Per-entity availability, deferred discovery publish, suggested precision

- Add HAAvailabilityConfig for per-entity availability_topic and payloads - Defer discovery until MQTT connected; publish availability after discovery - HASensor/HANumber: optional suggested_display_precision in discovery - HASerializer/HADictionary: extend for new keys; update device types and mocks - Docs and examples reflect availability and precision usage - Tests updated for discovery and availability behavior - Ignore .cursor/ in repo root
2026-10-04 02:48:13 +10:00 · 2026-05-05 17:47:55 +10:00
parent 8ba5482892
commit b9f4fd7f4b
62 changed files with 2705 additions and 283 deletions
@@ -6,3 +6,6 @@ tmp/

 # Sphinx inventory (legacy); we ship Markdown-only under docs/
 docs/*.inv
+
+# Cursor IDE (local rules, not part of the library)
+.cursor/
@@ -24,6 +24,7 @@ lib_deps =

 * Two-way communication (state reporting and command execution)
 * MQTT discovery (device is added to the Home Assistant panel automatically)
+* Rich discovery metadata for entities, devices, origin, templates and availability
 * MQTT Last Will and Testament
 * Support for custom MQTT messages (publishing and subscribing)
 * Auto reconnect with MQTT broker
@@ -48,6 +49,12 @@ If you need to manage discovery at runtime:

 When device discovery mode is enabled, runtime discovery refreshes automatically clear any stale retained per-entity config before republishing the device discovery payload.

+Recent discovery additions include:
+
+* Shared entity metadata such as `enabled_by_default`, `entity_picture`, `qos`, `encoding`
+* Device/origin metadata such as `model_id`, `hw_version`, `serial_number`, `suggested_area`, `via_device`, `connections`, `support_url`
+* Availability payload overrides and multi-topic availability discovery metadata
+
 ## Supported HA types

 | Home Assistant type | Supported |
@@ -13,6 +13,8 @@ Represents the physical board in Home Assistant: one device can expose multiple
 **Optional metadata** (each costs some RAM/flash; skip on tiny MCUs unless needed):

 - `setName`, `setSoftwareVersion`, `setManufacturer`, `setModel`, `setConfigurationUrl`
+- `setModelId`, `setHardwareVersion`, `setSerialNumber`, `setSuggestedArea`, `setViaDevice`
+- `addConnection("mac", "aa:bb:cc:dd:ee:ff")` or `setConnectionsJson("[[\"mac\",\"aa:bb:cc:dd:ee:ff\"]]")`

 String setters take **pointers whose contents are not copied** — use literals or storage that outlives the call.

@@ -41,8 +43,28 @@ mqtt.setDataPrefix("myDataPrefix");
 - **Default:** one retained discovery topic per entity (single-component discovery).
 - **Optional:** call `HAMqtt::enableDeviceDiscovery()` to publish a single **device** discovery payload with components under `cmps` (see project README for migration notes).

+Device discovery can also publish richer origin/device metadata, for example:
+
+```cpp
+device.setModelId("esp32-s3-devkit");
+device.setHardwareVersion("rev-b");
+device.setSerialNumber("SN-00042");
+device.setSuggestedArea("Garage");
+device.setViaDevice("main_gateway");
+device.addConnection("mac", "AA:BB:CC:DD:EE:FF");
+mqtt.setOriginSupportUrl("https://example.com/device-help");
+```
+
 For entity identifiers in Home Assistant, prefer **`setDefaultEntityId()`** over legacy **`setObjectId()`**.

+Common entity discovery metadata can be configured on most entity types via:
+
+- `setEnabledByDefault(bool)`
+- `setEntityPicture(const char*)`
+- `setQos(uint8_t)`
+- `setEncoding(const char*)`
+- `setEntityCategory(const char*)`
+
 ### Runtime discovery changes

 After changing discovery-related settings at runtime:
@@ -46,12 +46,70 @@ mqtt.publish("customTopic", "payload", true);     // retained

 ```cpp
 device.enableSharedAvailability();
+device.setPayloadAvailable("up");
+device.setPayloadNotAvailable("down");
 device.enableLastWill();   // broker publishes offline when TCP drops
 // device.setAvailability(false);  // optional: start as offline
 ```

 **Per-entity availability:** call `someEntity.setAvailability(true/false)` on each type. Does not use LWT the same way as shared mode; see examples under `examples/availability/`.

+Custom per-entity payloads are supported:
+
+```cpp
+sensor.setPayloadAvailable("ready");
+sensor.setPayloadNotAvailable("lost");
+```
+
+For multi-topic availability discovery, add full MQTT topics and a mode:
+
+```cpp
+sensor.setAvailabilityMode("all");
+sensor.addAvailabilityEntry("bridge/status");
+sensor.addAvailabilityEntry("sensor/status", "{{ value_json.state }}");
+```
+
+## Discovery helpers by entity
+
+Common entity discovery metadata is available on most entity classes:
+
+```cpp
+entity.setEnabledByDefault(false);
+entity.setEntityPicture("https://example.com/entity.png");
+entity.setQos(1);
+entity.setEncoding("utf-8");
+entity.setEntityCategory("diagnostic");
+```
+
+Read-only sensor presentation/template helpers:
+
+```cpp
+sensor.setSuggestedDisplayPrecision(2);
+sensor.setValueTemplate("{{ value_json.temperature }}");
+sensor.setJsonAttributesTemplate("{{ value_json.attrs | tojson }}");
+sensor.setLastResetValueTemplate("{{ value_json.last_reset }}");
+sensor.setDeviceClass("enum");
+sensor.setOptions("idle;charging;discharging;fault");
+```
+
+Writable entity template/payload helpers:
+
+```cpp
+mySwitch.setPayloadOn("ENABLE");
+mySwitch.setPayloadOff("DISABLE");
+mySwitch.setStateOn("running");
+mySwitch.setStateOff("stopped");
+mySwitch.setValueTemplate("{{ value_json.state }}");
+mySwitch.setCommandTemplate("{{ value_json.command }}");
+
+myNumber.setPayloadReset("RESET");
+myNumber.setCommandTemplate("{{ value | float | round(1) }}");
+
+mySelect.setCommandTemplate("{{ value_json.choice }}");
+myText.setCommandTemplate("{{ value_json.text }}");
+myButton.setPayloadPress("PRESS");
+```
+
 ## Compiler macros

 Defined in `ArduinoHADefines.h` or via build flags.
@@ -29,10 +29,19 @@ void setup() {
    // set device's details (optional)
    device.setName("Arduino");
    device.setSoftwareVersion("1.0.0");
+    mqtt.setOriginSupportUrl("https://example.com/device-help");

    sensor.setCurrentState(lastInputState); // optional
    sensor.setName("Door sensor"); // optional
    sensor.setDeviceClass("door"); // optional
+    sensor.setPayloadAvailable("ready");
+    sensor.setPayloadNotAvailable("lost");
+
+    // Optional multi-topic discovery metadata for external health sources.
+    // Runtime availability publishing still uses sensor.setAvailability(...).
+    // sensor.setAvailabilityMode("all");
+    // sensor.addAvailabilityEntry("bridge/status");
+    // sensor.addAvailabilityEntry("sensor/health", "{{ value_json.state }}");

    // This method enables availability for all device types registered on the device.
    // For example, if you have 5 sensors on the same device, you can enable
@@ -33,6 +33,8 @@ void setup() {
    // optional properties
    buttonA.setIcon("mdi:fire");
    buttonA.setName("Click me A");
+    // buttonA.setPayloadPress("PRESS_A");
+    // buttonA.setCommandTemplate("{{ value_json.command }}");
    buttonB.setIcon("mdi:home");
    buttonB.setName("Click me B");

@@ -33,6 +33,11 @@ void setup() {
    // set icon (optional)
    led.setIcon("mdi:lightbulb");
    led.setName("My LED");
+    // led.setPayloadOn("ENABLE");
+    // led.setPayloadOff("DISABLE");
+    // led.setStateOn("running");
+    // led.setStateOff("stopped");
+    // led.setCommandTemplate("{{ value_json.command }}");

    // handle switch state
    led.onCommand(onSwitchCommand);
@@ -52,6 +52,9 @@ void setup() {
    // number.setStep(0.5f); // minimum step: 0.001f
    // number.setMode(HANumber::ModeBox);
    // number.setMode(HANumber::ModeSlider);
+    // number.setValueTemplate("{{ value_json.level }}");
+    // number.setPayloadReset("RESET");
+    // number.setCommandTemplate("{{ value | float | round(1) }}");

