.1.0/24,10.0.0.1"),
+            (DnsmasqConfKeys.Address, "address=/example.com/127.0.0.1"),
+            (DnsmasqConfKeys.Domain, "domain=home.lan,192.168.1.0/24"),
+            (DnsmasqConfKeys.Cname, "cname=www.example.com,example.com"),
+            (DnsmasqConfKeys.MxHost, "mx-host=example.com,mail.example.com,10"),
+            (DnsmasqConfKeys.Srv, "srv-host=_http._tcp.example.com,host.example.com,80"),
+            (DnsmasqConfKeys.PtrRecord, "ptr-record=1.168.192.in-addr.arpa,router.lan"),
+            (DnsmasqConfKeys.TxtRecord, "txt-record=example.com,text"),
+            (DnsmasqConfKeys.NaptrRecord, "naptr-record=example.com,0,0,a,s,r"),
+            (DnsmasqConfKeys.DnsRr, "dns-rr=example.com,16,01:02"),
+            (DnsmasqConfKeys.HostRecord, "host-record=host.example.com,1.2.3.4"),
+            (DnsmasqConfKeys.DynamicHost, "dynamic-host=example.com"),
+            (DnsmasqConfKeys.CaaRecord, "caa-record=example.com,0,issue,letsencrypt.org"),
+            (DnsmasqConfKeys.RebindDomainOk, "rebind-domain-ok=example.com"),
+            (DnsmasqConfKeys.BogusNxdomain, "bogus-nxdomain=192.168.1.1"),
+            (DnsmasqConfKeys.IgnoreAddress, "ignore-address=192.168.1.1"),
+            (DnsmasqConfKeys.Alias, "alias=0.0.0.0,example.com"),
+            (DnsmasqConfKeys.FilterRr, "filter-rr=0.0.0.0,A"),
+            (DnsmasqConfKeys.CacheRr, "cache-rr=0.0.0.0,A"),
+            (DnsmasqConfKeys.Ipset, "ipset=/example.com/set1"),
+            (DnsmasqConfKeys.Nftset, "nftset=/example.com/table/set"),
+            (DnsmasqConfKeys.ConnmarkAllowlist, "connmark-allowlist=0xff,example.com"),
+            // Multi - auth / synth
+            (DnsmasqConfKeys.AuthServer, "auth-server=zone.example.com,eth0"),
+            (DnsmasqConfKeys.SynthDomain, "synth-domain=dynamic.example.com,192.168.2.1,192.168.2.100"),
+            (DnsmasqConfKeys.AuthZone, "auth-zone=example.com"),
+            (DnsmasqConfKeys.TrustAnchor, "trust-anchor=.,20326,8,2,E4F1769B8A0E3142E125223716F878F0A3B2C3D4"),
+            // Multi - DHCP
+            (DnsmasqConfKeys.DhcpRange, "dhcp-range=192.168.1.50,192.168.1.150,12h"),
+            (DnsmasqConfKeys.DhcpHost, "dhcp-host=aa:bb:cc:dd:ee:ff,192.168.1.10"),
+            (DnsmasqConfKeys.DhcpOption, "dhcp-option=3,192.168.1.1"),
+            (DnsmasqConfKeys.DhcpMatch, "dhcp-match=set:efi,option:client-arch,6"),
+            (DnsmasqConfKeys.DhcpMac, "dhcp-mac=set:vendor,aa:bb:cc:dd:ee:ff"),
+            (DnsmasqConfKeys.DhcpNameMatch, "dhcp-name-match=set:name,hostname*"),
+            (DnsmasqConfKeys.DhcpIgnoreNames, "dhcp-ignore-names=tag:guest"),
+            (DnsmasqConfKeys.DhcpBoot, "dhcp-boot=pxelinux.0"),
+            (DnsmasqConfKeys.Leasequery, "leasequery=10.0.0.0/24"),
+            (DnsmasqConfKeys.RaParam, "ra-param=eth0,high"),
+            (DnsmasqConfKeys.Slaac, "slaac=eth0"),
+            (DnsmasqConfKeys.PxeService, "pxe-service=x86PC,Install Linux"),
+            (DnsmasqConfKeys.DhcpRelay, "dhcp-relay=192.168.1.1,eth0"),
+            (DnsmasqConfKeys.DhcpCircuitid, "dhcp-circuitid=eth0,010203"),
+            (DnsmasqConfKeys.DhcpRemoteid, "dhcp-remoteid=010203"),
+            (DnsmasqConfKeys.DhcpSubscrid, "dhcp-subscrid=010203"),
+            (DnsmasqConfKeys.TagIf, "tag-if=set:tag,eth0"),
+            (DnsmasqConfKeys.SharedNetwork, "shared-network=name,192.168.1.0/24"),
+            (DnsmasqConfKeys.DhcpOptionPxe, "dhcp-option-pxe=set:known,1"),
+            (DnsmasqConfKeys.DhcpVendorclass, "dhcp-vendorclass=set:pxe,PXEClient"),
+            (DnsmasqConfKeys.DhcpUserclass, "dhcp-userclass=set:efi,EFI"),
+            (DnsmasqConfKeys.AddnHosts, "addn-hosts=/etc/hosts.extra"),
+            (DnsmasqConfKeys.Interface, "interface=eth0"),
+            (DnsmasqConfKeys.ListenAddress, "listen-address=127.0.0.1"),
+            (DnsmasqConfKeys.ResolvFile, "resolv-file=/etc/resolv.dnsmasq"),
+        };
+    }
+}

src/DnsmasqWebUI.Tests/Helpers/RealWorldCasesHelper.cs

@@ -0,0 +1,51 @@
+using System.Text.Json;
+
+namespace DnsmasqWebUI.Tests.Helpers;
+
+/// <summary>Expected parser/effective state for a real-world corpus case. Counts and booleans only.</summary>
+public sealed class CorpusExpected
+{
+    public int? ServerCountMin { get; set; }
+    public int? LocalCountMin { get; set; }
+    public int? AddressCountMin { get; set; }
+    public int? CacheSize { get; set; }
+    public int? AddnHostsCountMin { get; set; }
+    public int? DomainCountMin { get; set; }
+    public bool? NoHosts { get; set; }
+    public bool? NoResolv { get; set; }
+    public bool? BogusPriv { get; set; }
+    public string? Do0x20State { get; set; }
+    public int? Port { get; set; }
+    public bool? ExpandHosts { get; set; }
+    public int? CnameCountMin { get; set; }
+    public int? TxtRecordCountMin { get; set; }
+    public int? SrvCountMin { get; set; }
+    public int? PtrRecordCountMin { get; set; }
+    public int? MxHostCountMin { get; set; }
+    public int? AuthZoneCountMin { get; set; }
+    public int? SynthDomainCountMin { get; set; }
+    public int? AuthServerCountMin { get; set; }
+}
+
+/// <summary>Single real-world corpus case from dnsmasq-real-cases.json.</summary>
+public sealed class CorpusCase
+{
+    public string File { get; set; } = "";
+    public CorpusExpected Expected { get; set; } = new();
+    public List<string> SemanticInvalidOptions { get; set; } = [];
+}
+
+/// <summary>Loads real-world corpus index and resolves paths via TestDataHelper.</summary>
+public static class RealWorldCasesHelper
+{
+    private static readonly JsonSerializerOptions JsonOptions = new() { PropertyNameCaseInsensitive = true };
+
+    public static IReadOnlyList<CorpusCase> LoadCases()
+    {
+        var path = TestDataHelper.GetPath("real-world/dnsmasq-real-cases.json");
+        var json = File.ReadAllText(path);
+        return JsonSerializer.Deserialize<List<CorpusCase>>(json, JsonOptions) ?? [];
+    }
+
+    public static string Resolve(CorpusCase c) => TestDataHelper.GetPath(c.File);
+}

src/DnsmasqWebUI.Tests/Helpers/RealWorldCorpusIntegrityTests.cs

@@ -0,0 +1,50 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
+
+namespace DnsmasqWebUI.Tests.Helpers;
+
+/// <summary>Ensures corpus index and files stay in sync; fails fast when testdata drifts.</summary>
+public class RealWorldCorpusIntegrityTests
+{
+    [Fact]
+    public void EveryCorpusCase_PointsToExistingFile()
+    {
+        var cases = RealWorldCasesHelper.LoadCases();
+        Assert.NotEmpty(cases);
+        foreach (var c in cases)
+        {
+            var path = RealWorldCasesHelper.Resolve(c);
+            Assert.True(File.Exists(path), $"Corpus file missing: {c.File}");
+        }
+    }
+
+    [Fact]
+    public void EveryBadCase_DeclaresSemanticInvalidOptions()
+    {
+        var cases = RealWorldCasesHelper.LoadCases();
+        var badFiles = new[] { "bad/", "real-world/bad/" };
+        foreach (var c in cases)
+        {
+            var isBad = badFiles.Any(p => c.File.Contains(p, StringComparison.Ordinal));
+            if (isBad)
+                Assert.NotEmpty(c.SemanticInvalidOptions);
+        }
+    }
+
+    [Fact]
+    public void SemanticInvalidOptions_ArePresentInParsedValues()
+    {
+        foreach (var c in RealWorldCasesHelper.LoadCases())
+        {
+            if (c.SemanticInvalidOptions.Count == 0)
+                continue;
+            var mainPath = RealWorldCasesHelper.Resolve(c);
+            var paths = DnsmasqConfIncludeParser.GetIncludedPaths(mainPath);
+            foreach (var option in c.SemanticInvalidOptions)
+            {
+                var values = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, option);
+                Assert.NotEmpty(values);
+            }
+        }
+    }
+}

src/DnsmasqWebUI.Tests/Helpers/TestDataHelper.cs

@@ -1,4 +1,4 @@
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Helpers;
 
 /// <summary>
 /// Resolves paths to testdata files. Files are copied to output (testdata/) when the project builds.

src/DnsmasqWebUI.Tests/Models/EffectiveConfig/EffectiveConfigMultiDisplayContextTests.cs

@@ -0,0 +1,149 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Editing;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Models.Dnsmasq;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Models.EffectiveConfig;
+
+public class EffectiveConfigMultiDisplayContextTests
+{
+    private static EffectiveMultiValueConfigFieldDescriptor DomainDescriptor(
+        IReadOnlyList<ValueWithSource> baseline) =>
+        new(
+            EffectiveConfigSections.SectionHosts,
+            DnsmasqConfKeys.Domain,
+            Status: null,
+            ResolveItems: _ => baseline,
+            Behavior: new DefaultMultiValueEditBehavior(),
+            Validator: null);
+
+    private static ConfigValueSource ReadonlySource() =>
+        new("/etc/dnsmasq.conf", "dnsmasq.conf", IsManaged: false, LineNumber: 1);
+
+    [Fact]
+    public void From_BaselineOnly_UsesBaselineItems()
+    {
+        var baseline = new List<ValueWithSource>
+        {
+            new("a.example", null),
+            new("b.example", null)
+        };
+        var d = DomainDescriptor(baseline);
+
+        var ctx = EffectiveConfigMultiDisplayContext.From(
+            d, baseline, pendingList: null, hasPendingChange: false, draftList: null,
+            isEditMode: false, isActive: false, fieldKey: "k");
+
+        Assert.Same(baseline, ctx.BaselineItems);
+        Assert.Equal(["a.example", "b.example"], ctx.EffectiveValues);
+        Assert.False(ctx.HasPendingChange);
+        Assert.False(ctx.HasDraftChange);
+        Assert.False(ctx.HasPendingOrDraft);
+    }
+
+    [Fact]
+    public void From_PendingOverridesBaseline_PreservesSourcesWhereValuesMatch()
+    {
+        var ro = ReadonlySource();
+        var baseline = new List<ValueWithSource>
+        {
+            new("a.example", ro),
+            new("b.example", null)
+        };
+        var d = DomainDescriptor(baseline);
+        var pending = new List<string> { "a.example", "c.example" };
+
+        var ctx = EffectiveConfigMultiDisplayContext.From(
+            d, baseline, pending, hasPendingChange: true, draftList: null,
+            isEditMode: false, isActive: false, fieldKey: "k");
+
+        Assert.Equal(["a.example", "c.example"], ctx.EffectiveValues);
+        Assert.True(ctx.HasPendingChange);
+        Assert.Equal(ro, ctx.EffectiveItems[0].Source);
+        Assert.Null(ctx.EffectiveItems[1].Source);
+    }
+
+    [Fact]
+    public void From_DraftOverridesPending()
+    {
+        var baseline = new List<ValueWithSource> { new("a.example", null) };
+        var d = DomainDescriptor(baseline);
+        var pending = new List<string> { "b.example" };
+        var draft = new List<string> { "c.example" };
+
+        var ctx = EffectiveContext(d, baseline, pending, draft);
+
+        Assert.Equal(["c.example"], ctx.EffectiveValues);
+        Assert.True(ctx.HasDraftChange);
+        Assert.True(ctx.HasPendingOrDraft);
+    }
+
+    [Fact]
+    public void From_AllReadonlyNotEditMode_SetsRowSourceFromFirstItem()
+    {
+        var ro = ReadonlySource();
+        var baseline = new List<ValueWithSource>
+        {
+            new("a.example", ro)
+        };
+        var d = DomainDescriptor(baseline);
+
+        var ctx = EffectiveConfigMultiDisplayContext.From(
+            d, baseline, null, false, null,
+            isEditMode: false, isActive: false, fieldKey: "k");
+
+        Assert.Equal(ro, ctx.RowSource);
+    }
+
+    [Fact]
+    public void From_EditModeOrMixedWritable_ClearsRowSource()
+    {
+        var ro = ReadonlySource();
+        var baseline = new List<ValueWithSource>
+        {
+            new("a.example", ro)
+        };
+        var d = DomainDescriptor(baseline);
+
+        var ctxEdit = EffectiveConfigMultiDisplayContext.From(
+            d, baseline, null, false, null,
+            isEditMode: true, isActive: false, fieldKey: "k");
+
+        Assert.Null(ctxEdit.RowSource);
+
+        var mixed = new List<ValueWithSource>
+        {
+            new("a.example", ro),
+            new("b.example", null)
+        };
+        var d2 = DomainDescriptor(mixed);
+        var ctxMixed = EffectiveConfigMultiDisplayContext.From(
+            d2, mixed, null, false, null,
+            isEditMode: false, isActive: false, fieldKey: "k");
+
+        Assert.Null(ctxMixed.RowSource);
+    }
+
+    [Fact]
+    public void From_IsActiveEditor_RespectsCapabilityDisabled()
+    {
+        var baseline = new List<ValueWithSource> { new("a.example", null) };
+        var d = DomainDescriptor(baseline) with { IsCapabilityDisabled = true };
+
+        var ctx = EffectiveConfigMultiDisplayContext.From(
+            d, baseline, null, false, null,
+            isEditMode: true, isActive: true, fieldKey: "k");
+
+        Assert.False(ctx.IsActiveEditor);
+        Assert.False(ctx.ShowEditableBadge);
+    }
+
+    private static EffectiveConfigMultiDisplayContext EffectiveContext(
+        EffectiveMultiValueConfigFieldDescriptor d,
+        IReadOnlyList<ValueWithSource> baseline,
+        IReadOnlyList<string>? pending,
+        IReadOnlyList<string>? draft) =>
+        EffectiveConfigMultiDisplayContext.From(
+            d, baseline, pending, pending != null, draft,
+            isEditMode: false, isActive: false, fieldKey: "k");
+}

src/DnsmasqWebUI.Tests/Models/EffectiveConfig/ManagedHostsPendingChangeDiffTests.cs

@@ -0,0 +1,90 @@
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using DnsmasqWebUI.Models.Hosts;
+
+namespace DnsmasqWebUI.Tests.Models.EffectiveConfig;
+
+public class ManagedHostsPendingChangeDiffTests
+{
+    [Fact]
+    public void Build_same_entries_returns_empty()
+    {
+        var e = new HostEntry { Id = "a", LineNumber = 1, Address = "10.0.0.1", Names = new List<string> { "h" } };
+        var oldL = new List<HostEntry> { e };
+        var newL = new List<HostEntry>
+        {
+            new()
+            {
+                Id = e.Id,
+                LineNumber = e.LineNumber,
+                Address = e.Address,
+                Names = new List<string>(e.Names)
+            }
+        };
+        Assert.Empty(ManagedHostsPendingChangeDiff.Build(oldL, newL));
+    }
+
+    [Fact]
+    public void Build_added_entry()
+    {
+        var oldL = new List<HostEntry>();
+        var newL = new List<HostEntry>
+        {
+            new() { Id = "new:x", LineNumber = 1, Address = "192.168.0.1", Names = new List<string> { "router" } }
+        };
+        var d = ManagedHostsPendingChangeDiff.Build(oldL, newL);
+        var a = Assert.Single(d);
+        Assert.Equal(ManagedHostsLineDiffKind.Added, a.Kind);
+        Assert.Contains("192.168.0.1", a.AfterLine, StringComparison.Ordinal);
+        Assert.Contains("router", a.AfterLine, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Build_removed_entry()
+    {
+        var oldL = new List<HostEntry>
+        {
+            new() { Id = "1", LineNumber = 1, Address = "10.0.0.2", Names = new List<string> { "x" } }
+        };
+        var newL = new List<HostEntry>();
+        var d = ManagedHostsPendingChangeDiff.Build(oldL, newL);
+        var r = Assert.Single(d);
+        Assert.Equal(ManagedHostsLineDiffKind.Removed, r.Kind);
+        Assert.Contains("10.0.0.2", r.BeforeLine, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Build_modified_address()
+    {
+        var oldL = new List<HostEntry>
+        {
+            new() { Id = "k", LineNumber = 1, Address = "10.0.0.1", Names = new List<string> { "h" } }
+        };
+        var newL = new List<HostEntry>
+        {
+            new() { Id = "k", LineNumber = 1, Address = "10.0.0.9", Names = new List<string> { "h" } }
+        };
+        var d = ManagedHostsPendingChangeDiff.Build(oldL, newL);
+        var m = Assert.Single(d);
+        Assert.Equal(ManagedHostsLineDiffKind.Modified, m.Kind);
+        Assert.Contains("10.0.0.1", m.BeforeLine, StringComparison.Ordinal);
+        Assert.Contains("10.0.0.9", m.AfterLine, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Build_order_only()
+    {
+        var oldL = new List<HostEntry>
+        {
+            new() { Id = "a", LineNumber = 1, Address = "10.0.0.1", Names = new List<string> { "a" } },
+            new() { Id = "b", LineNumber = 2, Address = "10.0.0.2", Names = new List<string> { "b" } }
+        };
+        var newL = new List<HostEntry>
+        {
+            new() { Id = "b", LineNumber = 1, Address = "10.0.0.2", Names = new List<string> { "b" } },
+            new() { Id = "a", LineNumber = 2, Address = "10.0.0.1", Names = new List<string> { "a" } }
+        };
+        var d = ManagedHostsPendingChangeDiff.Build(oldL, newL);
+        var o = Assert.Single(d);
+        Assert.Equal(ManagedHostsLineDiffKind.OrderOnly, o.Kind);
+    }
+}

src/DnsmasqWebUI.Tests/Models/EffectiveConfig/PendingManagedHostsChangeTests.cs

@@ -0,0 +1,53 @@
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using DnsmasqWebUI.Models.Hosts;
+
+namespace DnsmasqWebUI.Tests.Models.EffectiveConfig;
+
+public class PendingManagedHostsChangeTests
+{
+    [Fact]
+    public void HasChanges_WhenEntriesDiffer_ReturnsTrue()
+    {
+        var oldEntries = new List<HostEntry> { new() { Id = "1", Address = "192.168.1.1", Names = new List<string> { "host1" } } };
+        var newEntries = new List<HostEntry> { new() { Id = "1", Address = "192.168.1.2", Names = new List<string> { "host1" } } };
+        var pending = new PendingManagedHostsChange(oldEntries, newEntries, "/etc/hosts");
+        Assert.True(pending.HasChanges);
+    }
+
+    [Fact]
+    public void HasChanges_WhenEntriesSame_ReturnsFalse()
+    {
+        var entries = new List<HostEntry> { new() { Id = "1", Address = "192.168.1.1", Names = new List<string> { "host1" } } };
+        var clone = entries.Select(e => new HostEntry { Id = e.Id, Address = e.Address, Names = new List<string>(e.Names) }).ToList();
+        var pending = new PendingManagedHostsChange(entries, clone, "/etc/hosts");
+        Assert.False(pending.HasChanges);
+    }
+
+    [Fact]
+    public void HasChanges_WhenCountDiffers_ReturnsTrue()
+    {
+        var oldEntries = new List<HostEntry> { new() { Id = "1", Address = "192.168.1.1", Names = new List<string>() } };
+        var newEntries = new List<HostEntry>
+        {
+            new() { Id = "1", Address = "192.168.1.1", Names = new List<string>() },
+            new() { Id = "2", Address = "192.168.1.2", Names = new List<string>() }
+        };
+        var pending = new PendingManagedHostsChange(oldEntries, newEntries, "/etc/hosts");
+        Assert.True(pending.HasChanges);
+    }
+
+    [Fact]
+    public void HasChanges_WhenInlineCommentDiffers_ReturnsTrue()
+    {
+        var oldEntries = new List<HostEntry>
+        {
+            new() { Id = "1", Address = "10.0.0.1", Names = new List<string> { "a" }, InlineComment = "old" }
+        };
+        var newEntries = new List<HostEntry>
+        {
+            new() { Id = "1", Address = "10.0.0.1", Names = new List<string> { "a" }, InlineComment = "new" }
+        };
+        var pending = new PendingManagedHostsChange(oldEntries, newEntries, "/etc/hosts");
+        Assert.True(pending.HasChanges);
+    }
+}

src/DnsmasqWebUI.Tests/Models/Hosts/HostsEffectiveNamesDomainRulesTests.cs

@@ -0,0 +1,93 @@
+using DnsmasqWebUI.Models.Hosts;
+
+namespace DnsmasqWebUI.Tests.Models.Hosts;
+
+public class HostsEffectiveNamesDomainRulesTests
+{
+    [Fact]
+    public void Expand_UsesMatchingScopedDomainForIpv4()
+    {
+        var names = new[] { "router" };
+        var domains = new[] { "home.lan", "corp.lan,10.20.0.0/16" };
+
+        var result = HostsEffectiveNames.Expand(names, expandHosts: true, domains, "10.20.1.9");
+
+        Assert.Equal(new[] { "router", "router.corp.lan" }, result);
+    }
+
+    [Fact]
+    public void Expand_FallsBackToDefaultDomainWhenNoScopedMatch()
+    {
+        var names = new[] { "cache" };
+        var domains = new[] { "home.lan", "corp.lan,10.20.0.0/16" };
+
+        var result = HostsEffectiveNames.Expand(names, expandHosts: true, domains, "10.99.1.9");
+
+        Assert.Equal(new[] { "cache", "cache.home.lan" }, result);
+    }
+
+    [Fact]
+    public void Expand_UsesLastParsedScopedRuleWhenRangesOverlap()
+    {
+        var names = new[] { "app" };
+        var domains = new[]
+        {
+            "home.lan",
+            "corp-wide.lan,10.0.0.0/8",
+            "corp-subnet.lan,10.20.0.0/16"
+        };
+
+        var result = HostsEffectiveNames.Expand(names, expandHosts: true, domains, "10.20.1.5");
+
+        Assert.Equal(new[] { "app", "app.corp-subnet.lan" }, result);
+    }
+
+    [Fact]
+    public void Expand_UsesDefaultDomainForIpv6Address()
+    {
+        var names = new[] { "node" };
+        var domains = new[] { "home.lan", "corp.lan,10.20.0.0/16" };
+
+        var result = HostsEffectiveNames.Expand(names, expandHosts: true, domains, "2001:db8::1");
+
+        Assert.Equal(new[] { "node", "node.home.lan" }, result);
+    }
+
+    [Fact]
+    public void ExplainSuffixSource_ScopedRuleMentionsRawLine()
+    {
+        var domains = new[] { "home.lan", "corp.lan,10.20.0.0/16" };
+        var msg = HostsEffectiveNames.ExplainSuffixSource(
+            expandHosts: true,
+            domains,
+            "10.20.1.9",
+            new[] { "router" });
+
+        Assert.Equal("Suffix from scoped rule: corp.lan,10.20.0.0/16", msg);
+    }
+
+    [Fact]
+    public void ExplainSuffixSource_DefaultDomainWhenNoScopedMatch()
+    {
+        var domains = new[] { "home.lan", "corp.lan,10.20.0.0/16" };
+        var msg = HostsEffectiveNames.ExplainSuffixSource(
+            expandHosts: true,
+            domains,
+            "10.99.1.9",
+            new[] { "cache" });
+
+        Assert.Equal("Suffix from default rule: home.lan", msg);
+    }
+
+    [Fact]
+    public void ExplainSuffixSource_ExpandHostsOff()
+    {
+        var msg = HostsEffectiveNames.ExplainSuffixSource(
+            expandHosts: false,
+            new[] { "home.lan" },
+            "10.0.0.1",
+            new[] { "a" });
+
+        Assert.Contains("expand-hosts is off", msg);
+    }
+}

src/DnsmasqWebUI.Tests/Models/Hosts/HostsEntryEditValidatorTests.cs

@@ -0,0 +1,34 @@
+using DnsmasqWebUI.Models.Hosts;
+
+namespace DnsmasqWebUI.Tests.Models.Hosts;
+
+public class HostsEntryEditValidatorTests
+{
+    [Fact]
+    public void Empty_is_invalid()
+    {
+        var e = HostsEntryEditValidator.GetErrors("", Array.Empty<string>());
+        Assert.NotEmpty(e);
+    }
+
+    [Fact]
+    public void Valid_ipv4_and_name_ok()
+    {
+        Assert.True(HostsEntryEditValidator.IsValid("192.168.1.1", new[] { "router" }));
+    }
+
+    [Fact]
+    public void Missing_names_invalid()
+    {
+        var e = HostsEntryEditValidator.GetErrors("10.0.0.1", Array.Empty<string>());
+        Assert.Contains(e, x => x.Contains("hostname", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public void Field_errors_split_address_and_names()
+    {
+        Assert.NotEmpty(HostsEntryEditValidator.GetAddressFieldErrors(""));
+        Assert.Empty(HostsEntryEditValidator.GetHostnameFieldErrors(new[] { "h" }));
+        Assert.NotEmpty(HostsEntryEditValidator.GetHostnameFieldErrors(Array.Empty<string>()));
+    }
+}

src/DnsmasqWebUI.Tests/Models/Hosts/HostsFileFilterBuilderTests.cs

@@ -0,0 +1,111 @@
+using DnsmasqWebUI.Models.Hosts;
+using DnsmasqWebUI.Models.Ui;
+
+namespace DnsmasqWebUI.Tests.Models.Hosts;
+
+public sealed class HostsFileFilterBuilderTests
+{
+    private static HostsPageRow Row(HostsRowSourceKind kind, string path, bool isComment = false) =>
+        new(
+            Id: "id",
+            SourceKind: kind,
+            SourcePath: path,
+            IsEditable: false,
+            IsActive: true,
+            InactiveReason: null,
+            Address: "127.0.0.1",
+            Names: [],
+            EffectiveNames: [],
+            IsComment: isComment,
+            LineNumber: 1);
+
+    [Fact]
+    public void Build_InjectsManagedPath_WhenNotInRows()
+    {
+        var managed = "/data/managed.hosts";
+        var builder = new HostsFileFilterBuilder([], managed);
+        var model = builder.Build();
+
+        Assert.NotNull(model.AllOption);
+        var managedSection = model.Sections.Single();
+        Assert.Equal("Managed hosts", managedSection.Label);
+        Assert.Equal("managed", managedSection.Kind);
+        Assert.Single(managedSection.Options);
+        Assert.Equal(managed, managedSection.Options[0].Value);
+        Assert.Equal(0, managedSection.Options[0].Count);
+    }
+
+    [Fact]
+    public void Build_OrdersGroupsManagedSystemAddn_AndCountsNonComments()
+    {
+        var rows = new[]
+        {
+            Row(HostsRowSourceKind.SystemHosts, "/etc/hosts"),
+            Row(HostsRowSourceKind.Managed, "/m/a.hosts"),
+            Row(HostsRowSourceKind.Managed, "/m/a.hosts", isComment: true),
+            Row(HostsRowSourceKind.AddnHosts, "/extra/b.hosts"),
+        };
+
+        var builder = new HostsFileFilterBuilder(rows, managedHostsPath: null);
+        var model = builder.Build();
+
+        Assert.Equal(3, model.Sections.Count);
+        Assert.Equal("managed", model.Sections[0].Kind);
+        Assert.Equal("system", model.Sections[1].Kind);
+        Assert.Equal("addn", model.Sections[2].Kind);
+
+        Assert.Single(model.Sections[0].Options);
+        Assert.Equal(1, model.Sections[0].Options[0].Count);
+    }
+
+    [Fact]
+    public void GetSummaryText_AllFiles_ShowsRecordCount()
+    {
+        var rows = new[] { Row(HostsRowSourceKind.Managed, "/m/x.hosts") };
+        var builder = new HostsFileFilterBuilder(rows, null);
+        Assert.Equal("All files · 1 records", builder.GetSummaryText(""));
+        Assert.Equal("All files · 1 records", builder.GetSummaryText("   "));
+    }
+
+    [Fact]
+    public void GetSummaryText_SelectedFile_UsesShortLabelAndPrefix()
+    {
+        var rows = new[] { Row(HostsRowSourceKind.Managed, "/m/my.hosts") };
+        var builder = new HostsFileFilterBuilder(rows, null);
+        Assert.Equal("Managed · my.hosts (1)", builder.GetSummaryText("/m/my.hosts"));
+    }
+
+    [Fact]
+    public void GetSummaryText_UnknownPath_FallsBackToShortLabel()
+    {
+        var builder = new HostsFileFilterBuilder([], null);
+        Assert.Equal("orphan.txt", builder.GetSummaryText("/tmp/orphan.txt"));
+    }
+
+    [Fact]
+    public void GetTriggerSummary_SingleSource_SplitsPrefixPrimaryAndCount()
+    {
+        var rows = new[] { Row(HostsRowSourceKind.AddnHosts, "/etc/extra.d/hosts") };
+        var builder = new HostsFileFilterBuilder(rows, null);
+        var s = builder.GetTriggerSummary("/etc/extra.d/hosts");
+
+        Assert.Equal(GroupedSelectTriggerSummaryKind.SingleSource, s.Kind);
+        Assert.Equal("Additional", s.CategoryPrefix);
+        Assert.Equal("hosts", s.PrimaryLabel);
+        Assert.Equal("1", s.SecondaryMeta);
+        Assert.Equal("Additional · hosts (1)", s.AccessibleFullText);
+    }
+
+    [Fact]
+    public void GetTriggerSummary_AllSources_WithRecords_HasSecondaryMeta()
+    {
+        var rows = new[] { Row(HostsRowSourceKind.Managed, "/m/x.hosts") };
+        var builder = new HostsFileFilterBuilder(rows, null);
+        var s = builder.GetTriggerSummary("");
+
+        Assert.Equal(GroupedSelectTriggerSummaryKind.AllSources, s.Kind);
+        Assert.Null(s.CategoryPrefix);
+        Assert.Equal("All files", s.PrimaryLabel);
+        Assert.Equal("1 records", s.SecondaryMeta);
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/DnsmasqConfTextTests.cs

@@ -0,0 +1,58 @@
+using DnsmasqWebUI.Infrastructure.Serialization;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+
+namespace DnsmasqWebUI.Tests.Serialization;
+
+public class DnsmasqConfTextTests
+{
+    [Fact]
+    public void DirectivePrefix_ReturnsOptionEquals()
+    {
+        Assert.Equal("dhcp-host=", DnsmasqConfText.DirectivePrefix(DnsmasqConfKeys.DhcpHost));
+        Assert.Equal("server=", DnsmasqConfText.DirectivePrefix(DnsmasqConfKeys.Server));
+    }
+
+    [Fact]
+    public void DirectiveLine_WhenValueNullOrEmpty_ReturnsOptionOnly()
+    {
+        Assert.Equal("dhcp-host", DnsmasqConfText.DirectiveLine("dhcp-host", null));
+        Assert.Equal("dhcp-host", DnsmasqConfText.DirectiveLine("dhcp-host", ""));
+    }
+
+    [Fact]
+    public void DirectiveLine_WhenValueProvided_ReturnsOptionEqualsValue()
+    {
+        Assert.Equal("dhcp-host=11:22:33:44:55:66,192.168.1.1", DnsmasqConfText.DirectiveLine("dhcp-host", "11:22:33:44:55:66,192.168.1.1"));
+    }
+
+    [Fact]
+    public void StripDirectivePrefix_WhenLineStartsWithPrefix_ReturnsRest()
+    {
+        var line = "dhcp-host=mac,ip";
+        Assert.Equal("mac,ip", DnsmasqConfText.StripDirectivePrefix(DnsmasqConfKeys.DhcpHost, line));
+    }
+
+    [Fact]
+    public void StripDirectivePrefix_WhenLineDoesNotStartWithPrefix_ReturnsFullLine()
+    {
+        var line = "other=value";
+        Assert.Equal("other=value", DnsmasqConfText.StripDirectivePrefix(DnsmasqConfKeys.DhcpHost, line));
+    }
+
+    [Fact]
+    public void StripDirectivePrefix_WhenLineIsCommented_PreservesLeadingHashInResult()
+    {
+        Assert.Equal("#mac,ip", DnsmasqConfText.StripDirectivePrefix(DnsmasqConfKeys.DhcpHost, "#dhcp-host=mac,ip"));
+        Assert.Equal("##mac,ip", DnsmasqConfText.StripDirectivePrefix(DnsmasqConfKeys.DhcpHost, "##dhcp-host=mac,ip"));
+    }
+
+    [Fact]
+    public void HasDirectivePrefix_MatchesOptionAndCommentedForms()
+    {
+        Assert.True(DnsmasqConfText.HasDirectivePrefix(DnsmasqConfKeys.DhcpHost, "dhcp-host=value"));
+        Assert.True(DnsmasqConfText.HasDirectivePrefix(DnsmasqConfKeys.DhcpHost, "#dhcp-host=value"));
+        Assert.True(DnsmasqConfText.HasDirectivePrefix(DnsmasqConfKeys.DhcpHost, "##dhcp-host=value"));
+        Assert.False(DnsmasqConfText.HasDirectivePrefix(DnsmasqConfKeys.DhcpHost, "server=8.8.8.8"));
+        Assert.False(DnsmasqConfText.HasDirectivePrefix(DnsmasqConfKeys.DhcpHost, "other"));
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/EffectiveConfigDirectiveSerializerTests.cs