    // You can set retain flag for the HA commands
    // number.setRetain(true);
@@ -30,6 +30,8 @@ void setup() {
    analogSensor.setIcon("mdi:home");
    analogSensor.setName("Analog voltage");
    analogSensor.setUnitOfMeasurement("V");
+    analogSensor.setSuggestedDisplayPrecision(2);
+    // analogSensor.setValueTemplate("{{ value_json.voltage }}");

    mqtt.begin(BROKER_ADDR);
 }
@@ -23,6 +23,10 @@ void setup() {
    // configure sensor (optional)
    valve.setIcon("mdi:home");
    valve.setName("Water valve");
+    // valve.setValueTemplate("{{ value_json.state }}");
+    // valve.setDeviceClass("enum");
+    // valve.setOptions("open;opening;closed");
+    // valve.setDefaultEntityId("sensor.water_valve");

    mqtt.begin(BROKER_ADDR);
 }
@@ -2,15 +2,58 @@
 #include "HADevice.h"
 #include "HAMqtt.h"
 #include "utils/HAUtils.h"
+#include "utils/HADictionary.h"
 #include "utils/HASerializer.h"
+#include <string.h>
+
+static bool appendEscapedJsonString(char*& cursor, char* end, const char* value)
+{
+    if (!cursor || !value || cursor >= end) {
+        return false;
+    }
+
+    if (cursor + 1 >= end) {
+        return false;
+    }
+
+    *cursor++ = '"';
+    for (const char* p = value; *p != '\0'; p++) {
+        if ((*p == '"' || *p == '\\') && cursor + 2 >= end) {
+            return false;
+        }
+
+        if (*p == '"' || *p == '\\') {
+            *cursor++ = '\\';
+        }
+
+        if (cursor + 1 >= end) {
+            return false;
+        }
+
+        *cursor++ = *p;
+    }
+
+    if (cursor + 1 >= end) {
+        return false;
+    }
+
+    *cursor++ = '"';
+    *cursor = 0;
+    return true;
+}

 #define HADEVICE_INIT \
    _ownsUniqueId(false), \
-    _serializer(new HASerializer(nullptr, 6)), \
+    _serializer(new HASerializer(nullptr, 16)), \
    _availabilityTopic(nullptr), \
    _sharedAvailability(false), \
    _available(true), \
-    _extendedUniqueIds(false)
+    _extendedUniqueIds(false), \
+    _payloadAvailable(nullptr), \
+    _payloadNotAvailable(nullptr), \
+    _connectionsJson(), \
+    _hasConnections(false), \
+    _connectionsPropertyRegistered(false)

 HADevice::HADevice() :
    _uniqueId(nullptr),
@@ -90,6 +133,153 @@ void HADevice::setConfigurationUrl(const char* url)
    );
 }

+void HADevice::setModelId(const char* modelId)
+{
+    if (!modelId) {
+        return;
+    }
+
+    _serializer->set(AHATOFSTR(HADeviceModelIdProperty), modelId);
+}
+
+void HADevice::setHardwareVersion(const char* hardwareVersion)
+{
+    if (!hardwareVersion) {
+        return;
+    }
+
+    _serializer->set(AHATOFSTR(HADeviceHwVersionProperty), hardwareVersion);
+}
+
+void HADevice::setSerialNumber(const char* serialNumber)
+{
+    if (!serialNumber) {
+        return;
+    }
+
+    _serializer->set(AHATOFSTR(HADeviceSerialNumberProperty), serialNumber);
+}
+
+void HADevice::setSuggestedArea(const char* suggestedArea)
+{
+    if (!suggestedArea) {
+        return;
+    }
+
+    _serializer->set(AHATOFSTR(HADeviceSuggestedAreaProperty), suggestedArea);
+}
+
+void HADevice::setViaDevice(const char* viaDevice)
+{
+    if (!viaDevice) {
+        return;
+    }
+
+    _serializer->set(AHATOFSTR(HADeviceViaDeviceProperty), viaDevice);
+}
+
+bool HADevice::addConnection(const char* type, const char* value)
+{
+    if (!type || !value || type[0] == '\0' || value[0] == '\0') {
+        return false;
+    }
+
+    char next[MaxConnectionsJsonLength];
+    if (_hasConnections) {
+        strncpy(next, _connectionsJson, MaxConnectionsJsonLength - 1);
+        next[MaxConnectionsJsonLength - 1] = 0;
+    } else {
+        strcpy(next, "[]");
+    }
+
+    const size_t len = strlen(next);
+    if (len < 2 || next[len - 1] != ']') {
+        return false;
+    }
+
+    char* cursor = next + len - 1;
+    char* end = next + MaxConnectionsJsonLength - 1;
+
+    if (cursor > next + 1) {
+        if (cursor + 1 >= end) {
+            return false;
+        }
+        *cursor++ = ',';
+    }
+
+    if (cursor + 1 >= end) {
+        return false;
+    }
+    *cursor++ = '[';
+    *cursor = 0;
+
+    if (!appendEscapedJsonString(cursor, end, type)) {
+        return false;
+    }
+
+    if (cursor + 1 >= end) {
+        return false;
+    }
+    *cursor++ = ',';
+    *cursor = 0;
+
+    if (!appendEscapedJsonString(cursor, end, value)) {
+        return false;
+    }
+
+    if (cursor + 2 >= end) {
+        return false;
+    }
+    *cursor++ = ']';
+    *cursor++ = ']';
+    *cursor = 0;
+
+    strncpy(_connectionsJson, next, MaxConnectionsJsonLength - 1);
+    _connectionsJson[MaxConnectionsJsonLength - 1] = 0;
+    _hasConnections = true;
+
+    if (!_connectionsPropertyRegistered) {
+        _serializer->set(
+            AHATOFSTR(HADeviceConnectionsProperty),
+            _connectionsJson,
+            HASerializer::JsonLiteralPropertyValue
+        );
+        _connectionsPropertyRegistered = true;
+    }
+
+    return true;
+}
+
+void HADevice::setConnectionsJson(const char* connectionsJson)
+{
+    if (!connectionsJson || connectionsJson[0] == '\0') {
+        return;
+    }
+
+    strncpy(_connectionsJson, connectionsJson, MaxConnectionsJsonLength - 1);
+    _connectionsJson[MaxConnectionsJsonLength - 1] = 0;
+    _hasConnections = true;
+
+    if (!_connectionsPropertyRegistered) {
+        _serializer->set(
+            AHATOFSTR(HADeviceConnectionsProperty),
+            _connectionsJson,
+            HASerializer::JsonLiteralPropertyValue
+        );
+        _connectionsPropertyRegistered = true;
+    }
+}
+
+void HADevice::setPayloadAvailable(const char* payload)
+{
+    _payloadAvailable = payload;
+}
+
+void HADevice::setPayloadNotAvailable(const char* payload)
+{
+    _payloadNotAvailable = payload;
+}
+
 void HADevice::setAvailability(bool online)
 {
    _available = online;
@@ -131,9 +321,13 @@ void HADevice::enableLastWill()
        return;
    }

+    const char* lw = (_payloadNotAvailable && _payloadNotAvailable[0] != '\0')
+        ? _payloadNotAvailable
+        : "offline";
+
    mqtt->setLastWill(
        _availabilityTopic,
-        "offline",
+        lw,
        true
    );
 }
@@ -145,11 +339,33 @@ void HADevice::publishAvailability() const
        return;
    }

-    const char* payload = _available ? HAOnline : HAOffline;
-    const uint16_t length = strlen_P(payload);
-
-    if (mqtt->beginPublish(_availabilityTopic, length, true)) {
-        mqtt->writePayload(AHATOFSTR(payload));
-        mqtt->endPublish();
+    if (_available) {
+        if (_payloadAvailable && _payloadAvailable[0] != '\0') {
+            const uint16_t len = strlen(_payloadAvailable);
+            if (mqtt->beginPublish(_availabilityTopic, len, true)) {
+                mqtt->writePayload(_payloadAvailable, len);
+                mqtt->endPublish();
+            }
+        } else {
+            const uint16_t len = strlen_P(HAOnline);
+            if (mqtt->beginPublish(_availabilityTopic, len, true)) {
+                mqtt->writePayload(AHATOFSTR(HAOnline));
+                mqtt->endPublish();
+            }
+        }
+    } else {
+        if (_payloadNotAvailable && _payloadNotAvailable[0] != '\0') {
+            const uint16_t len = strlen(_payloadNotAvailable);
+            if (mqtt->beginPublish(_availabilityTopic, len, true)) {
+                mqtt->writePayload(_payloadNotAvailable, len);
+                mqtt->endPublish();
+            }
+        } else {
+            const uint16_t len = strlen_P(HAOffline);
+            if (mqtt->beginPublish(_availabilityTopic, len, true)) {
+                mqtt->writePayload(AHATOFSTR(HAOffline));
+                mqtt->endPublish();
+            }
+        }
    }
 }
@@ -131,6 +131,35 @@ public:
     */
    void setConfigurationUrl(const char* url);