@@ -0,0 +1,66 @@
+using DnsmasqWebUI.Infrastructure.Serialization;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Serialization;
+
+public class EffectiveConfigDirectiveSerializerTests
+{
+    private readonly EffectiveConfigDirectiveSerializer _sut = new();
+
+    [Fact]
+    public void SerializeSingle_Flag_True_WritesBareKey()
+    {
+        var result = _sut.SerializeSingle(DnsmasqConfKeys.Conntrack, true);
+        Assert.Equal(DnsmasqConfKeys.Conntrack, result);
+    }
+
+    [Fact]
+    public void SerializeSingle_Flag_False_WritesEmpty()
+    {
+        var result = _sut.SerializeSingle(DnsmasqConfKeys.Conntrack, false);
+        Assert.Equal("", result);
+    }
+
+    [Fact]
+    public void SerializeSingle_SingleValue_WritesKeyEqualsValue()
+    {
+        var result = _sut.SerializeSingle(DnsmasqConfKeys.Port, 5353);
+        Assert.Equal("port=5353", result);
+    }
+
+    [Fact]
+    public void SerializeSingle_KeyOnlyOrValue_Empty_WritesBareKey()
+    {
+        var result = _sut.SerializeSingle(DnsmasqConfKeys.UseStaleCache, "");
+        Assert.Equal(DnsmasqConfKeys.UseStaleCache, result);
+    }
+
+    [Fact]
+    public void SerializeMulti_MultiValue_WritesEachDirective()
+    {
+        var result = _sut.SerializeMulti(DnsmasqConfKeys.Server, ["1.1.1.1", "8.8.8.8"]);
+        Assert.Equal(["server=1.1.1.1", "server=8.8.8.8"], result);
+    }
+
+    [Fact]
+    public void SerializeMulti_MultiKeyOnlyOrValue_WritesMixedForms()
+    {
+        var result = _sut.SerializeMulti(DnsmasqConfKeys.Leasequery, ["", "net:tag"]);
+        Assert.Equal(["leasequery", "leasequery=net:tag"], result);
+    }
+
+    [Fact]
+    public void SerializeSingle_InversePair_Enabled_WritesPositiveKey()
+    {
+        var result = _sut.SerializeSingle(DnsmasqConfKeys.Do0x20Encode, ExplicitToggleState.Enabled);
+        Assert.Equal(DnsmasqConfKeys.Do0x20Encode, result);
+    }
+
+    [Fact]
+    public void SerializeSingle_InversePair_Disabled_WritesNegativeKey()
+    {
+        var result = _sut.SerializeSingle(DnsmasqConfKeys.Do0x20Encode, ExplicitToggleState.Disabled);
+        Assert.Equal(DnsmasqConfKeys.No0x20Encode, result);
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/OptionHandlers/DhcpHostOptionValueHandlerTests.cs

@@ -0,0 +1,106 @@
+using DnsmasqWebUI.Infrastructure.Serialization.OptionHandlers;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Models.Dhcp;
+
+namespace DnsmasqWebUI.Tests.Serialization.OptionHandlers;
+
+public class DhcpHostOptionValueHandlerTests
+{
+    private readonly DhcpHostOptionValueHandler _sut = new();
+
+    [Fact]
+    public void OptionName_EqualsDnsmasqConfKeysDhcpHost()
+    {
+        Assert.Equal(DnsmasqConfKeys.DhcpHost, _sut.OptionName);
+    }
+
+    [Fact]
+    public void SerializeValue_EmitsValueOnlyForm()
+    {
+        var entry = new DhcpHostEntry
+        {
+            MacAddresses = new List<string> { "11:22:33:44:55:66" },
+            Address = "192.168.1.10"
+        };
+        var value = _sut.SerializeValue(entry);
+        Assert.Equal("11:22:33:44:55:66, 192.168.1.10", value);
+    }
+
+    [Fact]
+    public void SerializeValue_IgnoreEntry_EmitsIgnoreToken()
+    {
+        var entry = new DhcpHostEntry
+        {
+            MacAddresses = new List<string> { "aa:bb:cc:dd:ee:ff" },
+            Ignore = true
+        };
+        var value = _sut.SerializeValue(entry);
+        Assert.Contains("ignore", value);
+        Assert.Contains("aa:bb:cc:dd:ee:ff", value);
+    }
+
+    [Fact]
+    public void SerializeValue_EmptyEntry_ReturnsEmptyString()
+    {
+        var entry = new DhcpHostEntry();
+        var value = _sut.SerializeValue(entry);
+        Assert.Equal("", value);
+    }
+
+    [Fact]
+    public void TryParseValue_RoundTripsStructuredFields()
+    {
+        var input = new DhcpHostEntry
+        {
+            MacAddresses = new List<string> { "11:22:33:44:55:66" },
+            Address = "192.168.1.10",
+            Extra = new List<string> { "id:01:02:03", "set:test" },
+            Comment = "note",
+            IsComment = true
+        };
+        var value = _sut.SerializeValue(input);
+        var ok = _sut.TryParseValue(value, 1, out var output);
+        Assert.True(ok);
+        Assert.NotNull(output);
+        Assert.True(output!.IsComment);
+        Assert.Contains("id:01:02:03", output.Extra!);
+        Assert.Equal("note", output.Comment);
+    }
+
+    [Fact]
+    public void TryParseValue_IsComment_RoundTrips()
+    {
+        var entry = new DhcpHostEntry
+        {
+            MacAddresses = new List<string> { "aa:bb:cc:dd:ee:ff" },
+            Address = "192.168.1.1",
+            IsComment = true
+        };
+        var value = _sut.SerializeValue(entry);
+        Assert.StartsWith("#", value);
+        var ok = _sut.TryParseValue(value, 1, out var roundTripped);
+        Assert.True(ok);
+        Assert.NotNull(roundTripped);
+        Assert.True(roundTripped!.IsComment);
+        Assert.Single(roundTripped.MacAddresses!);
+        Assert.Equal("aa:bb:cc:dd:ee:ff", roundTripped.MacAddresses[0]);
+        Assert.Equal("192.168.1.1", roundTripped.Address);
+    }
+
+    [Fact]
+    public void TryParseValue_Comment_EmitsTrailingComment_AndRoundTrips()
+    {
+        var entry = new DhcpHostEntry
+        {
+            MacAddresses = new List<string> { "aa:bb:cc:dd:ee:ff" },
+            Address = "192.168.1.1",
+            Comment = " my note "
+        };
+        var value = _sut.SerializeValue(entry);
+        Assert.Contains(" # ", value);
+        var ok = _sut.TryParseValue(value, 1, out var roundTripped);
+        Assert.True(ok);
+        Assert.NotNull(roundTripped);
+        Assert.Equal("my note", roundTripped!.Comment?.Trim());
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/OptionHandlers/StructuredOptionValueHandlerRegistryTests.cs

@@ -0,0 +1,126 @@
+using System.Reflection;
+using DnsmasqWebUI.Infrastructure.Serialization.OptionHandlers;
+using DnsmasqWebUI.Infrastructure.Serialization.OptionHandlers.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Models.Dhcp;
+
+namespace DnsmasqWebUI.Tests.Serialization.OptionHandlers;
+
+/// <summary>Ensures structured handlers use DnsmasqConfKeys and registry has no duplicate option names.</summary>
+public class StructuredOptionValueHandlerRegistryTests
+{
+    [Fact]
+    public void DhcpHostOptionValueHandler_OptionName_EqualsDnsmasqConfKeysDhcpHost()
+    {
+        var handler = new DhcpHostOptionValueHandler();
+        Assert.Equal(DnsmasqConfKeys.DhcpHost, handler.OptionName);
+    }
+
+    [Fact]
+    public void DhcpHostOptionValueHandler_OptionName_IsFromDnsmasqConfKeys()
+    {
+        var handler = new DhcpHostOptionValueHandler();
+        var validKeys = GetDnsmasqConfKeysValues();
+        Assert.Contains(handler.OptionName, validKeys);
+    }
+
+    [Fact]
+    public void Registry_WithDhcpHostHandler_ReturnsHandlerForDhcpHost()
+    {
+        var handler = new DhcpHostOptionValueHandler();
+        var registry = new StructuredOptionValueHandlerRegistry(new[] { handler });
+        var resolved = registry.Get<DhcpHostEntry>(DnsmasqConfKeys.DhcpHost);
+        Assert.NotNull(resolved);
+        Assert.Equal(DnsmasqConfKeys.DhcpHost, resolved.OptionName);
+    }
+
+    [Fact]
+    public void Registry_IsStructured_WhenHandlerExists_ReturnsTrue()
+    {
+        var registry = new StructuredOptionValueHandlerRegistry([new DhcpHostOptionValueHandler()]);
+        Assert.True(registry.IsStructured(DnsmasqConfKeys.DhcpHost));
+        Assert.False(registry.IsStructured(DnsmasqConfKeys.Server));
+    }
+
+    [Fact]
+    public void Registry_GetRequired_WhenHandlerExists_ReturnsTypedHandler()
+    {
+        var registry = new StructuredOptionValueHandlerRegistry([new DhcpHostOptionValueHandler()]);
+        var handler = registry.GetRequired<DhcpHostEntry>(DnsmasqConfKeys.DhcpHost);
+        Assert.Equal(DnsmasqConfKeys.DhcpHost, handler.OptionName);
+    }
+
+    [Fact]
+    public void Registry_GetRequired_WhenOptionIsNotStructured_Throws()
+    {
+        var registry = new StructuredOptionValueHandlerRegistry([new DhcpHostOptionValueHandler()]);
+        var ex = Assert.Throws<InvalidOperationException>(() => registry.GetRequired<DhcpHostEntry>(DnsmasqConfKeys.Server));
+        Assert.Contains("not declared as a structured option", ex.Message);
+    }
+
+    [Fact]
+    public void Registry_DuplicateOptionNames_Throws()
+    {
+        var ex = Assert.Throws<InvalidOperationException>(() =>
+            new StructuredOptionValueHandlerRegistry([
+                new DhcpHostOptionValueHandler(),
+                new DuplicateDhcpHostHandler()
+            ]));
+        Assert.Contains("Duplicate structured option handlers", ex.Message);
+    }
+
+    [Fact]
+    public void Semantics_DhcpHost_HasStructuredValueTypeMatchingHandler()
+    {
+        var structuredType = EffectiveConfigSpecialOptionSemantics.GetStructuredValueType(DnsmasqConfKeys.DhcpHost);
+        Assert.NotNull(structuredType);
+        Assert.Equal(typeof(DhcpHostEntry), structuredType);
+        var handler = new DhcpHostOptionValueHandler();
+        Assert.Equal(structuredType, handler.ValueType);
+    }
+
+    [Fact]
+    public void Registry_HandlerWithoutStructuredMetadata_Throws()
+    {
+        var ex = Assert.Throws<InvalidOperationException>(() =>
+            new StructuredOptionValueHandlerRegistry([new InvalidServerHandler()]));
+        Assert.Contains("no StructuredValueType", ex.Message);
+    }
+
+    private static HashSet<string> GetDnsmasqConfKeysValues()
+    {
+        var set = new HashSet<string>(StringComparer.Ordinal);
+        foreach (var field in typeof(DnsmasqConfKeys).GetFields(BindingFlags.Public | BindingFlags.Static))
+        {
+            if (field.FieldType == typeof(string) && field.GetValue(null) is string value)
+                set.Add(value);
+        }
+        return set;
+    }
+
+    private sealed class DuplicateDhcpHostHandler : IStructuredOptionValueHandler<DhcpHostEntry>
+    {
+        public string OptionName => DnsmasqConfKeys.DhcpHost;
+        public Type ValueType => typeof(DhcpHostEntry);
+        public string SerializeLine(DhcpHostEntry value) => "";
+        public string SerializeValue(DhcpHostEntry value) => "";
+        public bool TryParseValue(string text, int lineNumber, out DhcpHostEntry? value)
+        {
+            value = null;
+            return false;
+        }
+    }
+
+    private sealed class InvalidServerHandler : IStructuredOptionValueHandler<string>
+    {
+        public string OptionName => DnsmasqConfKeys.Server;
+        public Type ValueType => typeof(string);
+        public string SerializeLine(string value) => "";
+        public string SerializeValue(string value) => value;
+        public bool TryParseValue(string text, int lineNumber, out string? value)
+        {
+            value = text;
+            return true;
+        }
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/Parsers/Dnsmasq/DnsmasqCompileOptionsParserTests.cs

@@ -0,0 +1,72 @@
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.Dnsmasq;
+using DnsmasqWebUI.Models.Dnsmasq;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.Dnsmasq;
+
+/// <summary>
+/// Tests for parsing "Compile time options: ..." from dnsmasq --version output.
+/// </summary>
+public class DnsmasqCompileOptionsParserTests
+{
+    [Fact]
+    public void Parse_WhenNoCompileLine_ReturnsAllCapabilitiesFalse()
+    {
+        var result = DnsmasqCompileOptionsParser.Parse("Dnsmasq version 2.89\nCopyright ...", null);
+        Assert.False(result.Dhcp);
+        Assert.False(result.Tftp);
+        Assert.False(result.Dnssec);
+        Assert.False(result.Dbus);
+        Assert.NotNull(result.RawTokens);
+        Assert.Empty(result.RawTokens);
+    }
+
+    [Fact]
+    public void Parse_WhenCompileLineHasDnssec_SetsDnssecTrue()
+    {
+        var stdout = "Dnsmasq version 2.89\nCompile time options: IPv6 GNU-getopt no-DBus no-Idn DHCP DHCPv6 TFTP DNSSEC auth";
+        var result = DnsmasqCompileOptionsParser.Parse(stdout, null);
+        Assert.True(result.Dnssec);
+        Assert.True(result.Dhcp);
+        Assert.True(result.Tftp);
+        Assert.False(result.Dbus);
+        Assert.Contains("DNSSEC", result.RawTokens, StringComparer.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void Parse_WhenCompileLineHasDhcpOnly_SetsDhcpTrueOthersFalse()
+    {
+        var result = DnsmasqCompileOptionsParser.Parse(null, "Compile time options: DHCP no-DBus no-DNSSEC");
+        Assert.True(result.Dhcp);
+        Assert.False(result.Tftp);
+        Assert.False(result.Dnssec);
+        Assert.False(result.Dbus);
+    }
+
+    [Fact]
+    public void Parse_WhenCompileLineHasDhcpv6_SetsDhcpTrue()
+    {
+        var result = DnsmasqCompileOptionsParser.Parse("Compile time options: DHCPv6", null);
+        Assert.True(result.Dhcp);
+    }
+
+    [Fact]
+    public void Parse_WhenCompileLineHasTftp_SetsTftpTrue()
+    {
+        var result = DnsmasqCompileOptionsParser.Parse("Compile time options: TFTP", null);
+        Assert.True(result.Tftp);
+    }
+
+    [Fact]
+    public void Parse_WhenCompileLineHasDbus_SetsDbusTrue()
+    {
+        var result = DnsmasqCompileOptionsParser.Parse("Compile time options: DBus", null);
+        Assert.True(result.Dbus);
+    }
+
+    [Fact]
+    public void Parse_CombinesStdoutAndStderr()
+    {
+        var result = DnsmasqCompileOptionsParser.Parse("Version line\n", "Compile time options: DNSSEC");
+        Assert.True(result.Dnssec);
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfDhcpHostLineParserTests.cs

@@ -1,7 +1,9 @@
 using DnsmasqWebUI.Models.Dhcp;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Tests for DnsmasqConfDhcpHostLineParser. Format: dhcp-host=[hwaddr][,id:...][,set:tag][,tag:tag][,ip][,hostname][,lease][,ignore]

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfDirectiveParserTests.cs

@@ -1,7 +1,7 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Tests for DnsmasqConfDirectiveParser. Key/value parsing (TryParseKeyValue) and comment stripping (StripComment)

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfFileLineParserTests.cs

@@ -1,8 +1,10 @@
 using DnsmasqWebUI.Models.Config;
 using DnsmasqWebUI.Models.Dhcp;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Tests for DnsmasqConfFileLineParser. Parses dnsmasq config file lines into Blank, Comment, AddnHosts, DhcpHost, Other.

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserCoreBehaviourTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Parser semantics: flags (option present/absent/with value), last-wins, case-sensitive, path order.</summary>

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserDhcpTftpDnssecTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>DHCP advanced, TFTP/PXE, DNSSEC, enable-dbus/ubus, fast-dns-retry.</summary>
@@ -283,7 +283,7 @@ public class DnsmasqConfIncludeParserDhcpTftpDnssecTests
     }
 
     [Fact]
-    public void GetFlagFromConfigFiles_DnssecCheckUnsigned_WhenPresent_ReturnsTrue()
+    public void GetLastValueFromConfigFiles_DnssecCheckUnsigned_WhenPresent_ReturnsValue()
     {
         var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-dnsseccu-" + Guid.NewGuid().ToString("N"));
         Directory.CreateDirectory(dir);
@@ -291,8 +291,26 @@ public class DnsmasqConfIncludeParserDhcpTftpDnssecTests
         try
         {
             File.WriteAllText(conf, "dnssec-check-unsigned\n");
-            var result = DnsmasqConfIncludeParser.GetFlagFromConfigFiles(new[] { conf }, DnsmasqConfKeys.DnssecCheckUnsigned);
+            var (value, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(new[] { conf }, DnsmasqConfKeys.DnssecCheckUnsigned);
-            Assert.True(result);
+            Assert.NotNull(value);
+        }
+        finally
+        {
+            Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public void GetLastValueFromConfigFiles_DnssecCheckUnsigned_WhenEqualsNo_ReturnsNo()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-dnsseccu-no-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var conf = Path.Combine(dir, "dnsmasq.conf");
+        try
+        {
+            File.WriteAllText(conf, "dnssec-check-unsigned=no\n");
+            var (value, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(new[] { conf }, DnsmasqConfKeys.DnssecCheckUnsigned);
+            Assert.Equal("no", value);
         }
         finally
         {

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserFlagsTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Boolean flags: no-hosts, bogus-priv, strict-order, domain-needed, no-poll, bind-*, rebind-*, clear-on-reload, filter*, localise-queries, log-debug, dhcp-authoritative, leasefile-ro.</summary>

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserHostsAndLeaseTests.cs

@@ -1,8 +1,10 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Hosts (addn-hosts, hostsdir) and DHCP lease file parsing.</summary>
@@ -26,7 +28,7 @@ public class DnsmasqConfIncludeParserHostsAndLeaseTests
         var mainPath = TestDataHelper.GetPath("dnsmasq-test.conf");
         Assert.True(File.Exists(mainPath), "Testdata dnsmasq-test.conf required");
         var paths = new[] { mainPath };
-        var servers = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.ServerLocalKeys);
+        var servers = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Server);
         var addnHosts = DnsmasqConfIncludeParser.GetAddnHostsPathsFromConfigFiles(paths);
         var addresses = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Address);
         var listenAddrs = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.ListenAddress);

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserIncludeTests.cs

@@ -1,9 +1,9 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
 using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Config discovery: conf-file=, conf-dir=, GetIncludedPaths, GetFirstConfDir, GetIncludedPathsWithSource, conf-dir suffix.</summary>

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserInterfacesAndFilteringTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Interfaces, auth-server, DHCP/option/resolv multi-value, rebind/bogus/ignore/alias, filter-rr, cache-rr.</summary>

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserNewOptionsTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Positive parser tests for added options: key wired and "option present" behaviour.
@@ -79,6 +79,137 @@ public class DnsmasqConfIncludeParserNewOptionsTests
         WriteFlagAndAssertTrue(DnsmasqConfKeys.ProxyDnssec);
     }
 
+    [Fact]
+    public void GetLastValueFromConfigFiles_ConnmarkAllowlistEnable_WhenPresent_ReturnsValue()
+    {
+        WriteLastWinsKeyOnlyAndAssertPresent(DnsmasqConfKeys.ConnmarkAllowlistEnable);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_NoRoundRobin_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.NoRoundRobin);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_DnssecNoTimecheck_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.DnssecNoTimecheck);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_DnssecDebug_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.DnssecDebug);
+    }
+
+    [Fact]
+    public void GetMultiValueFromConfigFiles_Leasequery_WhenPresent_ReturnsValues()
+    {
+        var dir = CreateTempDir();
+        var conf = Path.Combine(dir, "dnsmasq.conf");
+        try
+        {
+            File.WriteAllText(conf, "leasequery\n");
+            var result = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(new[] { conf }, DnsmasqConfKeys.Leasequery);
+            Assert.Single(result);
+            Assert.Equal("", result[0]);
+        }
+        finally { Directory.Delete(dir, recursive: true); }
+    }
+
+    [Fact]
+    public void GetMultiValueFromConfigFiles_Leasequery_WithValue_IsParsed()
+    {
+        var dir = CreateTempDir();
+        var conf = Path.Combine(dir, "dnsmasq.conf");
+        try
+        {
+            File.WriteAllText(conf, "leasequery=10.0.0.0/24\n");
+            var result = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(new[] { conf }, DnsmasqConfKeys.Leasequery);
+            Assert.Equal("10.0.0.0/24", Assert.Single(result));
+        }
+        finally { Directory.Delete(dir, recursive: true); }
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_QuietDhcp_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.QuietDhcp);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_QuietTftp_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.QuietTftp);
+    }
+
+    [Fact]
+    public void GetLastValueFromConfigFiles_DhcpGenerateNames_WhenPresent_ReturnsValue()
+    {
+        WriteLastWinsKeyOnlyAndAssertPresent(DnsmasqConfKeys.DhcpGenerateNames);
+    }
+
+    [Fact]
+    public void GetLastValueFromConfigFiles_DhcpBroadcast_WhenPresent_ReturnsValue()
+    {
+        WriteLastWinsKeyOnlyAndAssertPresent(DnsmasqConfKeys.DhcpBroadcast);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_DhcpSequentialIp_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.DhcpSequentialIp);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_DhcpIgnoreClid_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.DhcpIgnoreClid);
+    }
+
+    [Fact]
+    public void GetLastValueFromConfigFiles_BootpDynamic_WhenPresent_ReturnsValue()
+    {
+        WriteLastWinsKeyOnlyAndAssertPresent(DnsmasqConfKeys.BootpDynamic);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_NoPing_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.NoPing);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_ScriptArp_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.ScriptArp);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_ScriptOnRenewal_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.ScriptOnRenewal);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_DhcpNoOverride_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.DhcpNoOverride);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_QuietDhcp6_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.QuietDhcp6);
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_QuietRa_WhenPresent_ReturnsTrue()
+    {
+        WriteFlagAndAssertTrue(DnsmasqConfKeys.QuietRa);
+    }
+
     // --- Multi-value (6): key=value line(s) → GetMultiValue returns value(s) ---
 
     [Fact]
@@ -258,16 +389,27 @@ public class DnsmasqConfIncludeParserNewOptionsTests
     }
 
     [Fact]
-    public void GetLastValueFromConfigFiles_Conntrack_WhenSet_ReturnsValue()
+    public void GetFlagFromConfigFiles_Conntrack_WhenPresent_ReturnsTrue()
     {
         var dir = CreateTempDir();
         var conf = Path.Combine(dir, "dnsmasq.conf");
-        var value = "42";
         try
         {
-            File.WriteAllText(conf, $"conntrack={value}\n");
+            File.WriteAllText(conf, "conntrack\n");
-            var (result, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(new[] { conf }, DnsmasqConfKeys.Conntrack);
+            Assert.True(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(new[] { conf }, DnsmasqConfKeys.Conntrack));
-            Assert.Equal(value, result);
+        }
+        finally { Directory.Delete(dir, recursive: true); }
+    }
+
+    [Fact]
+    public void GetFlagFromConfigFiles_Conntrack_WhenAbsent_ReturnsFalse()
+    {
+        var dir = CreateTempDir();
+        var conf = Path.Combine(dir, "dnsmasq.conf");
+        try
+        {
+            File.WriteAllText(conf, "port=53\n");
+            Assert.False(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(new[] { conf }, DnsmasqConfKeys.Conntrack));
         }
         finally { Directory.Delete(dir, recursive: true); }
     }
@@ -284,6 +426,19 @@ public class DnsmasqConfIncludeParserNewOptionsTests
         finally { Directory.Delete(dir, recursive: true); }
     }
 
+    private static void WriteLastWinsKeyOnlyAndAssertPresent(string key)
+    {
+        var dir = CreateTempDir();
+        var conf = Path.Combine(dir, "dnsmasq.conf");
+        try
+        {
+            File.WriteAllText(conf, key + "\n");
+            var (value, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(new[] { conf }, key);
+            Assert.NotNull(value);
+        }
+        finally { Directory.Delete(dir, recursive: true); }
+    }
+
     private static string CreateTempDir()
     {
         var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-newopts-" + Guid.NewGuid().ToString("N"));

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserOfficialExampleTests.cs

@@ -1,7 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
+using DnsmasqWebUI.Tests.Helpers;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Tests that the parser correctly handles the official dnsmasq example (testdata/dnsmasq.official.conf.example).
@@ -45,7 +46,8 @@ public class DnsmasqConfIncludeParserOfficialExampleTests
     {
         var mainPath = GetOfficialExamplePath();
         var paths = new[] { mainPath };
-        var servers = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.ServerLocalKeys);
+        var servers = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Server);
+        var locals = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Local);
         var dhcpOptionForce = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.DhcpOptionForce);
         var ipset = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Ipset);
         var nftset = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Nftset);
@@ -53,6 +55,7 @@ public class DnsmasqConfIncludeParserOfficialExampleTests
         var dhcpNameMatch = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.DhcpNameMatch);
         var dhcpIgnoreNames = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.DhcpIgnoreNames);
         Assert.Empty(servers);
+        Assert.Empty(locals);
         Assert.Empty(dhcpOptionForce);
         Assert.Empty(ipset);
         Assert.Empty(nftset);
@@ -77,32 +80,6 @@ public class DnsmasqConfIncludeParserOfficialExampleTests
         Assert.False(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, DnsmasqConfKeys.LogDhcp));
     }
 
-    [Fact]
-    public void OfficialExample_FileContainsExpectedOptionNames()
-    {
-        var path = GetOfficialExamplePath();
-        var content = File.ReadAllText(path);
-        // Sanity: official example documents the options we support (as commented lines).
-        Assert.Contains("read-ethers", content);
-        Assert.Contains("dhcp-option-force", content);
-        Assert.Contains("dhcp-rapid-commit", content);
-        Assert.Contains("dhcp-script", content);
-        Assert.Contains("tftp-no-fail", content);
-        Assert.Contains("tftp-no-blocksize", content);
-        Assert.Contains("mx-target", content);
-        Assert.Contains("localmx", content);
-        Assert.Contains("selfmx", content);
-        Assert.Contains("enable-ra", content);
-        Assert.Contains("log-dhcp", content);
-        Assert.Contains("ipset=", content);
-        Assert.Contains("nftset=", content);
-        Assert.Contains("dhcp-mac", content);
-        Assert.Contains("dhcp-name-match", content);
-        Assert.Contains("dhcp-ignore-names", content);
-        // SRV records use option name srv-host (not "srv")
-        Assert.Contains("srv-host", content);
-    }
-
     [Fact]
     public void GetAddnHostsPathsFromConfigFiles_OfficialExample_AllCommented_ReturnsEmpty()
     {
@@ -121,4 +98,23 @@ public class DnsmasqConfIncludeParserOfficialExampleTests
         var noHosts = DnsmasqConfIncludeParser.GetNoHostsFromConfigFiles(paths);
         Assert.False(noHosts);
     }
+
+    /// <summary>Official-like sample with commented and active lines: commented ignored, active parsed, state reflects active only.</summary>
+    [Fact]
+    public void OfficialLikeActive_CommentedLinesIgnored_ActiveLinesParsed()
+    {
+        var mainPath = TestDataHelper.GetPath("real-world/edge/dnsmasq-real-official-like-active.conf");
+        Assert.True(File.Exists(mainPath));
+        var paths = DnsmasqConfIncludeParser.GetIncludedPaths(mainPath);
+
+        var (portVal, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(paths, DnsmasqConfKeys.Port);
+        Assert.NotNull(portVal);
+        Assert.True(int.TryParse(portVal, out var port) && port == 5353);
+
+        var servers = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Server);
+        Assert.Single(servers);
+        Assert.Equal("1.1.1.1", servers[0]);
+
+        Assert.True(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, DnsmasqConfKeys.ExpandHosts));
+    }
 }

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserOptionCoverageTests.cs

@@ -0,0 +1,73 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
+
+/// <summary>
+/// Ensures every option in the coverage list is parsed consistently: one config line per option,
+/// dispatch by parser behavior (Flag / LastWins / Multi), assert we get a value back.
+/// Add new options to <see cref="OptionCoverageData.GetParserCoverageEntries"/> when adding to the app.
+/// </summary>
+public class DnsmasqConfIncludeParserOptionCoverageTests
+{
+    public static IEnumerable<object[]> GetCoverageEntries()
+    {
+        foreach (var (optionKey, configLine) in OptionCoverageData.GetParserCoverageEntries())
+            yield return new object[] { optionKey, configLine };
+    }
+
+    [Theory]
+    [MemberData(nameof(GetCoverageEntries))]
+    public void EveryOption_ParseSingleLine_ReturnsExpectedResult(string optionKey, string configLine)
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-opt-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var conf = Path.Combine(dir, "dnsmasq.conf");
+        try
+        {
+            File.WriteAllText(conf, configLine + "\n");
+            var paths = new[] { conf };
+
+            if (optionKey == DnsmasqConfKeys.AddnHosts)
+            {
+                var addn = DnsmasqConfIncludeParser.GetAddnHostsPathsFromConfigFiles(paths);
+                Assert.True(addn.Count >= 1, $"addn-hosts should parse from: {configLine}");
+                return;
+            }
+
+            var behavior = EffectiveConfigParserBehaviorMap.GetBehavior(optionKey);
+
+            switch (behavior)
+            {
+                case EffectiveConfigParserBehavior.Flag:
+                {
+                    var flag = DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, optionKey);
+                    Assert.True(flag, $"Flag option {optionKey} should be true when set.");
+                    break;
+                }
+                case EffectiveConfigParserBehavior.LastWins:
+                {
+                    var (value, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(paths, optionKey);
+                    Assert.NotNull(value);
+                    Assert.True(value!.Length > 0, $"LastWins option {optionKey} should return non-empty value.");
+                    break;
+                }
+                case EffectiveConfigParserBehavior.Multi:
+                {
+                    var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, optionKey);
+                    Assert.True(list.Count >= 1, $"Multi option {optionKey} should return at least one value.");
+                    break;
+                }
+                default:
+                    Assert.Fail($"Unknown behavior for {optionKey}");
+                    break;
+            }
+        }
+        finally
+        {
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserRealWorldCorpusTests.cs

@@ -0,0 +1,148 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
+
+/// <summary>
+/// Corpus-driven parser tests using testdata/real-world. Asserts counts, booleans, and effective state only.
+/// </summary>
+public class DnsmasqConfIncludeParserRealWorldCorpusTests
+{
+    public static IEnumerable<object[]> GetCases()
+    {
+        foreach (var c in RealWorldCasesHelper.LoadCases())
+            yield return new object[] { c };
+    }
+
+    [Theory]
+    [MemberData(nameof(GetCases))]
+    public void GetIncludedPaths_RealWorldCorpus_ReturnsAtLeastMain(CorpusCase c)
+    {
+        var mainPath = RealWorldCasesHelper.Resolve(c);
+        Assert.True(File.Exists(mainPath), $"Corpus file missing: {c.File}");
+
+        var paths = DnsmasqConfIncludeParser.GetIncludedPaths(mainPath);
+        Assert.NotNull(paths);
+        Assert.NotEmpty(paths);
+        Assert.Contains(Path.GetFullPath(mainPath), paths);
+    }
+
+    [Theory]
+    [MemberData(nameof(GetCases))]
+    public void ParseEffectiveSignals_FromRealWorldCorpus(CorpusCase c)
+    {
+        var e = c.Expected;
+        var hasAny = e.ServerCountMin is not null || e.NoHosts is not null || e.Do0x20State is not null ||
+                     e.Port is not null || e.ExpandHosts is not null || e.LocalCountMin is not null ||
+                     e.AddressCountMin is not null || e.CacheSize is not null || e.AddnHostsCountMin is not null ||
+                     e.DomainCountMin is not null || e.NoResolv is not null || e.BogusPriv is not null ||
+                     e.CnameCountMin is not null || e.TxtRecordCountMin is not null || e.SrvCountMin is not null ||
+                     e.PtrRecordCountMin is not null || e.MxHostCountMin is not null || e.AuthZoneCountMin is not null ||
+                     e.SynthDomainCountMin is not null || e.AuthServerCountMin is not null;
+        if (!hasAny)
+            return;
+
+        var mainPath = RealWorldCasesHelper.Resolve(c);
+        var paths = DnsmasqConfIncludeParser.GetIncludedPaths(mainPath);
+
+        if (e.ServerCountMin is int minServers)
+        {
+            var servers = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Server);
+            Assert.True(servers.Count >= minServers, $"Expected at least {minServers} server(s) for {c.File}");
+        }
+        if (e.LocalCountMin is int minLocal)
+        {
+            var locals = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Local);
+            Assert.True(locals.Count >= minLocal, $"Expected at least {minLocal} local(s) for {c.File}");
+        }
+        if (e.AddressCountMin is int minAddr)
+        {
+            var addrs = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Address);
+            Assert.True(addrs.Count >= minAddr, $"Expected at least {minAddr} address(es) for {c.File}");
+        }
+        if (e.CacheSize is int cacheSize)
+        {
+            var (val, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(paths, DnsmasqConfKeys.CacheSize);
+            Assert.NotNull(val);
+            Assert.True(int.TryParse(val, out var n) && n == cacheSize);
+        }
+        if (e.AddnHostsCountMin is int minAddn)
+        {
+            var addn = DnsmasqConfIncludeParser.GetAddnHostsPathsFromConfigFiles(paths);
+            Assert.True(addn.Count >= minAddn);
+        }
+        if (e.DomainCountMin is int minDomain)
+        {
+            var domains = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Domain);
+            Assert.True(domains.Count >= minDomain);
+        }
+        if (e.NoHosts is bool noHostsExpected)
+        {
+            var noHosts = DnsmasqConfIncludeParser.GetNoHostsFromConfigFiles(paths);
+            Assert.Equal(noHostsExpected, noHosts);
+        }
+        if (e.NoResolv is true)
+        {
+            Assert.True(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, DnsmasqConfKeys.NoResolv));
+        }
+        if (e.BogusPriv is true)
+        {
+            Assert.True(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, DnsmasqConfKeys.BogusPriv));
+        }
+        if (e.Do0x20State == "Disabled")
+        {
+            Assert.True(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, DnsmasqConfKeys.No0x20Encode));
+        }
+        if (e.Port is int portExpected)
+        {
+            var (portVal, _) = DnsmasqConfIncludeParser.GetLastValueFromConfigFiles(paths, DnsmasqConfKeys.Port);
+            Assert.NotNull(portVal);
+            Assert.True(int.TryParse(portVal, out var port) && port == portExpected);
+        }
+        if (e.ExpandHosts is true)
+        {
+            Assert.True(DnsmasqConfIncludeParser.GetFlagFromConfigFiles(paths, DnsmasqConfKeys.ExpandHosts));
+        }
+        if (e.CnameCountMin is int minCname)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Cname);
+            Assert.True(list.Count >= minCname);
+        }
+        if (e.TxtRecordCountMin is int minTxt)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.TxtRecord);
+            Assert.True(list.Count >= minTxt);
+        }
+        if (e.SrvCountMin is int minSrv)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.Srv);
+            Assert.True(list.Count >= minSrv);
+        }
+        if (e.PtrRecordCountMin is int minPtr)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.PtrRecord);
+            Assert.True(list.Count >= minPtr);
+        }
+        if (e.MxHostCountMin is int minMx)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.MxHost);
+            Assert.True(list.Count >= minMx);
+        }
+        if (e.AuthZoneCountMin is int minAz)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.AuthZone);
+            Assert.True(list.Count >= minAz);
+        }
+        if (e.SynthDomainCountMin is int minSd)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.SynthDomain);
+            Assert.True(list.Count >= minSd);
+        }
+        if (e.AuthServerCountMin is int minAs)
+        {
+            var list = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, DnsmasqConfKeys.AuthServer);
+            Assert.True(list.Count >= minAs);
+        }
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserRecordsTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>DNS records and local names: hostsdir, domain, cname, mx-host, srv, ptr/txt/naptr/host-record, dynamic-host, interface-name.</summary>