+    void setModelId(const char* modelId);
+    void setHardwareVersion(const char* hardwareVersion);
+    void setSerialNumber(const char* serialNumber);
+    void setSuggestedArea(const char* suggestedArea);
+    void setViaDevice(const char* viaDevice);
+
+    /**
+     * Adds one MQTT device connection entry (e.g. `("mac", "aa:bb:cc:dd:ee:ff")`).
+     * Connections are serialized as JSON arrays inside the discovery `dev` object.
+     *
+     * @returns Returns `false` when the internal JSON buffer would overflow.
+     */
+    bool addConnection(const char* type, const char* value);
+
+    /**
+     * Sets the `connections` array as raw JSON (e.g. [[\"mac\",\"aa:bb:cc:dd:ee:ff\"]]).
+     * The payload is copied into an internal buffer.
+     */
+    void setConnectionsJson(const char* connectionsJson);
+
+    void setPayloadAvailable(const char* payload);
+    void setPayloadNotAvailable(const char* payload);
+
+    inline const char* getPayloadAvailable() const
+        { return _payloadAvailable; }
+
+    inline const char* getPayloadNotAvailable() const
+        { return _payloadNotAvailable; }
+
    /**
     * Sets device's availability and publishes MQTT message on the availability topic.
     * If the device is not connected to an MQTT broker or the shared availability is not enabled then nothing happens.
@@ -178,6 +207,13 @@ private:

    /// Specifies whether extended unique IDs feature is enabled.
    bool _extendedUniqueIds;
+
+    const char* _payloadAvailable;
+    const char* _payloadNotAvailable;
+    static const uint16_t MaxConnectionsJsonLength = 192;
+    char _connectionsJson[MaxConnectionsJsonLength];
+    bool _hasConnections;
+    bool _connectionsPropertyRegistered;
 };

 #endif
@@ -1,6 +1,7 @@
 #include "HAMqtt.h"

 #include <cstdio>
+#include <cstring>

 #ifndef ARDUINOHA_TEST
 #include <PubSubClient.h>
@@ -22,6 +23,7 @@
    _discoveryPrefix(DefaultDiscoveryPrefix), \
    _dataPrefix(DefaultDataPrefix), \
    _deviceDiscoveryEnabled(false), \
+    _originSupportUrl(nullptr), \
    _username(nullptr), \
    _password(nullptr), \
    _lastConnectionAttemptAt(0), \
@@ -32,7 +34,12 @@
    _lastWillTopic(nullptr), \
    _lastWillMessage(nullptr), \
    _lastWillRetain(false), \
-    _currentState(StateDisconnected)
+    _currentState(StateDisconnected), \
+    _messageDispatchDepth(0), \
+    _deferredQueue{}, \
+    _deferredHead(0), \
+    _deferredCount(0), \
+    _deferredBuilder()

 static const char* DefaultDiscoveryPrefix = "homeassistant";
 static const char* DefaultDataPrefix = "aha";
@@ -76,6 +83,8 @@ HAMqtt::HAMqtt(

 HAMqtt::~HAMqtt()
 {
+    clearDeferredBuilder();
+    clearDeferredQueue();
    delete[] _devicesTypes;

 #ifdef ARDUINOHA_TEST
@@ -177,6 +186,7 @@ bool HAMqtt::disconnect()

    ARDUINOHA_DEBUG_PRINTLN(F("AHA: disconnecting"))

+    clearDeferredBuilder();
    _initialized = false;
    _lastConnectionAttemptAt = 0;
    _mqtt->disconnect();
@@ -198,6 +208,10 @@ void HAMqtt::loop()
    if (!result) {
        connectToServer();
    }
+
+    if (_messageDispatchDepth == 0 && isConnected()) {
+        flushDeferredPublishes();
+    }
 }

 bool HAMqtt::isConnected() const
@@ -233,17 +247,33 @@ void HAMqtt::addDeviceType(HABaseDeviceType* deviceType)

 bool HAMqtt::publish(const char* topic, const char* payload, bool retained)
 {
-    if (!isConnected()) {
+    if (!isConnected() || !topic || !payload) {
        return false;
    }

+    const size_t len = strlen(payload);
+    if (len > UINT16_MAX) {
+        return false;
+    }
+
+    const uint16_t payloadLength = static_cast<uint16_t>(len);
+
    ARDUINOHA_DEBUG_PRINT(F("AHA: publishing "))
    ARDUINOHA_DEBUG_PRINT(topic)
    ARDUINOHA_DEBUG_PRINT(F(", len: "))
-    ARDUINOHA_DEBUG_PRINTLN(strlen(payload))
+    ARDUINOHA_DEBUG_PRINTLN(payloadLength)

-    _mqtt->beginPublish(topic, strlen(payload), retained);
-    _mqtt->write((const uint8_t*)(payload), strlen(payload));
+    if (isProcessingMessage()) {
+        return enqueueDeferredPublish(
+            topic,
+            reinterpret_cast<const uint8_t*>(payload),
+            payloadLength,
+            retained
+        );
+    }
+
+    _mqtt->beginPublish(topic, payloadLength, retained);
+    _mqtt->write(reinterpret_cast<const uint8_t*>(payload), payloadLength);
    return _mqtt->endPublish();
 }

@@ -258,7 +288,29 @@ bool HAMqtt::beginPublish(
    ARDUINOHA_DEBUG_PRINT(F(", len: "))
    ARDUINOHA_DEBUG_PRINTLN(payloadLength)

-    return _mqtt->beginPublish(topic, payloadLength, retained);
+    if (!isConnected() || !topic) {
+        return false;
+    }
+
+    if (!isProcessingMessage()) {
+        return _mqtt->beginPublish(topic, payloadLength, retained);
+    }
+
+    if (_deferredBuilder.active) {
+        return false;
+    }
+
+    const size_t topicLen = strlen(topic);
+
+    _deferredBuilder.topic = new char[topicLen + 1];
+    memcpy(_deferredBuilder.topic, topic, topicLen + 1);
+    _deferredBuilder.payload = payloadLength > 0 ? new uint8_t[payloadLength] : nullptr;
+    _deferredBuilder.expectedLength = payloadLength;
+    _deferredBuilder.writtenLength = 0;
+    _deferredBuilder.retained = retained;
+    _deferredBuilder.active = true;
+    _deferredBuilder.valid = true;
+    return true;
 }

 void HAMqtt::writePayload(const char* data, const uint16_t length)
@@ -268,17 +320,71 @@ void HAMqtt::writePayload(const char* data, const uint16_t length)

 void HAMqtt::writePayload(const uint8_t* data, const uint16_t length)
 {
+    if (isProcessingMessage() && _deferredBuilder.active) {
+        if (!_deferredBuilder.valid ||
+            (static_cast<uint32_t>(_deferredBuilder.writtenLength) + length) > _deferredBuilder.expectedLength) {
+            _deferredBuilder.valid = false;
+            return;
+        }
+
+        if (length > 0) {
+            memcpy(
+                _deferredBuilder.payload + _deferredBuilder.writtenLength,
+                data,
+                length
+            );
+        }
+
+        _deferredBuilder.writtenLength = static_cast<uint16_t>(_deferredBuilder.writtenLength + length);
+        return;
+    }
+
    _mqtt->write(data, length);
 }

 void HAMqtt::writePayload(const __FlashStringHelper* src)
 {
+    if (isProcessingMessage() && _deferredBuilder.active) {
+        PGM_P p = reinterpret_cast<PGM_P>(src);
+        const uint16_t chunkLen = static_cast<uint16_t>(strlen_P(p));
+        if (!_deferredBuilder.valid ||
+            (static_cast<uint32_t>(_deferredBuilder.writtenLength) + chunkLen) > _deferredBuilder.expectedLength) {
+            _deferredBuilder.valid = false;
+            return;
+        }
+
+        if (chunkLen > 0) {
+            memcpy_P(_deferredBuilder.payload + _deferredBuilder.writtenLength, p, chunkLen);
+            _deferredBuilder.writtenLength = static_cast<uint16_t>(_deferredBuilder.writtenLength + chunkLen);
+        }
+
+        return;
+    }
+
    _mqtt->print(src);
 }

 bool HAMqtt::endPublish()
 {
-    return _mqtt->endPublish();
+    if (!isProcessingMessage()) {
+        return _mqtt->endPublish();
+    }
+
+    if (!_deferredBuilder.active ||
+        !_deferredBuilder.valid ||
+        _deferredBuilder.writtenLength != _deferredBuilder.expectedLength) {
+        clearDeferredBuilder();
+        return false;
+    }
+
+    const bool ok = enqueueDeferredPublish(
+        _deferredBuilder.topic,
+        _deferredBuilder.payload,
+        _deferredBuilder.expectedLength,
+        _deferredBuilder.retained
+    );
+    clearDeferredBuilder();
+    return ok;
 }

 bool HAMqtt::subscribe(const char* topic)
@@ -296,6 +402,8 @@ void HAMqtt::processMessage(const char* topic, const uint8_t* payload, uint16_t
    ARDUINOHA_DEBUG_PRINT(F(", len: "))
    ARDUINOHA_DEBUG_PRINTLN(length)