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserServerAndResolvTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Server/local, rev-server, dhcp-range, all-servers, log-queries.</summary>
@@ -23,11 +23,13 @@ public class DnsmasqConfIncludeParserServerAndResolvTests
         {
             File.WriteAllText(f1, $"server={v1}\nlocal={v2}\n");
             File.WriteAllText(f2, $"server={v3}\n");
-            var result = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(new[] { f1, f2 }, DnsmasqConfKeys.ServerLocalKeys);
+            var resultServer = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(new[] { f1, f2 }, DnsmasqConfKeys.Server);
-            Assert.Equal(3, result.Count);
+            var resultLocal = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(new[] { f1, f2 }, DnsmasqConfKeys.Local);
-            Assert.Equal(v1, result[0]);
+            Assert.Equal(2, resultServer.Count);
-            Assert.Equal(v2, result[1]);
+            Assert.Equal(v1, resultServer[0]);
-            Assert.Equal(v3, result[2]);
+            Assert.Equal(v3, resultServer[1]);
+            Assert.Single(resultLocal);
+            Assert.Equal(v2, resultLocal[0]);
         }
         finally
         {

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqConfIncludeParserSingleValueTests.cs

@@ -1,8 +1,8 @@
-using DnsmasqWebUI.Infrastructure.Helpers.Config;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
 using DnsmasqWebUI.Models.Dnsmasq;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 
 /// <summary>Single-value options (last wins): local-ttl, pid-file, user, group, auth-ttl, edns-packet-max, query-port, port-limit, min/max-port, log-async, local-service, dhcp-lease-max, neg/max/min-cache-ttl, dhcp-ttl.</summary>

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqDhcpRangeValueParserTests.cs

@@ -0,0 +1,42 @@
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.EffectiveConfig;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
+
+public class DnsmasqDhcpRangeValueParserTests
+{
+    [Fact]
+    public void TryParse_ValidRange_ReturnsStructuredTokens()
+    {
+        var ok = DnsmasqDhcpRangeValueParser.TryParse(
+            "tag:guest,set:known,192.168.1.50,192.168.1.150,12h",
+            out var parsed,
+            out var error);
+
+        Assert.True(ok);
+        Assert.Null(error);
+        Assert.NotNull(parsed);
+        Assert.Equal(["tag:guest", "set:known"], parsed!.Tags);
+        Assert.Equal("192.168.1.50", parsed.StartToken);
+        Assert.Equal("192.168.1.150", parsed.SecondToken);
+        Assert.Equal(["12h"], parsed.RemainingTokens);
+    }
+
+    [Fact]
+    public void TryParse_MalformedTrailingComma_ReturnsError()
+    {
+        var ok = DnsmasqDhcpRangeValueParser.TryParse("172.28.0.10,", out var parsed, out var error);
+
+        Assert.False(ok);
+        Assert.Null(parsed);
+        Assert.Equal("dhcp-range contains an empty comma-separated segment.", error);
+    }
+
+    [Fact]
+    public void GetIPv4StartEnd_ReturnsParsedIpv4Range()
+    {
+        var result = DnsmasqDhcpRangeValueParser.GetIPv4StartEnd("tag:guest,192.168.1.50,192.168.1.150,12h");
+
+        Assert.Equal(("192.168.1.50", "192.168.1.150"), result);
+    }
+}

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/DnsmasqLeasesFileLineParserTests.cs

@@ -1,7 +1,9 @@
 using DnsmasqWebUI.Models.Dhcp;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Tests for DnsmasqLeasesFileLineParser. Format per dnsmasq author (dnsmasq-discuss 2006): five space-separated

src/DnsmasqWebUI.Tests/Serialization/Parsers/DnsmasqConfig/HostsFileLineParserTests.cs

@@ -1,7 +1,9 @@
 using DnsmasqWebUI.Models.Hosts;
-using DnsmasqWebUI.Infrastructure.Parsers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
 
-namespace DnsmasqWebUI.Tests;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.DnsmasqConfig;
 
 /// <summary>
 /// Tests for HostsFileLineParser. Format: IP_address canonical_hostname [aliases...] (hosts(5), RFC 952).
@@ -137,6 +139,17 @@ public class HostsFileLineParserTests
         Assert.Equal(address, e.Address);
         Assert.Single(e.Names);
         Assert.Equal(name, e.Names[0]);
+        Assert.Equal(comment, e.InlineComment);
+    }
+
+    [Fact]
+    public void ToLine_WithInlineComment_AppendsHashAndRoundTrips()
+    {
+        var line = "192.168.0.5 router # edge gateway";
+        var e = HostsFileLineParser.ParseLine(line, 1);
+        Assert.NotNull(e);
+        var back = HostsFileLineParser.ToLine(e!);
+        Assert.Equal(line, back);
     }
 
     [Fact]

src/DnsmasqWebUI.Tests/Serialization/Parsers/EffectiveConfig/DomainRuleFieldsTests.cs

@@ -0,0 +1,63 @@
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Serialization.Parsers.EffectiveConfig;
+
+public class DomainRuleFieldsTests
+{
+    [Theory]
+    [InlineData("home.arpa", "home.arpa")]
+    [InlineData("#", "# (resolv.conf search)")]
+    [InlineData("example.com,192.168.0.0/24", "example.com · 192.168.0.0/24")]
+    [InlineData("example.com,192.168.0.0/24,local", "example.com · 192.168.0.0/24 · local DNS")]
+    [InlineData("example.com,eth0", "example.com · interface eth0")]
+    [InlineData("example.com,local", "example.com · local DNS")]
+    public void FormatSummary_FormatsExpected(string line, string expectedContains)
+    {
+        var s = DomainRuleFields.FormatSummary(line);
+        Assert.Equal(expectedContains, s);
+    }
+
+    [Fact]
+    public void Parse_RoundTrip_Unconditional()
+    {
+        var f = DomainRuleFields.Parse("my.domain");
+        Assert.False(f.IsRaw);
+        Assert.Equal("my.domain", f.ToConfigLine());
+    }
+
+    [Fact]
+    public void Parse_RoundTrip_RangeAndLocal()
+    {
+        var line = "my.domain,10.0.0.0/24,local";
+        var f = DomainRuleFields.Parse(line);
+        Assert.False(f.IsRaw);
+        Assert.Equal(line, f.ToConfigLine());
+    }
+
+    [Fact]
+    public void Parse_RoundTrip_Interface()
+    {
+        var line = "my.domain,br0";
+        var f = DomainRuleFields.Parse(line);
+        Assert.False(f.IsRaw);
+        Assert.Equal(DomainRuleScope.InterfaceName, f.Scope);
+        Assert.Equal(line, f.ToConfigLine());
+    }
+
+    [Fact]
+    public void Parse_TooManyTokens_UsesRaw()
+    {
+        var line = "a,b,c,d";
+        var f = DomainRuleFields.Parse(line);
+        Assert.True(f.IsRaw);
+        Assert.Equal(line, f.ToConfigLine());
+    }
+
+    [Fact]
+    public void FromRawConfigLine_PreservesLine()
+    {
+        var f = DomainRuleFields.FromRawConfigLine("  weird,line,here  ");
+        Assert.True(f.IsRaw);
+        Assert.Equal("weird,line,here", f.ToConfigLine());
+    }
+}

src/DnsmasqWebUI.Tests/Services/Dnsmasq/Config/ConfigSetCacheEffectiveConfigTests.cs

@@ -0,0 +1,186 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config;
+using DnsmasqWebUI.Models.Config;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Services.Dnsmasq.Config;
+
+/// <summary>
+/// Tests effective-config resolution in ConfigSetCache (BuildEffectiveConfig / BuildEffectiveConfigSources).
+/// Verifies no-0x20-encode precedence and source attribution per dnsmasq docs.
+/// </summary>
+public class ConfigSetCacheEffectiveConfigTests
+{
+    private static (string Dir, string MainPath, string ManagedPath, ConfigSetCache Cache) CreateCacheWithManaged(string managedContent)
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-cache-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        File.WriteAllText(mainPath, "port=53\n");
+        File.WriteAllText(managedPath, managedContent);
+        var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+        var cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+        return (dir, mainPath, managedPath, cache);
+    }
+
+    [Fact]
+    public async Task Do0x20_BothPresent_No0x20Wins()
+    {
+        var (dir, _, managedPath, cache) = CreateCacheWithManaged("do-0x20-encode\nno-0x20-encode\n");
+        try
+        {
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(ExplicitToggleState.Disabled, snapshot.Config.Do0x20EncodeState);
+            Assert.NotNull(snapshot.Sources.Do0x20Encode);
+            Assert.Equal(Path.GetFullPath(managedPath), snapshot.Sources.Do0x20Encode.FilePath, StringComparer.OrdinalIgnoreCase);
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir)) Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task Do0x20_OnlyDo_Enabled()
+    {
+        var (dir, _, _, cache) = CreateCacheWithManaged("do-0x20-encode\n");
+        try
+        {
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(ExplicitToggleState.Enabled, snapshot.Config.Do0x20EncodeState);
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir)) Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task Do0x20_OnlyNo_Disabled()
+    {
+        var (dir, _, managedPath, cache) = CreateCacheWithManaged("no-0x20-encode\n");
+        try
+        {
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(ExplicitToggleState.Disabled, snapshot.Config.Do0x20EncodeState);
+            Assert.NotNull(snapshot.Sources.Do0x20Encode);
+            Assert.Equal(Path.GetFullPath(managedPath), snapshot.Sources.Do0x20Encode.FilePath, StringComparer.OrdinalIgnoreCase);
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir)) Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task Do0x20_Neither_Default()
+    {
+        var (dir, _, _, cache) = CreateCacheWithManaged("port=53\n");
+        try
+        {
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(ExplicitToggleState.Default, snapshot.Config.Do0x20EncodeState);
+            Assert.Null(snapshot.Sources.Do0x20Encode);
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir)) Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task Do0x20_SourceAttribution_WhenBothPresent_IsNo0x20Line()
+    {
+        var (dir, _, managedPath, cache) = CreateCacheWithManaged("no-0x20-encode\ndo-0x20-encode\n");
+        try
+        {
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(ExplicitToggleState.Disabled, snapshot.Config.Do0x20EncodeState);
+            Assert.NotNull(snapshot.Sources.Do0x20Encode);
+            Assert.Equal(Path.GetFullPath(managedPath), snapshot.Sources.Do0x20Encode.FilePath, StringComparer.OrdinalIgnoreCase);
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir)) Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task StripFlags_ParseState_And_Source()
+    {
+        var (dir, _, managedPath, cache) = CreateCacheWithManaged("strip-mac\nstrip-subnet\n");
+        try
+        {
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.True(snapshot.Config.StripMac);
+            Assert.True(snapshot.Config.StripSubnet);
+            Assert.NotNull(snapshot.Sources.StripMac);
+            Assert.NotNull(snapshot.Sources.StripSubnet);
+            Assert.Equal(Path.GetFullPath(managedPath), snapshot.Sources.StripMac!.FilePath, StringComparer.OrdinalIgnoreCase);
+            Assert.Equal(Path.GetFullPath(managedPath), snapshot.Sources.StripSubnet!.FilePath, StringComparer.OrdinalIgnoreCase);
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir)) Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task RealWorldCorpus_EdgeCommentedActiveMix_Do0x20StateAndSource()
+    {
+        var mainPath = TestDataHelper.GetPath("real-world/edge/dnsmasq-real-edge-commented-active-mix.conf");
+        Assert.True(File.Exists(mainPath));
+        var dir = Path.GetDirectoryName(mainPath)!;
+        var managedName = "zz-managed.conf";
+        var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+        using var cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+        cache.Invalidate();
+        var snapshot = await cache.GetSnapshotAsync();
+        Assert.Equal(ExplicitToggleState.Disabled, snapshot.Config.Do0x20EncodeState);
+        Assert.NotNull(snapshot.Sources.Do0x20Encode);
+        Assert.Single(snapshot.Config.ServerValues);
+        Assert.Equal("1.1.1.1", snapshot.Config.ServerValues[0]);
+    }
+
+    [Fact]
+    public async Task RealWorldCorpus_GoodHomeBasic_ServerCountAndSource()
+    {
+        var mainPath = TestDataHelper.GetPath("real-world/good/dnsmasq-real-home-basic.conf");
+        Assert.True(File.Exists(mainPath));
+        var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = "zz-managed.conf" });
+        using var cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+        cache.Invalidate();
+        var snapshot = await cache.GetSnapshotAsync();
+        Assert.True(snapshot.Config.ServerValues.Count >= 2);
+        Assert.Equal(2, snapshot.Sources.ServerValues.Count);
+    }
+
+    [Fact]
+    public async Task RealWorldCorpus_GoodResolverRich_LocalAddressCacheSizeFlags()
+    {
+        var mainPath = TestDataHelper.GetPath("real-world/good/dnsmasq-real-resolver-rich.conf");
+        Assert.True(File.Exists(mainPath));
+        var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = "zz-managed.conf" });
+        using var cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+        cache.Invalidate();
+        var snapshot = await cache.GetSnapshotAsync();
+        Assert.True(snapshot.Config.ServerValues.Count >= 2);
+        Assert.True(snapshot.Config.LocalValues.Count >= 2);
+        Assert.True(snapshot.Config.AddressValues.Count >= 2);
+        Assert.Equal(1000, snapshot.Config.CacheSize);
+        Assert.True(snapshot.Config.NoResolv);
+        Assert.True(snapshot.Config.BogusPriv);
+        Assert.True(snapshot.Config.ExpandHosts);
+    }
+}

src/DnsmasqWebUI.Tests/Services/Dnsmasq/Config/DnsmasqConfigServiceApplyChangesTests.cs

@@ -0,0 +1,735 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config;
+using DnsmasqWebUI.Models.Config;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+
+namespace DnsmasqWebUI.Tests.Services.Dnsmasq.Config;
+
+/// <summary>
+/// Save-path tests for DnsmasqConfigService.ApplyEffectiveConfigChangesAsync.
+/// Verifies that pending changes produce the correct managed config lines.
+/// </summary>
+public class DnsmasqConfigServiceApplyChangesTests
+{
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_ConntrackTrue_WritesBareFlagLine()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Conntrack, false, true, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            Assert.True(File.Exists(managedPath));
+            var content = await File.ReadAllTextAsync(managedPath);
+            var lines = content.TrimEnd().Split('\n').Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
+            Assert.Contains(lines, l => l == "conntrack");
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_ConntrackFalse_RemovesFlagLine()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            File.WriteAllText(managedPath, "conntrack\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            cache.Invalidate();
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Conntrack, true, false, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            var lines = content.TrimEnd().Split('\n').Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
+            Assert.DoesNotContain(lines, l => l == "conntrack" || l.StartsWith("conntrack=", StringComparison.Ordinal));
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_StripMacTrue_WritesBareFlagLine()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.StripMac, false, true, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            Assert.True(File.Exists(managedPath));
+            var content = await File.ReadAllTextAsync(managedPath);
+            var lines = content.TrimEnd().Split('\n').Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
+            Assert.Contains(lines, l => l == DnsmasqConfKeys.StripMac);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_StripSubnetFalse_RemovesFlagLine()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            File.WriteAllText(managedPath, "strip-subnet\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            cache.Invalidate();
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.StripSubnet, true, false, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            var lines = content.TrimEnd().Split('\n').Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
+            Assert.DoesNotContain(lines, l => l == DnsmasqConfKeys.StripSubnet || l.StartsWith($"{DnsmasqConfKeys.StripSubnet}=", StringComparison.Ordinal));
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_DnssecCheckUnsignedNo_WritesEqualsNo()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionDnssec, DnsmasqConfKeys.DnssecCheckUnsigned, null, "no", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            Assert.True(File.Exists(managedPath));
+            var text = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("dnssec-check-unsigned=no", text);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_SingleValueNull_RemovesExistingLine()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            File.WriteAllText(managedPath, "port=54\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            cache.Invalidate();
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Port, "54", null, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            var lines = content.TrimEnd().Split('\n').Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
+            Assert.DoesNotContain(lines, l => l == DnsmasqConfKeys.Port || l.StartsWith($"{DnsmasqConfKeys.Port}=", StringComparison.Ordinal));
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_KeyOnlyOrValue_KeyOnly_WritesBareKey()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.UseStaleCache, null, "", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            Assert.True(File.Exists(managedPath));
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("use-stale-cache", content);
+            Assert.DoesNotContain("use-stale-cache=", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_InversePair_Enabled_WritesDo0x20Encode()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Do0x20Encode, ExplicitToggleState.Default, ExplicitToggleState.Enabled, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            Assert.True(File.Exists(managedPath));
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("do-0x20-encode", content);
+            Assert.DoesNotContain("no-0x20-encode", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_Do0x20_Default_RemovesBothLines()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            File.WriteAllText(managedPath, "do-0x20-encode\nno-0x20-encode\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            cache.Invalidate();
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Do0x20Encode, ExplicitToggleState.Disabled, ExplicitToggleState.Default, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            var lines = content.TrimEnd().Split('\n').Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
+            Assert.DoesNotContain(lines, l => l == "do-0x20-encode" || l == "no-0x20-encode");
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_Do0x20Enabled_RoundTripsToEffectiveState()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-roundtrip-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Do0x20Encode, ExplicitToggleState.Default, ExplicitToggleState.Enabled, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+            cache.Invalidate();
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(ExplicitToggleState.Enabled, snapshot.Config.Do0x20EncodeState);
+            Assert.NotNull(snapshot.Sources.Do0x20Encode);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_UseStaleCache_RoundTripsToEffectiveState()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-roundtrip-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.UseStaleCache, null, "60", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+            cache.Invalidate();
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal("60", snapshot.Config.UseStaleCache);
+            Assert.NotNull(snapshot.Sources.UseStaleCache);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_Server_RoundTripsToEffectiveState()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-roundtrip-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Server, null, new List<string> { "1.1.1.1", "8.8.8.8" }, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+            cache.Invalidate();
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.Equal(2, snapshot.Config.ServerValues.Count);
+            Assert.Contains("1.1.1.1", snapshot.Config.ServerValues);
+            Assert.Contains("8.8.8.8", snapshot.Config.ServerValues);
+            Assert.Equal(2, snapshot.Sources.ServerValues.Count);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_Conntrack_RoundTripsToEffectiveState()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-roundtrip-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Conntrack, false, true, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+            cache.Invalidate();
+            var snapshot = await cache.GetSnapshotAsync();
+            Assert.True(snapshot.Config.Conntrack);
+            Assert.NotNull(snapshot.Sources.Conntrack);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_Do0x20_Disabled_WritesNo0x20Encode()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionResolver, DnsmasqConfKeys.Do0x20Encode, ExplicitToggleState.Default, ExplicitToggleState.Disabled, null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("no-0x20-encode", content);
+            Assert.DoesNotContain("do-0x20-encode", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_UseStaleCache_Value_WritesKeyEqualsValue()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.UseStaleCache, null, "60", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("use-stale-cache=60", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_AddMac_KeyOnly_WritesBareKey()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.AddMac, null, "", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("add-mac", content);
+            Assert.DoesNotContain("add-mac=", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_AddMac_ValueBase64_WritesKeyEqualsValue()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.AddMac, null, "base64", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("add-mac=base64", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_AddSubnet_KeyOnly_WritesBareKey()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.AddSubnet, null, "", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("add-subnet", content);
+            Assert.DoesNotContain("add-subnet=", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyChanges_Umbrella_KeyOnly_WritesBareKey()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(EffectiveConfigSections.SectionCache, DnsmasqConfKeys.Umbrella, null, "", null)
+            };
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var content = await File.ReadAllTextAsync(managedPath);
+            Assert.Contains("umbrella", content);
+            Assert.DoesNotContain("umbrella=", content);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task ApplyEffectiveConfigChangesAsync_Leasequery_MultiKeyOnlyOrValue_DoesNotDuplicateReadonlyValues()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-apply-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var readonlyPath = Path.Combine(dir, "readonly.conf");
+        var managedName = "zz-managed.conf";
+        var managedPath = Path.Combine(dir, managedName);
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, $"port=53\nconf-file={readonlyPath}\n");
+            File.WriteAllText(readonlyPath, "leasequery\nleasequery=10.0.0.0/24\n");
+            File.WriteAllText(managedPath, "leasequery=172.16.0.0/16\n");
+
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            cache.Invalidate();
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            // Simulate UI effective values (readonly + managed). Save should write only managed-only values.
+            var changes = new List<PendingEffectiveConfigChange>
+            {
+                new(
+                    EffectiveConfigSections.SectionDhcp,
+                    DnsmasqConfKeys.Leasequery,
+                    null,
+                    new List<string> { "", "10.0.0.0/24", "192.168.50.0/24" },
+                    null)
+            };
+
+            await configService.ApplyEffectiveConfigChangesAsync(changes);
+
+            var lines = (await File.ReadAllLinesAsync(managedPath))
+                .Select(l => l.Trim())
+                .Where(l => l.StartsWith("leasequery", StringComparison.Ordinal))
+                .ToList();
+
+            Assert.Single(lines);
+            Assert.Equal("leasequery=192.168.50.0/24", lines[0]);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+}

src/DnsmasqWebUI.Tests/Services/Dnsmasq/Config/DnsmasqConfigSetServiceTests.cs

@@ -1,11 +1,11 @@
 using DnsmasqWebUI.Models.Config;
 using DnsmasqWebUI.Models.Dnsmasq;
 using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
-using DnsmasqWebUI.Infrastructure.Services;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Options;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Services.Dnsmasq.Config;
 
 /// <summary>
 /// Tests for DnsmasqConfigSetService, including GetEffectiveConfigWithSources.
@@ -25,7 +25,8 @@ public class DnsmasqConfigSetServiceTests
         Assert.Empty(config.AddnHostsPaths);
         Assert.NotNull(sources);
         Assert.Empty(sources.AddnHostsPaths);
-        Assert.Empty(sources.ServerLocalValues);
+        Assert.Empty(sources.ServerValues);
+        Assert.Empty(sources.LocalValues);
         Assert.Empty(sources.DhcpRanges);
         Assert.Null(sources.NoHosts);
         Assert.Null(sources.Port);
@@ -59,7 +60,8 @@ public class DnsmasqConfigSetServiceTests
             Assert.Equal(cacheSize, config.CacheSize);
             Assert.Single(config.AddnHostsPaths);
             Assert.Equal(Path.GetFullPath(addnHostsPath), config.AddnHostsPaths[0]);
-            Assert.Empty(config.ServerLocalValues);
+            Assert.Empty(config.ServerValues);
+            Assert.Empty(config.LocalValues);
             Assert.Empty(config.DhcpRanges);
 
             Assert.NotNull(sources);

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/CrossOption/CrossOptionRulesTests.cs

@@ -0,0 +1,462 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Rules;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig.CrossOption;
+
+public class CrossOptionRulesTests
+{
+    private static EffectiveConfigCrossOptionContext Ctx(EffectiveDnsmasqConfig cfg) =>
+        new(CrossOptionTestHelpers.Status(cfg), []);
+
+    [Fact]
+    public void NoResolvWithoutUpstreamsRule_Warns_when_no_server_and_no_resolv_file()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { NoResolv = true };
+        var rule = new NoResolvWithoutUpstreamsRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        var key = EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.Server);
+        Assert.Single(issues);
+        Assert.Equal(key, issues[0].FieldKey);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+    }
+
+    [Fact]
+    public void NoResolvWithoutUpstreamsRule_No_issue_when_resolv_file_configured()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            NoResolv = true,
+            ResolvFiles = ["/run/resolv.conf"]
+        };
+        var rule = new NoResolvWithoutUpstreamsRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void ConntrackWithQueryPortRule_Error_when_both_set()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { Conntrack = true, QueryPort = 5353 };
+        var rule = new ConntrackWithQueryPortRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Error, issues[0].Severity);
+        Assert.Contains("query-port", issues[0].Message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void RebindExceptionsRequireStopDnsRebindRule_Warns_on_localhost_ok_without_stop()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { RebindLocalhostOk = true };
+        var rule = new RebindExceptionsRequireStopDnsRebindRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+    }
+
+    [Fact]
+    public void BogusPrivBlocksPrivateReverseServerRule_Warns_for_private_in_addr_server()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            ServerValues = ["/0.168.192.in-addr.arpa/10.0.0.1"]
+        };
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.Server),
+            issues[0].FieldKey);
+    }
+
+    [Theory]
+    [InlineData("/10.in-addr.arpa/8.8.8.8")]
+    [InlineData("/31.172.in-addr.arpa/8.8.8.8")]
+    public void BogusPrivBlocksPrivateReverseServerRule_Warns_for_rfc1918_zone_roots(string serverValue)
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            ServerValues = [serverValue]
+        };
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        Assert.Single(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Theory]
+    [InlineData("/210.in-addr.arpa/8.8.8.8")]
+    [InlineData("/110.in-addr.arpa/8.8.8.8")]
+    [InlineData("/1.0.0.192.in-addr.arpa/8.8.8.8")]
+    [InlineData("/15.172.in-addr.arpa/8.8.8.8")]
+    [InlineData("/32.172.in-addr.arpa/8.8.8.8")]
+    [InlineData("/10.0.0.192.in-addr.arpa/8.8.8.8")]
+    public void BogusPrivBlocksPrivateReverseServerRule_No_issue_for_non_private_in_addr_substrings(string serverValue)
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            ServerValues = [serverValue]
+        };
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Theory]
+    [InlineData("192.168.1.0/24,8.8.8.8")]
+    [InlineData("10.0.0.0/8,8.8.8.8")]
+    [InlineData("172.16.0.0/12,8.8.8.8")]
+    public void BogusPrivBlocksPrivateReverseServerRule_Warns_for_rfc1918_rev_server(string revServerValue)
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            RevServerValues = [revServerValue]
+        };
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.RevServer),
+            issues[0].FieldKey);
+    }
+
+    [Theory]
+    [InlineData("8.8.8.0/24,1.1.1.1")]
+    [InlineData("1.0.0.0/8,1.1.1.1")]
+    public void BogusPrivBlocksPrivateReverseServerRule_No_issue_for_public_rev_server(string revServerValue)
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            RevServerValues = [revServerValue]
+        };
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void BogusPrivBlocksPrivateReverseServerRule_Emits_separate_issues_for_server_and_rev_server()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            ServerValues = ["/0.168.192.in-addr.arpa/10.0.0.1"],
+            RevServerValues = ["192.168.2.0/24,8.8.8.8"]
+        };
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Equal(2, issues.Count);
+        Assert.Contains(
+            issues,
+            i => i.FieldKey == EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.Server));
+        Assert.Contains(
+            issues,
+            i => i.FieldKey == EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.RevServer));
+    }
+
+    [Fact]
+    public void BogusPrivBlocksPrivateReverseServerRule_Pending_rev_server_overrides_disk()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            BogusPriv = true,
+            RevServerValues = ["8.8.8.0/24,1.1.1.1"]
+        };
+        var pending = new[]
+        {
+            new PendingOptionChange(
+                "resolver",
+                DnsmasqConfKeys.RevServer,
+                Array.Empty<string>(),
+                new[] { "192.168.1.0/24,8.8.8.8" },
+                null)
+        };
+        var ctx = new EffectiveConfigCrossOptionContext(CrossOptionTestHelpers.Status(cfg), pending);
+        var rule = new BogusPrivBlocksPrivateReverseServerRule();
+        var issues = rule.Evaluate(ctx);
+        Assert.Single(issues);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.RevServer),
+            issues[0].FieldKey);
+    }
+
+    [Fact]
+    public void NoPingWithDhcpSequentialIpRule_Warns_when_both_set()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            NoPing = true,
+            DhcpSequentialIp = true
+        };
+        var rule = new NoPingWithDhcpSequentialIpRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.DhcpSequentialIp),
+            issues[0].FieldKey);
+    }
+
+    [Theory]
+    [InlineData(true, false)]
+    [InlineData(false, true)]
+    [InlineData(false, false)]
+    public void NoPingWithDhcpSequentialIpRule_No_issue_unless_both(bool noPing, bool sequential)
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            NoPing = noPing,
+            DhcpSequentialIp = sequential
+        };
+        var rule = new NoPingWithDhcpSequentialIpRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void DnsPortZeroWithTftpOrPxeRule_Warns_when_port_zero_and_enable_tftp()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            Port = 0,
+            EnableTftp = true
+        };
+        var rule = new DnsPortZeroWithTftpOrPxeRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.Port),
+            issues[0].FieldKey);
+    }
+
+    [Fact]
+    public void DnsPortZeroWithTftpOrPxeRule_Warns_when_port_zero_and_pxe_service()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            Port = 0,
+            PxeServiceValues = ["x86PC,Boot from network,pxelinux"]
+        };
+        var rule = new DnsPortZeroWithTftpOrPxeRule();
+        Assert.Single(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void DnsPortZeroWithTftpOrPxeRule_No_issue_when_port_nonzero_even_with_netboot()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            Port = 53,
+            EnableTftp = true,
+            PxeServiceValues = ["x86PC,Boot from network,pxelinux"]
+        };
+        var rule = new DnsPortZeroWithTftpOrPxeRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void DnsPortZeroWithTftpOrPxeRule_No_issue_when_port_zero_without_tftp_or_pxe()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { Port = 0 };
+        var rule = new DnsPortZeroWithTftpOrPxeRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void DnssecPrerequisitesRule_Error_when_build_lacks_dnssec()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { Dnssec = true };
+        var status = CrossOptionTestHelpers.Status(cfg, dnsmasqSupportsDnssec: false);
+        var ctx = new EffectiveConfigCrossOptionContext(status, []);
+        var rule = new DnssecPrerequisitesRule();
+        var issues = rule.Evaluate(ctx);
+        var dnssecKey = EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.Dnssec);
+        Assert.Contains(issues, i =>
+            i.Severity == FieldIssueSeverity.Error && i.FieldKey == dnssecKey);
+    }
+
+    [Fact]
+    public void DnssecPrerequisitesRule_Warns_when_no_trust_anchors()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { Dnssec = true };
+        var rule = new DnssecPrerequisitesRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        var trustAnchorKey = EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.TrustAnchor);
+        Assert.Contains(issues, i =>
+            i.Severity == FieldIssueSeverity.Warning &&
+            i.FieldKey == trustAnchorKey &&
+            i.Message.Contains("trust-anchor", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public void ProxyDnssecCacheWarningRule_Warns_when_cache_not_zero()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            ProxyDnssec = true,
+            CacheSize = 150
+        };
+        var rule = new ProxyDnssecCacheWarningRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.CacheSize),
+            issues[0].FieldKey);
+    }
+
+    [Fact]
+    public void ConnmarkAllowlistEnableRequiresAllowlistRule_Error_when_enable_key_only()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { ConnmarkAllowlistEnable = "" };
+        var rule = new ConnmarkAllowlistEnableRequiresAllowlistRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Error, issues[0].Severity);
+    }
+
+    [Fact]
+    public void ConnmarkAllowlistEnableRequiresAllowlistRule_No_issue_when_allowlists_present()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            ConnmarkAllowlistEnable = "0xff",
+            ConnmarkAllowlistValues = ["0x1,*.example.com"]
+        };
+        var rule = new ConnmarkAllowlistEnableRequiresAllowlistRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void QueryPortIgnoredForSourceBoundServerRule_Warns_when_server_has_at()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            QueryPort = 12345,
+            ServerValues = ["10.0.0.1@192.168.1.1"]
+        };
+        var rule = new QueryPortIgnoredForSourceBoundServerRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+    }
+
+    [Fact]
+    public void AddSubnetCacheBehaviorRule_Warns_when_add_subnet_set()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { AddSubnet = "24,96" };
+        var rule = new AddSubnetCacheBehaviorRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.AddSubnet),
+            issues[0].FieldKey);
+    }
+
+    [Fact]
+    public void Filterwin2kSrvWarningRule_Warns_when_enabled()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { Filterwin2k = true };
+        var rule = new Filterwin2kSrvWarningRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Contains("SRV", issues[0].Message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void AddressLocalDnsmasq286CompatibilityRule_Warns_for_domain_address()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            AddressValues = ["/example.com/192.0.2.1"]
+        };
+        var rule = new AddressLocalDnsmasq286CompatibilityRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+    }
+
+    [Fact]
+    public void AddressLocalDnsmasq286CompatibilityRule_No_issue_when_matching_local_exists()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            AddressValues = ["/example.com/192.0.2.1"],
+            LocalValues = ["/example.com/"]
+        };
+        var rule = new AddressLocalDnsmasq286CompatibilityRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void AddressLocalDnsmasq286CompatibilityRule_No_issue_for_nxdomain_form_without_ip()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            AddressValues = ["/ads.example/"]
+        };
+        var rule = new AddressLocalDnsmasq286CompatibilityRule();
+        Assert.Empty(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void AddressLocalDnsmasq286CompatibilityRule_Warns_for_hash_target_without_local()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            AddressValues = ["/blocked.example/#"]
+        };
+        var rule = new AddressLocalDnsmasq286CompatibilityRule();
+        Assert.Single(rule.Evaluate(Ctx(cfg)));
+    }
+
+    [Fact]
+    public void DnssecCheckUnsignedRequiresDnssecRule_Warns_when_dnssec_check_unsigned_set_without_dnssec()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            Dnssec = false,
+            DnssecCheckUnsigned = ""
+        };
+        var rule = new DnssecCheckUnsignedRequiresDnssecRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.DnssecCheckUnsigned),
+            issues[0].FieldKey);
+    }
+
+    [Fact]
+    public void LocalServiceIgnoredByBindSettingsRule_Warns_when_local_service_with_interface_filters()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            LocalService = "net",
+            Interfaces = ["eth0"]
+        };
+        var rule = new LocalServiceIgnoredByBindSettingsRule();
+        var issues = rule.Evaluate(Ctx(cfg));
+        Assert.Single(issues);
+        Assert.Equal(FieldIssueSeverity.Warning, issues[0].Severity);
+        Assert.Equal(
+            EffectiveConfigCrossOptionContext.FieldKeyForOption(DnsmasqConfKeys.LocalService),
+            issues[0].FieldKey);
+    }
+
+    [Fact]
+    public void Pending_overlay_overrides_config_for_cross_option_rules()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { NoResolv = false };
+        var pending = new[]
+        {
+            new PendingOptionChange("resolver", DnsmasqConfKeys.NoResolv, false, true, null)
+        };
+        var ctx = new EffectiveConfigCrossOptionContext(CrossOptionTestHelpers.Status(cfg), pending);
+        var rule = new NoResolvWithoutUpstreamsRule();
+        var issues = rule.Evaluate(ctx);
+        Assert.Single(issues);
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/CrossOption/CrossOptionTestHelpers.cs