+    _messageDispatchDepth++;
+
    if (_messageCallback) {
        _messageCallback(topic, payload, length);
    }
@@ -303,6 +411,12 @@ void HAMqtt::processMessage(const char* topic, const uint8_t* payload, uint16_t
    for (uint8_t i = 0; i < _devicesTypesNb; i++) {
        _devicesTypes[i]->onMqttMessage(topic, payload, length);
    }
+
+    _messageDispatchDepth--;
+
+    if (_messageDispatchDepth == 0) {
+        flushDeferredPublishes();
+    }
 }

 void HAMqtt::connectToServer()
@@ -398,15 +512,26 @@ bool HAMqtt::publishDeviceDiscovery()
        return false;
    }

-    char originPayload[64];
+    char originPayload[192];
    originPayload[0] = 0;
-    snprintf(
-        originPayload,
-        sizeof(originPayload),
-        "{\"name\":\"%s\",\"sw\":\"%s\"}",
-        DeviceDiscoveryOriginName,
-        ARDUINOHA_LIBRARY_VERSION
-    );
+    if (_originSupportUrl && _originSupportUrl[0] != '\0') {
+        snprintf(
+            originPayload,
+            sizeof(originPayload),
+            "{\"name\":\"%s\",\"sw\":\"%s\",\"url\":\"%s\"}",
+            DeviceDiscoveryOriginName,
+            ARDUINOHA_LIBRARY_VERSION,
+            _originSupportUrl
+        );
+    } else {
+        snprintf(
+            originPayload,
+            sizeof(originPayload),
+            "{\"name\":\"%s\",\"sw\":\"%s\"}",
+            DeviceDiscoveryOriginName,
+            ARDUINOHA_LIBRARY_VERSION
+        );
+    }
    const uint16_t originPayloadLength = strlen(originPayload);

    const uint16_t topicLength =
@@ -517,4 +642,124 @@ void HAMqtt::setState(ConnectionState state)
    if (_stateChangedCallback) {
        _stateChangedCallback(_currentState);
    }
+}
+
+bool HAMqtt::enqueueDeferredPublish(
+    const char* topic,
+    const uint8_t* payload,
+    uint16_t length,
+    bool retained
+)
+{
+    if (!topic || _deferredCount >= DeferredQueueCapacity) {
+        return false;
+    }
+
+    if (length > 0 && payload == nullptr) {
+        return false;
+    }
+
+    const uint8_t slot = static_cast<uint8_t>((_deferredHead + _deferredCount) % DeferredQueueCapacity);
+    DeferredPublishMessage& msg = _deferredQueue[slot];
+
+    const size_t topicLen = strlen(topic);
+    msg.topic = new char[topicLen + 1];
+    memcpy(msg.topic, topic, topicLen + 1);
+
+    if (length > 0) {
+        msg.payload = new uint8_t[length];
+        memcpy(msg.payload, payload, length);
+    } else {
+        msg.payload = nullptr;
+    }
+
+    msg.length = length;
+    msg.retained = retained;
+    _deferredCount++;
+
+#ifdef ARDUINOHA_TEST
+    _deferredPublishEnqueueCountForTest++;
+#endif
+
+    return true;
+}
+
+void HAMqtt::clearDeferredMessage(DeferredPublishMessage& msg)
+{
+    delete[] msg.topic;
+    delete[] msg.payload;
+    msg.topic = nullptr;
+    msg.payload = nullptr;
+    msg.length = 0;
+    msg.retained = false;
+}
+
+void HAMqtt::clearDeferredQueue()
+{
+    while (_deferredCount > 0) {
+        DeferredPublishMessage& msg = _deferredQueue[_deferredHead];
+        clearDeferredMessage(msg);
+        _deferredHead = static_cast<uint8_t>((_deferredHead + 1) % DeferredQueueCapacity);
+        _deferredCount--;
+    }
+
+    _deferredHead = 0;
+}
+
+void HAMqtt::clearDeferredBuilder()
+{
+    delete[] _deferredBuilder.topic;
+    delete[] _deferredBuilder.payload;
+    _deferredBuilder.topic = nullptr;
+    _deferredBuilder.payload = nullptr;
+    _deferredBuilder.expectedLength = 0;
+    _deferredBuilder.writtenLength = 0;
+    _deferredBuilder.retained = false;
+    _deferredBuilder.active = false;
+    _deferredBuilder.valid = false;
+}
+
+bool HAMqtt::flushDeferredPublishes()
+{
+    while (_deferredCount > 0) {
+        DeferredPublishMessage& msg = _deferredQueue[_deferredHead];
+
+        if (!isConnected()) {
+#ifdef ARDUINOHA_TEST
+            _deferredFlushFailedForTest = true;
+            _lastDeferredFlushErrorForTest = DeferredFlushErrorNotConnected;
+#endif
+            return false;
+        }
+
+        if (!_mqtt->beginPublish(msg.topic, msg.length, msg.retained)) {
+#ifdef ARDUINOHA_TEST
+            _deferredFlushFailedForTest = true;
+            _lastDeferredFlushErrorForTest = DeferredFlushErrorBeginPublish;
+#endif
+            return false;
+        }
+
+        if (msg.length > 0 && msg.payload != nullptr) {
+            _mqtt->write(msg.payload, msg.length);
+        }
+
+        if (!_mqtt->endPublish()) {
+#ifdef ARDUINOHA_TEST
+            _deferredFlushFailedForTest = true;
+            _lastDeferredFlushErrorForTest = DeferredFlushErrorEndPublish;
+#endif
+            return false;
+        }
+
+        clearDeferredMessage(msg);
+        _deferredHead = static_cast<uint8_t>((_deferredHead + 1) % DeferredQueueCapacity);
+        _deferredCount--;
+    }
+
+#ifdef ARDUINOHA_TEST
+    _deferredFlushFailedForTest = false;
+    _lastDeferredFlushErrorForTest = DeferredFlushErrorNone;
+#endif
+    return true;
 }
@@ -136,6 +136,15 @@ public:
     */
    bool publishDeviceDiscovery();

+    /**
+     * Sets optional `support_url` in the discovery `origin` object (must remain valid).
+     */
+    inline void setOriginSupportUrl(const char* url)
+        { _originSupportUrl = url; }
+
+    inline const char* getOriginSupportUrl() const
+        { return _originSupportUrl; }
+
    /**
     * Returns instance of the device assigned to the HAMqtt class.
     * It's the same object (pointer) that was passed to the HAMqtt constructor.
@@ -310,6 +319,10 @@ public:
     * Message won't be published if the connection with the MQTT broker is not established.
     * In this case method returns false.
     *
+     * While handling an inbound MQTT message (see isProcessingMessage()), a successful
+     * return means the message was queued for send after dispatch completes, not that it
+     * was already transmitted. Outside that context, behavior is unchanged.
+     *
     * @param topic The topic to publish.
     * @param payload The payload to publish (it may be empty const char).
     * @param retained Specifies whether message should be retained.
@@ -402,12 +415,47 @@ public:
     */
    void processMessage(const char* topic, const uint8_t* payload, uint16_t length);