@@ -0,0 +1,226 @@
+using DnsmasqWebUI.Models.Dnsmasq;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig.CrossOption;
+
+internal static class CrossOptionTestHelpers
+{
+    /// <summary>Minimal baseline effective config; override with record <c>with</c> in tests.</summary>
+    public static EffectiveDnsmasqConfig BaselineConfig() =>
+        new(
+            NoHosts: false,
+            AddnHostsPaths: Array.Empty<string>(),
+            HostsdirPath: null,
+            ServerValues: Array.Empty<string>(),
+            LocalValues: Array.Empty<string>(),
+            RevServerValues: Array.Empty<string>(),
+            AddressValues: Array.Empty<string>(),
+            Interfaces: Array.Empty<string>(),
+            ListenAddresses: Array.Empty<string>(),
+            ExceptInterfaces: Array.Empty<string>(),
+            DhcpRanges: Array.Empty<string>(),
+            DhcpHostLines: Array.Empty<string>(),
+            DhcpOptionLines: Array.Empty<string>(),
+            DhcpMatchValues: Array.Empty<string>(),
+            DhcpBootValues: Array.Empty<string>(),
+            DhcpIgnoreValues: Array.Empty<string>(),
+            DhcpVendorclassValues: Array.Empty<string>(),
+            DhcpUserclassValues: Array.Empty<string>(),
+            RaParamValues: Array.Empty<string>(),
+            SlaacValues: Array.Empty<string>(),
+            PxeServiceValues: Array.Empty<string>(),
+            TrustAnchorValues: Array.Empty<string>(),
+            ResolvFiles: Array.Empty<string>(),
+            RebindDomainOkValues: Array.Empty<string>(),
+            BogusNxdomainValues: Array.Empty<string>(),
+            IgnoreAddressValues: Array.Empty<string>(),
+            AliasValues: Array.Empty<string>(),
+            FilterRrValues: Array.Empty<string>(),
+            CacheRrValues: Array.Empty<string>(),
+            AuthServerValues: Array.Empty<string>(),
+            NoDhcpInterfaceValues: Array.Empty<string>(),
+            NoDhcpv4InterfaceValues: Array.Empty<string>(),
+            NoDhcpv6InterfaceValues: Array.Empty<string>(),
+            DomainValues: Array.Empty<string>(),
+            CnameValues: Array.Empty<string>(),
+            MxHostValues: Array.Empty<string>(),
+            SrvValues: Array.Empty<string>(),
+            PtrRecordValues: Array.Empty<string>(),
+            TxtRecordValues: Array.Empty<string>(),
+            NaptrRecordValues: Array.Empty<string>(),
+            HostRecordValues: Array.Empty<string>(),
+            DynamicHostValues: Array.Empty<string>(),
+            InterfaceNameValues: Array.Empty<string>(),
+            DhcpOptionForceLines: Array.Empty<string>(),
+            IpsetValues: Array.Empty<string>(),
+            NftsetValues: Array.Empty<string>(),
+            DhcpMacValues: Array.Empty<string>(),
+            DhcpNameMatchValues: Array.Empty<string>(),
+            DhcpIgnoreNamesValues: Array.Empty<string>(),
+            DhcpHostsfilePaths: Array.Empty<string>(),
+            DhcpOptsfilePaths: Array.Empty<string>(),
+            DhcpHostsdirPaths: Array.Empty<string>(),
+            DhcpOptsdirPaths: Array.Empty<string>(),
+            ConnmarkAllowlistValues: Array.Empty<string>(),
+            CaaRecordValues: Array.Empty<string>(),
+            DnsRrValues: Array.Empty<string>(),
+            SynthDomainValues: Array.Empty<string>(),
+            AuthZoneValues: Array.Empty<string>(),
+            AuthSoaValues: Array.Empty<string>(),
+            AuthSecServersValues: Array.Empty<string>(),
+            AuthPeerValues: Array.Empty<string>(),
+            DhcpRelayValues: Array.Empty<string>(),
+            DhcpCircuitidValues: Array.Empty<string>(),
+            DhcpRemoteidValues: Array.Empty<string>(),
+            DhcpSubscridValues: Array.Empty<string>(),
+            DhcpProxyValues: Array.Empty<string>(),
+            TagIfValues: Array.Empty<string>(),
+            BridgeInterfaceValues: Array.Empty<string>(),
+            SharedNetworkValues: Array.Empty<string>(),
+            DhcpOptionPxeValues: Array.Empty<string>(),
+            ExpandHosts: false,
+            BogusPriv: false,
+            StrictOrder: false,
+            AllServers: false,
+            NoResolv: false,
+            DomainNeeded: false,
+            NoPoll: false,
+            BindInterfaces: false,
+            BindDynamic: false,
+            NoNegcache: false,
+            DnsLoopDetect: false,
+            StopDnsRebind: false,
+            RebindLocalhostOk: false,
+            ClearOnReload: false,
+            Filterwin2k: false,
+            FilterA: false,
+            FilterAaaa: false,
+            LocaliseQueries: false,
+            LogDebug: false,
+            DhcpAuthoritative: false,
+            LeasefileRo: false,
+            EnableTftp: false,
+            TftpSecure: false,
+            TftpNoFail: false,
+            TftpNoBlocksize: false,
+            Dnssec: false,
+            DnssecCheckUnsigned: null,
+            ReadEthers: false,
+            DhcpRapidCommit: false,
+            Localmx: false,
+            Selfmx: false,
+            EnableRa: false,
+            LogDhcp: false,
+            KeepInForeground: false,
+            NoDaemon: false,
+            ProxyDnssec: false,
+            ConnmarkAllowlistEnable: null,
+            NoRoundRobin: false,
+            DnssecNoTimecheck: false,
+            DnssecDebug: false,
+            LeasequeryValues: Array.Empty<string>(),
+            DhcpGenerateNames: null,
+            DhcpBroadcast: null,
+            DhcpSequentialIp: false,
+            DhcpIgnoreClid: false,
+            BootpDynamic: null,
+            NoPing: false,
+            ScriptArp: false,
+            ScriptOnRenewal: false,
+            DhcpNoOverride: false,
+            QuietDhcp: false,
+            QuietDhcp6: false,
+            QuietRa: false,
+            QuietTftp: false,
+            DhcpLeaseFilePath: null,
+            CacheSize: null,
+            Port: null,
+            LocalTtl: null,
+            PidFilePath: null,
+            User: null,
+            Group: null,
+            LogFacility: null,
+            LogQueries: null,
+            AuthTtl: null,
+            EdnsPacketMax: null,
+            QueryPort: null,
+            PortLimit: null,
+            MinPort: null,
+            MaxPort: null,
+            LogAsync: null,
+            LocalService: null,
+            DhcpLeaseMax: null,
+            NegTtl: null,
+            MaxTtl: null,
+            MaxCacheTtl: null,
+            MinCacheTtl: null,
+            DhcpTtl: null,
+            TftpRootPath: null,
+            PxePrompt: null,
+            EnableDbus: null,
+            EnableUbus: null,
+            FastDnsRetry: null,
+            DhcpScriptPath: null,
+            MxTarget: null,
+            DnsForwardMax: null,
+            DumpfilePath: null,
+            Dumpmask: null,
+            AddCpeId: null,
+            DnssecTimestamp: null,
+            DnssecLimits: null,
+            DhcpAlternatePort: null,
+            DhcpDuid: null,
+            DhcpLuascriptPath: null,
+            DhcpScriptuser: null,
+            DhcpPxeVendor: null,
+            UseStaleCache: null,
+            AddMac: null,
+            StripMac: false,
+            AddSubnet: null,
+            StripSubnet: false,
+            Umbrella: null,
+            Do0x20EncodeState: ExplicitToggleState.Default,
+            Conntrack: false);
+
+    public static DnsmasqServiceStatus Status(EffectiveDnsmasqConfig config, bool dnsmasqSupportsDnssec = true) =>
+        new(
+            SystemHostsPath: null,
+            SystemHostsPathExists: false,
+            ManagedHostsFilePath: null,
+            ManagedHostsPathExists: false,
+            NoHosts: false,
+            AddnHostsPaths: Array.Empty<string>(),
+            EffectiveConfig: config,
+            EffectiveConfigSources: null,
+            MainConfigPath: null,
+            ManagedFilePath: null,
+            LeasesPath: null,
+            MainConfigPathExists: false,
+            ManagedFilePathExists: false,
+            LeasesPathConfigured: false,
+            LeasesPathExists: false,
+            ConfigFiles: null,
+            ReloadCommandConfigured: false,
+            StatusCommandConfigured: false,
+            StatusShowConfigured: false,
+            LogsConfigured: false,
+            LogsPath: null,
+            StatusShowCommand: null,
+            LogsCommand: null,
+            DnsmasqStatus: "active",
+            StatusCommandExitCode: null,
+            StatusCommandStdout: null,
+            StatusCommandStderr: null,
+            StatusShowOutput: null,
+            LogsOutput: null,
+            DhcpRangeStart: null,
+            DhcpRangeEnd: null,
+            DnsmasqVersion: "2.91",
+            MinimumSupportedDnsmasqVersion: "2.91",
+            DnsmasqVersionSupported: true,
+            DnsmasqVersionError: null,
+            DnsmasqSupportsDhcp: true,
+            DnsmasqSupportsTftp: true,
+            DnsmasqSupportsDnssec: dnsmasqSupportsDnssec,
+            DnsmasqSupportsDbus: false);
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/CrossOption/EffectiveConfigCrossOptionContextTests.cs

@@ -0,0 +1,46 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig.CrossOption;
+
+public class EffectiveConfigCrossOptionContextTests
+{
+    [Fact]
+    public void GetMulti_WhenPendingNewValueIsNull_ReturnsEmpty_NotDiskValues()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { ServerValues = ["1.1.1.1", "8.8.8.8"] };
+        var pending = new[]
+        {
+            new PendingOptionChange("resolver", DnsmasqConfKeys.Server, new List<string> { "1.1.1.1" }, null, null)
+        };
+        var ctx = new EffectiveConfigCrossOptionContext(CrossOptionTestHelpers.Status(cfg), pending);
+        Assert.Empty(ctx.GetMulti(DnsmasqConfKeys.Server, c => c.ServerValues));
+    }
+
+    [Fact]
+    public void GetMulti_WhenPendingNewValueIsList_ReturnsPending_NotDisk()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { ServerValues = ["9.9.9.9"] };
+        var pending = new[]
+        {
+            new PendingOptionChange("resolver", DnsmasqConfKeys.Server, null, new List<string> { "1.1.1.1" }, null)
+        };
+        var ctx = new EffectiveConfigCrossOptionContext(CrossOptionTestHelpers.Status(cfg), pending);
+        var v = ctx.GetMulti(DnsmasqConfKeys.Server, c => c.ServerValues);
+        Assert.Single(v);
+        Assert.Equal("1.1.1.1", v[0]);
+    }
+
+    [Fact]
+    public void GetMulti_WhenPendingNewValueIsWrongType_ReturnsEmpty_NotDiskValues()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with { ServerValues = ["1.1.1.1"] };
+        var pending = new[]
+        {
+            new PendingOptionChange("resolver", DnsmasqConfKeys.Server, null, "not-a-list", null)
+        };
+        var ctx = new EffectiveConfigCrossOptionContext(CrossOptionTestHelpers.Status(cfg), pending);
+        Assert.Empty(ctx.GetMulti(DnsmasqConfKeys.Server, c => c.ServerValues));
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/CrossOption/EffectiveConfigCrossOptionValidationServiceTests.cs

@@ -0,0 +1,30 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Rules;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig.CrossOption;
+
+public class EffectiveConfigCrossOptionValidationServiceTests
+{
+    [Fact]
+    public void Validate_aggregates_issues_from_all_rules()
+    {
+        var cfg = CrossOptionTestHelpers.BaselineConfig() with
+        {
+            Conntrack = true,
+            QueryPort = 1,
+            Filterwin2k = true
+        };
+        var status = CrossOptionTestHelpers.Status(cfg);
+        IReadOnlyList<IEffectiveConfigCrossOptionRule> rules =
+        [
+            new ConntrackWithQueryPortRule(),
+            new Filterwin2kSrvWarningRule()
+        ];
+        var service = new EffectiveConfigCrossOptionValidationService(rules);
+
+        var issues = service.Validate(status, []);
+
+        Assert.Equal(2, issues.Count);
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigEditSessionChangedEventTests.cs

@@ -0,0 +1,82 @@
+using System.Linq;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Abstractions;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using DnsmasqWebUI.Models.Hosts;
+using Microsoft.Extensions.Logging.Abstractions;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+public class EffectiveConfigEditSessionChangedEventTests
+{
+    [Fact]
+    public void TrackCommit_RaisesChanged()
+    {
+        var saveService = new StubSaveService();
+        var session = new EffectiveConfigEditSession(saveService);
+        session.Ui.EnterEditMode();
+        var raised = false;
+        session.Changed += () => raised = true;
+        session.Draft.TrackCommit(new EffectiveConfigEditCommittedArgs("resolver", "port", null, 5353, null));
+        Assert.True(raised);
+    }
+
+    [Fact]
+    public void EnterEditMode_RaisesChanged()
+    {
+        var saveService = new StubSaveService();
+        var session = new EffectiveConfigEditSession(saveService);
+        var raised = false;
+        session.Changed += () => raised = true;
+        session.Ui.EnterEditMode();
+        Assert.True(raised);
+    }
+
+    [Fact]
+    public void RevertChange_RaisesChanged()
+    {
+        var saveService = new StubSaveService();
+        var session = new EffectiveConfigEditSession(saveService);
+        session.Ui.EnterEditMode();
+        session.Draft.TrackCommit(new EffectiveConfigEditCommittedArgs("resolver", "port", null, 5353, null));
+        var raised = false;
+        session.Changed += () => raised = true;
+        session.Draft.RevertChange("resolver", "port");
+        Assert.True(raised);
+    }
+
+    [Fact]
+    public void Ui_EnterEditMode_DoesNotClearDraft()
+    {
+        var saveService = new StubSaveService();
+        var session = new EffectiveConfigEditSession(saveService);
+        var oldEntries = new List<HostEntry> { new() { Address = "1.2.3.4", Names = new List<string> { "a" } } };
+        var newEntries = new List<HostEntry> { new() { Address = "1.2.3.4", Names = new List<string> { "b" } } };
+        session.Draft.SetManagedHostsDraft(oldEntries, newEntries, "/tmp/managed.hosts");
+        Assert.Single(session.Draft.PendingChanges);
+        session.Ui.EnterEditMode();
+        Assert.Single(session.Draft.PendingChanges.OfType<PendingManagedHostsChange>());
+    }
+
+    [Fact]
+    public void SetManagedHostsDraft_StoresChange_AndRevertManagedHostsDraft_RemovesIt()
+    {
+        var saveService = new StubSaveService();
+        var session = new EffectiveConfigEditSession(saveService);
+        session.Ui.EnterEditMode();
+        var oldEntries = new List<HostEntry> { new() { Address = "1.2.3.4", Names = new List<string> { "a" } } };
+        var newEntries = new List<HostEntry> { new() { Address = "1.2.3.4", Names = new List<string> { "a", "b" } } };
+        session.Draft.SetManagedHostsDraft(oldEntries, newEntries, "/etc/hosts");
+        Assert.Single(session.Draft.PendingChanges.OfType<PendingManagedHostsChange>());
+        session.Draft.RevertManagedHostsDraft();
+        Assert.Empty(session.Draft.PendingChanges.OfType<PendingManagedHostsChange>());
+    }
+
+    private sealed class StubSaveService : IEffectiveConfigSaveService
+    {
+        public Task<EffectiveConfigSaveResult> SaveAsync(IReadOnlyList<PendingDnsmasqChange> changes, CancellationToken ct = default) =>
+            Task.FromResult(EffectiveConfigSaveResult.NoChanges());
+        public Task<EffectiveConfigRestoreResult> RestoreAsync(IReadOnlyList<DnsmasqManagedBackup> backups, CancellationToken ct = default) =>
+            Task.FromResult(new EffectiveConfigRestoreResult(false, false, -1, null, "Stub"));
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigFeatureRequirementsTests.cs

@@ -0,0 +1,140 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Models.Dnsmasq;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>
+/// Tests for option -> feature mapping and capability checks.
+/// </summary>
+public class EffectiveConfigFeatureRequirementsTests
+{
+    [Theory]
+    [InlineData(DnsmasqConfKeys.Dnssec, DnsmasqFeature.Dnssec)]
+    [InlineData(DnsmasqConfKeys.DnssecCheckUnsigned, DnsmasqFeature.Dnssec)]
+    [InlineData(DnsmasqConfKeys.TrustAnchor, DnsmasqFeature.Dnssec)]
+    [InlineData(DnsmasqConfKeys.DhcpRange, DnsmasqFeature.Dhcp)]
+    [InlineData(DnsmasqConfKeys.EnableTftp, DnsmasqFeature.Tftp)]
+    [InlineData(DnsmasqConfKeys.EnableDbus, DnsmasqFeature.Dbus)]
+    public void GetRequiredFeature_ReturnsExpectedFeature(string optionName, DnsmasqFeature expected)
+    {
+        var feature = EffectiveConfigFeatureRequirements.GetRequiredFeature(optionName);
+        Assert.NotNull(feature);
+        Assert.Equal(expected, feature.Value);
+    }
+
+    [Fact]
+    public void GetRequiredFeature_ForUnknownOption_ReturnsNull()
+    {
+        var feature = EffectiveConfigFeatureRequirements.GetRequiredFeature("no-such-option");
+        Assert.Null(feature);
+    }
+
+    [Fact]
+    public void IsSupportedByCapabilities_WhenCapabilityPresent_ReturnsTrue()
+    {
+        var caps = new DnsmasqCompileCapabilities(true, true, true, false,
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "DHCP", "TFTP", "DNSSEC" });
+        Assert.True(EffectiveConfigFeatureRequirements.IsSupportedByCapabilities(DnsmasqConfKeys.DnssecCheckUnsigned, caps));
+        Assert.True(EffectiveConfigFeatureRequirements.IsSupportedByCapabilities(DnsmasqConfKeys.DhcpRange, caps));
+    }
+
+    [Fact]
+    public void IsSupportedByCapabilities_WhenDnssecMissing_ReturnsFalseForDnssecOptions()
+    {
+        var caps = new DnsmasqCompileCapabilities(true, true, false, false,
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase));
+        Assert.False(EffectiveConfigFeatureRequirements.IsSupportedByCapabilities(DnsmasqConfKeys.Dnssec, caps));
+        Assert.False(EffectiveConfigFeatureRequirements.IsSupportedByCapabilities(DnsmasqConfKeys.DnssecCheckUnsigned, caps));
+    }
+
+    [Fact]
+    public void IsSupportedByCapabilities_ForOptionWithNoRequiredFeature_ReturnsTrue()
+    {
+        var caps = new DnsmasqCompileCapabilities(false, false, false, false,
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase));
+        Assert.True(EffectiveConfigFeatureRequirements.IsSupportedByCapabilities(DnsmasqConfKeys.Port, caps));
+    }
+
+    [Fact]
+    public void GetCapabilityDisabled_WhenStatusSupportsFeature_ReturnsNotDisabled()
+    {
+        var status = CreateStatusWithCapabilities(dnssec: true);
+        var (isDisabled, reason) = EffectiveConfigFeatureRequirements.GetCapabilityDisabled(DnsmasqConfKeys.DnssecCheckUnsigned, status);
+        Assert.False(isDisabled);
+        Assert.Null(reason);
+    }
+
+    [Fact]
+    public void GetCapabilityDisabled_WhenStatusMissingDnssec_ReturnsDisabledWithReason()
+    {
+        var status = CreateStatusWithCapabilities(dnssec: false);
+        var (isDisabled, reason) = EffectiveConfigFeatureRequirements.GetCapabilityDisabled(DnsmasqConfKeys.DnssecCheckUnsigned, status);
+        Assert.True(isDisabled);
+        Assert.NotNull(reason);
+    }
+
+    [Fact]
+    public void GetCapabilityDisabled_WhenStatusNull_ReturnsNotDisabled()
+    {
+        var (isDisabled, _) = EffectiveConfigFeatureRequirements.GetCapabilityDisabled(DnsmasqConfKeys.DnssecCheckUnsigned, null);
+        Assert.False(isDisabled);
+    }
+
+    /// <summary>
+    /// Save path uses IsSupportedByCapabilities(optionName, version.Capabilities) to reject changes before write.
+    /// This test asserts that logic: a build without DNSSEC would reject dnssec-check-unsigned.
+    /// </summary>
+    [Fact]
+    public void SaveGuard_WhenBuildHasNoDnssec_DnssecOptionChangesWouldBeRejected()
+    {
+        var noDnssecCaps = new DnsmasqCompileCapabilities(true, true, false, false,
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "DHCP", "TFTP" });
+        Assert.False(EffectiveConfigFeatureRequirements.IsSupportedByCapabilities(DnsmasqConfKeys.DnssecCheckUnsigned, noDnssecCaps));
+        Assert.NotNull(EffectiveConfigFeatureRequirements.GetUnsupportedReason(DnsmasqFeature.Dnssec));
+    }
+
+    private static DnsmasqServiceStatus CreateStatusWithCapabilities(bool dhcp = true, bool tftp = true, bool dnssec = true, bool dbus = false)
+    {
+        return new DnsmasqServiceStatus(
+            SystemHostsPath: null,
+            SystemHostsPathExists: false,
+            ManagedHostsFilePath: null,
+            ManagedHostsPathExists: false,
+            NoHosts: false,
+            AddnHostsPaths: Array.Empty<string>(),
+            EffectiveConfig: null,
+            EffectiveConfigSources: null,
+            MainConfigPath: null,
+            ManagedFilePath: null,
+            LeasesPath: null,
+            MainConfigPathExists: false,
+            ManagedFilePathExists: false,
+            LeasesPathConfigured: false,
+            LeasesPathExists: false,
+            ConfigFiles: null,
+            ReloadCommandConfigured: false,
+            StatusCommandConfigured: false,
+            StatusShowConfigured: false,
+            LogsConfigured: false,
+            LogsPath: null,
+            StatusShowCommand: null,
+            LogsCommand: null,
+            DnsmasqStatus: "active",
+            StatusCommandExitCode: null,
+            StatusCommandStdout: null,
+            StatusCommandStderr: null,
+            StatusShowOutput: null,
+            LogsOutput: null,
+            DhcpRangeStart: null,
+            DhcpRangeEnd: null,
+            DnsmasqVersion: "2.91",
+            MinimumSupportedDnsmasqVersion: "2.91",
+            DnsmasqVersionSupported: true,
+            DnsmasqVersionError: null,
+            DnsmasqSupportsDhcp: dhcp,
+            DnsmasqSupportsTftp: tftp,
+            DnsmasqSupportsDnssec: dnssec,
+            DnsmasqSupportsDbus: dbus);
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigFieldBuilderCapabilityTests.cs

@@ -0,0 +1,103 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Models.Dnsmasq;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>
+/// Tests that field descriptors get IsCapabilityDisabled set when the status indicates the option is not supported by the dnsmasq build.
+/// </summary>
+public class EffectiveConfigFieldBuilderCapabilityTests
+{
+    [Fact]
+    public void GetSingleDescriptor_WhenDnssecOptionAndStatusHasNoDnssec_ReturnsDescriptorWithCapabilityDisabled()
+    {
+        var status = CreateStatusWithCapabilities(dnssec: false);
+        var descriptor = EffectiveConfigFieldBuilder.GetSingleDescriptor(
+            null,
+            DnsmasqConfKeys.DnssecCheckUnsigned,
+            status,
+            _ => null,
+            _ => null,
+            null);
+
+        Assert.True(descriptor.IsCapabilityDisabled);
+        Assert.NotNull(descriptor.CapabilityDisabledReason);
+    }
+
+    [Fact]
+    public void GetSingleDescriptor_WhenDnssecOptionAndStatusHasDnssec_ReturnsDescriptorWithCapabilityNotDisabled()
+    {
+        var status = CreateStatusWithCapabilities(dnssec: true);
+        var descriptor = EffectiveConfigFieldBuilder.GetSingleDescriptor(
+            null,
+            DnsmasqConfKeys.DnssecCheckUnsigned,
+            status,
+            _ => null,
+            _ => null,
+            null);
+
+        Assert.False(descriptor.IsCapabilityDisabled);
+        Assert.Null(descriptor.CapabilityDisabledReason);
+    }
+
+    [Fact]
+    public void GetSingleDescriptor_WhenOptionWithNoFeatureRequirement_ReturnsDescriptorWithCapabilityNotDisabled()
+    {
+        var status = CreateStatusWithCapabilities(dnssec: false);
+        var descriptor = EffectiveConfigFieldBuilder.GetSingleDescriptor(
+            null,
+            DnsmasqConfKeys.Port,
+            status,
+            _ => null,
+            _ => null,
+            null);
+
+        Assert.False(descriptor.IsCapabilityDisabled);
+        Assert.Null(descriptor.CapabilityDisabledReason);
+    }
+
+    private static DnsmasqServiceStatus CreateStatusWithCapabilities(bool dhcp = true, bool tftp = true, bool dnssec = true, bool dbus = false)
+    {
+        return new DnsmasqServiceStatus(
+            SystemHostsPath: null,
+            SystemHostsPathExists: false,
+            ManagedHostsFilePath: null,
+            ManagedHostsPathExists: false,
+            NoHosts: false,
+            AddnHostsPaths: Array.Empty<string>(),
+            EffectiveConfig: null,
+            EffectiveConfigSources: null,
+            MainConfigPath: null,
+            ManagedFilePath: null,
+            LeasesPath: null,
+            MainConfigPathExists: false,
+            ManagedFilePathExists: false,
+            LeasesPathConfigured: false,
+            LeasesPathExists: false,
+            ConfigFiles: null,
+            ReloadCommandConfigured: false,
+            StatusCommandConfigured: false,
+            StatusShowConfigured: false,
+            LogsConfigured: false,
+            LogsPath: null,
+            StatusShowCommand: null,
+            LogsCommand: null,
+            DnsmasqStatus: "active",
+            StatusCommandExitCode: null,
+            StatusCommandStdout: null,
+            StatusCommandStderr: null,
+            StatusShowOutput: null,
+            LogsOutput: null,
+            DhcpRangeStart: null,
+            DhcpRangeEnd: null,
+            DnsmasqVersion: "2.91",
+            MinimumSupportedDnsmasqVersion: "2.91",
+            DnsmasqVersionSupported: true,
+            DnsmasqVersionError: null,
+            DnsmasqSupportsDhcp: dhcp,
+            DnsmasqSupportsTftp: tftp,
+            DnsmasqSupportsDnssec: dnssec,
+            DnsmasqSupportsDbus: dbus);
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigRenderFragmentRegistryMultiTests.cs

@@ -0,0 +1,45 @@
+using DnsmasqWebUI.Components.EffectiveConfig;
+using DnsmasqWebUI.Components.EffectiveConfig.CustomDisplays;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Rendering;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Handlers;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using Microsoft.AspNetCore.Components;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+public class EffectiveConfigRenderFragmentRegistryMultiTests
+{
+    [Fact]
+    public void BuildMultiFieldComponentFragment_Domain_ReturnsFragment()
+    {
+        var registry = new EffectiveConfigRenderFragmentRegistry(new OptionSemanticValidator([new DomainSemanticHandler()]));
+        var fragment = registry.BuildMultiFieldComponentFragment(
+            EffectiveConfigSections.SectionHosts,
+            DnsmasqConfKeys.Domain,
+            EventCallback<IReadOnlyList<string>>.Empty);
+
+        Assert.NotNull(fragment);
+    }
+
+    [Fact]
+    public void DomainMultiValueDisplay_InheritsMultiBase()
+    {
+        Assert.Equal(typeof(EffectiveConfigMultiValueDisplayBase), typeof(DomainMultiValueDisplay).BaseType);
+    }
+
+    /// <summary>Custom domain UI must still use RegisterSemanticMultiDescriptor wiring so per-item validation is not dropped.</summary>
+    [Fact]
+    public void GetMultiDescriptorFactory_Domain_WiresSemanticValidator()
+    {
+        var registry = new EffectiveConfigRenderFragmentRegistry(new OptionSemanticValidator([new DomainSemanticHandler()]));
+        var factory = registry.GetMultiDescriptorFactory(EffectiveConfigSections.SectionHosts, DnsmasqConfKeys.Domain);
+        Assert.NotNull(factory);
+
+        var descriptor = factory!(EffectiveConfigSections.SectionHosts, DnsmasqConfKeys.Domain, status: null, getItems: _ => null);
+        Assert.NotNull(descriptor.Validator);
+        Assert.Null(descriptor.Validator!.ValidateItem("example.com", Array.Empty<string>(), null));
+        Assert.NotNull(descriptor.Validator.ValidateItem("not a valid domain name!", Array.Empty<string>(), null));
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigSaveServiceCapabilityTests.cs

@@ -0,0 +1,119 @@
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Hosts.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Reload.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Validation.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Version.Abstractions;
+using DnsmasqWebUI.Models.Hosts;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Abstractions;
+using DnsmasqWebUI.Models.Config;
+using DnsmasqWebUI.Models.Dnsmasq;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>
+/// Save path capability guard: unsupported-option changes return UnsupportedCapabilities
+/// before validation or reload can run.
+/// </summary>
+public class EffectiveConfigSaveServiceCapabilityTests
+{
+    [Fact]
+    public async Task SaveAsync_WhenCapabilitiesMissingDnssec_ReturnsUnsupportedCapabilitiesErrorCode()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-cap-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        var managedName = "zz-managed.conf";
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = managedName });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var versionService = new StubVersionService(CreateSupportedVersionInfo(dnssec: false));
+            var semanticValidationService = new EffectiveConfigSemanticValidationService(new OptionSemanticValidator(Array.Empty<IOptionSemanticHandler>()));
+
+            var saveService = new EffectiveConfigSaveService(
+                setService,
+                configService,
+                cache,
+                new StubHostsFileService(),
+                new UnexpectedValidationService(),
+                semanticValidationService,
+                new UnexpectedReloadService(),
+                versionService,
+                NullLogger<EffectiveConfigSaveService>.Instance);
+
+            var changes = new List<PendingDnsmasqChange>
+            {
+                new PendingOptionChange(EffectiveConfigSections.SectionDnssec, DnsmasqConfKeys.DnssecCheckUnsigned, null, "no", null)
+            };
+
+            var result = await saveService.SaveAsync(changes);
+
+            Assert.Equal(EffectiveConfigSaveResult.ErrorCodes.UnsupportedCapabilities, result.ErrorCode);
+            Assert.False(File.Exists(Path.Combine(dir, managedName)));
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    private sealed class StubVersionService : IDnsmasqVersionService
+    {
+        private readonly DnsmasqVersionInfo _info;
+
+        public StubVersionService(DnsmasqVersionInfo info) => _info = info;
+
+        public Task<DnsmasqVersionInfo> GetVersionInfoAsync(CancellationToken ct = default) =>
+            Task.FromResult(_info);
+    }
+
+    private static DnsmasqVersionInfo CreateSupportedVersionInfo(bool dnssec)
+    {
+        var capabilities = new DnsmasqCompileCapabilities(
+            Dhcp: true,
+            Tftp: true,
+            Dnssec: dnssec,
+            Dbus: false,
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "DHCP", "TFTP" });
+
+        return new DnsmasqVersionInfo(
+            new Version(2, 91),
+            new Version(2, 91),
+            ProbeSucceeded: true,
+            IsSupported: true,
+            "dnsmasq --version",
+            null,
+            capabilities);
+    }
+
+    private sealed class UnexpectedValidationService : IConfigValidationService
+    {
+        public Task<ConfigValidationResult> ValidateAsync(CancellationToken ct = default) =>
+            throw new InvalidOperationException("ValidateAsync should not be called when capabilities are unsupported.");
+    }
+
+    private sealed class UnexpectedReloadService : IReloadService
+    {
+        public Task<ReloadResult> ReloadAsync(CancellationToken ct = default) =>
+            throw new InvalidOperationException("ReloadAsync should not be called when capabilities are unsupported.");
+    }
+
+    private sealed class StubHostsFileService : IHostsFileService
+    {
+        public Task<IReadOnlyList<HostEntry>> ReadAsync(CancellationToken ct = default) => Task.FromResult<IReadOnlyList<HostEntry>>(new List<HostEntry>());
+        public Task WriteAsync(IReadOnlyList<HostEntry> entries, CancellationToken ct = default) => Task.CompletedTask;
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigSaveServiceMultiBackupTests.cs

@@ -0,0 +1,216 @@
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Hosts.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Reload.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Validation.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Version.Abstractions;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using DnsmasqWebUI.Models.Hosts;
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Config.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Abstractions;
+using DnsmasqWebUI.Models.Config;
+using DnsmasqWebUI.Models.Contracts;
+using DnsmasqWebUI.Models.Dhcp;
+using DnsmasqWebUI.Models.Dnsmasq;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>
+/// Tests for multi-file backup/restore and managed-hosts-only save.
+/// </summary>
+public class EffectiveConfigSaveServiceMultiBackupTests
+{
+    [Fact]
+    public async Task SaveAsync_WhenOnlyManagedHostsChange_BacksUpManagedHostsFile_WritesHosts_ValidatesAndReloads()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-hosts-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        ConfigSetCache? cache = null;
+        try
+        {
+            File.WriteAllText(mainPath, "port=53\n");
+            var options = Options.Create(new DnsmasqOptions
+            {
+                MainConfigPath = mainPath,
+                ManagedFileName = "zz-managed.conf",
+                ManagedHostsFileName = "zz-dnsmasq-webui.hosts"
+            });
+            cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+            var setService = new DnsmasqConfigSetService(cache);
+            var configService = new DnsmasqConfigService(setService, cache, NullLogger<DnsmasqConfigService>.Instance);
+
+            var set = await setService.GetConfigSetAsync();
+            var managedHostsPath = set.ManagedHostsFilePath!;
+            File.WriteAllText(managedHostsPath, "192.168.1.1 host1\n");
+
+            var writtenEntries = new List<IReadOnlyList<HostEntry>>();
+            var capturingHostsService = new CapturingHostsFileService(writtenEntries);
+
+            var versionService = new StubVersionService(CreateSupportedVersionInfo());
+            var semanticValidationService = new EffectiveConfigSemanticValidationService(new OptionSemanticValidator(Array.Empty<IOptionSemanticHandler>()));
+            var saveService = new EffectiveConfigSaveService(
+                setService,
+                configService,
+                cache,
+                capturingHostsService,
+                new StubValidationService(success: true),
+                semanticValidationService,
+                new StubReloadService(success: true),
+                versionService,
+                NullLogger<EffectiveConfigSaveService>.Instance);
+
+            var oldEntries = new List<HostEntry> { new() { Address = "192.168.1.1", Names = new List<string> { "host1" }, Id = "192.168.1.1|host1" } };
+            var newEntries = new List<HostEntry>
+            {
+                new() { Address = "192.168.1.1", Names = new List<string> { "host1" }, Id = "192.168.1.1|host1" },
+                new() { Address = "192.168.1.2", Names = new List<string> { "host2" }, Id = "192.168.1.2|host2" }
+            };
+            var changes = new List<PendingDnsmasqChange>
+            {
+                new PendingManagedHostsChange(oldEntries, newEntries, managedHostsPath)
+            };
+
+            var result = await saveService.SaveAsync(changes);
+
+            Assert.True(result.Saved);
+            Assert.True(result.Validated);
+            Assert.True(result.Restarted);
+            Assert.Null(result.ErrorCode);
+            Assert.Single(result.Backups);
+            Assert.Equal(DnsmasqManagedTargetKind.ManagedHosts, result.Backups[0].Kind);
+            Assert.Equal(managedHostsPath, result.Backups[0].TargetPath);
+            Assert.True(File.Exists(result.Backups[0].BackupPath));
+            Assert.Single(writtenEntries);
+            Assert.Equal(2, writtenEntries[0].Count);
+        }
+        finally
+        {
+            cache?.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    [Fact]
+    public async Task RestoreAsync_WhenBackupsContainTwoTargets_RestoresBothThenReloads()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), "dnsmasq-restore-" + Guid.NewGuid().ToString("N"));
+        Directory.CreateDirectory(dir);
+        var mainPath = Path.Combine(dir, "dnsmasq.conf");
+        File.WriteAllText(mainPath, "port=53\n");
+        var target1 = Path.Combine(dir, "target1.conf");
+        var target2 = Path.Combine(dir, "target2.hosts");
+        var backup1 = Path.Combine(dir, "backup1.bak");
+        var backup2 = Path.Combine(dir, "backup2.bak");
+        File.WriteAllText(target1, "original1");
+        File.WriteAllText(target2, "original2");
+        File.WriteAllText(backup1, "restored1");
+        File.WriteAllText(backup2, "restored2");
+
+        var backups = new List<DnsmasqManagedBackup>
+        {
+            new(DnsmasqManagedTargetKind.ManagedConfig, target1, backup1),
+            new(DnsmasqManagedTargetKind.ManagedHosts, target2, backup2)
+        };
+
+        var options = Options.Create(new DnsmasqOptions { MainConfigPath = mainPath, ManagedFileName = "x.conf" });
+        var cache = new ConfigSetCache(options, NullLogger<ConfigSetCache>.Instance);
+        var setService = new DnsmasqConfigSetService(cache);
+        try
+        {
+            var saveService = new EffectiveConfigSaveService(
+                setService,
+                new StubConfigService(),
+                cache,
+                new StubHostsFileService(),
+                new StubValidationService(success: true),
+                new EffectiveConfigSemanticValidationService(new OptionSemanticValidator(Array.Empty<IOptionSemanticHandler>())),
+                new StubReloadService(success: true),
+                new StubVersionService(CreateSupportedVersionInfo()),
+                NullLogger<EffectiveConfigSaveService>.Instance);
+
+            var result = await saveService.RestoreAsync(backups);
+
+            Assert.True(result.Restored);
+            Assert.True(result.Restarted);
+            Assert.Equal("restored1", File.ReadAllText(target1));
+            Assert.Equal("restored2", File.ReadAllText(target2));
+        }
+        finally
+        {
+            cache.Dispose();
+            if (Directory.Exists(dir))
+                Directory.Delete(dir, recursive: true);
+        }
+    }
+
+    private static DnsmasqVersionInfo CreateSupportedVersionInfo()
+    {
+        var capabilities = new DnsmasqCompileCapabilities(
+            Dhcp: true, Tftp: true, Dnssec: true, Dbus: false,
+            new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "DHCP", "TFTP", "DNSSEC" });
+        return new DnsmasqVersionInfo(
+            new Version(2, 91), new Version(2, 91),
+            ProbeSucceeded: true, IsSupported: true, "dnsmasq --version", null, capabilities);
+    }
+
+    private sealed class CapturingHostsFileService : IHostsFileService
+    {
+        private readonly List<IReadOnlyList<HostEntry>> _written;
+
+        public CapturingHostsFileService(List<IReadOnlyList<HostEntry>> written) => _written = written;
+
+        public Task<IReadOnlyList<HostEntry>> ReadAsync(CancellationToken ct = default) =>
+            Task.FromResult<IReadOnlyList<HostEntry>>(new List<HostEntry>());
+
+        public Task WriteAsync(IReadOnlyList<HostEntry> entries, CancellationToken ct = default)
+        {
+            _written.Add(entries);
+            return Task.CompletedTask;
+        }
+    }
+
+    private sealed class StubVersionService : IDnsmasqVersionService
+    {
+        private readonly DnsmasqVersionInfo _info;
+        public StubVersionService(DnsmasqVersionInfo info) => _info = info;
+        public Task<DnsmasqVersionInfo> GetVersionInfoAsync(CancellationToken ct = default) => Task.FromResult(_info);
+    }
+
+    private sealed class StubValidationService : IConfigValidationService
+    {
+        private readonly bool _success;
+        public StubValidationService(bool success) => _success = success;
+        public Task<ConfigValidationResult> ValidateAsync(CancellationToken ct = default) =>
+            Task.FromResult(new ConfigValidationResult(_success, true, _success ? 0 : 1, null, null, null));
+    }
+
+    private sealed class StubReloadService : IReloadService
+    {
+        private readonly bool _success;
+        public StubReloadService(bool success) => _success = success;
+        public Task<ReloadResult> ReloadAsync(CancellationToken ct = default) =>
+            Task.FromResult(new ReloadResult(_success, _success ? 0 : 1, null, null));
+    }
+
+    private sealed class StubHostsFileService : IHostsFileService
+    {
+        public Task<IReadOnlyList<HostEntry>> ReadAsync(CancellationToken ct = default) =>
+            Task.FromResult<IReadOnlyList<HostEntry>>(new List<HostEntry>());
+        public Task WriteAsync(IReadOnlyList<HostEntry> entries, CancellationToken ct = default) => Task.CompletedTask;
+    }
+
+    private sealed class StubConfigService : IDnsmasqConfigService
+    {
+        public Task ApplyEffectiveConfigChangesAsync(IReadOnlyList<PendingEffectiveConfigChange> changes, CancellationToken ct = default) => Task.CompletedTask;
+        public Task<IReadOnlyList<DhcpHostEntry>> ReadDhcpHostsAsync(CancellationToken ct = default) => Task.FromResult<IReadOnlyList<DhcpHostEntry>>(Array.Empty<DhcpHostEntry>());
+        public Task WriteDhcpHostsAsync(IReadOnlyList<DhcpHostEntry> entries, CancellationToken ct = default) => Task.CompletedTask;
+        public Task<ManagedConfigContent> ReadManagedConfigAsync(CancellationToken ct = default) => Task.FromResult(new ManagedConfigContent(Array.Empty<DnsmasqConfLine>(), ""));
+        public Task WriteManagedConfigAsync(IReadOnlyList<DnsmasqConfLine> lines, CancellationToken ct = default) => Task.CompletedTask;
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveConfigSemanticsWiringTests.cs

@@ -0,0 +1,60 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Rendering;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Handlers;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>
+/// Wiring tests that ensure special-option semantics actually feed parser and registry behavior.
+/// </summary>
+public class EffectiveConfigSemanticsWiringTests
+{
+    [Fact]
+    public void Registry_WiresSemanticValidator_ForDnsRr()
+    {
+        var registry = new EffectiveConfigRenderFragmentRegistry(new OptionSemanticValidator([new DnsRrSemanticHandler()]));
+        var factory = registry.GetMultiDescriptorFactory(EffectiveConfigSections.SectionDnsRecords, DnsmasqConfKeys.DnsRr);
+        Assert.NotNull(factory);
+        var descriptor = factory!(EffectiveConfigSections.SectionDnsRecords, DnsmasqConfKeys.DnsRr, status: null, getItems: _ => null);
+        Assert.NotNull(descriptor.Validator);
+        Assert.Null(descriptor.Validator!.ValidateItem("example.com,16,01:02", Array.Empty<string>()));
+        Assert.NotNull(descriptor.Validator.ValidateItem("example.com,not-a-number", Array.Empty<string>()));
+    }
+
+    [Fact]
+    public void Registry_WiresLeasequeryMultiValidator_FromSpecialSemantics()
+    {
+        var registry = new EffectiveConfigRenderFragmentRegistry(new OptionSemanticValidator([new LeasequerySemanticHandler()]));
+        var factory = registry.GetMultiDescriptorFactory(EffectiveConfigSections.SectionDhcp, DnsmasqConfKeys.Leasequery);
+        Assert.NotNull(factory);
+
+        var descriptor = factory!(
+            EffectiveConfigSections.SectionDhcp,
+            DnsmasqConfKeys.Leasequery,
+            status: null,
+            getItems: _ => null);
+
+        Assert.NotNull(descriptor.Validator);
+        Assert.NotNull(descriptor.Validator!.ValidateItem("not-an-ip", Array.Empty<string>()));
+        Assert.Null(descriptor.Validator.ValidateItem("10.0.0.0/24", Array.Empty<string>()));
+    }
+
+    /// <summary>Pre-save semantic blocking: invalid leasequery value produces errors; SaveService uses this and returns SemanticValidationFailed before write.</summary>
+    [Fact]
+    public void SemanticValidationService_InvalidLeasequery_ReturnsError()
+    {
+        var validator = new OptionSemanticValidator([new LeasequerySemanticHandler()]);
+        var service = new EffectiveConfigSemanticValidationService(validator);
+        var changes = new List<PendingEffectiveConfigChange>
+        {
+            new(EffectiveConfigSections.SectionDhcp, DnsmasqConfKeys.Leasequery, null,
+                new List<string> { "not-an-ip" }, null)
+        };
+        var issues = service.Validate(changes);
+        Assert.NotEmpty(issues);
+        Assert.Contains(issues, i => i.Severity == FieldIssueSeverity.Error);
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/EffectiveDnsmasqConfigTests.cs

@@ -1,6 +1,6 @@
 using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
 
-namespace DnsmasqWebUI.Tests;
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
 
 /// <summary>
 /// Tests for EffectiveDnsmasqConfig, including GetLogsPath (log-facility as file path).
@@ -12,7 +12,8 @@ public class EffectiveDnsmasqConfigTests
             NoHosts: false,
             AddnHostsPaths: Array.Empty<string>(),
             HostsdirPath: null,
-            ServerLocalValues: Array.Empty<string>(),
+            ServerValues: Array.Empty<string>(),
+            LocalValues: Array.Empty<string>(),
             RevServerValues: Array.Empty<string>(),
             AddressValues: Array.Empty<string>(),
             Interfaces: Array.Empty<string>(),
@@ -53,6 +54,24 @@ public class EffectiveDnsmasqConfigTests
             DhcpHostsfilePaths: Array.Empty<string>(),
             DhcpOptsfilePaths: Array.Empty<string>(),
             DhcpHostsdirPaths: Array.Empty<string>(),
+            DhcpOptsdirPaths: Array.Empty<string>(),
+            ConnmarkAllowlistValues: Array.Empty<string>(),
+            CaaRecordValues: Array.Empty<string>(),
+            DnsRrValues: Array.Empty<string>(),
+            SynthDomainValues: Array.Empty<string>(),
+            AuthZoneValues: Array.Empty<string>(),
+            AuthSoaValues: Array.Empty<string>(),
+            AuthSecServersValues: Array.Empty<string>(),
+            AuthPeerValues: Array.Empty<string>(),
+            DhcpRelayValues: Array.Empty<string>(),
+            DhcpCircuitidValues: Array.Empty<string>(),
+            DhcpRemoteidValues: Array.Empty<string>(),
+            DhcpSubscridValues: Array.Empty<string>(),
+            DhcpProxyValues: Array.Empty<string>(),
+            TagIfValues: Array.Empty<string>(),
+            BridgeInterfaceValues: Array.Empty<string>(),
+            SharedNetworkValues: Array.Empty<string>(),
+            DhcpOptionPxeValues: Array.Empty<string>(),
             ExpandHosts: false,
             BogusPriv: false,
             StrictOrder: false,
@@ -79,7 +98,7 @@ public class EffectiveDnsmasqConfigTests
             TftpNoFail: false,
             TftpNoBlocksize: false,
             Dnssec: false,
-            DnssecCheckUnsigned: false,
+            DnssecCheckUnsigned: null,
             ReadEthers: false,
             DhcpRapidCommit: false,
             Localmx: false,
@@ -89,6 +108,24 @@ public class EffectiveDnsmasqConfigTests
             KeepInForeground: false,
             NoDaemon: false,
             ProxyDnssec: false,
+            ConnmarkAllowlistEnable: null,
+            NoRoundRobin: false,
+            DnssecNoTimecheck: false,
+            DnssecDebug: false,
+            LeasequeryValues: Array.Empty<string>(),
+            DhcpGenerateNames: null,
+            DhcpBroadcast: null,
+            DhcpSequentialIp: false,
+            DhcpIgnoreClid: false,
+            BootpDynamic: null,
+            NoPing: false,
+            ScriptArp: false,
+            ScriptOnRenewal: false,
+            DhcpNoOverride: false,
+            QuietDhcp: false,
+            QuietDhcp6: false,
+            QuietRa: false,
+            QuietTftp: false,
             DhcpLeaseFilePath: null,
             CacheSize: null,
             Port: null,
@@ -119,7 +156,25 @@ public class EffectiveDnsmasqConfigTests
             FastDnsRetry: null,
             DhcpScriptPath: null,
             MxTarget: null,
-            Conntrack: null
+            DnsForwardMax: null,
+            DumpfilePath: null,
+            Dumpmask: null,
+            AddCpeId: null,
+            DnssecTimestamp: null,
+            DnssecLimits: null,
+            DhcpAlternatePort: null,
+            DhcpDuid: null,
+            DhcpLuascriptPath: null,
+            DhcpScriptuser: null,
+            DhcpPxeVendor: null,
+            UseStaleCache: null,
+            AddMac: null,
+            StripMac: false,
+            AddSubnet: null,
+            StripSubnet: false,
+            Umbrella: null,
+            Do0x20EncodeState: ExplicitToggleState.Default,
+            Conntrack: false
         );
 
     [Fact]

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/OptionSemanticValidatorRealWorldCorpusTests.cs

@@ -0,0 +1,50 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Handlers;
+using DnsmasqWebUI.Infrastructure.Serialization.Parsers.DnsmasqConfig;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using DnsmasqWebUI.Tests.Helpers;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>Corpus-driven semantic validation: bad samples produce errors for expected option keys only.</summary>
+public class OptionSemanticValidatorRealWorldCorpusTests
+{
+    private readonly IOptionSemanticValidator _validator = new OptionSemanticValidator([
+        new DomainSemanticHandler(),
+        new DnsRrSemanticHandler(),
+        new SynthDomainSemanticHandler(),
+        new AuthServerSemanticHandler(),
+        new SrvSemanticHandler(),
+    ]);
+
+    public static IEnumerable<object[]> GetCasesWithInvalidOptions()
+    {
+        foreach (var c in RealWorldCasesHelper.LoadCases())
+        {
+            if (c.SemanticInvalidOptions.Count > 0)
+                yield return new object[] { c };
+        }
+    }
+
+    [Theory]
+    [MemberData(nameof(GetCasesWithInvalidOptions))]
+    public void SemanticInvalidOptions_FromCorpus_AreRejected(CorpusCase c)
+    {
+        var mainPath = RealWorldCasesHelper.Resolve(c);
+        var paths = DnsmasqConfIncludeParser.GetIncludedPaths(mainPath);
+        var semantics = new OptionValidationSemantics(OptionValidationKind.Complex, allowEmpty: true);
+
+        foreach (var option in c.SemanticInvalidOptions)
+        {
+            var values = DnsmasqConfIncludeParser.GetMultiValueFromConfigFiles(paths, option);
+            Assert.NotEmpty(values);
+
+            var anyInvalid = values.Any(v =>
+                _validator.ValidateMultiItem(option, v, semantics) is not null);
+
+            Assert.True(anyInvalid, $"Expected at least one invalid value for option '{option}' in {c.File}");
+        }
+    }
+}

src/DnsmasqWebUI.Tests/Services/EffectiveConfig/OptionSemanticValidatorSpecializedTests.cs

@@ -0,0 +1,119 @@
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Metadata;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Abstractions;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Handlers;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Tests.Services.EffectiveConfig;
+
+/// <summary>
+/// Ensures every specialized option (one with a semantic handler) has at least one valid and one invalid
+/// test case; asserts only Null/NotNull, not error message text.
+/// </summary>
+public class OptionSemanticValidatorSpecializedTests
+{
+    private static readonly OptionValidationSemantics ComplexAllowEmpty = new(OptionValidationKind.Complex, allowEmpty: true);
+
+    private readonly IOptionSemanticValidator _validator = new OptionSemanticValidator([
+        new LeasequerySemanticHandler(),
+        new ServerSemanticHandler(),
+        new LocalSemanticHandler(),
+        new RevServerSemanticHandler(),
+        new AddressSemanticHandler(),
+        new TrustAnchorSemanticHandler(),
+        new AliasSemanticHandler(),
+        new IpsetSemanticHandler(),
+        new NftsetSemanticHandler(),
+        new IgnoreAddressSemanticHandler(),
+        new ConnmarkAllowlistSemanticHandler(),
+        new DhcpRangeSemanticHandler(),
+        new DhcpHostSemanticHandler(),
+        new DhcpOptionSemanticHandler(),
+        new DhcpMatchSemanticHandler(),
+        new DhcpMacSemanticHandler(),
+        new DhcpRelaySemanticHandler(),
+        new DhcpProxySemanticHandler(),
+        new RaParamSemanticHandler(),
+        new DhcpNameMatchSemanticHandler(),
+        new DhcpIgnoreSemanticHandler(),
+        new DhcpVendorclassSemanticHandler(),
+        new DhcpUserclassSemanticHandler(),
+        new TagIfSemanticHandler(),
+        new BridgeInterfaceSemanticHandler(),
+        new SharedNetworkSemanticHandler(),
+        new DhcpOptionPxeSemanticHandler(),
+        new RebindDomainOkSemanticHandler(),
+        new BogusNxdomainSemanticHandler(),
+        new DhcpIgnoreNamesSemanticHandler(),
+        new DhcpBootSemanticHandler(),
+        new SlaacSemanticHandler(),
+        new PxeServiceSemanticHandler(),
+        new DhcpCircuitidSemanticHandler(),
+        new DhcpRemoteidSemanticHandler(),
+        new DhcpSubscrIdSemanticHandler(),
+        new FilterRrSemanticHandler(),
+        new CacheRrSemanticHandler(),
+        new InterfaceNameSemanticHandler(),
+        new AuthServerSemanticHandler(),
+        new CnameSemanticHandler(),
+        new MxHostSemanticHandler(),
+        new PtrRecordSemanticHandler(),
+        new InterfaceNameRecordSemanticHandler(),
+        new CaaRecordSemanticHandler(),
+        new SrvSemanticHandler(),
+        new NaptrRecordSemanticHandler(),
+        new DnsRrSemanticHandler(),
+        new DynamicHostSemanticHandler(),
+        new AuthSoaSemanticHandler(),
+        new AuthSecServersSemanticHandler(),
+        new AuthPeerSemanticHandler(),
+        new HostRecordSemanticHandler(),
+        new TxtRecordSemanticHandler(),
+        new DomainSemanticHandler(),
+        new SynthDomainSemanticHandler(),
+        new AuthZoneSemanticHandler(),
+    ]);
+
+    /// <summary>Option key, one valid value (validator returns null), one invalid value (validator returns non-null).</summary>
+    public static IEnumerable<object[]> GetSpecializedValidInvalidPairs()
+    {
+        yield return new object[] { DnsmasqConfKeys.Leasequery, "10.0.0.0/24", "not-an-ip" };
+        yield return new object[] { DnsmasqConfKeys.Server, "1.1.1.1", "" };
+        yield return new object[] { DnsmasqConfKeys.Local, "/lan/", "" };
+        yield return new object[] { DnsmasqConfKeys.Address, "/example.com/127.0.0.1", "/bad..name/1.2.3.4" };
+        yield return new object[] { DnsmasqConfKeys.Domain, "home.lan,192.168.1.0/24", "example.com,192.168.1.0/24,local,extra" };
+        yield return new object[] { DnsmasqConfKeys.AuthServer, "zone.example.com,eth0", ",eth0" };
+        yield return new object[] { DnsmasqConfKeys.SynthDomain, "dynamic.example.com,192.168.2.1,192.168.2.100", "example.com," };
+        yield return new object[] { DnsmasqConfKeys.DnsRr, "example.com,16,01:02", "example.com,not-a-number" };
+        yield return new object[] { DnsmasqConfKeys.Srv, "_http._tcp.example.com,host.example.com,80", "_sip._tcp,target,99999" };
+        yield return new object[] { DnsmasqConfKeys.NaptrRecord, "example.com,0,0,a,s,r", "example.com,not-num,0,a,s,r" };
+        yield return new object[] { DnsmasqConfKeys.TxtRecord, "example.com,text", "" };
+        yield return new object[] { DnsmasqConfKeys.Cname, "www.example.com,example.com", "bad..name,example.com" };
+        yield return new object[] { DnsmasqConfKeys.MxHost, "example.com,mail.example.com,10", "bad..name,mail.example.com,10" };
+        yield return new object[] { DnsmasqConfKeys.PtrRecord, "1.168.192.in-addr.arpa,router.lan", "bad..arpa,host" };
+        yield return new object[] { DnsmasqConfKeys.RebindDomainOk, "example.com", "bad..name" };
+        yield return new object[] { DnsmasqConfKeys.BogusNxdomain, "192.168.1.1", "not-an-ip" };
+        yield return new object[] { DnsmasqConfKeys.ConnmarkAllowlist, "0xff,example.com", "not-a-mark,example.com" };
+        yield return new object[] { DnsmasqConfKeys.DhcpRange, "192.168.1.50,192.168.1.150,12h", "not-an-ip,192.168.1.150" };
+        yield return new object[] { DnsmasqConfKeys.DhcpHost, "aa:bb:cc:dd:ee:ff,192.168.1.10", "ignore" };
+        yield return new object[] { DnsmasqConfKeys.DhcpOption, "3,192.168.1.1", "option:," };
+        yield return new object[] { DnsmasqConfKeys.DhcpMatch, "set:efi,option:client-arch,6", "option:client-arch,6" };
+        yield return new object[] { DnsmasqConfKeys.DhcpMac, "set:vendor,aa:bb:cc:dd:ee:ff", "aa:bb:cc:dd:ee:ff" };
+        yield return new object[] { DnsmasqConfKeys.DhcpNameMatch, "set:tag,hostname*", "hostname*" };
+        yield return new object[] { DnsmasqConfKeys.DhcpIgnoreNames, "tag:guest", "guest" };
+        yield return new object[] { DnsmasqConfKeys.AuthZone, "example.com", "bad..name" };
+        yield return new object[] { DnsmasqConfKeys.FilterRr, "A,AAAA", "" };
+        yield return new object[] { DnsmasqConfKeys.CacheRr, "A,TXT", "" };
+    }
+
+    [Theory]
+    [MemberData(nameof(GetSpecializedValidInvalidPairs))]
+    public void SpecializedOption_ValidAccepted_InvalidRejected(string optionKey, string validValue, string invalidValue)
+    {
+        var validErr = _validator.ValidateMultiItem(optionKey, validValue, ComplexAllowEmpty);
+        Assert.Null(validErr);
+
+        var invalidErr = _validator.ValidateMultiItem(optionKey, invalidValue, ComplexAllowEmpty);
+        Assert.NotNull(invalidErr);
+    }
+}

src/DnsmasqWebUI.Tests/Services/Hosts/HostsPageProjectionServiceTests.cs

@@ -0,0 +1,80 @@
+using DnsmasqWebUI.Infrastructure.Services.Dnsmasq.Hosts;
+using DnsmasqWebUI.Models.Hosts;
+
+namespace DnsmasqWebUI.Tests.Services.Hosts;
+
+public class HostsPageProjectionServiceTests
+{
+    private readonly HostsPageProjectionService _sut = new();
+
+    [Fact]
+    public void BuildGroups_SourcePathFilter_KeepsOnlyThatFile()
+    {
+        var rows = new HostsPageRow[]
+        {
+            new(
+                "m1",
+                HostsRowSourceKind.Managed,
+                "/data/managed.hosts",
+                IsEditable: true,
+                IsActive: true,
+                InactiveReason: null,
+                Address: "10.0.0.1",
+                Names: new[] { "a" },
+                EffectiveNames: new[] { "a" },
+                IsComment: false,
+                LineNumber: 1),
+            new(
+                "x1",
+                HostsRowSourceKind.AddnHosts,
+                "/etc/extra.hosts",
+                IsEditable: false,
+                IsActive: true,
+                InactiveReason: null,
+                Address: "10.0.0.2",
+                Names: new[] { "b" },
+                EffectiveNames: new[] { "b" },
+                IsComment: false,
+                LineNumber: 1),
+        };
+
+        var query = new HostsPageQueryState(
+            Search: "",
+            Grouping: HostsGroupingMode.Source,
+            Sort: HostsSortMode.LineNumber,
+            Descending: false,
+            SourceKindFilter: null,
+            SourcePathFilter: "/etc/extra.hosts",
+            EditableFilter: null,
+            ActiveFilter: null);
+
+        var groups = _sut.BuildGroups(rows, query);
+
+        Assert.Single(groups);
+        Assert.Equal("/etc/extra.hosts", groups[0].Subtitle);
+        Assert.Single(groups[0].Rows);
+    }
+
+    [Fact]
+    public void BuildGroups_SourcePathFilter_EmptyMeansAllFiles()
+    {
+        var rows = new HostsPageRow[]
+        {
+            new("m1", HostsRowSourceKind.Managed, "/a", true, true, null, "1.1.1.1", new[] { "a" }, new[] { "a" }, false, 1),
+            new("x1", HostsRowSourceKind.AddnHosts, "/b", false, true, null, "2.2.2.2", new[] { "b" }, new[] { "b" }, false, 1),
+        };
+
+        var query = new HostsPageQueryState(
+            "",
+            HostsGroupingMode.Source,
+            HostsSortMode.LineNumber,
+            false,
+            null,
+            SourcePathFilter: null,
+            null,
+            null);
+
+        var groups = _sut.BuildGroups(rows, query);
+        Assert.Equal(2, groups.Count);
+    }
+}

src/DnsmasqWebUI/Components/App.razor

@@ -23,7 +23,7 @@
 
 <body>
     <Routes @rendermode="InteractiveServer" />
-    <script src="js/ec-option-help.js"></script>
+    <script src="js/copy-to-clipboard.js"></script>
     <script src="_framework/blazor.web.js"></script>
 </body>
 

src/DnsmasqWebUI/Components/Dnsmasq/AppLogs/AppLogsFiltersModal.razor

@@ -1,4 +1,4 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq
+@namespace DnsmasqWebUI.Components.Dnsmasq.AppLogs
 @inject ILoggingClient LoggingClient
 @inject IJSRuntime JSRuntime
 @implements IAsyncDisposable
@@ -16,7 +16,7 @@
                 <div class="input-group input-group-sm mb-2">
                     <input type="text" class="form-control" placeholder="e.g. Microsoft.AspNetCore."
                            @bind="_newPrefix" @bind:event="oninput" @onkeydown="OnNewPrefixKeydown" />
-                    <button type="button" class="btn btn-outline-primary" @onclick="AddPrefix" disabled="@string.IsNullOrWhiteSpace(_newPrefix)">Add</button>
+                    <button type="button" class="btn btn-outline-primary" @onclick="AddPrefix" disabled="@string.IsNullOrWhiteSpace(_newPrefix)"><i class="bi bi-plus me-1" aria-hidden="true"></i>Add</button>
                 </div>
                 <ul class="list-group list-group-flush" style="max-height: 12rem; overflow-y: auto;">
                     @foreach (var prefix in _prefixes)
@@ -35,10 +35,10 @@
                 </ul>
             </div>
             <div class="modal-footer d-flex justify-content-between align-items-center">
-                <button type="button" class="btn btn-secondary" @onclick="RestoreDefaults" disabled="@_saving">Restore defaults</button>
+                <button type="button" class="btn btn-secondary" @onclick="RestoreDefaults" disabled="@_saving"><i class="bi bi-arrow-counterclockwise me-1" aria-hidden="true"></i>Restore defaults</button>
                 <div>
-                    <button type="button" class="btn btn-secondary" @onclick="Close">Cancel</button>
+                    <button type="button" class="btn btn-secondary" @onclick="Close"><i class="bi bi-x me-1" aria-hidden="true"></i>Cancel</button>
-                    <button type="button" class="btn btn-primary" @onclick="Save" disabled="@_saving">@(_saving ? "Saving…" : "Save")</button>
+                    <button type="button" class="btn btn-primary" @onclick="Save" disabled="@_saving">@if (_saving) { <span class="spinner-border spinner-border-sm me-1" role="status" aria-hidden="true"></span> } else { <i class="bi bi-floppy-fill me-1" aria-hidden="true"></i> }@(_saving ? "Saving…" : "Save")</button>
                 </div>
             </div>
         </div>

src/DnsmasqWebUI/Components/Dnsmasq/AppLogs/AppLogsFiltersModal.razor.cs

@@ -1,9 +1,10 @@
+using DnsmasqWebUI.Extensions.Interop;
 using DnsmasqWebUI.Infrastructure.Client.Abstractions;
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Components.Web;
 using Microsoft.JSInterop;
 
-namespace DnsmasqWebUI.Components.Dnsmasq;
+namespace DnsmasqWebUI.Components.Dnsmasq.AppLogs;
 
 public partial class AppLogsFiltersModal : IAsyncDisposable
 {
@@ -51,32 +52,29 @@ public partial class AppLogsFiltersModal : IAsyncDisposable
     {
         if (firstRender)
         {
-            try
+            _jsModule = await JSRuntime.InvokeAsyncSafe<IJSObjectReference>("import", default, "./js/dialog.js");
+            if (_jsModule != null)
             {
-                _jsModule = await JSRuntime.InvokeAsync<IJSObjectReference>("import", "./js/settings-modal.js");
                 _dotNetRef = DotNetObjectReference.Create(this);
                 _moduleLoaded = true;
             }
-            catch (InvalidOperationException) { }
-            catch (JSDisconnectedException) { }
-            catch (JSException) { }
         }
 
         if (IsVisible && _moduleLoaded && _jsModule != null)
         {
             if (!_dialogInitialized)
             {
-                await _jsModule.InvokeVoidAsync("initDialog", _dialogRef, _dotNetRef);
+                await _jsModule.InvokeVoidAsyncSafe("initDialog", _dialogRef, _dotNetRef);
                 _dialogInitialized = true;
             }
-            await _jsModule.InvokeVoidAsync("showModal", _dialogRef);
+            await _jsModule.InvokeVoidAsyncSafe("showModal", _dialogRef);
         }
     }
 
     private async Task Close()
     {
         if (_jsModule != null)
-            await _jsModule.InvokeVoidAsync("closeModal", _dialogRef);
+            await _jsModule.InvokeVoidAsyncSafe("closeModal", _dialogRef);
         await OnClose.InvokeAsync();
     }
 
@@ -145,10 +143,8 @@ public partial class AppLogsFiltersModal : IAsyncDisposable
         _cts.Cancel();
         _cts.Dispose();
         _dotNetRef?.Dispose();
-        if (_jsModule != null)
+        _dotNetRef = null;
-        {
+        await _jsModule.DisposeAsyncSafe();
-            try { await _jsModule.DisposeAsync(); }
+        _jsModule = null;
-            catch { /* ignore */ }
-        }
     }
 }

src/DnsmasqWebUI/Components/Dnsmasq/AppLogs/AppLogsSection.razor

@@ -1,4 +1,4 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq
+@namespace DnsmasqWebUI.Components.Dnsmasq.AppLogs
 @* App logs — live view via SignalR from ILogger *@
 @using DnsmasqWebUI.Models.Logs
 @using Microsoft.AspNetCore.SignalR.Client
@@ -31,3 +31,7 @@
 </p>
 <AppLogsFiltersModal IsVisible="_filtersModalVisible" OnClose="CloseFiltersModal" />
 <LogsPreView Id="app-logs-pre" Placeholder="@_initialPlaceholder" Freeze="_logsContentReceived" />
+<div class="mt-2 d-flex flex-wrap gap-2 align-items-center">
+    <button class="btn btn-primary btn-sm" @onclick="RequestRefreshAsync" disabled="@_refreshing"><i class="bi bi-arrow-repeat me-1" aria-hidden="true"></i>Refresh</button>
+    <a href="api/logging/logs/download" download="app.log" class="btn btn-primary btn-sm"><i class="bi bi-download me-1" aria-hidden="true"></i>Download logs</a>
+</div>

src/DnsmasqWebUI/Components/Dnsmasq/AppLogs/AppLogsSection.razor.cs

@@ -1,10 +1,11 @@
+using DnsmasqWebUI.Extensions.Interop;
 using DnsmasqWebUI.Infrastructure.Client.Abstractions;
 using DnsmasqWebUI.Models.Logs;
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.JSInterop;
 
-namespace DnsmasqWebUI.Components.Dnsmasq;
+namespace DnsmasqWebUI.Components.Dnsmasq.AppLogs;
 
 /// <summary>
 /// App logs block: connects to LogsHub, receives AppLogsUpdate pushes, polls at interval as fallback.
@@ -18,6 +19,7 @@ public partial class AppLogsSection : IAsyncDisposable
 
     private bool _justUpdated;
     private bool _logsContentReceived;
+    private bool _refreshing;
     private int _intervalSeconds;
     private string _logLevel = "Information";
     private bool _logLevelDisabled;
@@ -60,13 +62,12 @@ public partial class AppLogsSection : IAsyncDisposable
 
         _hubConnection.On<LogsUpdatePayload>("AppLogsUpdate", OnAppLogsUpdate);
 
-        try
+        _logsJs = await JSRuntime.InvokeAsyncSafe<IJSObjectReference>("import", default, "./js/logs.js");
+        if (_logsJs == null)
         {
-            _logsJs = await JSRuntime.InvokeAsync<IJSObjectReference>("import", "./js/logs.js");
+            Logger.LogDebug("AppLogsSection: logs JS module unavailable (prerender, disconnect, or import failure)");
+            return;
         }
-        catch (InvalidOperationException ex) { Logger.LogDebug(ex, "AppLogsSection: JS import skipped (prerender)"); return; }
-        catch (JSDisconnectedException ex) { Logger.LogDebug(ex, "AppLogsSection: JS import skipped (circuit disconnected)"); return; }
-        catch (JSException ex) { Logger.LogDebug(ex, "AppLogsSection: JS import failed"); return; }
 
         await _hubConnection.StartAsync(_cts.Token);
         RestartPollTimer();
@@ -90,6 +91,25 @@ public partial class AppLogsSection : IAsyncDisposable
     private void OpenFiltersModal() => _filtersModalVisible = true;
     private void CloseFiltersModal() => _filtersModalVisible = false;
 