+    /**
+     * True while handling an inbound MQTT message (user onMessage and device onMqttMessage).
+     * Publish attempts in this window are queued and flushed when dispatch completes.
+     */
+    inline bool isProcessingMessage() const
+        { return _messageDispatchDepth > 0; }
+
 #ifdef ARDUINOHA_TEST
    inline uint8_t getDevicesTypesNb() const
        { return _devicesTypesNb; }

    inline HABaseDeviceType** getDevicesTypes() const
        { return _devicesTypes; }
+
+    inline uint16_t getDeferredPublishEnqueueCountForTest() const
+        { return _deferredPublishEnqueueCountForTest; }
+
+    inline void resetDeferredPublishTestCounters()
+    {
+        _deferredPublishEnqueueCountForTest = 0;
+        _deferredFlushFailedForTest = false;
+        _lastDeferredFlushErrorForTest = 0;
+    }
+
+    inline uint8_t getPendingDeferredPublishesForTest() const
+        { return _deferredCount; }
+
+    inline bool hasDeferredFlushFailureForTest() const
+        { return _deferredFlushFailedForTest; }
+
+    inline uint8_t getLastDeferredFlushErrorForTest() const
+        { return _lastDeferredFlushErrorForTest; }
+
+    inline bool didDeferredFlushFailDueToDisconnectForTest() const
+        { return _lastDeferredFlushErrorForTest == 1; }
+
+    inline bool didDeferredFlushFailAtBeginPublishForTest() const
+        { return _lastDeferredFlushErrorForTest == 2; }
+
+    inline bool didDeferredFlushFailAtEndPublishForTest() const
+        { return _lastDeferredFlushErrorForTest == 3; }
 #endif

 private:
@@ -433,6 +481,51 @@ private:
     */
    void setState(ConnectionState state);

+    struct DeferredPublishMessage {
+        char* topic;
+        uint8_t* payload;
+        uint16_t length;
+        bool retained;
+    };
+
+    struct DeferredPublishBuilder {
+        bool active;
+        bool valid;
+        char* topic;
+        uint8_t* payload;
+        uint16_t expectedLength;
+        uint16_t writtenLength;
+        bool retained;
+    };
+
+    enum DeferredFlushError {
+        DeferredFlushErrorNone = 0,
+        DeferredFlushErrorNotConnected,
+        DeferredFlushErrorBeginPublish,
+        DeferredFlushErrorEndPublish
+    };
+
+    static const uint8_t DeferredQueueCapacity = 8;
+
+    bool enqueueDeferredPublish(
+        const char* topic,
+        const uint8_t* payload,
+        uint16_t length,
+        bool retained
+    );
+
+    void clearDeferredMessage(DeferredPublishMessage& msg);
+
+    void clearDeferredQueue();
+
+    void clearDeferredBuilder();
+
+    /**
+     * Sends queued publishes in order. On transport failure, stops and leaves the
+     * remaining queue intact for a later retry (e.g. from loop()).
+     */
+    bool flushDeferredPublishes();
+
 #ifdef ARDUINOHA_TEST
    PubSubClientMock* _mqtt;
 #else
@@ -470,6 +563,8 @@ private:
    /// Enables MQTT device discovery mode when set to true.
    bool _deviceDiscoveryEnabled;

+    const char* _originSupportUrl;
+
    /// The username used for the authentication. It's set in the HAMqtt::begin method.
    const char* _username;

@@ -502,6 +597,21 @@ private:

    /// The last known state of the MQTT connection.
    ConnectionState _currentState;
+
+    /// Nesting depth for inbound message dispatch (processMessage).
+    uint8_t _messageDispatchDepth;
+
+    DeferredPublishMessage _deferredQueue[DeferredQueueCapacity];
+    uint8_t _deferredHead;
+    uint8_t _deferredCount;
+
+    DeferredPublishBuilder _deferredBuilder;
+
+#ifdef ARDUINOHA_TEST
+    uint16_t _deferredPublishEnqueueCountForTest = 0;
+    bool _deferredFlushFailedForTest = false;
+    uint8_t _lastDeferredFlushErrorForTest = 0;
+#endif
 };

 #endif
@@ -2,7 +2,9 @@
 #include "../HAMqtt.h"
 #include "../HADevice.h"
 #include "../utils/HAUtils.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"
+#include <string.h>

 HABaseDeviceType::HABaseDeviceType(
    const __FlashStringHelper* componentName,
@@ -15,6 +17,16 @@ HABaseDeviceType::HABaseDeviceType(
    _defaultEntityId(nullptr),
    _entityCategory(nullptr),
    _serializer(nullptr),
+    _hasEnabledByDefault(false),
+    _enabledByDefault(true),
+    _entityPicture(nullptr),
+    _hasQos(false),
+    _qosNumeric(),
+    _encoding(nullptr),
+    _payloadAvailable(nullptr),
+    _payloadNotAvailable(nullptr),
+    _availabilityMode(nullptr),
+    _availabilityList(),
    _availability(AvailabilityDefault)
 {
    if (mqtt()) {
@@ -166,13 +178,86 @@ void HABaseDeviceType::publishAvailability()
        return;
    }

-    publishOnDataTopic(
-        AHATOFSTR(HAAvailabilityTopic),
-        _availability == AvailabilityOnline
+    const bool online = (_availability == AvailabilityOnline);
+
+    if (_availabilityList.count() > 0) {
+        char defaultBuf[12];
+        const __FlashStringHelper* flashPayload = online
            ? AHATOFSTR(HAOnline)
-            : AHATOFSTR(HAOffline),
-        true
-    );
+            : AHATOFSTR(HAOffline);
+
+        for (uint8_t i = 0; i < _availabilityList.count(); i++) {
+            const HAAvailabilityConfig::Entry& e = _availabilityList.getEntry(i);
+            const char* payload = nullptr;
+
+            if (online) {
+                if (e.payloadAvailable && e.payloadAvailable[0] != '\0') {
+                    payload = e.payloadAvailable;
+                } else if (_payloadAvailable && _payloadAvailable[0] != '\0') {
+                    payload = _payloadAvailable;
+                } else {
+                    strncpy_P(
+                        defaultBuf,
+                        reinterpret_cast<PGM_P>(AHAFROMFSTR(flashPayload)),
+                        sizeof(defaultBuf) - 1
+                    );
+                    defaultBuf[sizeof(defaultBuf) - 1] = 0;
+                    payload = defaultBuf;
+                }
+            } else {
+                if (e.payloadNotAvailable && e.payloadNotAvailable[0] != '\0') {
+                    payload = e.payloadNotAvailable;
+                } else if (_payloadNotAvailable && _payloadNotAvailable[0] != '\0') {
+                    payload = _payloadNotAvailable;
+                } else {
+                    strncpy_P(
+                        defaultBuf,
+                        reinterpret_cast<PGM_P>(AHAFROMFSTR(flashPayload)),
+                        sizeof(defaultBuf) - 1
+                    );
+                    defaultBuf[sizeof(defaultBuf) - 1] = 0;
+                    payload = defaultBuf;
+                }
+            }
+
+            publishAbsolute(e.topic, payload, true);
+        }
+
+        return;
+    }
+
+    const char* ramPayload = online
+        ? effectivePayloadAvailable()
+        : effectivePayloadNotAvailable();
+
+    if (ramPayload) {
+        publishOnDataTopic(AHATOFSTR(HAAvailabilityTopic), ramPayload, true);
+    } else {
+        publishOnDataTopic(
+            AHATOFSTR(HAAvailabilityTopic),
+            online ? AHATOFSTR(HAOnline) : AHATOFSTR(HAOffline),
+            true
+        );
+    }
+}
+
+bool HABaseDeviceType::publishAbsolute(
+    const char* fullTopic,
+    const char* payload,
+    bool retained
+)
+{
+    if (!fullTopic || !payload || !mqtt()) {
+        return false;
+    }
+
+    const uint16_t len = strlen(payload);
+    if (!mqtt()->beginPublish(fullTopic, len, retained)) {
+        return false;
+    }
+
+    mqtt()->writePayload(payload, len);
+    return mqtt()->endPublish();
 }