+    private async Task RequestRefreshAsync()
+    {
+        if (_hubConnection?.State != HubConnectionState.Connected)
+            return;
+        _refreshing = true;
+        StateHasChanged();
+        try
+        {
+            await _hubConnection.InvokeAsync("RequestAppLogsSnapshot", _cts.Token);
+        }
+        catch (OperationCanceledException) { }
+        catch (Exception) { /* ignore */ }
+        finally
+        {
+            _refreshing = false;
+            StateHasChanged();
+        }
+    }
+
     private async Task OnLogLevelChanged()
     {
         if (string.IsNullOrEmpty(_logLevel)) return;
@@ -137,23 +157,18 @@ public partial class AppLogsSection : IAsyncDisposable
             await InvokeAsync(async () =>
             {
                 if (_logsJs == null) return;
-                try
+                if (payload.Mode == "replace")
-                {
+                    await _logsJs.InvokeVoidAsyncSafe("replaceLogs", AppLogsPreId, payload.Content, LogsOptions);
-                    if (payload.Mode == "replace")
+                else
-                        await _logsJs.InvokeVoidAsync("replaceLogs", AppLogsPreId, payload.Content, LogsOptions);
+                    await _logsJs.InvokeVoidAsyncSafe("appendLogs", AppLogsPreId, payload.Content, LogsOptions);
-                    else
+                _logsContentReceived = true;
-                        await _logsJs.InvokeVoidAsync("appendLogs", AppLogsPreId, payload.Content, LogsOptions);
+                SetJustUpdated();
-                    _logsContentReceived = true;
+                StateHasChanged();
-                    SetJustUpdated();
-                    StateHasChanged();
-                }
-                catch (JSDisconnectedException) { /* Circuit disconnected; ignore */ }
-                catch (InvalidOperationException) { /* Prerender or circuit disposed; ignore */ }
-                catch (JSException) { /* JS error; ignore */ }
             });
         }
         catch (ObjectDisposedException) { /* Component disposed; ignore */ }
         catch (InvalidOperationException) { /* Circuit disconnected; ignore */ }
+        catch (JSDisconnectedException) { /* Circuit gone before InvokeAsync completed */ }
     }
 
     private void SetJustUpdated()
@@ -183,13 +198,7 @@ public partial class AppLogsSection : IAsyncDisposable
             await _hubConnection.DisposeAsync();
             _hubConnection = null;
         }
-        if (_logsJs != null)
+        await _logsJs.DisposeAsyncSafe();
-        {
+        _logsJs = null;
-            try { await _logsJs.DisposeAsync(); }
-            catch (InvalidOperationException ex) { Logger.LogDebug(ex, "AppLogsSection: DisposeAsync skipped (prerender)"); }
-            catch (JSDisconnectedException ex) { Logger.LogDebug(ex, "AppLogsSection: DisposeAsync skipped (circuit disconnected)"); }
-            catch (JSException ex) { Logger.LogDebug(ex, "AppLogsSection: DisposeAsync failed"); }
-            _logsJs = null;
-        }
     }
 }

src/DnsmasqWebUI/Components/Dnsmasq/ConfigFileList.razor

@@ -0,0 +1,74 @@
+@namespace DnsmasqWebUI.Components.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+
+<div class="config-file-list">
+    @{
+        var configFileList = Status.ConfigFiles?.Count > 0 ? Status.ConfigFiles : ConfigSet?.Files;
+        var hasList = configFileList != null && configFileList.Count > 0;
+        var mainEntry = hasList ? configFileList![0] : null;
+        var hasMoreThanOne = hasList && configFileList!.Count > 1;
+        var fileCount = hasList ? configFileList!.Count : 2;
+        var showToggle = hasMoreThanOne || (!hasList && Status.ManagedFilePath != null);
+    }
+    <div class="config-file-list-header">
+        <p class="config-file-list-title mb-0">Config files (load order)</p>
+        @if (showToggle)
+        {
+            <button type="button"
+                    class="config-file-list-toggle"
+                    @onclick="ToggleExpanded"
+                    aria-expanded="@_expanded"
+                    aria-label="@(_expanded ? "Show only main config" : "Show all config files")">
+                <i class="bi @(_expanded ? "bi-chevron-up" : "bi-chevron-down")" aria-hidden="true"></i>
+                <span>@(_expanded ? "Show less" : $"Show all ({fileCount} files)")</span>
+            </button>
+        }
+    </div>
+    <div class="config-file-list-content-row">
+        <div class="config-file-list-list">
+            <ul class="list-unstyled config-file-list-main">
+                @if (hasList)
+                {
+                    <ConfigFileListItem Entry="@mainEntry" Status="Status" />
+                }
+                else
+                {
+                    <li><strong>Main config:</strong> @(Status.MainConfigPath ?? "—") @(Status.MainConfigPathExists ? "✓" : "(missing)")</li>
+                }
+            </ul>
+            @if (showToggle)
+            {
+                <div class="config-file-list-expandable @(_expanded ? "expanded" : null)">
+                    <div class="config-file-list-expandable-inner">
+                        <ul class="list-unstyled">
+                            @if (hasList)
+                            {
+                                @foreach (var f in configFileList!.Skip(1))
+                                {
+                                    <ConfigFileListItem Entry="f" Status="Status" />
+                                }
+                            }
+                            else
+                            {
+                                <li><strong>Managed file:</strong> @(Status.ManagedFilePath ?? "—") @(Status.ManagedFilePathExists ? "✓" : "(not created yet)")</li>
+                            }
+                        </ul>
+                    </div>
+                </div>
+            }
+        </div>
+    </div>
+</div>
+
+@code {
+    [Parameter, EditorRequired]
+    public DnsmasqServiceStatus Status { get; set; } = null!;
+
+    [Parameter]
+    public DnsmasqConfigSet? ConfigSet { get; set; }
+
+    private bool _expanded;
+
+    private void ToggleExpanded() => _expanded = !_expanded;
+}

src/DnsmasqWebUI/Components/Dnsmasq/ConfigFileList.razor.css

@@ -0,0 +1,106 @@
+/* Config file list: card-style block with expandable list */
+.config-file-list {
+    --cfl-radius: var(--app-radius, 0.375rem);
+    --cfl-spacing: var(--app-spacing-md, 1rem);
+    --cfl-border: 1px solid #e9ecef;
+    --cfl-bg: #f8f9fa;
+    --cfl-bg-hover: #e9ecef;
+}
+
+.config-file-list {
+    border-radius: var(--cfl-radius);
+    border: var(--cfl-border);
+    background: var(--cfl-bg);
+    padding: var(--cfl-spacing);
+    margin-top: 0.5rem;
+}
+
+.config-file-list-header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    gap: 0.75rem;
+    margin-bottom: 0.5rem;
+}
+
+.config-file-list .config-file-list-title {
+    font-size: 0.9375rem;
+    font-weight: 600;
+    color: #212529;
+    margin-bottom: 0;
+}
+
+.config-file-list ul {
+    margin: 0;
+    padding-left: 1.25rem;
+    font-size: 0.875rem;
+    line-height: 1.6;
+    color: #495057;
+}
+
+.config-file-list ul li {
+    padding: 0.2rem 0;
+}
+
+/* List content row (toggle is in header now) */
+.config-file-list-content-row {
+    display: flex;
+    align-items: flex-start;
+    gap: 0.75rem;
+}
+
+.config-file-list-list {
+    flex: 1;
+    min-width: 0;
+}
+
+.config-file-list .config-file-list-toggle {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.35rem;
+    flex-shrink: 0;
+    padding: 0.35rem 0.5rem;
+    font-size: 0.8125rem;
+    font-weight: 500;
+    color: #0d6efd;
+    background: transparent;
+    border: none;
+    border-radius: var(--cfl-radius);
+    cursor: pointer;
+    transition: background-color 0.15s ease, color 0.15s ease;
+}
+
+.config-file-list .config-file-list-toggle:hover {
+    background: var(--cfl-bg-hover);
+    color: #0a58ca;
+}
+
+.config-file-list .config-file-list-toggle:focus-visible {
+    outline: 0;
+    box-shadow: 0 0 0 0.2rem rgba(13, 110, 253, 0.25);
+}
+
+.config-file-list .config-file-list-toggle .bi {
+    font-size: 0.875rem;
+    transition: transform 0.2s ease;
+}
+
+/* Expandable section: animate height with grid 0fr → 1fr */
+.config-file-list-expandable {
+    display: grid;
+    grid-template-rows: 0fr;
+    transition: grid-template-rows 0.25s ease-out;
+}
+
+.config-file-list-expandable.expanded {
+    grid-template-rows: 1fr;
+}
+
+.config-file-list-expandable-inner {
+    min-height: 0;
+    overflow: hidden;
+}
+
+.config-file-list-expandable-inner ul {
+    padding-top: 0.15rem;
+}

src/DnsmasqWebUI/Components/Dnsmasq/ConfigFileListItem.razor

@@ -0,0 +1,30 @@
+@namespace DnsmasqWebUI.Components.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+
+<li>
+    @if (Entry.IsManaged)
+    {
+        <StatusBadge Kind="StatusBadgeKind.Managed" Text="managed" Class="me-1" />
+    }
+    else
+    {
+        <StatusBadge Kind="StatusBadgeKind.SourceMain" Text="@(Entry.Source.ToString().ToLowerInvariant())" Class="me-1" />
+    }
+    @Entry.Path
+    @{
+        var isMain = string.Equals(Entry.Path, Status.MainConfigPath, StringComparison.Ordinal);
+        var isManaged = Entry.IsManaged;
+        var exists = isMain ? Status.MainConfigPathExists : (isManaged ? Status.ManagedFilePathExists : (bool?)null);
+    }
+    @if (exists == true) { <text> ✓</text> }
+    @if (exists == false) { <text> @(isManaged ? "(not created yet)" : "(missing)")</text> }
+</li>
+
+@code {
+    [Parameter, EditorRequired]
+    public DnsmasqConfigSetEntry Entry { get; set; } = null!;
+
+    [Parameter, EditorRequired]
+    public DnsmasqServiceStatus Status { get; set; } = null!;
+}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/CustomDisplays/FlagValueDisplay.razor

@@ -1,24 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig.CustomDisplays
-@using DnsmasqWebUI.Models.Dnsmasq
-
-@* Reusable value-only display for boolean/flag options. Edit mode: checkbox (unless readonly); View: "Enabled" / "Disabled". *@
-@if (DisplayMode == EffectiveConfigDisplayMode.Edit && Descriptor.GetSource()?.IsReadOnly != true)
-{
-    var isSet = Descriptor.GetValue() is bool b && b;
-    <input type="checkbox" class="form-check-input" checked="@isSet" @onchange="OnCheckedChange" />
-}
-else
-{
-    @(Descriptor.GetValue() is bool isSet && isSet ? "Enabled" : "Disabled")
-}
-
-@code {
-    [Parameter] public EffectiveConfigFieldDescriptor Descriptor { get; set; } = null!;
-    [CascadingParameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
-    [Parameter] public EventCallback<bool> CheckedChanged { get; set; }
-
-    private async Task OnCheckedChange(ChangeEventArgs e)
-    {
-        await CheckedChanged.InvokeAsync(e.Value is true);
-    }
-}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/CustomDisplays/PortValueDisplay.razor

@@ -1,27 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig.CustomDisplays
-@using DnsmasqWebUI.Models.Dnsmasq
-
-@* Value-only display for the port option. Edit mode: number input (unless readonly); View: text with "(default DNS port)". *@
-@if (DisplayMode == EffectiveConfigDisplayMode.Edit && Descriptor.GetSource()?.IsReadOnly != true)
-{
-    var port = Descriptor.GetValue() is int p ? p : 53;
-    <input type="number" class="form-control form-control-sm" style="max-width: 6rem;" min="1" max="65535" value="@port" @oninput="OnPortInput" />
-}
-else
-{
-    @(Descriptor.GetValue() is int port ? $"{port} (default DNS port)" : "(not set)")
-}
-
-@code {
-    [Parameter] public EffectiveConfigFieldDescriptor Descriptor { get; set; } = null!;
-    [CascadingParameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
-    [Parameter] public EventCallback<int?> PortChanged { get; set; }
-
-    private async Task OnPortInput(ChangeEventArgs e)
-    {
-        if (int.TryParse(e.Value?.ToString(), out var port) && port >= 1 && port <= 65535)
-            await PortChanged.InvokeAsync(port);
-        else
-            await PortChanged.InvokeAsync(null);
-    }
-}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/EffectiveConfigFieldDisplay.razor

@@ -1,60 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig
-@using DnsmasqWebUI.Models.Dnsmasq
-@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
-@using DnsmasqWebUI.Models.Config
-@using DnsmasqWebUI.Infrastructure.Helpers.Config
-@using DnsmasqWebUI.Infrastructure.Services.Abstractions
-@inject IEffectiveConfigRenderFragmentRegistry RenderFragmentRegistry
-
-@* Custom fragment renders only the value; we keep the row shell (label + value slot + badge) here for consistency. *@
-@if (_customFragment is { } fragment)
-{
-    var labelTooltip = DnsmasqOptionTooltips.Get(Descriptor.OptionName);
-    <li class="ec-field" title="@(Descriptor.GetSource()?.GetReadOnlyTooltip())">
-        <span id="@_anchorId" class="ec-field-label @(_optionHelpKey != null ? "ec-field-label-help" : null)" title="@(labelTooltip ?? Descriptor.GetSource()?.GetReadOnlyTooltip())" @onclick="RaiseOptionHelpRequested" @onmouseleave="RaiseLabelMouseLeave"><strong>@Descriptor.OptionName:</strong></span>
-        <span class="ec-field-value">
-            @fragment(Descriptor)
-            @if (Descriptor.GetSource()?.IsReadOnly == true)
-            {
-                <span class="badge bg-secondary ec-badge-inline">readonly</span>
-            }
-        </span>
-    </li>
-}
-else if (Descriptor.IsMultiValue)
-{
-    var items = Descriptor.GetItems();
-    <EffectiveConfigMultiValueRow Label="@Descriptor.OptionName" Items="@items" LabelTooltip="@_labelTooltip" OptionHelpKey="@_optionHelpKey" OptionHelpAnchorId="@_anchorId" OnOptionHelpRequested="@OnOptionHelpRequested" />
-}
-else
-{
-    var value = Descriptor.GetValue();
-    var displayValue = value == null ? "(not set)" : (value is IReadOnlyList<string> list ? (list.Count == 0 ? "(none)" : string.Join(", ", list)) : value.ToString());
-    <EffectiveConfigOptionItem Label="@Descriptor.OptionName" DisplayValue="@(displayValue ?? "(not set)")" Source="@Descriptor.GetSource()" LabelTooltip="@_labelTooltip" OptionHelpKey="@_optionHelpKey" OptionHelpAnchorId="@_anchorId" OnOptionHelpRequested="@OnOptionHelpRequested" />
-}
-
-@code {
-    [Parameter] public EffectiveConfigFieldDescriptor Descriptor { get; set; } = null!;
-    [CascadingParameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
-    [Parameter] public EventCallback<ConfigOptionHelpRequestEventArgs> OnOptionHelpRequested { get; set; }
-
-    private readonly string _anchorId = "ec-help-" + Guid.NewGuid().ToString("N")[..8];
-    private RenderFragment<EffectiveConfigFieldDescriptor>? _customFragment;
-    private string? _labelTooltip;
-    private string? _optionHelpKey;
-
-    protected override void OnParametersSet()
-    {
-        _customFragment = RenderFragmentRegistry.GetDisplayFragment(Descriptor.SectionId, Descriptor.OptionName);
-        _labelTooltip = DnsmasqOptionTooltips.Get(Descriptor.OptionName);
-        _optionHelpKey = DnsmasqOptionTooltips.GetOptionHelpKey(Descriptor.OptionName);
-    }
-
-    private async Task RaiseOptionHelpRequested()
-    {
-        if (string.IsNullOrEmpty(_optionHelpKey)) return;
-        await OnOptionHelpRequested.InvokeAsync(new ConfigOptionHelpRequestEventArgs { HelpKey = _optionHelpKey, OptionLabel = Descriptor.OptionName, AnchorId = _anchorId });
-    }
-
-    private async Task RaiseLabelMouseLeave() => await OnOptionHelpRequested.InvokeAsync(new ConfigOptionHelpRequestEventArgs { AnchorId = _anchorId, IsLabelMouseLeave = true });
-}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/EffectiveConfigMultiValueItem.razor

@@ -1,15 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig
-@using DnsmasqWebUI.Models.Dnsmasq
-
-<span class="ec-field-value-item" title="@(Source?.GetReadOnlyTooltip())">
-    @Value
-    @if (Source?.IsReadOnly == true)
-    {
-        <span class="badge bg-secondary ec-badge-inline">readonly</span>
-    }
-</span>
-
-@code {
-    [Parameter] public string Value { get; set; } = "";
-    [Parameter] public ConfigValueSource? Source { get; set; }
-}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/EffectiveConfigMultiValueRow.razor

@@ -1,72 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig
-@using DnsmasqWebUI.Models.Dnsmasq
-@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
-
-<li class="ec-field">
-    <span id="@OptionHelpAnchorId" class="ec-field-label @(OptionHelpKey != null ? "ec-field-label-help" : null)" title="@LabelTooltip" @onclick="RaiseOptionHelpRequested" @onmouseleave="RaiseLabelMouseLeave"><strong>@Label:</strong></span>
-    @if (DisplayMode == EffectiveConfigDisplayMode.Edit)
-    {
-        <span class="ec-field-value ec-field-value-multi">
-            <textarea class="form-control form-control-sm" rows="@(Math.Max(2, (Items?.Count ?? 0) + 1))" @oninput="OnLinesInput" placeholder="One value per line">@_editLines</textarea>
-        </span>
-    }
-    else
-    {
-        <span class="ec-field-value ec-field-value-multi">
-            @if (Items?.Count > 0)
-            {
-                <ol class="ec-field-value-list">
-                    @foreach (var item in Items!)
-                    {
-                        <li><EffectiveConfigMultiValueItem Value="@item.Value" Source="@item.Source" /></li>
-                    }
-                </ol>
-            }
-            else
-            {
-                <span class="text-muted">(none)</span>
-            }
-        </span>
-    }
-</li>
-
-@code {
-    [Parameter] public string Label { get; set; } = "";
-    [Parameter] public IReadOnlyList<ValueWithSource>? Items { get; set; }
-    [Parameter] public EventCallback<IReadOnlyList<string>> ItemsChanged { get; set; }
-    [Parameter] public string? LabelTooltip { get; set; }
-    [Parameter] public string? OptionHelpKey { get; set; }
-    [Parameter] public string? OptionHelpAnchorId { get; set; }
-    [CascadingParameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
-    [Parameter] public EventCallback<ConfigOptionHelpRequestEventArgs> OnOptionHelpRequested { get; set; }
-
-    private string _editLines = "";
-
-    private async Task RaiseOptionHelpRequested()
-    {
-        if (string.IsNullOrEmpty(OptionHelpKey) || string.IsNullOrEmpty(OptionHelpAnchorId)) return;
-        await OnOptionHelpRequested.InvokeAsync(new ConfigOptionHelpRequestEventArgs { HelpKey = OptionHelpKey, OptionLabel = Label, AnchorId = OptionHelpAnchorId });
-    }
-
-    private async Task RaiseLabelMouseLeave()
-    {
-        if (string.IsNullOrEmpty(OptionHelpAnchorId)) return;
-        await OnOptionHelpRequested.InvokeAsync(new ConfigOptionHelpRequestEventArgs { AnchorId = OptionHelpAnchorId, IsLabelMouseLeave = true });
-    }
-
-    protected override void OnParametersSet()
-    {
-        if (Items != null && Items.Count > 0)
-            _editLines = string.Join("\n", Items.Select(i => i.Value));
-        else
-            _editLines = "";
-    }
-
-    private async Task OnLinesInput(ChangeEventArgs e)
-    {
-        var text = e.Value?.ToString() ?? "";
-        _editLines = text;
-        var lines = text.Split('\n', StringSplitOptions.RemoveEmptyEntries).Select(l => l.Trim()).Where(l => l.Length > 0).ToList();
-        await ItemsChanged.InvokeAsync(lines);
-    }
-}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/EffectiveConfigOptionItem.razor

@@ -1,55 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig
-@using DnsmasqWebUI.Models.Dnsmasq
-@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
-
-<li class="ec-field" title="@(Source?.GetReadOnlyTooltip())">
-    <span id="@OptionHelpAnchorId" class="ec-field-label @(OptionHelpKey != null ? "ec-field-label-help" : null)" title="@(LabelTooltip ?? Source?.GetReadOnlyTooltip())" @onclick="RaiseOptionHelpRequested" @onmouseleave="RaiseLabelMouseLeave"><strong>@Label:</strong></span>
-    @if (DisplayMode == EffectiveConfigDisplayMode.Edit && Source?.IsReadOnly != true)
-    {
-        <span class="ec-field-value">
-            <input type="text" class="form-control form-control-sm" value="@DisplayValue" @oninput="OnValueInput" />
-        </span>
-    }
-    else
-    {
-        <span class="ec-field-value">
-            @DisplayValue
-            @if (Source?.IsReadOnly == true)
-            {
-                <span class="badge bg-secondary ec-badge-inline">readonly</span>
-            }
-        </span>
-    }
-</li>
-
-@code {
-    [Parameter] public string Label { get; set; } = "";
-    [Parameter] public string DisplayValue { get; set; } = "";
-    [Parameter] public ConfigValueSource? Source { get; set; }
-    /// <summary>Optional explainer shown on hover over the label (e.g. from DnsmasqOptionTooltips).</summary>
-    [Parameter] public string? LabelTooltip { get; set; }
-    [Parameter] public string? OptionHelpKey { get; set; }
-    [Parameter] public string? OptionHelpAnchorId { get; set; }
-    /// <summary>When Edit and not readonly: raised when the user changes the value. Not yet wired to save.</summary>
-    [Parameter] public EventCallback<string> DisplayValueChanged { get; set; }
-    [CascadingParameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
-    [Parameter] public EventCallback<ConfigOptionHelpRequestEventArgs> OnOptionHelpRequested { get; set; }
-
-    private async Task RaiseOptionHelpRequested()
-    {
-        if (string.IsNullOrEmpty(OptionHelpKey) || string.IsNullOrEmpty(OptionHelpAnchorId)) return;
-        await OnOptionHelpRequested.InvokeAsync(new ConfigOptionHelpRequestEventArgs { HelpKey = OptionHelpKey, OptionLabel = Label, AnchorId = OptionHelpAnchorId });
-    }
-
-    private async Task RaiseLabelMouseLeave()
-    {
-        if (string.IsNullOrEmpty(OptionHelpAnchorId)) return;
-        await OnOptionHelpRequested.InvokeAsync(new ConfigOptionHelpRequestEventArgs { AnchorId = OptionHelpAnchorId, IsLabelMouseLeave = true });
-    }
-
-    private async Task OnValueInput(ChangeEventArgs e)
-    {
-        var value = e.Value?.ToString() ?? "";
-        await DisplayValueChanged.InvokeAsync(value);
-    }
-}

src/DnsmasqWebUI/Components/Dnsmasq/EffectiveConfig/EffectiveConfigSection.razor

@@ -1,144 +0,0 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig
-@using DnsmasqWebUI.Models.Dnsmasq
-@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
-@implements IAsyncDisposable
-
-@if (Status != null)
-{
-<div class="ec-container">
-    <ConfigOptionHelpModal HelpKey="@_optionHelpKey" AnchorId="@_optionHelpAnchorId" Visible="@_showOptionHelp" Title="@_optionHelpTitle"
-        OnClose="CloseOptionHelp" OnMouseEnterModal="CancelCloseTimerAsync" OnMouseLeaveModal="ScheduleCloseAsync" />
-    @if (ShowSearchBox)
-    {
-        <div class="ec-toolbar">
-            <input type="search" id="ec-search-input" class="form-control form-control-sm" placeholder="Search..." autocomplete="off"
-                   @bind="_searchTerm" @bind:event="oninput" @bind:after="StateHasChanged" />
-            <button type="button" class="btn btn-sm btn-outline-secondary" @onclick="CollapseAll" title="Collapse all sections" aria-label="Collapse all sections">
-                <i class="bi bi-arrows-collapse" aria-hidden="true"></i>
-            </button>
-        </div>
-    }
-    <div class="ec-sections small">
-        @{
-            var views = EffectiveConfigViews.GetViewsForContext(Context);
-            var descriptorsBySection = EffectiveConfigViews.GetDescriptorsBySection(Status, views);
-            var hasSearch = !string.IsNullOrWhiteSpace(_searchTerm);
-            var term = _searchTerm?.Trim() ?? "";
-        }
-        @foreach (var view in views)
-        {
-            if (!descriptorsBySection.TryGetValue(view.SectionId, out var contextDescriptors))
-                continue;
-            var sectionDescriptors = hasSearch
-                ? contextDescriptors.Where(d => DescriptorMatchesSearch(d, term)).ToList()
-                : contextDescriptors.ToList();
-            if (sectionDescriptors.Count == 0)
-                continue;
-            var isOpen = hasSearch ? true : IsOpen(view.SectionId);
-            <EffectiveConfigSectionPanel SectionId="@view.SectionId" Title="@view.Title" Descriptors="@sectionDescriptors" IsOpen="@isOpen" OnToggle="@OnSectionToggle" DisplayMode="@DisplayMode" OnOptionHelpRequested="@HandleOptionHelpRequested" />
-        }
-    </div>
-</div>
-}
-
-@code {
-    [Parameter] public DnsmasqServiceStatus? Status { get; set; }
-    [Parameter] public EffectiveConfigContext Context { get; set; } = EffectiveConfigContext.All;
-    [Parameter] public bool ShowSearchBox { get; set; } = true;
-    /// <summary>View = read-only; Edit = editable (future). Cascaded to field displays.</summary>
-    [Parameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
-
-    private string _searchTerm = "";
-    private HashSet<string> _openPanels = new();
-    private string? _optionHelpKey;
-    private string? _optionHelpAnchorId;
-    private string _optionHelpTitle = "Option help";
-    private bool _showOptionHelp;
-    private CancellationTokenSource? _closeCts;
-
-    private bool IsOpen(string id) => _openPanels.Contains(id);
-
-    private async Task HandleOptionHelpRequested(ConfigOptionHelpRequestEventArgs args)
-    {
-        if (args.IsLabelMouseLeave)
-        {
-            if (args.AnchorId == _optionHelpAnchorId)
-                ScheduleClose();
-            return;
-        }
-        _optionHelpKey = args.HelpKey;
-        _optionHelpTitle = args.OptionLabel;
-        _optionHelpAnchorId = args.AnchorId;
-        _showOptionHelp = true;
-        CancelCloseTimer();
-        await InvokeAsync(StateHasChanged);
-    }
-
-    private void CancelCloseTimer()
-    {
-        _closeCts?.Cancel();
-        _closeCts = null;
-    }
-
-    private Task CancelCloseTimerAsync() { CancelCloseTimer(); return Task.CompletedTask; }
-
-    private void ScheduleClose()
-    {
-        _closeCts?.Cancel();
-        _closeCts = new CancellationTokenSource();
-        var token = _closeCts.Token;
-        _ = Task.Run(async () =>
-        {
-            try
-            {
-                await Task.Delay(300, token);
-            }
-            catch (OperationCanceledException) { return; }
-            await InvokeAsync(() =>
-            {
-                if (token.IsCancellationRequested) return;
-                _showOptionHelp = false;
-                _closeCts = null;
-                StateHasChanged();
-            });
-        }, token);
-    }
-
-    private Task ScheduleCloseAsync() { ScheduleClose(); return Task.CompletedTask; }
-
-    private void CloseOptionHelp()
-    {
-        CancelCloseTimer();
-        _showOptionHelp = false;
-        StateHasChanged();
-    }
-
-    private void OnSectionToggle(string id)
-    {
-        if (_openPanels.Contains(id))
-            _openPanels.Remove(id);
-        else
-            _openPanels.Add(id);
-    }
-
-    private void CollapseAll()
-    {
-        _openPanels.Clear();
-        StateHasChanged();
-    }
-
-    private static bool DescriptorMatchesSearch(EffectiveConfigFieldDescriptor d, string term)
-    {
-        if (string.IsNullOrEmpty(term)) return true;
-        var searchable = (d.OptionName + " " + (DnsmasqOptionTooltips.Get(d.OptionName) ?? "")).Trim();
-        return searchable.Contains(term, StringComparison.OrdinalIgnoreCase);
-    }
-
-    public ValueTask DisposeAsync()
-    {
-        _closeCts?.Cancel();
-        _closeCts?.Dispose();
-        _closeCts = null;
-        return ValueTask.CompletedTask;
-    }
-}

src/DnsmasqWebUI/Components/Dnsmasq/Logs/LogsPreView.razor

@@ -1,4 +1,4 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq
+@namespace DnsmasqWebUI.Components.Dnsmasq.Logs
 @* Renders a pre element for logs. Once Freeze is true, stops re-rendering so Blazor does not overwrite JS-owned content. *@
 <pre id="@Id" class="pre-block mb-0" style="max-height: 24rem;">@Placeholder</pre>
 

src/DnsmasqWebUI/Components/Dnsmasq/Logs/LogsSection.razor

@@ -1,4 +1,4 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq
+@namespace DnsmasqWebUI.Components.Dnsmasq.Logs
 @* Recent logs — live view via SignalR from LogsCommand; client polls at interval, server pushes deltas *@
 @using DnsmasqWebUI.Models.Logs
 @using Microsoft.AspNetCore.SignalR.Client
@@ -27,14 +27,14 @@
         <LogsPreView Id="dnsmasq-logs-pre" Placeholder="@_initialPlaceholder" Freeze="_logsContentReceived" />
     }
     <div class="mt-2 d-flex flex-wrap gap-2 align-items-center">
-        <button class="btn btn-primary btn-sm" @onclick="RequestRefreshAsync" disabled="@_refreshing">Refresh</button>
+        <button class="btn btn-primary btn-sm" @onclick="RequestRefreshAsync" disabled="@_refreshing"><i class="bi bi-arrow-repeat me-1" aria-hidden="true"></i>Refresh</button>
         @if (_status.LogsPath != null)
         {
-            <a href="api/status/logs/download" download="dnsmasq.log" class="btn btn-primary btn-sm">Download logs</a>
+            <a href="api/status/logs/download" download="dnsmasq.log" class="btn btn-primary btn-sm"><i class="bi bi-download me-1" aria-hidden="true"></i>Download logs</a>
         }
         else
         {
-            <button type="button" class="btn btn-primary btn-sm" disabled title="No log file path detected. Set log-facility=/path/to/file in your dnsmasq config to enable download.">Download logs</button>
+            <button type="button" class="btn btn-primary btn-sm" disabled title="No log file path detected. Set log-facility=/path/to/file in your dnsmasq config to enable download."><i class="bi bi-download me-1" aria-hidden="true"></i>Download logs</button>
         }
     </div>
 }

src/DnsmasqWebUI/Components/Dnsmasq/Logs/LogsSection.razor.cs

@@ -1,10 +1,11 @@
+using DnsmasqWebUI.Extensions.Interop;
 using DnsmasqWebUI.Models.Dnsmasq;
 using DnsmasqWebUI.Models.Logs;
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.JSInterop;
 
-namespace DnsmasqWebUI.Components.Dnsmasq;
+namespace DnsmasqWebUI.Components.Dnsmasq.Logs;
 
 /// <summary>
 /// Recent logs block: connects to LogsHub, polls at interval via RequestDnsmasqLogs,
@@ -62,13 +63,12 @@ public partial class LogsSection : IAsyncDisposable
 
         _hubConnection.On<LogsUpdatePayload>("DnsmasqLogsUpdate", OnDnsmasqLogsUpdate);
 
-        try
+        _logsJs = await JSRuntime.InvokeAsyncSafe<IJSObjectReference>("import", default, "./js/logs.js");
+        if (_logsJs == null)
         {
-            _logsJs = await JSRuntime.InvokeAsync<IJSObjectReference>("import", "./js/logs.js");
+            Logger.LogDebug("LogsSection: logs JS module unavailable (prerender, disconnect, or import failure)");
+            return;
         }
-        catch (InvalidOperationException ex) { Logger.LogDebug(ex, "LogsSection: JS import skipped (prerender)"); return; }
-        catch (JSDisconnectedException ex) { Logger.LogDebug(ex, "LogsSection: JS import skipped (circuit disconnected)"); return; }
-        catch (JSException ex) { Logger.LogDebug(ex, "LogsSection: JS import failed"); return; }
 
         await _hubConnection.StartAsync(_cts.Token);
         RestartPollTimer();
@@ -123,23 +123,18 @@ public partial class LogsSection : IAsyncDisposable
             await InvokeAsync(async () =>
             {
                 if (_logsJs == null) return;
-                try
+                if (payload.Mode == "replace")
-                {
+                    await _logsJs.InvokeVoidAsyncSafe("replaceLogs", LogsPreId, payload.Content, LogsOptions);
-                    if (payload.Mode == "replace")
+                else
-                        await _logsJs.InvokeVoidAsync("replaceLogs", LogsPreId, payload.Content, LogsOptions);
+                    await _logsJs.InvokeVoidAsyncSafe("appendLogs", LogsPreId, payload.Content, LogsOptions);
-                    else
+                _logsContentReceived = true;
-                        await _logsJs.InvokeVoidAsync("appendLogs", LogsPreId, payload.Content, LogsOptions);
+                SetJustUpdated();
-                    _logsContentReceived = true;
+                StateHasChanged();
-                    SetJustUpdated();
-                    StateHasChanged();
-                }
-                catch (JSDisconnectedException) { /* Circuit disconnected; ignore */ }
-                catch (InvalidOperationException) { /* Prerender or circuit disposed; ignore */ }
-                catch (JSException) { /* JS error; ignore */ }
             });
         }
         catch (ObjectDisposedException) { /* Component disposed; ignore */ }
         catch (InvalidOperationException) { /* Circuit disconnected; ignore */ }
+        catch (JSDisconnectedException) { /* Circuit gone before InvokeAsync completed */ }
     }
 
     private void SetJustUpdated()
@@ -169,13 +164,7 @@ public partial class LogsSection : IAsyncDisposable
             await _hubConnection.DisposeAsync();
             _hubConnection = null;
         }
-        if (_logsJs != null)
+        await _logsJs.DisposeAsyncSafe();
-        {
+        _logsJs = null;
-            try { await _logsJs.DisposeAsync(); }
-            catch (InvalidOperationException ex) { Logger.LogDebug(ex, "LogsSection: DisposeAsync skipped (prerender)"); }
-            catch (JSDisconnectedException ex) { Logger.LogDebug(ex, "LogsSection: DisposeAsync skipped (circuit disconnected)"); }
-            catch (JSException ex) { Logger.LogDebug(ex, "LogsSection: DisposeAsync failed"); }
-            _logsJs = null;
-        }
     }
 }

src/DnsmasqWebUI/Components/Dnsmasq/Status/StatusSection.razor

@@ -1,4 +1,4 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq
+@namespace DnsmasqWebUI.Components.Dnsmasq.Status
 @* Service status — output of StatusShowCommand; only this component re-renders on its timer *@
 @if (_status != null && _status.StatusShowConfigured)
 {
@@ -24,7 +24,21 @@
     {
         <pre class="pre-block mb-0" style="max-height: 22rem;">@_status.StatusShowOutput</pre>
     }
-    <div class="mt-2">
+    <div class="mt-2 d-flex align-items-center gap-2 flex-wrap">
-        <button class="btn btn-primary btn-sm" @onclick="RefreshAsync" disabled="@_refreshing">Refresh</button>
+        <button class="btn btn-primary btn-sm" @onclick="RefreshAsync" disabled="@_refreshing"><i class="bi bi-arrow-repeat me-1" aria-hidden="true"></i>Refresh</button>
+        @if (ReloadCommandConfigured && OnReloadRequested.HasDelegate)
+        {
+            <button class="btn btn-primary btn-sm" @onclick="InvokeReloadAsync" disabled="@IsReloading" title="Reload dnsmasq config (e.g. SIGHUP)">
+                @if (IsReloading)
+                {
+                    <span class="spinner-border spinner-border-sm me-1" role="status" aria-hidden="true"></span>
+                }
+                else
+                {
+                    <i class="bi bi-arrow-repeat me-1" aria-hidden="true"></i>
+                }
+                Reload
+            </button>
+        }
     </div>
 }

src/DnsmasqWebUI/Components/Dnsmasq/Status/StatusSection.razor.cs

@@ -2,7 +2,7 @@ using DnsmasqWebUI.Infrastructure.Client.Abstractions;
 using DnsmasqWebUI.Models.Dnsmasq;
 using Microsoft.AspNetCore.Components;
 