 bool HABaseDeviceType::publishOnDataTopic(
@@ -290,4 +375,225 @@ HASerializer* HABaseDeviceType::buildDeviceDiscoverySerializer()
 bool HABaseDeviceType::supportsDeviceDiscovery() const
 {
    return false;
+}
+
+void HABaseDeviceType::setEnabledByDefault(bool enabled)
+{
+    _enabledByDefault = enabled;
+    _hasEnabledByDefault = true;
+}
+
+void HABaseDeviceType::clearEnabledByDefault()
+{
+    _hasEnabledByDefault = false;
+}
+
+void HABaseDeviceType::setEntityPicture(const char* url)
+{
+    _entityPicture = url;
+}
+
+void HABaseDeviceType::clearEntityPicture()
+{
+    _entityPicture = nullptr;
+}
+
+void HABaseDeviceType::setQos(uint8_t qos)
+{
+    if (qos > 2) {
+        qos = 2;
+    }
+
+    _qosNumeric = HANumeric(static_cast<uint8_t>(qos), 0);
+    _hasQos = true;
+}
+
+void HABaseDeviceType::clearQos()
+{
+    _hasQos = false;
+    _qosNumeric.reset();
+}
+
+void HABaseDeviceType::setEncoding(const char* encoding)
+{
+    _encoding = encoding;
+}
+
+void HABaseDeviceType::clearEncoding()
+{
+    _encoding = nullptr;
+}
+
+void HABaseDeviceType::setPayloadAvailable(const char* payload)
+{
+    _payloadAvailable = payload;
+}
+
+void HABaseDeviceType::setPayloadNotAvailable(const char* payload)
+{
+    _payloadNotAvailable = payload;
+}
+
+void HABaseDeviceType::setAvailabilityMode(const char* mode)
+{
+    _availabilityMode = mode;
+}
+
+bool HABaseDeviceType::addAvailabilityEntry(
+    const char* topic,
+    const char* valueTemplate,
+    const char* payloadAvailable,
+    const char* payloadNotAvailable
+)
+{
+    return _availabilityList.add(
+        topic,
+        valueTemplate,
+        payloadAvailable,
+        payloadNotAvailable
+    );
+}
+
+void HABaseDeviceType::clearAvailabilityEntries()
+{
+    _availabilityList.clear();
+}
+
+void HABaseDeviceType::applyCommonEntityProperties(
+    HASerializer* serializer,
+    bool includeEncoding
+) const
+{
+    if (!serializer) {
+        return;
+    }
+
+    if (_hasEnabledByDefault) {
+        serializer->set(
+            AHATOFSTR(HAEnabledByDefaultProperty),
+            &_enabledByDefault,
+            HASerializer::BoolPropertyType
+        );
+    }
+
+    if (nonEmptyString(_entityPicture)) {
+        serializer->set(AHATOFSTR(HAEntityPictureProperty), _entityPicture);
+    }
+
+    if (_hasQos) {
+        serializer->set(
+            AHATOFSTR(HAQosProperty),
+            &_qosNumeric,
+            HASerializer::NumberPropertyType
+        );
+    }
+
+    if (includeEncoding && nonEmptyString(_encoding)) {
+        serializer->set(AHATOFSTR(HAEncodingProperty), _encoding);
+    }
+}
+
+const char* HABaseDeviceType::effectivePayloadAvailable() const
+{
+    if (_payloadAvailable && _payloadAvailable[0] != '\0') {
+        return _payloadAvailable;
+    }
+
+    HAMqtt* m = mqtt();
+    if (!m) {
+        return nullptr;
+    }
+
+    const HADevice* d = m->getDevice();
+    if (d && d->isSharedAvailabilityEnabled()) {
+        return d->getPayloadAvailable();
+    }
+
+    return nullptr;
+}
+
+const char* HABaseDeviceType::effectivePayloadNotAvailable() const
+{
+    if (_payloadNotAvailable && _payloadNotAvailable[0] != '\0') {
+        return _payloadNotAvailable;
+    }
+
+    HAMqtt* m = mqtt();
+    if (!m) {
+        return nullptr;
+    }
+
+    const HADevice* d = m->getDevice();
+    if (d && d->isSharedAvailabilityEnabled()) {
+        return d->getPayloadNotAvailable();
+    }
+
+    return nullptr;
+}
+
+void HABaseDeviceType::configureAvailabilityEntries(HASerializer* serializer) const
+{
+    if (!serializer || !mqtt()) {
+        return;
+    }
+
+    const HADevice* device = mqtt()->getDevice();
+    if (!device) {
+        return;
+    }
+
+    const bool isSharedAvailability = device->isSharedAvailabilityEnabled();
+    const bool availabilityActive = isAvailabilityConfigured();
+
+    if (!isSharedAvailability && !availabilityActive) {
+        return;
+    }
+
+    const char* pa = effectivePayloadAvailable();
+    if (nonEmptyString(pa)) {
+        serializer->set(
+            AHATOFSTR(HAPayloadAvailableProperty),
+            pa,
+            HASerializer::ConstCharPropertyValue
+        );
+    }
+
+    const char* pn = effectivePayloadNotAvailable();
+    if (nonEmptyString(pn)) {
+        serializer->set(
+            AHATOFSTR(HAPayloadNotAvailableProperty),
+            pn,
+            HASerializer::ConstCharPropertyValue
+        );
+    }
+
+    if (nonEmptyString(_availabilityMode)) {
+        serializer->set(
+            AHATOFSTR(HAAvailabilityModeProperty),
+            _availabilityMode,
+            HASerializer::ConstCharPropertyValue
+        );
+    }
+
+    const bool useList =
+        !isSharedAvailability
+        && availabilityActive
+        && _availabilityList.count() > 0;
+
+    if (useList) {
+        auto* entry = serializer->addEntry();
+        entry->type = HASerializer::AvailabilityArrayEntryType;
+        entry->subtype = 0;
+        entry->property = AHATOFSTR(HAAvailabilityListProperty);
+        entry->value = const_cast<HAAvailabilityConfig*>(&_availabilityList);
+        return;
+    }
+
+    auto* e = serializer->addEntry();
+    e->type = HASerializer::TopicEntryType;
+    e->subtype = 0;
+    e->property = AHATOFSTR(HAAvailabilityTopic);
+    e->value = isSharedAvailability
+        ? const_cast<char*>(device->getAvailabilityTopic())
+        : nullptr;
 }
@@ -3,6 +3,8 @@

 #include <Arduino.h>
 #include "../ArduinoHADefines.h"
+#include "../utils/HAAvailabilityConfig.h"
+#include "../utils/HANumeric.h"

 class HAMqtt;
 class HASerializer;
@@ -127,6 +129,36 @@ public:
    inline const char* getEntityCategory() const
        { return _entityCategory; }

+    void setEnabledByDefault(bool enabled);
+    void clearEnabledByDefault();
+
+    void setEntityPicture(const char* url);
+    void clearEntityPicture();
+
+    void setQos(uint8_t qos);
+    void clearQos();
+
+    void setEncoding(const char* encoding);
+    void clearEncoding();
+
+    void setPayloadAvailable(const char* payload);
+    void setPayloadNotAvailable(const char* payload);
+
+    void setAvailabilityMode(const char* mode);
+
+    /**
+     * Adds a full-topic availability entry for discovery (`avty` list) and publishing.
+     * Only used when this entity does not use shared device availability.
+     */
+    bool addAvailabilityEntry(
+        const char* topic,
+        const char* valueTemplate = nullptr,
+        const char* payloadAvailable = nullptr,
+        const char* payloadNotAvailable = nullptr
+    );
+
+    void clearAvailabilityEntries();
+
    /**
     * Sets availability of the device type.
     * Setting the initial availability enables availability reporting for this device type.
@@ -186,6 +218,19 @@ protected:
     */
    virtual void buildSerializer() { };

+    /**
+     * Writes shared MQTT discovery fields (enabled_by_default, entity_picture, qos, encoding).
+     */
+    void applyCommonEntityProperties(
+        HASerializer* serializer,
+        bool includeEncoding = true
+    ) const;
+
+    /**
+     * Populates availability-related discovery entries. Called from HASerializer::WithAvailability.
+     */
+    void configureAvailabilityEntries(HASerializer* serializer) const;
+
    /**
     * This method is called each time the MQTT connection is acquired.
     * Each device type should publish its configuration and availability.
@@ -266,6 +311,11 @@ protected:
        bool isProgmemData = false
    );

+    /**
+     * Publishes a RAM payload on an already fully-qualified MQTT topic.
+     */
+    bool publishAbsolute(const char* fullTopic, const char* payload, bool retained = false);
+
    /**
     * Adds the preferred entity ID property to the serializer.
     * `default_entity_id` takes precedence and the legacy `object_id` is only
@@ -310,6 +360,17 @@ protected:
    /// HASerializer that belongs to this device type. It can be nullptr.
    HASerializer* _serializer;

+    bool _hasEnabledByDefault;
+    bool _enabledByDefault;
+    const char* _entityPicture;
+    bool _hasQos;
+    HANumeric _qosNumeric;
+    const char* _encoding;
+    const char* _payloadAvailable;
+    const char* _payloadNotAvailable;
+    const char* _availabilityMode;
+    HAAvailabilityConfig _availabilityList;
+
 private:
    enum Availability {
        AvailabilityDefault = 0,
@@ -319,7 +380,12 @@ private:

    /// The current availability of this device type. AvailabilityDefault means that the initial availability was never set.
    Availability _availability;
+
+    const char* effectivePayloadAvailable() const;
+    const char* effectivePayloadNotAvailable() const;
+
    friend class HAMqtt;
+    friend class HASerializer;
 };

 #endif
@@ -2,12 +2,18 @@
 #ifndef EX_ARDUINOHA_BINARY_SENSOR

 #include "../HAMqtt.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"

 HABinarySensor::HABinarySensor(const char* uniqueId) :
    HABaseDeviceType(AHATOFSTR(HAComponentBinarySensor), uniqueId),
    _class(nullptr),
    _icon(nullptr),
+    _payloadOn(nullptr),
+    _payloadOff(nullptr),
+    _forceUpdate(false),
+    _offDelay(),
+    _valueTemplate(nullptr),
    _currentState(false)
 {

@@ -19,12 +25,9 @@ bool HABinarySensor::setState(const bool state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 void HABinarySensor::setExpireAfter(uint16_t expireAfter)
@@ -36,20 +39,68 @@ void HABinarySensor::setExpireAfter(uint16_t expireAfter)
    }
 }

+void HABinarySensor::setOffDelay(uint16_t seconds)
+{
+    if (seconds > 0) {
+        _offDelay.setBaseValue(seconds);
+    } else {
+        _offDelay.reset();
+    }
+}
+
+void HABinarySensor::clearOffDelay()
+{
+    _offDelay.reset();
+}
+
+void HABinarySensor::setValueTemplate(const char* valueTemplate)
+{
+    _valueTemplate = valueTemplate;
+}
+
 void HABinarySensor::buildSerializer()
 {
    if (_serializer || !uniqueId()) {
        return;
    }

-    _serializer = new HASerializer(this, 10); // 10 - max properties nb
+    _serializer = new HASerializer(this, 20);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

+    if (nonEmptyString(_payloadOn)) {
+        _serializer->set(AHATOFSTR(HAPayloadOnProperty), _payloadOn);
+    }
+
+    if (nonEmptyString(_payloadOff)) {
+        _serializer->set(AHATOFSTR(HAPayloadOffProperty), _payloadOff);
+    }
+
+    if (_forceUpdate) {
+        _serializer->set(
+            AHATOFSTR(HAForceUpdateProperty),
+            &_forceUpdate,
+            HASerializer::BoolPropertyType
+        );
+    }
+
+    if (_offDelay.isSet()) {
+        _serializer->set(
+            AHATOFSTR(HAOffDelayProperty),
+            &_offDelay,
+            HASerializer::NumberPropertyType
+        );
+    }
+
+    if (nonEmptyString(_valueTemplate)) {
+        _serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
    if (_expireAfter.isSet()) {
        _serializer->set(
            AHATOFSTR(HAExpireAfterProperty),
@@ -69,7 +120,7 @@ HASerializer* HABinarySensor::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 10);
+    HASerializer* serializer = new HASerializer(this, 20);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentBinarySensor),
@@ -78,10 +129,39 @@ HASerializer* HABinarySensor::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

+    if (nonEmptyString(_payloadOn)) {
+        serializer->set(AHATOFSTR(HAPayloadOnProperty), _payloadOn);
+    }
+
+    if (nonEmptyString(_payloadOff)) {
+        serializer->set(AHATOFSTR(HAPayloadOffProperty), _payloadOff);
+    }
+
+    if (_forceUpdate) {
+        serializer->set(
+            AHATOFSTR(HAForceUpdateProperty),
+            &_forceUpdate,
+            HASerializer::BoolPropertyType
+        );
+    }
+
+    if (_offDelay.isSet()) {
+        serializer->set(
+            AHATOFSTR(HAOffDelayProperty),
+            &_offDelay,
+            HASerializer::NumberPropertyType
+        );
+    }
+
+    if (nonEmptyString(_valueTemplate)) {
+        serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
    if (_expireAfter.isSet()) {
        serializer->set(
            AHATOFSTR(HAExpireAfterProperty),
@@ -110,9 +190,33 @@ void HABinarySensor::onMqttConnected()

 bool HABinarySensor::publishState(const bool state)
 {
+    if (state) {
+        if (nonEmptyString(_payloadOn)) {
+            return publishOnDataTopic(
+                AHATOFSTR(HAStateTopic),
+                _payloadOn,
+                true
+            );
+        }
+
+        return publishOnDataTopic(
+            AHATOFSTR(HAStateTopic),
+            AHATOFSTR(HAStateOn),
+            true
+        );
+    }
+
+    if (nonEmptyString(_payloadOff)) {
+        return publishOnDataTopic(
+            AHATOFSTR(HAStateTopic),
+            _payloadOff,
+            true
+        );
+    }
+
    return publishOnDataTopic(
        AHATOFSTR(HAStateTopic),
-        AHATOFSTR(state ? HAStateOn : HAStateOff),
+        AHATOFSTR(HAStateOff),
        true
    );
 }
@@ -72,6 +72,20 @@ public:
    inline void setIcon(const char* icon)
        { _icon = icon; }

+    inline void setPayloadOn(const char* payload)
+        { _payloadOn = payload; }
+
+    inline void setPayloadOff(const char* payload)
+        { _payloadOff = payload; }
+
+    inline void setForceUpdate(bool forceUpdate)
+        { _forceUpdate = forceUpdate; }
+
+    void setOffDelay(uint16_t seconds);
+    void clearOffDelay();
+
+    void setValueTemplate(const char* valueTemplate);
+
 protected:
    virtual void buildSerializer() override;
    virtual HASerializer* buildDeviceDiscoverySerializer() override;
@@ -97,6 +111,12 @@ private:
    /// It defines the number of seconds after the sensor’s state expires, if it’s not updated. By default the sensors state never expires.
    HANumeric _expireAfter;

+    const char* _payloadOn;
+    const char* _payloadOff;
+    bool _forceUpdate;
+    HANumeric _offDelay;
+    const char* _valueTemplate;
+
    /// Current state of the sensor. By default it's false.
    bool _currentState;

@@ -2,32 +2,55 @@
 #ifndef EX_ARDUINOHA_BUTTON

 #include "../HAMqtt.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"
+#include <string.h>

 HAButton::HAButton(const char* uniqueId) :
    HABaseDeviceType(AHATOFSTR(HAComponentButton), uniqueId),
    _class(nullptr),
    _icon(nullptr),
    _retain(false),
+    _payloadPress(nullptr),
+    _commandTemplate(nullptr),
    _commandCallback(nullptr)
 {

 }

+void HAButton::setPayloadPress(const char* payload)
+{
+    _payloadPress = payload;
+}
+
+void HAButton::setCommandTemplate(const char* commandTemplate)
+{
+    _commandTemplate = commandTemplate;
+}
+
 void HAButton::buildSerializer()
 {
    if (_serializer || !uniqueId()) {
        return;
    }

-    _serializer = new HASerializer(this, 10); // 10 - max properties nb
+    _serializer = new HASerializer(this, 18);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

+    if (nonEmptyString(_payloadPress)) {
+        _serializer->set(AHATOFSTR(HAPayloadPressProperty), _payloadPress);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        _serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    // optional property
    if (_retain) {
        _serializer->set(
@@ -48,7 +71,7 @@ HASerializer* HAButton::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 10);
+    HASerializer* serializer = new HASerializer(this, 18);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentButton),
@@ -57,10 +80,19 @@ HASerializer* HAButton::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

+    if (nonEmptyString(_payloadPress)) {
+        serializer->set(AHATOFSTR(HAPayloadPressProperty), _payloadPress);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    if (_retain) {
        serializer->set(
            AHATOFSTR(HARetainProperty),
@@ -108,6 +140,16 @@ void HAButton::onMqttMessage(
        uniqueId(),
        AHATOFSTR(HACommandTopic)
    )) {
+        if (
+            nonEmptyString(_payloadPress)
+            && (
+                length != strlen(_payloadPress)
+                || memcmp(payload, _payloadPress, length) != 0
+            )
+        ) {
+            return;
+        }
+
        if (_commandCallback) {
            _commandCallback(this);
        }
@@ -54,6 +54,9 @@ public:
    inline void setRetain(const bool retain)
        { _retain = retain; }