-namespace DnsmasqWebUI.Components.Dnsmasq;
+namespace DnsmasqWebUI.Components.Dnsmasq.Status;
 
 /// <summary>
 /// Service status block: polls StatusShowCommand output at its own interval and re-renders only itself.
@@ -19,6 +19,11 @@ public partial class StatusSection : IDisposable
 
     [Parameter] public bool IsReloading { get; set; }
 
+    /// <summary>When set and reload is configured, show a "Reload config" button next to Refresh.</summary>
+    [Parameter] public EventCallback OnReloadRequested { get; set; }
+
+    [Parameter] public bool ReloadCommandConfigured { get; set; }
+
     [Parameter] public EventCallback OnOpenSettings { get; set; }
 
     [Inject] private IStatusClient StatusClient { get; set; } = null!;
@@ -55,6 +60,8 @@ public partial class StatusSection : IDisposable
 
     private static readonly TimeSpan MinUpdatingDuration = TimeSpan.FromSeconds(1);
 
+    private Task InvokeReloadAsync() => OnReloadRequested.InvokeAsync();
+
     private async Task RefreshAsync()
     {
         var started = DateTime.UtcNow;

src/DnsmasqWebUI/Components/EffectiveConfig/Common/CopyableCodeLine.razor

@@ -0,0 +1,22 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig
+@using DnsmasqWebUI.Extensions.Interop
+@inject IJSRuntime JSRuntime
+
+<div class="d-flex align-items-center gap-1 @CssClass">
+    <code class="flex-grow-1 text-break @CodeCssClass">@Text</code>
+    <button type="button" class="btn btn-sm btn-outline-secondary py-0" @onclick="CopyAsync" title="@CopyTitle"><i class="bi bi-clipboard me-1" aria-hidden="true"></i>Copy</button>
+</div>
+
+@code {
+    [Parameter] public string Text { get; set; } = "";
+    [Parameter] public string? CssClass { get; set; }
+    [Parameter] public string? CodeCssClass { get; set; }
+    [Parameter] public string CopyTitle { get; set; } = "Copy";
+
+    private async Task CopyAsync()
+    {
+        if (string.IsNullOrEmpty(Text)) return;
+        // window.copyToClipboard from wwwroot/js/copy-to-clipboard.js; swallow disconnect / clipboard failures.
+        await JSRuntime.InvokeVoidAsyncSafe("copyToClipboard", args: new object?[] { Text });
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/Common/EffectiveConfigMultiValueDisplayBase.cs

@@ -0,0 +1,22 @@
+using Microsoft.AspNetCore.Components;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+
+namespace DnsmasqWebUI.Components.EffectiveConfig;
+
+/// <summary>
+/// Base for custom effective-config multi-value displays; mirrors <see cref="EffectiveConfigValueDisplayBase"/> for singles.
+/// </summary>
+public abstract class EffectiveConfigMultiValueDisplayBase : ComponentBase
+{
+    [Parameter]
+    public EffectiveConfigMultiDisplayContext Context { get; set; } = null!;
+
+    [Parameter]
+    public EventCallback<IReadOnlyList<string>> OnValuesChanged { get; set; }
+
+    protected IReadOnlyList<ValueWithSource> EffectiveItems => Context.EffectiveItems;
+
+    protected IReadOnlyList<string> EffectiveValues => Context.EffectiveValues;
+
+    protected Task NotifyValuesChanged(IReadOnlyList<string> values) => OnValuesChanged.InvokeAsync(values);
+}

src/DnsmasqWebUI/Components/EffectiveConfig/Common/EffectiveConfigValueDisplayBase.cs

@@ -0,0 +1,39 @@
+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.Web;
+using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig;
+using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Abstractions;
+
+namespace DnsmasqWebUI.Components.EffectiveConfig;
+
+/// <summary>
+/// Base for effective-config custom value displays. Provides shared parameters,
+/// <see cref="NotifyValueChanged"/>, and <see cref="GetEffectiveDisplayValue"/> so pending changes are shown before save.
+/// </summary>
+public abstract class EffectiveConfigValueDisplayBase : ComponentBase
+{
+    [Parameter]
+    public EffectiveConfigFieldDescriptor Descriptor { get; set; } = null!;
+
+    [CascadingParameter]
+    public bool IsActiveEditor { get; set; }
+
+    [CascadingParameter]
+    public EventCallback<FocusEventArgs> OnCommitRequested { get; set; }
+
+    [Parameter]
+    public EventCallback<object?> ValueChanged { get; set; }
+
+    [CascadingParameter]
+    public IEffectiveConfigEditSession? Session { get; set; }
+
+    protected Task NotifyValueChanged(object? value) => ValueChanged.InvokeAsync(value);
+
+    /// <summary>Returns the value to display: pending change NewValue if this field has one, else descriptor value (not yet written to disk).</summary>
+    protected object? GetEffectiveDisplayValue()
+    {
+        var pending = Session?.Draft.PendingChanges.OfType<PendingOptionChange>().FirstOrDefault(c =>
+            string.Equals(c.SectionId, Descriptor.SectionId, StringComparison.OrdinalIgnoreCase) &&
+            string.Equals(c.OptionName, Descriptor.OptionName, StringComparison.OrdinalIgnoreCase));
+        return pending != null ? pending.NewValue : Descriptor.GetValue();
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/Composition/EffectiveConfigPanels.razor

@@ -0,0 +1,47 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig
+@using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Abstractions
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+@inject IEffectiveConfigDescriptorProvider DescriptorProvider
+
+<div class="ec-sections small">
+    @{
+        var views = EffectiveConfigViews.GetViewsForContext(Context);
+        var descriptorsBySection = Status != null ? DescriptorProvider.GetBySection(Status, views) : new Dictionary<string, IReadOnlyList<EffectiveConfigFieldDescriptor>>();
+        var hasSearch = !string.IsNullOrWhiteSpace(SearchTerm);
+        var term = SearchTerm?.Trim() ?? "";
+    }
+    @foreach (var view in views)
+    {
+        if (!descriptorsBySection.TryGetValue(view.SectionId, out var contextDescriptors))
+            continue;
+        var sectionDescriptors = hasSearch
+            ? contextDescriptors.Where(d => DescriptorMatchesSearch(d, term)).ToList()
+            : contextDescriptors.ToList();
+        if (sectionDescriptors.Count == 0)
+            continue;
+        var isOpen = hasSearch || IsSectionOpen(view.SectionId);
+        <EffectiveConfigSectionPanel SectionId="@view.SectionId" Title="@view.Title" Descriptors="@sectionDescriptors" IsOpen="@isOpen" OnToggle="@OnSectionToggle"
+            DisplayMode="@( IsEditMode ? EffectiveConfigDisplayMode.Edit : EffectiveConfigDisplayMode.View )"
+            IsEditMode="@IsEditMode" ActiveFieldKey="@ActiveFieldKey" />
+    }
+</div>
+
+@code {
+    [Parameter] public DnsmasqServiceStatus? Status { get; set; }
+    [Parameter] public EffectiveConfigContext Context { get; set; } = EffectiveConfigContext.All;
+    [Parameter] public string SearchTerm { get; set; } = "";
+    [Parameter] public HashSet<string> OpenSectionIds { get; set; } = new();
+    [Parameter] public EventCallback<string> OnSectionToggle { get; set; }
+    [Parameter] public bool IsEditMode { get; set; }
+    [Parameter] public string? ActiveFieldKey { get; set; }
+
+    private bool IsSectionOpen(string id) => OpenSectionIds.Contains(id);
+
+    private static bool DescriptorMatchesSearch(EffectiveConfigFieldDescriptor d, string term)
+    {
+        if (string.IsNullOrEmpty(term)) return true;
+        var searchable = (d.OptionName + " " + (DnsmasqOptionTooltips.Get(d.OptionName) ?? "")).Trim();
+        return searchable.Contains(term, StringComparison.OrdinalIgnoreCase);
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/Composition/EffectiveConfigSection.razor

@@ -0,0 +1,265 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+@using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Abstractions
+@using DnsmasqWebUI.Infrastructure.Services.EffectiveConfig.Validation.Abstractions
+@inject IEffectiveConfigEditSession Session
+@inject IEffectiveConfigCrossOptionValidationService CrossOptionValidation
+@inject IJSRuntime JSRuntime
+@implements IDisposable
+
+@if (Status != null)
+{
+<div class="ec-container" @onclick="DeactivateActiveFieldIfClicked">
+    <OptionHelpController @ref="_optionHelpControllerRef" Visible="@_showOptionHelp" HelpKey="@_optionHelpKey" AnchorId="@_optionHelpAnchorId" Title="@_optionHelpTitle" OnCloseRequested="CloseOptionHelp" />
+    <ReadonlyPopoverController @ref="_readonlyPopoverControllerRef" Visible="@_showReadonlyPopover" AnchorId="@_readonlyPopoverAnchorId" Source="@_readonlyPopoverSource" OptionName="@(_readonlyPopoverOptionName ?? "")" Value="@_readonlyPopoverValue" ManagedFilePath="@(Status?.ManagedFilePath)" OnCloseRequested="CloseReadonlyPopover" />
+    @{
+        var _sectionViews = EffectiveConfigViews.GetViewsForContext(Context);
+        var _allSectionsExpanded = _sectionViews.Count > 0 && _sectionViews.All(v => _openPanels.Contains(v.SectionId));
+    }
+    <EffectiveConfigToolbar ShowSearchBox="@ShowSearchBox" SearchTerm="@_searchTerm" SearchTermChanged="@OnSearchTermChanged"
+        IsEditMode="@Session.Ui.IsEditMode" PendingChangesCount="@Session.Draft.PendingChanges.Count"
+        ValidationSummary="@Session.Draft.GetValidationSummary()"
+        AllSectionsExpanded="@_allSectionsExpanded"
+        OnExpandAll="ExpandAll" OnCollapseAll="CollapseAll" OnEnterEditMode="EnterEditMode" OnExitEditModeWithConfirm="ExitEditModeWithConfirmAsync" OnOpenSaveModal="OpenSaveModal" />
+    <CascadingValue Value="@Session">
+    <CascadingValue Value="@_uiContext">
+        <EffectiveConfigPanels Status="@Status" Context="@Context" SearchTerm="@_searchTerm" OpenSectionIds="@_openPanels"
+            OnSectionToggle="OnSectionToggle" IsEditMode="@Session.Ui.IsEditMode" ActiveFieldKey="@Session.Ui.ActiveFieldKey" />
+    </CascadingValue>
+    </CascadingValue>
+    <EffectiveConfigSaveFlow ShowModal="@_showSaveModal" PendingChanges="@Session.Draft.PendingChanges" Status="@Status" Session="@Session"
+        OnClose="CloseSaveModal" OnRevertedNotify="OnRevertedFromSaveModal" OnSaveCompleted="OnSaveCompleted" OnContinueEditingAfterSavedFailure="ContinueEditingAfterSavedFailureAsync" OnCloseAndEndEdit="CloseSaveModalAndEndEdit" />
+</div>
+}
+
+@code {
+    [Parameter] public DnsmasqServiceStatus? Status { get; set; }
+    [Parameter] public EffectiveConfigContext Context { get; set; } = EffectiveConfigContext.All;
+    [Parameter] public bool ShowSearchBox { get; set; } = true;
+    [Parameter] public EventCallback OnSaveCompleted { get; set; }
+
+    private string _searchTerm = "";
+    private HashSet<string> _openPanels = new();
+    private bool _showSaveModal;
+
+    private string? _optionHelpKey;
+    private string? _optionHelpAnchorId;
+    private string _optionHelpTitle = "Option help";
+    private bool _showOptionHelp;
+    private OptionHelpController? _optionHelpControllerRef;
+
+    private bool _showReadonlyPopover;
+    private ReadonlyPopoverController? _readonlyPopoverControllerRef;
+    private string? _readonlyPopoverAnchorId;
+    private ConfigValueSource? _readonlyPopoverSource;
+    private string? _readonlyPopoverOptionName;
+    private object? _readonlyPopoverValue;
+
+    private EffectiveConfigUiContext? _uiContext;
+
+    protected override void OnInitialized()
+    {
+        Session.Changed += HandleSessionChanged;
+        _uiContext = new EffectiveConfigUiContext
+        {
+            RequestOptionHelpAsync = HandleOptionHelpRequested,
+            RequestReadonlyPopoverAsync = HandleReadonlyBadgeClicked,
+            ScheduleReadonlyPopoverCloseAsync = () =>
+            {
+                _readonlyPopoverControllerRef?.ScheduleCloseFromBadgeLeave();
+                return Task.CompletedTask;
+            },
+            ActivateFieldAsync = fieldKey => { ActivateField(fieldKey); return Task.CompletedTask; },
+            DeactivateFieldAsync = () => { Session.Ui.DeactivateField(); return InvokeAsync(StateHasChanged); },
+            CommitFieldAsync = args => { HandleFieldEditCommitted(args); return Task.CompletedTask; },
+            RevertFieldAsync = (sectionId, optionName) => { Session.Draft.RevertChange(sectionId, optionName); RunCrossOptionEvaluator(); return InvokeAsync(StateHasChanged); }
+        };
+    }
+
+    private void HandleSessionChanged() => _ = InvokeAsync(StateHasChanged);
+
+    public void Dispose()
+    {
+        Session.Changed -= HandleSessionChanged;
+    }
+
+    private async Task OnSearchTermChanged(string value)
+    {
+        _searchTerm = value ?? "";
+        await InvokeAsync(StateHasChanged);
+    }
+
+    private void CloseOptionHelp()
+    {
+        _showOptionHelp = false;
+        StateHasChanged();
+    }
+
+    private async Task HandleOptionHelpRequested(ConfigOptionHelpRequestEventArgs args)
+    {
+        if (args.IsLabelMouseLeave)
+        {
+            if (args.AnchorId == _optionHelpAnchorId)
+                _optionHelpControllerRef?.ScheduleCloseFromLabelLeave();
+            await InvokeAsync(StateHasChanged);
+            return;
+        }
+        _optionHelpControllerRef?.CancelCloseFromLabelEnter();
+        _optionHelpKey = args.HelpKey;
+        _optionHelpTitle = args.OptionLabel;
+        _optionHelpAnchorId = args.AnchorId;
+        _showOptionHelp = true;
+        await InvokeAsync(StateHasChanged);
+    }
+
+    private void CloseReadonlyPopover()
+    {
+        _showReadonlyPopover = false;
+        StateHasChanged();
+    }
+
+    private async Task HandleReadonlyBadgeClicked(ReadonlyBadgeClickedEventArgs args)
+    {
+        _readonlyPopoverControllerRef?.CancelCloseFromBadgeEnter();
+        _readonlyPopoverAnchorId = args.AnchorId;
+        _readonlyPopoverSource = args.Source;
+        _readonlyPopoverOptionName = args.OptionName;
+        _readonlyPopoverValue = args.Value;
+        _showReadonlyPopover = true;
+        await InvokeAsync(StateHasChanged);
+    }
+
+    private void OnSectionToggle(string id)
+    {
+        if (_openPanels.Contains(id))
+            _openPanels.Remove(id);
+        else
+            _openPanels.Add(id);
+        StateHasChanged();
+    }
+
+    private void ExpandAll()
+    {
+        foreach (var view in EffectiveConfigViews.GetViewsForContext(Context))
+            _openPanels.Add(view.SectionId);
+        StateHasChanged();
+    }
+
+    private void CollapseAll()
+    {
+        _openPanels.Clear();
+        StateHasChanged();
+    }
+
+    private void EnterEditMode()
+    {
+        Session.Ui.EnterEditMode();
+        RefreshCrossOptionAfterEnteringEditMode();
+        StateHasChanged();
+    }
+
+    private async Task ExitEditModeWithConfirmAsync()
+    {
+        if (Session.Draft.PendingChanges.Count > 0)
+        {
+            var module = await JSRuntime.InvokeAsyncSafe<IJSObjectReference>("import", default, "./js/dialog.js");
+            if (module == null)
+                return;
+
+            try
+            {
+                var confirmed = await module.InvokeAsyncSafe<bool>("confirmMessage", "Discard unsaved changes and exit edit mode?");
+                if (confirmed != true)
+                    return;
+            }
+            finally
+            {
+                await module.DisposeAsyncSafe();
+            }
+        }
+        Session.Draft.DiscardAllDraft();
+        Session.Ui.ExitEditMode();
+        StateHasChanged();
+    }
+
+    private void DeactivateActiveFieldIfClicked()
+    {
+        if (Session.Ui.IsEditMode && Session.Ui.ActiveFieldKey != null)
+        {
+            Session.Ui.DeactivateField();
+            StateHasChanged();
+        }
+    }
+
+    private void ActivateField(string fieldKey)
+    {
+        Session.Ui.ActivateField(fieldKey);
+        StateHasChanged();
+    }
+
+    private void HandleFieldEditCommitted(EffectiveConfigEditCommittedArgs args)
+    {
+        Session.Draft.TrackCommit(args);
+        Session.Ui.DeactivateField();
+        RunCrossOptionEvaluator();
+        StateHasChanged();
+    }
+
+    private void RunCrossOptionEvaluator()
+    {
+        var optionChanges = Session.Draft.PendingChanges.OfType<PendingOptionChange>().ToList();
+        var issues = CrossOptionValidation.Validate(Status, optionChanges);
+        Session.Draft.SetCrossOptionIssues(issues);
+    }
+
+    /// <summary>
+    /// After entering edit mode, repopulate cross-option issues from disk + pending.
+    /// </summary>
+    private void RefreshCrossOptionAfterEnteringEditMode()
+    {
+        if (Status != null)
+            RunCrossOptionEvaluator();
+    }
+
+    private void OnRevertedFromSaveModal()
+    {
+        RunCrossOptionEvaluator();
+        StateHasChanged();
+    }
+
+    private void OpenSaveModal()
+    {
+        var hasPending = Session.Draft.PendingChanges.Count > 0;
+        var hasValidation = Session.Draft.GetValidationSummary().Count > 0;
+        if (!hasPending && !hasValidation)
+            return;
+        _showSaveModal = true;
+        StateHasChanged();
+    }
+
+    private void CloseSaveModal()
+    {
+        _showSaveModal = false;
+        StateHasChanged();
+    }
+
+    private async Task ContinueEditingAfterSavedFailureAsync()
+    {
+        _showSaveModal = false;
+        Session.Draft.DiscardAllDraft();
+        Session.Ui.ExitEditMode();
+        await OnSaveCompleted.InvokeAsync();
+        Session.Ui.EnterEditMode();
+        RefreshCrossOptionAfterEnteringEditMode();
+        StateHasChanged();
+    }
+
+    private void CloseSaveModalAndEndEdit()
+    {
+        _showSaveModal = false;
+        Session.Draft.DiscardAllDraft();
+        Session.Ui.ExitEditMode();
+        StateHasChanged();
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/Composition/EffectiveConfigSection.razor.css

@@ -13,16 +13,37 @@
     overflow: visible;
 }
 
-.ec-toolbar {
+/* Toolbar: single row, search left and actions right. Use ::deep so styles apply to EffectiveConfigToolbar (child) markup. */
+::deep .ec-toolbar {
     display: flex;
+    flex-wrap: nowrap;
     align-items: center;
     gap: 0.5rem;
     margin-bottom: 0.75rem;
+    min-width: 0;
 }
 
-.ec-toolbar input[type="search"] {
+::deep .ec-toolbar-search {
-    flex: 1;
+    flex: 1 1 auto;
     min-width: 0;
+    max-width: 24rem;
+}
+
+::deep .ec-toolbar-actions {
+    display: flex;
+    flex-wrap: nowrap;
+    flex-shrink: 0;
+    align-items: center;
+    gap: 0.5rem;
+    margin-left: auto;
+}
+
+::deep .ec-toolbar-changes-link {
+    cursor: pointer;
+}
+
+::deep .ec-toolbar-changes-link:hover {
+    text-decoration: underline;
 }
 
 .ec-sections {
@@ -104,6 +125,22 @@
     opacity: 1;
 }
 
+/* Animated expand/collapse: grid 0fr → 1fr */
+::deep .ec-section-collapse {
+    display: grid;
+    grid-template-rows: 0fr;
+    transition: grid-template-rows 0.25s ease-out;
+}
+
+::deep .ec-section-collapse-open {
+    grid-template-rows: 1fr;
+}
+
+::deep .ec-section-collapse-inner {
+    min-height: 0;
+    overflow: hidden;
+}
+
 ::deep .ec-section-body {
     padding: 0.25rem 1rem 0.5rem 1rem;
     padding-left: 1rem;
@@ -135,6 +172,16 @@
     margin-bottom: 0.35rem;
 }
 
+/* Option label + field-level badges (editable / ok / cancel) on one row */
+::deep .ec-field-label-row {
+    display: inline-flex;
+    flex-wrap: wrap;
+    align-items: baseline;
+    gap: 0.25rem 0.5rem;
+    flex: 0 1 auto;
+    min-width: 0;
+}
+
 ::deep .ec-field:last-child {
     margin-bottom: 0;
 }
@@ -156,10 +203,40 @@
 }
 
 ::deep .ec-field-value {
+    display: flex;
+    flex-wrap: wrap;
+    align-items: center;
     flex: 1 1 auto;
     min-width: 0;
     overflow-wrap: break-word;
     word-break: break-word;
+    gap: 0.25rem;
+}
+
+/* When a field is active: value + badges in one block so any click inside (checkbox, input, ok/cancel) doesn't deactivate */
+::deep .ec-field-value-when-editing {
+    display: inline-flex;
+    flex-wrap: nowrap;
+    align-items: center;
+    gap: 0.25rem;
+    min-width: 0;
+    max-width: 100%;
+}
+
+/* Edit wrapper (checkbox/input) shrinks to content */
+::deep .ec-field-edit-wrapper {
+    flex: 0 1 auto;
+    display: inline-flex;
+    align-items: center;
+    min-width: 0;
+    max-width: 100%;
+}
+
+/* Input/select in value area can shrink so the editable badge stays on the same line */
+::deep .ec-field-value > .form-control,
+::deep .ec-field-value > .form-select {
+    flex: 1 1 auto;
+    min-width: 0;
 }
 
 /* Multi-value: full width below label, indented ordered list. min-width: 0 so flex doesn't prevent wrapping. */
@@ -190,6 +267,24 @@
     margin-bottom: 0;
 }
 
+::deep .ec-field-value-list li.ec-multi-list-empty-hint {
+    list-style: none;
+    margin-left: -1.25rem;
+}
+
+/* Shared with default and custom (e.g. domain) multi-value editors */
+::deep .ec-field-value-list li.ec-multi-list-add-item {
+    list-style: none;
+    margin-left: -1.25rem;
+    margin-top: 0.25rem;
+    padding-top: 0.25rem;
+    border-top: 1px dashed var(--bs-border-color, #dee2e6);
+}
+
+::deep .ec-field-value-list li.ec-multi-list-add-item > .ec-multi-list-row-controls > .status-badge-inline {
+    margin-left: auto;
+}
+
 /* Long paths/URLs wrap; allow break anywhere so nothing is clipped */
 ::deep .ec-field-value-item {
     display: inline;
@@ -201,18 +296,31 @@
     margin-right: 0.25rem;
 }
 
-/* Badge: vertically centered, inline with value so when it wraps it stays part of the value flow */
+/* StatusBadge inside field rows: alignment; spacing comes from StatusBadge .status-badge-inline */
-::deep .ec-field .badge,
+::deep .ec-field .status-badge,
-::deep .ec-field-value-item .badge {
+::deep .ec-field-value-item .status-badge {
     display: inline-flex;
     align-items: center;
     line-height: 1;
 }
 
-/* Inline badge (inside value): gap from text; when it wraps to own line the margin gives a subtle indent */
+/* Only when field is in edit mode: push ok/cancel/revert to end and allow them to wrap first on narrow widths */
-::deep .ec-badge-inline {
+::deep .ec-field-value-when-editing > .status-badge-inline {
-    margin-left: 0.35rem;
+    flex: 0 0 auto;
     white-space: nowrap;
+    margin-left: auto;
+}
+
+@media (max-width: 575.98px) {
+    ::deep .ec-field-value-when-editing {
+        flex-wrap: wrap;
+    }
+
+    ::deep .ec-field-value-when-editing > .status-badge-inline {
+        flex-basis: 100%;
+        margin-left: 0;
+        margin-top: 0.15rem;
+    }
 }
 
 @media (max-width: 767.98px) {

src/DnsmasqWebUI/Components/EffectiveConfig/Composition/EffectiveConfigSectionPanel.razor

@@ -1,4 +1,4 @@
-@namespace DnsmasqWebUI.Components.Dnsmasq.EffectiveConfig
+@namespace DnsmasqWebUI.Components.EffectiveConfig
 @using DnsmasqWebUI.Models.Dnsmasq
 @using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
 
@@ -8,14 +8,18 @@
             <span class="ec-section-title fw-bold">@Title</span>
             <i class="bi @(IsOpen ? "bi-chevron-down" : "bi-chevron-right") ec-section-chevron" aria-hidden="true"></i>
         </button>
-        <div class="collapse @(IsOpen ? "show" : "")">
+        <div class="ec-section-collapse @(IsOpen ? "ec-section-collapse-open" : "")">
-            <div class="ec-section-body">
+            <div class="ec-section-collapse-inner">
+                <div class="ec-section-body">
                 <ul class="list-unstyled mb-0">
                     @foreach (var f in Descriptors)
                     {
-                        <EffectiveConfigFieldDisplay Descriptor="@f" OnOptionHelpRequested="@OnOptionHelpRequested" />
+                        var fieldKey = $"{SectionId}:{f.OptionName}";
+                        <EffectiveConfigFieldDisplay Descriptor="@f" FieldKey="@fieldKey"
+                            IsEditMode="@IsEditMode" IsActive="@(ActiveFieldKey == fieldKey)" />
                     }
                 </ul>
+                </div>
             </div>
         </div>
     </div>
@@ -27,10 +31,10 @@
     [Parameter] public IReadOnlyList<EffectiveConfigFieldDescriptor> Descriptors { get; set; } = null!;
     [Parameter] public bool IsOpen { get; set; }
     [Parameter] public EventCallback<string> OnToggle { get; set; }
-    /// <summary>Raised when user requests option help (click or mouse leave from label). Passed through from Section.</summary>
+    /// <summary>Cascaded from EffectiveConfigSection. View = read-only; Edit = editable.</summary>
-    [Parameter] public EventCallback<ConfigOptionHelpRequestEventArgs> OnOptionHelpRequested { get; set; }
-    /// <summary>Cascaded from EffectiveConfigSection. View = read-only; Edit = editable (future).</summary>
     [Parameter] public EffectiveConfigDisplayMode DisplayMode { get; set; } = EffectiveConfigDisplayMode.View;
+    [Parameter] public bool IsEditMode { get; set; }
+    [Parameter] public string? ActiveFieldKey { get; set; }
 
     private async Task ToggleSection() => await OnToggle.InvokeAsync(SectionId);
 }

src/DnsmasqWebUI/Components/EffectiveConfig/Composition/EffectiveConfigToolbar.razor

@@ -0,0 +1,111 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig
+
+<div class="ec-toolbar @(IsEditMode ? "ec-edit-toolbar" : "")">
+    @if (ShowSearchBox)
+    {
+        <input type="search" id="ec-search-input" class="form-control form-control-sm ec-toolbar-search" placeholder="Search..." autocomplete="off"
+               value="@SearchTerm" @oninput="OnSearchInput" />
+    }
+    <div class="ec-toolbar-actions">
+        <button type="button" class="btn btn-sm btn-outline-secondary" @onclick="OnToggleExpandCollapse"
+                title="@(AllSectionsExpanded ? "Collapse all sections" : "Expand all sections")"
+                aria-label="@(AllSectionsExpanded ? "Collapse all sections" : "Expand all sections")">
+            <i class="bi @(AllSectionsExpanded ? "bi-arrows-collapse" : "bi-arrows-expand")" aria-hidden="true"></i>
+        </button>
+        @if (IsEditMode)
+        {
+            <button type="button" class="btn btn-sm btn-primary" @onclick="OnOpenSaveModal" disabled="@(PendingChangesCount == 0)" title="Save changes to managed config" aria-label="Save">
+                <i class="bi bi-floppy-fill" aria-hidden="true"></i>
+            </button>
+            <button type="button" class="btn btn-sm btn-outline-secondary" @onclick="OnExitEditModeWithConfirm" title="Exit edit mode" aria-label="Exit edit mode">
+                <i class="bi bi-box-arrow-right" aria-hidden="true"></i>
+            </button>
+            @if (PendingChangesCount > 0)
+            {
+                <span class="text-muted small ec-toolbar-changes-link" role="button" tabindex="0"
+                      @onclick="OnOpenSaveModal"
+                      @onkeydown="OnChangesLinkKeyDown"
+                      title="Open save dialog"
+                      aria-label="Open save dialog">
+                    @PendingChangesCount change(s)
+                </span>
+            }
+            @if (ValidationErrorCount > 0 || ValidationWarningCount > 0)
+            {
+                <span class="small ec-toolbar-validation-count" aria-live="polite">
+                    @if (ValidationErrorCount > 0)
+                    {
+                        <span class="text-danger fw-medium ec-toolbar-changes-link" role="button" tabindex="0"
+                              title="@ValidationErrorTooltip"
+                              aria-label="Open validation summary"
+                              @onclick="OnOpenSaveModal"
+                              @onkeydown="OnValidationLinkKeyDown">
+                            @ValidationErrorCount error(s)
+                        </span>
+                    }
+                    @if (ValidationErrorCount > 0 && ValidationWarningCount > 0) { <span class="text-muted">·</span> }
+                    @if (ValidationWarningCount > 0)
+                    {
+                        <span class="text-warning ec-toolbar-changes-link" role="button" tabindex="0"
+                              title="@ValidationWarningTooltip"
+                              aria-label="Open validation summary"
+                              @onclick="OnOpenSaveModal"
+                              @onkeydown="OnValidationLinkKeyDown">
+                            @ValidationWarningCount warning(s)
+                        </span>
+                    }
+                </span>
+            }
+        }
+        else
+        {
+            <button type="button" class="btn btn-sm btn-outline-secondary" @onclick="OnEnterEditMode" title="Edit effective config" aria-label="Edit">
+                <i class="bi bi-pencil" aria-hidden="true"></i>
+            </button>
+        }
+    </div>
+</div>
+
+@code {
+    [Parameter] public bool ShowSearchBox { get; set; } = true;
+    [Parameter] public string SearchTerm { get; set; } = "";
+    [Parameter] public EventCallback<string> SearchTermChanged { get; set; }
+    [Parameter] public bool IsEditMode { get; set; }
+    [Parameter] public int PendingChangesCount { get; set; }
+    [Parameter] public IReadOnlyList<FieldIssue>? ValidationSummary { get; set; }
+    private int ValidationErrorCount => ValidationSummary?.Count(i => i.Severity == FieldIssueSeverity.Error) ?? 0;
+    private int ValidationWarningCount => ValidationSummary?.Count(i => i.Severity == FieldIssueSeverity.Warning) ?? 0;
+    private string ValidationErrorTooltip => ValidationSummary == null ? "" : string.Join("\n", ValidationSummary.Where(i => i.Severity == FieldIssueSeverity.Error).Select(i => i.Message));
+    private string ValidationWarningTooltip => ValidationSummary == null ? "" : string.Join("\n", ValidationSummary.Where(i => i.Severity == FieldIssueSeverity.Warning).Select(i => i.Message));
+    [Parameter] public bool AllSectionsExpanded { get; set; }
+    [Parameter] public EventCallback OnExpandAll { get; set; }
+    [Parameter] public EventCallback OnCollapseAll { get; set; }
+
+    private async Task OnToggleExpandCollapse()
+    {
+        if (AllSectionsExpanded)
+            await OnCollapseAll.InvokeAsync();
+        else
+            await OnExpandAll.InvokeAsync();
+    }
+    [Parameter] public EventCallback OnEnterEditMode { get; set; }
+    [Parameter] public EventCallback OnExitEditModeWithConfirm { get; set; }
+    [Parameter] public EventCallback OnOpenSaveModal { get; set; }
+
+    private async Task OnSearchInput(ChangeEventArgs e)
+    {
+        await SearchTermChanged.InvokeAsync(e.Value?.ToString() ?? "");
+    }
+
+    private async Task OnChangesLinkKeyDown(KeyboardEventArgs e)
+    {
+        if (e.Key == "Enter" || e.Key == " ")
+            await OnOpenSaveModal.InvokeAsync();
+    }
+
+    private async Task OnValidationLinkKeyDown(KeyboardEventArgs e)
+    {
+        if (e.Key == "Enter" || e.Key == " ")
+            await OnOpenSaveModal.InvokeAsync();
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/CustomDisplays/Do0x20EncodeDisplay.razor

@@ -0,0 +1,68 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig.CustomDisplays
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+@inherits EffectiveConfigValueDisplayBase
+
+@* do-0x20-encode / no-0x20-encode: tri-state. Switch shows Enabled vs not-Enabled; uncheck maps back to Default when that was the value at activation, else Disabled. *@
+@if (IsActiveEditor && Descriptor.GetSource()?.IsReadOnly != true)
+{
+    var isOn = GetState() == ExplicitToggleState.Enabled;
+    <div class="form-check form-switch ec-effective-switch">
+        <input type="checkbox"
+               class="form-check-input"
+               checked="@isOn"
+               aria-label="Enable @Descriptor.OptionName"
+               title="Set @Descriptor.OptionName"
+               @onchange="OnCheckedChange"
+               @onfocusout="OnCommitRequested" />
+    </div>
+}
+else
+{
+    @* Intentionally show both Default and Disabled as "Disabled" (product choice: collapse unset and off). Do not "fix" to show "Default" for unset. *@
+    @(GetState() == ExplicitToggleState.Enabled ? "Enabled" : "Disabled")
+}
+
+@code {
+    private ExplicitToggleState _stateAtActivation;
+    private bool _wasActiveEditor;
+
+    private ExplicitToggleState GetState()
+    {
+        var v = GetEffectiveDisplayValue();
+        if (v is ExplicitToggleState s) return s;
+        return ExplicitToggleState.Default;
+    }
+
+    protected override void OnParametersSet()
+    {
+        if (!IsActiveEditor)
+            _stateAtActivation = GetState();
+        else if (!_wasActiveEditor)
+            _stateAtActivation = GetState();
+        _wasActiveEditor = IsActiveEditor;
+    }
+
+    private async Task OnCheckedChange(ChangeEventArgs e)
+    {
+        var isChecked = e.Value is true;
+        if (isChecked)
+        {
+            await NotifyValueChanged(ExplicitToggleState.Enabled);
+            return;
+        }
+
+        var pending = Session?.Draft.PendingChanges.OfType<PendingOptionChange>().FirstOrDefault(c =>
+            string.Equals(c.SectionId, Descriptor.SectionId, StringComparison.OrdinalIgnoreCase) &&
+            string.Equals(c.OptionName, Descriptor.OptionName, StringComparison.OrdinalIgnoreCase));
+        if (pending?.OldValue is ExplicitToggleState previousState)
+        {
+            await NotifyValueChanged(previousState);
+            return;
+        }
+
+        // No existing pending edit for this field: map unchecked based on the state at activation.
+        // Default and Disabled both display as "Disabled" in view mode, so we preserve true intent here.
+        await NotifyValueChanged(_stateAtActivation == ExplicitToggleState.Default ? ExplicitToggleState.Default : ExplicitToggleState.Disabled);
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/CustomDisplays/DomainEffectiveConfigListEditor.razor

@@ -0,0 +1,579 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig.CustomDisplays
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+@using DnsmasqWebUI.Infrastructure.Serialization.Parsers.EffectiveConfig
+@using DnsmasqWebUI.Infrastructure.Services.UI.Notifications.Abstractions
+@inject INotificationService NotificationService
+
+<div class="ec-field-value ec-field-value-multi ec-domain-rule-editor" @onclick:stopPropagation="true">
+    <ol class="ec-field-value-list ec-domain-rule-list">
+        @if (_displayItems.Count > 0)
+        {
+            @for (var i = 0; i < _displayItems.Count; i++)
+            {
+                var item = _displayItems[i];
+                var anchorId = $"{ReadonlyBadgeAnchorIdBase}-{i}";
+                var itemReadonly = item.Source?.IsReadOnly == true;
+                var rowIndex = i;
+                var rowValue = item.Value;
+
+                <li class="ec-domain-rule-row @(_editingIndex == rowIndex && !itemReadonly ? "ec-domain-rule-row-editing" : "")" @key="anchorId">
+                    <div class="ec-domain-rule-row-body">
+                        @if (_editingIndex == rowIndex && !itemReadonly)
+                        {
+                            <div class="ec-domain-rule-form">
+                                <div class="ec-domain-rule-toolbar">
+                                    <div class="ec-domain-rule-toolbar__group">
+                                        <span class="form-label mb-0">Editor mode</span>
+                                        <button type="button"
+                                                class="btn btn-link btn-sm text-muted ec-domain-rule-help p-0 border-0"
+                                                title="@DomainRuleEditorHelpText"
+                                                aria-label="@DomainRuleEditorHelpText"
+                                                @onclick="ShowDomainRuleEditorHelp">
+                                            <i class="bi bi-question-circle" aria-hidden="true"></i>
+                                        </button>
+                                    </div>
+                                    <div class="ec-domain-rule-mode-toggle" role="group" aria-label="Domain rule editor mode">
+                                        <button type="button"
+                                                class="btn btn-sm ec-domain-rule-mode-btn @(!_draftUseRaw ? "ec-domain-rule-mode-btn--active" : null)"
+                                                aria-pressed="@(!_draftUseRaw ? "true" : "false")"
+                                                @onclick="() => OnDraftUseRawChanged(false)">
+                                            Guided
+                                        </button>
+                                        <button type="button"
+                                                class="btn btn-sm ec-domain-rule-mode-btn @(_draftUseRaw ? "ec-domain-rule-mode-btn--active" : null)"
+                                                aria-pressed="@(_draftUseRaw ? "true" : "false")"
+                                                @onclick="() => OnDraftUseRawChanged(true)">
+                                            Raw line
+                                        </button>
+                                    </div>
+                                </div>
+                                @if (_draftUseRaw)
+                                {
+                                    <input class="form-control form-control-sm font-monospace"
+                                           @bind="_draftRawLine" @bind:event="oninput"
+                                           placeholder="domain[,subnet|IP|interface[,local]]" />
+                                }
+                                else
+                                {
+                                    <div>
+                                        <label class="form-label" for="@($"{anchorId}-dom")">Domain</label>
+                                        <input id="@($"{anchorId}-dom")" class="form-control form-control-sm"
+                                               placeholder="e.g. home.arpa or #"
+                                               @bind="_draftDomain" @bind:event="oninput" />
+                                        <div class="ec-domain-rule-hint-row">
+                                            <div class="ec-domain-rule-hint">Use <code>#</code> to take the search domain from resolv.conf.</div>
+                                            <button type="button"
+                                                    class="btn btn-link btn-sm text-muted ec-domain-rule-help p-0 border-0"
+                                                    title="@HashDomainHelpText"
+                                                    aria-label="@HashDomainHelpText"
+                                                    @onclick="ShowHashDomainHelp">
+                                                <i class="bi bi-question-circle" aria-hidden="true"></i>
+                                            </button>
+                                        </div>
+                                    </div>
+                                    <div>
+                                        <label class="form-label" for="@($"{anchorId}-scope")">Applies to</label>
+                                        <select id="@($"{anchorId}-scope")" class="form-select form-select-sm"
+                                                @bind="_draftScopeSelect" @bind:after="OnDraftScopeAfterChange">
+                                            <option value="unconditional">Any client address (default)</option>
+                                            <option value="range">Limit to this subnet or IP</option>
+                                            <option value="interface">Limit to subnets on this interface</option>
+                                        </select>
+                                    </div>
+                                    @if (_draftScopeSelect == "range")
+                                    {
+                                        <div>
+                                            <label class="form-label" for="@($"{anchorId}-mid")">Subnet or IP</label>
+                                            <input id="@($"{anchorId}-mid")" class="form-control form-control-sm"
+                                                   placeholder="e.g. 192.168.0.0/24 or 192.168.0.1"
+                                                   @bind="_draftMiddle" @bind:event="oninput" />
+                                            <div class="ec-domain-rule-hint">Single IP, CIDR, or start,end pair per dnsmasq docs.</div>
+                                        </div>
+                                        <div class="form-check">
+                                            <input type="checkbox" class="form-check-input" id="@($"{anchorId}-loc")"
+                                                   @bind="_draftAddLocal" />
+                                            <label class="form-check-label" for="@($"{anchorId}-loc")">
+                                                Also add matching <code>--local</code> forward and reverse DNS
+                                            </label>
+                                        </div>
+                                    }
+                                    else if (_draftScopeSelect == "interface")
+                                    {
+                                        <div>
+                                            <label class="form-label" for="@($"{anchorId}-if")">Interface</label>
+                                            <input id="@($"{anchorId}-if")" class="form-control form-control-sm"
+                                                   placeholder="e.g. eth0 or br0"
+                                                   @bind="_draftMiddle" @bind:event="oninput" />
+                                        </div>
+                                    }
+                                    else if (_draftScopeSelect == "unconditional")
+                                    {
+                                        <div class="form-check ec-domain-rule-local-check">
+                                            <input type="checkbox" class="form-check-input" id="@($"{anchorId}-loc2")"
+                                                   @bind="_draftAddLocal" />
+                                            <label class="form-check-label" for="@($"{anchorId}-loc2")">
+                                                Append <code>,local</code>
+                                            </label>
+                                            <button type="button"
+                                                    class="btn btn-link btn-sm text-muted ec-domain-rule-help p-0 border-0"
+                                                    title="@LocalSuffixHelpText"
+                                                    aria-label="@LocalSuffixHelpText"
+                                                    @onclick="ShowLocalSuffixHelp">
+                                                <i class="bi bi-question-circle" aria-hidden="true"></i>
+                                            </button>
+                                        </div>
+                                    }
+                                }
+                                <div class="ec-domain-rule-actions">
+                                    <StatusBadge Kind="StatusBadgeKind.ActionOk" Text="save" Clickable="true"
+                                                 Title="Apply change" AriaLabel="Apply change"
+                                                 PreventBlurOnMouseDown="true" OnClick="@(() => SaveEdit(rowIndex))" Class="status-badge-inline" />
+                                    <StatusBadge Kind="StatusBadgeKind.ActionCancel" Text="cancel" Clickable="true"
+                                                 Title="Discard edit" AriaLabel="Cancel edit"
+                                                 PreventBlurOnMouseDown="true" OnClick="CancelInline" Class="status-badge-inline" />
+                                </div>
+                            </div>
+                        }
+                        else
+                        {
+                            <div class="ec-domain-rule-summary">
+                                <span class="ec-field-value-item">@DisplayLine(rowValue)</span>
+                                @if (!string.Equals(DomainRuleFields.FormatSummary(rowValue), rowValue, StringComparison.Ordinal))
+                                {
+                                    <code class="text-muted small">@rowValue</code>
+                                }
+                                <span class="status-badge-inline">
+                                    <OptionStateBadge
+                                        AnchorId="@anchorId"
+                                        Source="@item.Source"
+                                        OptionName="@OptionName"
+                                        Value="@rowValue"
+                                        IsInteractive="@IsEditMode"
+                                        ShowEditableBadge="@(!itemReadonly)"
+                                        EditableAsButton="@(!itemReadonly)"
+                                        OnEditableClickRequested="@(!itemReadonly ? EventCallback.Factory.Create(this, () => { BeginEdit(rowIndex, rowValue); return Task.CompletedTask; }) : default)" />
+                                    @if (!itemReadonly)
+                                    {
+                                        <StatusBadge Kind="StatusBadgeKind.ActionRevert" Text="remove" Clickable="true"
+                                                     Title="Remove this value" AriaLabel="Remove"
+                                                     PreventBlurOnMouseDown="true"
+                                                     OnClick="@(() => RemoveAt(rowIndex))" Class="status-badge-inline" />
+                                    }
+                                </span>
+                            </div>
+                        }
+                    </div>
+                </li>
+            }
+        }
+        else if (!AllowAddManagedValue)
+        {
+            <li class="ec-multi-list-row ec-multi-list-empty-hint">
+                <span class="text-muted">(none)</span>
+            </li>
+        }
+
+        @if (AllowAddManagedValue)
+        {
+            <li class="ec-multi-list-row ec-multi-list-add-item @(_addingNew ? "ec-multi-list-row-with-controls" : "")" @key="AddItemKey">
+                @if (_addingNew)
+                {
+                    <div class="ec-domain-rule-form">
+                        <div class="ec-domain-rule-toolbar">
+                            <div class="ec-domain-rule-toolbar__group">
+                                <span class="form-label mb-0">Editor mode</span>
+                                <button type="button"
+                                        class="btn btn-link btn-sm text-muted ec-domain-rule-help p-0 border-0"
+                                        title="@DomainRuleEditorHelpText"
+                                        aria-label="@DomainRuleEditorHelpText"
+                                        @onclick="ShowDomainRuleEditorHelp">
+                                    <i class="bi bi-question-circle" aria-hidden="true"></i>
+                                </button>
+                            </div>
+                            <div class="ec-domain-rule-mode-toggle" role="group" aria-label="Domain rule editor mode">
+                                <button type="button"
+                                        class="btn btn-sm ec-domain-rule-mode-btn @(!_draftUseRaw ? "ec-domain-rule-mode-btn--active" : null)"
+                                        aria-pressed="@(!_draftUseRaw ? "true" : "false")"
+                                        @onclick="() => OnDraftUseRawChanged(false)">
+                                    Guided
+                                </button>
+                                <button type="button"
+                                        class="btn btn-sm ec-domain-rule-mode-btn @(_draftUseRaw ? "ec-domain-rule-mode-btn--active" : null)"
+                                        aria-pressed="@(_draftUseRaw ? "true" : "false")"
+                                        @onclick="() => OnDraftUseRawChanged(true)">
+                                    Raw line
+                                </button>
+                            </div>
+                        </div>
+                        @if (_draftUseRaw)
+                        {
+                            <input class="form-control form-control-sm font-monospace"
+                                   @bind="_draftRawLine" @bind:event="oninput"
+                                   placeholder="domain[,subnet|IP|interface[,local]]" />
+                        }
+                        else
+                        {
+                            <div>
+                                <label class="form-label" for="domain-add-dom">Domain</label>
+                                <input id="domain-add-dom" class="form-control form-control-sm"
+                                       placeholder="e.g. home.arpa or #"
+                                       @bind="_draftDomain" @bind:event="oninput" />
+                                <div class="ec-domain-rule-hint-row">
+                                    <div class="ec-domain-rule-hint">Use <code>#</code> to take the search domain from resolv.conf.</div>
+                                    <button type="button"
+                                            class="btn btn-link btn-sm text-muted ec-domain-rule-help p-0 border-0"
+                                            title="@HashDomainHelpText"
+                                            aria-label="@HashDomainHelpText"
+                                            @onclick="ShowHashDomainHelp">
+                                        <i class="bi bi-question-circle" aria-hidden="true"></i>
+                                    </button>
+                                </div>
+                            </div>
+                            <div>
+                                <label class="form-label" for="domain-add-scope">Applies to</label>
+                                <select id="domain-add-scope" class="form-select form-select-sm"
+                                        @bind="_draftScopeSelect" @bind:after="OnDraftScopeAfterChange">
+                                    <option value="unconditional">Any client address (default)</option>
+                                    <option value="range">Limit to this subnet or IP</option>
+                                    <option value="interface">Limit to subnets on this interface</option>
+                                </select>
+                            </div>
+                            @if (_draftScopeSelect == "range")
+                            {
+                                <div>
+                                    <label class="form-label" for="domain-add-mid">Subnet or IP</label>
+                                    <input id="domain-add-mid" class="form-control form-control-sm"
+                                           placeholder="e.g. 192.168.0.0/24 or 192.168.0.1"
+                                           @bind="_draftMiddle" @bind:event="oninput" />
+                                    <div class="ec-domain-rule-hint">Single IP, CIDR, or start,end pair per dnsmasq docs.</div>
+                                </div>
+                                <div class="form-check">
+                                    <input type="checkbox" class="form-check-input" id="domain-add-loc"
+                                           @bind="_draftAddLocal" />
+                                    <label class="form-check-label" for="domain-add-loc">
+                                        Also add matching <code>--local</code> forward and reverse DNS
+                                    </label>
+                                </div>
+                            }
+                            else if (_draftScopeSelect == "interface")
+                            {
+                                <div>
+                                    <label class="form-label" for="domain-add-if">Interface</label>
+                                    <input id="domain-add-if" class="form-control form-control-sm"
+                                           placeholder="e.g. eth0 or br0"
+                                           @bind="_draftMiddle" @bind:event="oninput" />
+                                </div>
+                            }
+                            else if (_draftScopeSelect == "unconditional")
+                            {
+                                <div class="form-check ec-domain-rule-local-check">
+                                    <input type="checkbox" class="form-check-input" id="domain-add-loc2"
+                                           @bind="_draftAddLocal" />
+                                    <label class="form-check-label" for="domain-add-loc2">
+                                        Append <code>,local</code>
+                                    </label>
+                                    <button type="button"
+                                            class="btn btn-link btn-sm text-muted ec-domain-rule-help p-0 border-0"
+                                            title="@LocalSuffixHelpText"
+                                            aria-label="@LocalSuffixHelpText"
+                                            @onclick="ShowLocalSuffixHelp">
+                                        <i class="bi bi-question-circle" aria-hidden="true"></i>
+                                    </button>
+                                </div>
+                            }
+                        }
+                        <div class="ec-domain-rule-actions">
+                            <StatusBadge Kind="StatusBadgeKind.ActionOk" Text="add" Clickable="true"
+                                         Title="Add this value" AriaLabel="Add"
+                                         PreventBlurOnMouseDown="true" OnClick="SaveNew" Class="status-badge-inline" />
+                            <StatusBadge Kind="StatusBadgeKind.ActionCancel" Text="cancel" Clickable="true"
+                                         Title="Discard" AriaLabel="Cancel"
+                                         PreventBlurOnMouseDown="true" OnClick="CancelInline" Class="status-badge-inline" />
+                        </div>
+                    </div>
+                }
+                else
+                {
+                    <StatusBadge Kind="StatusBadgeKind.Editable" Text="add item" Clickable="true"
+                                 Title="Add a new value" AriaLabel="Add item"
+                                 OnClick="BeginAdd" Class="status-badge-inline ec-multi-list-add-btn" />
+                }
+            </li>
+        }
+    </ol>
+</div>
+
+@code {
+    [Parameter] public IReadOnlyList<ValueWithSource>? SourceItems { get; set; }
+    [Parameter] public string OptionName { get; set; } = "domain";
+    [Parameter] public string ReadonlyBadgeAnchorIdBase { get; set; } = "";
+
+    [Parameter] public bool IsEditMode { get; set; }
+    [Parameter] public bool AllowAddManagedValue { get; set; } = true;
+
+    [Parameter] public IMultiValueEditBehavior? Behavior { get; set; }
+    [Parameter] public IMultiValueOptionValidator? Validator { get; set; }
+    [Parameter] public string? FieldKey { get; set; }
+
+    [Parameter] public EventCallback<IReadOnlyList<string>> OnValuesChanged { get; set; }
+
+    private const string AddItemKey = "domain-add-item";
+    private static readonly TimeSpan ValidationToastDedupeWindow = TimeSpan.FromSeconds(2);
+
+    private int? _editingIndex;
+    private bool _addingNew;
+    private bool _didAutoOpenAdd;
+    private string? _lastValidationErrorMessage;
+    private DateTime _lastValidationErrorUtc;
+
+    private List<ValueWithSource> _displayItems = new();
+
+    private bool _draftUseRaw;
+    private string _draftRawLine = "";
+    private string _draftDomain = "";
+    private string _draftScopeSelect = "unconditional";
+    private string _draftMiddle = "";
+    private bool _draftAddLocal;
+
+    private IReadOnlyList<string> _currentValues => _displayItems.Select(x => x.Value).ToList();
+
+    protected override void OnParametersSet()
+    {
+        _displayItems = (SourceItems ?? Array.Empty<ValueWithSource>()).ToList();
+
+        if (!_didAutoOpenAdd && (SourceItems?.Count ?? 0) == 0 && AllowAddManagedValue)
+        {
+            _didAutoOpenAdd = true;
+            _addingNew = true;
+            ResetDraftForNew();
+        }
+    }
+
+    private static string DisplayLine(string rowValue) =>
+        DomainRuleFields.FormatSummary(rowValue);
+
+    private void ResetDraftForNew()
+    {
+        _draftUseRaw = false;
+        _draftRawLine = "";
+        _draftDomain = "";
+        _draftScopeSelect = "unconditional";
+        _draftMiddle = "";
+        _draftAddLocal = false;
+    }
+
+    private void BeginEdit(int index, string current)
+    {
+        _addingNew = false;
+        _editingIndex = index;
+        LoadDraftFromLine(current);
+    }
+
+    private void BeginAdd()
+    {
+        _editingIndex = null;
+        _addingNew = true;
+        ResetDraftForNew();
+    }
+
+    private void CancelInline()
+    {
+        _editingIndex = null;
+        _addingNew = false;
+        _lastValidationErrorMessage = null;
+        ResetDraftForNew();
+    }
+
+    private void LoadDraftFromLine(string line)
+    {
+        var parsed = DomainRuleFields.Parse(line);
+        if (parsed.IsRaw)
+        {
+            _draftUseRaw = true;
+            _draftRawLine = parsed.RawLineFallback ?? line;
+            _draftDomain = "";
+            _draftScopeSelect = "unconditional";
+            _draftMiddle = "";
+            _draftAddLocal = false;
+            return;
+        }
+
+        _draftUseRaw = false;
+        _draftRawLine = "";
+        _draftDomain = parsed.DomainPart;
+        _draftScopeSelect = parsed.Scope switch
+        {
+            DomainRuleScope.AddressRangeOrIp => "range",
+            DomainRuleScope.InterfaceName => "interface",
+            _ => "unconditional",
+        };
+        _draftMiddle = parsed.MiddlePart;
+        _draftAddLocal = parsed.AddLocalForRange;
+    }
+
+    private void OnDraftUseRawChanged(bool useRaw)
+    {
+        if (useRaw && !_draftUseRaw)
+        {
+            var fields = BuildFieldsFromDraftStructured();
+            _draftRawLine = fields.ToConfigLine();
+        }
+        else if (!useRaw && _draftUseRaw)
+            LoadDraftFromLine(_draftRawLine.Trim());
+
+        _draftUseRaw = useRaw;
+    }
+
+    private void ShowDomainRuleEditorHelp() => NotificationService.ShowInfo(DomainRuleEditorHelpText);
+
+    private void ShowLocalSuffixHelp() => NotificationService.ShowInfo(LocalSuffixHelpText);
+
+    private void ShowHashDomainHelp() => NotificationService.ShowInfo(HashDomainHelpText);
+
+    private void OnDraftScopeAfterChange()
+    {
+        if (_draftScopeSelect == "unconditional")
+            _draftMiddle = "";
+        if (_draftScopeSelect == "interface")
+            _draftAddLocal = false;
+    }
+
+    private DomainRuleFields BuildFieldsFromDraftStructured()
+    {
+        var dom = (_draftDomain ?? "").Trim();
+        var mid = (_draftMiddle ?? "").Trim();
+        var scope = _draftScopeSelect switch
+        {
+            "range" => DomainRuleScope.AddressRangeOrIp,
+            "interface" => DomainRuleScope.InterfaceName,
+            _ => DomainRuleScope.Unconditional,
+        };
+
+        if (scope == DomainRuleScope.Unconditional)
+            return new DomainRuleFields(dom, DomainRuleScope.Unconditional, "", _draftAddLocal, null);
+
+        if (scope == DomainRuleScope.InterfaceName)
+            return new DomainRuleFields(dom, DomainRuleScope.InterfaceName, mid, false, null);
+
+        if (mid.Length == 0 && _draftAddLocal)
+            return new DomainRuleFields(dom, DomainRuleScope.Unconditional, "", true, null);
+
+        return new DomainRuleFields(dom, DomainRuleScope.AddressRangeOrIp, mid, _draftAddLocal, null);
+    }
+
+    private DomainRuleFields BuildFieldsFromDraft() =>
+        _draftUseRaw ? DomainRuleFields.FromRawConfigLine(_draftRawLine) : BuildFieldsFromDraftStructured();
+
+    private void ShowValidationError(string message)
+    {
+        var now = DateTime.UtcNow;
+        if (string.Equals(_lastValidationErrorMessage, message, StringComparison.Ordinal) &&
+            (now - _lastValidationErrorUtc) < ValidationToastDedupeWindow)
+            return;
+        _lastValidationErrorMessage = message;
+        _lastValidationErrorUtc = now;
+        NotificationService.ShowError(message);
+    }
+
+    private async Task SaveEdit(int index)
+    {
+        var next = _currentValues.ToList();
+        if (index < 0 || index >= next.Count) return;
+
+        var fields = BuildFieldsFromDraft();
+        var normalized = fields.ToConfigLine();
+        if (string.IsNullOrWhiteSpace(normalized))
+        {
+            ShowValidationError("Domain name (or #) is required.");
+            return;
+        }
+
+        if (!_draftUseRaw && _draftScopeSelect == "interface" && string.IsNullOrWhiteSpace(_draftMiddle))
+        {
+            ShowValidationError("Interface name is required for this scope.");
+            return;
+        }
+
+        normalized = Behavior?.Normalize(normalized) ?? normalized.Trim();
+
+        var validationError = Validator?.ValidateItem(normalized, _currentValues, index);
+        if (validationError != null)
+        {
+            ShowValidationError(validationError);
+            return;
+        }
+
+        if (Behavior?.AllowDuplicates == false && next.Where((v, i) => i != index).Any(v => string.Equals(v, normalized, StringComparison.Ordinal)))
+        {
+            ShowValidationError("Duplicate values are not allowed.");
+            return;
+        }
+
+        next[index] = normalized;
+        _displayItems[index] = _displayItems[index] with { Value = normalized };
+        await OnValuesChanged.InvokeAsync(next);
+        CancelInline();
+    }
+
+    private async Task SaveNew()
+    {
+        var fields = BuildFieldsFromDraft();
+        var normalized = fields.ToConfigLine();
+        if (string.IsNullOrWhiteSpace(normalized))
+        {
+            ShowValidationError("Domain name (or #) is required.");
+            return;
+        }
+
+        if (!_draftUseRaw && _draftScopeSelect == "interface" && string.IsNullOrWhiteSpace(_draftMiddle))
+        {
+            ShowValidationError("Interface name is required for this scope.");
+            return;
+        }
+
+        normalized = Behavior?.Normalize(normalized) ?? normalized.Trim();
+
+        var current = _currentValues;
+        var validationError = Validator?.ValidateItem(normalized, current, null);
+        if (validationError != null)
+        {
+            ShowValidationError(validationError);
+            return;
+        }
+
+        if (Behavior?.AllowDuplicates == false && current.Contains(normalized, StringComparer.Ordinal))
+        {
+            ShowValidationError("Duplicate values are not allowed.");
+            return;
+        }
+
+        var next = current.ToList();
+        next.Add(normalized);
+        _displayItems.Add(new ValueWithSource(normalized, null));
+        await OnValuesChanged.InvokeAsync(next);
+        CancelInline();
+    }
+
+    private async Task RemoveAt(int index)
+    {
+        if (index < 0 || index >= _displayItems.Count) return;
+        var item = _displayItems[index];
+        if (item?.Source?.IsReadOnly == true) return;
+
+        var next = _displayItems.Select(x => x.Value).ToList();
+        next.RemoveAt(index);
+        _displayItems.RemoveAt(index);
+        await OnValuesChanged.InvokeAsync(next);
+        StateHasChanged();
+    }
+
+    private const string DomainRuleEditorHelpText =
+        "domain= sets the suffix dnsmasq uses for DHCP and local DNS naming. Guided mode builds the rule from fields; Raw line mode lets you enter the exact dnsmasq config line directly.";
+
+    private const string LocalSuffixHelpText =
+        "Appending ,local behaves like a matching --local rule for this domain, making dnsmasq answer locally instead of forwarding it upstream. This is uncommon for an unconditional domain= rule.";
+
+    private const string HashDomainHelpText =
+        "Use # as the domain value to take the search domain from resolv.conf instead of hard-coding a suffix in dnsmasq.";
+}

src/DnsmasqWebUI/Components/EffectiveConfig/CustomDisplays/DomainEffectiveConfigListEditor.razor.css

@@ -0,0 +1,150 @@
+.ec-domain-rule-editor {
+    display: block;
+    padding: 0.75rem 1rem;
+    margin-top: 0.25rem;
+    border: 1px solid var(--bs-border-color, #dee2e6);
+    border-radius: 0.375rem;
+    background-color: var(--bs-body-bg, #fff);
+}
+
+/* Keep <ol> markers (decimal) like the default multi-value editor; do not reset list-style here. */
+.ec-domain-rule-editor .ec-field-value-list {
+    margin-bottom: 0;
+}
+
+.ec-domain-rule-row {
+    min-height: 2rem;
+}
+
+.ec-domain-rule-row-body {
+    display: flex;
+    flex-direction: column;
+    gap: 0.5rem;
+}
+
+.ec-domain-rule-row.ec-domain-rule-row-editing .ec-domain-rule-row-body {
+    align-items: stretch;
+}
+
+.ec-domain-rule-form {
+    display: flex;
+    flex-direction: column;
+    gap: 0.5rem;
+    width: 100%;
+    max-width: 36rem;
+    margin-left: 0.5rem;
+}
+
+.ec-domain-rule-form .form-label {
+    margin-bottom: 0.15rem;
+    font-size: 0.8rem;
+    font-weight: 600;
+    color: var(--bs-secondary-color, #6c757d);
+}
+
+.ec-domain-rule-toolbar {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    gap: 0.5rem 0.75rem;
+    flex-wrap: wrap;
+}
+
+.ec-domain-rule-toolbar__group {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.35rem;
+}
+
+.ec-domain-rule-mode-toggle {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.2rem;
+    padding: 0.2rem;
+    border: 1px solid var(--bs-border-color, #dee2e6);
+    border-radius: 999px;
+    background: linear-gradient(180deg, #ffffff 0%, #f8fafc 100%);
+}
+
+.ec-domain-rule-mode-btn {
+    border: 0;
+    border-radius: 999px;
+    padding: 0.2rem 0.65rem;
+    font-size: 0.75rem;
+    font-weight: 600;
+    color: #475569;
+    background: transparent;
+    box-shadow: none;
+}
+
+.ec-domain-rule-mode-btn:hover,
+.ec-domain-rule-mode-btn:focus-visible {
+    color: #0f172a;
+    background: rgba(148, 163, 184, 0.12);
+}
+
+.ec-domain-rule-mode-btn--active,
+.ec-domain-rule-mode-btn--active:hover,
+.ec-domain-rule-mode-btn--active:focus-visible {
+    color: #fff;
+    background: linear-gradient(180deg, #0d6efd 0%, #0a58ca 100%);
+}
+
+.ec-domain-rule-help {
+    line-height: 1;
+    text-decoration: none;
+}
+
+.ec-domain-rule-help:hover,
+.ec-domain-rule-help:focus-visible {
+    color: var(--bs-primary) !important;
+}
+
+.ec-domain-rule-actions {
+    display: flex;
+    align-items: center;
+    justify-content: flex-end;
+    flex-wrap: wrap;
+    gap: 0.35rem;
+}
+
+.ec-domain-rule-editor .ec-field-value-list li.ec-multi-list-add-item .ec-domain-rule-actions .status-badge-inline,
+.ec-domain-rule-actions .status-badge-inline {
+    margin-left: 0;
+}
+
+.ec-domain-rule-summary {
+    display: flex;
+    align-items: center;
+    flex-wrap: wrap;
+    gap: 0.35rem;
+    margin-left: 0.5rem;
+}
+
+.ec-domain-rule-raw {
+    font-family: var(--bs-font-monospace);
+    font-size: 0.85rem;
+}
+
+.ec-domain-rule-hint {
+    font-size: 0.75rem;
+    color: var(--bs-secondary-color, #6c757d);
+    margin-top: -0.25rem;
+}
+
+.ec-domain-rule-hint-row {
+    display: flex;
+    align-items: flex-start;
+    gap: 0.25rem;
+}
+
+.ec-domain-rule-local-check {
+    display: flex;
+    align-items: flex-start;
+    gap: 0.35rem;
+}
+
+.ec-domain-rule-local-check .form-check-label {
+    flex: 1 1 auto;
+    min-width: 0;
+}

src/DnsmasqWebUI/Components/EffectiveConfig/CustomDisplays/DomainMultiValueDisplay.razor

@@ -0,0 +1,56 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig.CustomDisplays
+@using DnsmasqWebUI.Models.Dnsmasq
+@using DnsmasqWebUI.Models.Dnsmasq.EffectiveConfig
+@using DnsmasqWebUI.Infrastructure.Serialization.Parsers.EffectiveConfig
+@inherits EffectiveConfigMultiValueDisplayBase
+
+@if (Context.IsActiveEditor)
+{
+    <DomainEffectiveConfigListEditor
+        SourceItems="EffectiveItems"
+        OptionName="@Context.Descriptor.OptionName"
+        ReadonlyBadgeAnchorIdBase="@_anchorBase"
+        IsEditMode="@Context.IsEditMode"
+        AllowAddManagedValue="@Context.IsEditMode"
+        FieldKey="@Context.FieldKey"
+        Behavior="@_multiDesc?.Behavior"
+        Validator="@_multiDesc?.Validator"
+        OnValuesChanged="@NotifyValuesChanged" />
+}
+else
+{
+    <div class="ec-field-value ec-field-value-multi">
+        <ol class="ec-field-value-list">
+            @if (Context.EffectiveItems.Count > 0)
+            {
+                @foreach (var (item, index) in Context.EffectiveItems.Select((item, index) => (item, index)))
+                {
+                    var anchorId = $"{_anchorBase}-{index}";
+                    <li>
+                        <EffectiveConfigMultiValueItem
+                                Value="@item.Value"
+                                DisplayValue="@DomainRuleFields.FormatSummary(item.Value)"
+                                Source="@item.Source"
+                                OptionName="@Context.Descriptor.OptionName"
+                                IsEditMode="@Context.IsEditMode"
+                                ReadonlyBadgeAnchorId="@anchorId"
+                                FieldKey="@Context.FieldKey" />
+                    </li>
+                }
+            }
+            else
+            {
+                <li class="ec-multi-list-empty-hint">
+                    <span class="text-muted">(none)</span>
+                </li>
+            }
+        </ol>
+    </div>
+}
+
+@code {
+    private readonly string _anchorBase = "ec-domain-" + Guid.NewGuid().ToString("N")[..8];
+
+    private EffectiveMultiValueConfigFieldDescriptor? _multiDesc =>
+        Context.Descriptor as EffectiveMultiValueConfigFieldDescriptor;
+}

src/DnsmasqWebUI/Components/EffectiveConfig/CustomDisplays/FlagValueDisplay.razor

@@ -0,0 +1,29 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig.CustomDisplays
+@using DnsmasqWebUI.Models.Dnsmasq
+@inherits EffectiveConfigValueDisplayBase
+
+@* Reusable value-only display for boolean/flag options. When active editor: switch (unless readonly); View: "Enabled" / "Disabled". Pending value shown until save. *@
+@if (IsActiveEditor && Descriptor.GetSource()?.IsReadOnly != true)
+{
+    var isSet = GetEffectiveDisplayValue() is bool b && b;
+    <div class="form-check form-switch ec-effective-switch">
+        <input type="checkbox"
+               class="form-check-input"
+               checked="@isSet"
+               aria-label="Enable @Descriptor.OptionName"
+               title="Set @Descriptor.OptionName"
+               @onchange="OnCheckedChange"
+               @onfocusout="OnCommitRequested" />
+    </div>
+}
+else
+{
+    @(GetEffectiveDisplayValue() is bool isSet && isSet ? "Enabled" : "Disabled")
+}
+
+@code {
+    private async Task OnCheckedChange(ChangeEventArgs e)
+    {
+        await NotifyValueChanged(e.Value is true);
+    }
+}

src/DnsmasqWebUI/Components/EffectiveConfig/CustomDisplays/IntegerValueDisplay.razor

@@ -0,0 +1,53 @@
+@namespace DnsmasqWebUI.Components.EffectiveConfig.CustomDisplays
+@using DnsmasqWebUI.Models.Dnsmasq
+@inherits EffectiveConfigValueDisplayBase
+
+@* Value-only display for int? options. Pending value shown until save. *@
+@if (IsActiveEditor && Descriptor.GetSource()?.IsReadOnly != true)
+{
+    var current = GetEffectiveDisplayValue() is int i ? i : DefaultValue;
+    <input type="number" class="form-control form-control-sm" style="max-width: 8rem;"
+           min="@Min" max="@Max" value="@(current?.ToString() ?? "")" @oninput="OnInput" @onfocusout="OnCommitRequested" />
+}
+else
+{
+    var v = GetEffectiveDisplayValue() is int n ? n : (int?)null;
+    if (v is null)
+    {
+        @("(not set)")
+    }
+    else
+    {
+        @v
+        @if (!string.IsNullOrEmpty(ViewSuffix)) { <text> @ViewSuffix</text> }
+        @if (!string.IsNullOrEmpty(Unit)) { <text> @Unit</text> }
+    }
+}
+
+@code {
+    private EffectiveIntegerConfigFieldDescriptor? IntDescriptor => Descriptor as EffectiveIntegerConfigFieldDescriptor;
+    private string? ViewSuffix => IntDescriptor?.ViewSuffix;
+    private string? Unit => IntDescriptor?.Unit;
+    private int Min => IntDescriptor?.Min ?? 0;
+    private int Max => IntDescriptor?.Max ?? int.MaxValue;
+    private int? DefaultValue => IntDescriptor?.DefaultValue;
+
+    private async Task OnInput(ChangeEventArgs e)
+    {
+        var raw = e.Value?.ToString();
+        object? value = null;
+        if (string.IsNullOrWhiteSpace(raw))
+        {
+            value = null;
+        }
+        else if (int.TryParse(raw, out var num))
+        {
+            value = num;
+        }
+        else
+        {
+            value = raw;
+        }
+        await NotifyValueChanged(value);
+    }
+}