+    void setPayloadPress(const char* payload);
+    void setCommandTemplate(const char* commandTemplate);
+
    /**
     * Registers callback that will be called each time the press command from HA is received.
     * Please note that it's not possible to register multiple callbacks for the same button.
@@ -104,6 +107,9 @@ private:
    /// The retain flag for the HA commands.
    bool _retain;

+    const char* _payloadPress;
+    const char* _commandTemplate;
+
    /// The command callback that will be called once clicking the button in HA panel.
    HABUTTON_CALLBACK(_commandCallback);

@@ -27,10 +27,11 @@ void HACamera::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 9); // 9 - max properties nb
+    _serializer = new HASerializer(this, 18);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer, false);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
    _serializer->set(
@@ -49,7 +50,7 @@ HASerializer* HACamera::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 9);
+    HASerializer* serializer = new HASerializer(this, 18);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentCamera),
@@ -58,6 +59,7 @@ HASerializer* HACamera::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer, false);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
    serializer->set(
@@ -29,12 +29,13 @@ bool HACover::setState(const CoverState state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
+    if (state == StateUnknown) {
+        return false;
    }

-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 bool HACover::setPosition(const int16_t position, const bool force)
@@ -43,12 +44,13 @@ bool HACover::setPosition(const int16_t position, const bool force)
        return true;
    }

-    if (publishPosition(position)) {
-        _currentPosition = position;
-        return true;
+    if (position == DefaultPosition || !(_features & PositionFeature)) {
+        return false;
    }

-    return false;
+    const bool published = publishPosition(position);
+    _currentPosition = position;
+    return published;
 }

 void HACover::buildSerializer()
@@ -57,10 +59,11 @@ void HACover::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 13); // 13 - max properties nb
+    _serializer = new HASerializer(this, 22);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
@@ -97,7 +100,7 @@ HASerializer* HACover::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 13);
+    HASerializer* serializer = new HASerializer(this, 22);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentCover),
@@ -106,6 +109,7 @@ HASerializer* HACover::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
@@ -19,12 +19,13 @@ bool HADeviceTracker::setState(const TrackerState state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
+    if (state == StateUnknown) {
+        return false;
    }

-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 void HADeviceTracker::buildSerializer()
@@ -33,10 +34,11 @@ void HADeviceTracker::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 9); // 9 - max properties nb
+    _serializer = new HASerializer(this, 18);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
    _serializer->set(
@@ -55,7 +57,7 @@ HASerializer* HADeviceTracker::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 9);
+    HASerializer* serializer = new HASerializer(this, 18);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentDeviceTracker),
@@ -64,6 +66,7 @@ HASerializer* HADeviceTracker::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
    serializer->set(
@@ -31,12 +31,9 @@ bool HAFan::setState(const bool state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 bool HAFan::setSpeed(const uint16_t speed, const bool force)
@@ -45,12 +42,13 @@ bool HAFan::setSpeed(const uint16_t speed, const bool force)
        return true;
    }

-    if (publishSpeed(speed)) {
-        _currentSpeed = speed;
-        return true;
+    if (!(_features & SpeedsFeature)) {
+        return false;
    }

-    return false;
+    const bool published = publishSpeed(speed);
+    _currentSpeed = speed;
+    return published;
 }

 void HAFan::buildSerializer()
@@ -59,10 +57,11 @@ void HAFan::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 15); // 15 - max properties nb
+    _serializer = new HASerializer(this, 24);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -115,7 +114,7 @@ HASerializer* HAFan::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 15);
+    HASerializer* serializer = new HASerializer(this, 24);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentFan),
@@ -124,6 +123,7 @@ HASerializer* HAFan::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -89,12 +89,9 @@ bool HAHVAC::setCurrentTemperature(const HANumeric& temperature, const bool forc
        return true;
    }

-    if (publishCurrentTemperature(temperature)) {
-        _currentTemperature = temperature;
-        return true;
-    }
-
-    return false;
+    const bool published = publishCurrentTemperature(temperature);
+    _currentTemperature = temperature;
+    return published;
 }

 bool HAHVAC::setAction(const Action action, const bool force)
@@ -103,12 +100,9 @@ bool HAHVAC::setAction(const Action action, const bool force)
        return true;
    }

-    if (publishAction(action)) {
-        _action = action;
-        return true;
-    }
-
-    return false;
+    const bool published = publishAction(action);
+    _action = action;
+    return published;
 }

 bool HAHVAC::setAuxState(const bool state, const bool force)
@@ -117,12 +111,9 @@ bool HAHVAC::setAuxState(const bool state, const bool force)
        return true;
    }

-    if (publishAuxState(state)) {
-        _auxState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishAuxState(state);
+    _auxState = state;
+    return published;
 }

 bool HAHVAC::setFanMode(const FanMode mode, const bool force)
@@ -131,12 +122,9 @@ bool HAHVAC::setFanMode(const FanMode mode, const bool force)
        return true;
    }

-    if (publishFanMode(mode)) {
-        _fanMode = mode;
-        return true;
-    }
-
-    return false;
+    const bool published = publishFanMode(mode);
+    _fanMode = mode;
+    return published;
 }

 bool HAHVAC::setSwingMode(const SwingMode mode, const bool force)
@@ -145,12 +133,9 @@ bool HAHVAC::setSwingMode(const SwingMode mode, const bool force)
        return true;
    }

-    if (publishSwingMode(mode)) {
-        _swingMode = mode;
-        return true;
-    }
-
-    return false;
+    const bool published = publishSwingMode(mode);
+    _swingMode = mode;
+    return published;
 }

 bool HAHVAC::setMode(const Mode mode, const bool force)
@@ -159,12 +144,9 @@ bool HAHVAC::setMode(const Mode mode, const bool force)
        return true;
    }

-    if (publishMode(mode)) {
-        _mode = mode;
-        return true;
-    }
-
-    return false;
+    const bool published = publishMode(mode);
+    _mode = mode;
+    return published;
 }

 bool HAHVAC::setTargetTemperature(const HANumeric& temperature, const bool force)
@@ -177,12 +159,9 @@ bool HAHVAC::setTargetTemperature(const HANumeric& temperature, const bool force
        return true;
    }

-    if (publishTargetTemperature(temperature)) {
-        _targetTemperature = temperature;
-        return true;
-    }
-
-    return false;
+    const bool published = publishTargetTemperature(temperature);
+    _targetTemperature = temperature;
+    return published;
 }

 void HAHVAC::buildSerializer()
@@ -191,10 +170,11 @@ void HAHVAC::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 29); // 29 - max properties nb
+    _serializer = new HASerializer(this, 40);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -369,7 +349,7 @@ HASerializer* HAHVAC::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 29);
+    HASerializer* serializer = new HASerializer(this, 40);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentClimate),
@@ -378,6 +358,7 @@ HASerializer* HAHVAC::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -78,12 +78,9 @@ bool HALight::setState(const bool state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 bool HALight::setBrightness(const uint8_t brightness, const bool force)
@@ -92,12 +89,13 @@ bool HALight::setBrightness(const uint8_t brightness, const bool force)
        return true;
    }

-    if (publishBrightness(brightness)) {
-        _currentBrightness = brightness;
-        return true;
+    if (!(_features & BrightnessFeature)) {
+        return false;
    }

-    return false;
+    const bool published = publishBrightness(brightness);
+    _currentBrightness = brightness;
+    return published;
 }

 bool HALight::setColorTemperature(const uint16_t temperature, const bool force)
@@ -106,12 +104,13 @@ bool HALight::setColorTemperature(const uint16_t temperature, const bool force)
        return true;
    }

-    if (publishColorTemperature(temperature)) {
-        _currentColorTemperature = temperature;
-        return true;
+    if (!(_features & ColorTemperatureFeature)) {
+        return false;
    }

-    return false;
+    const bool published = publishColorTemperature(temperature);
+    _currentColorTemperature = temperature;
+    return published;
 }

 bool HALight::setRGBColor(const RGBColor& color, const bool force)
@@ -120,12 +119,13 @@ bool HALight::setRGBColor(const RGBColor& color, const bool force)
        return true;
    }

-    if (publishRGBColor(color)) {
-        _currentRGBColor = color;
-        return true;
+    if (!(_features & RGBFeature) || !color.isSet) {
+        return false;
    }

-    return false;
+    const bool published = publishRGBColor(color);
+    _currentRGBColor = color;
+    return published;
 }

 void HALight::buildSerializer()
@@ -134,10 +134,11 @@ void HALight::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 20); // 20 - max properties nb
+    _serializer = new HASerializer(this, 30);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -208,7 +209,7 @@ HASerializer* HALight::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 20);
+    HASerializer* serializer = new HASerializer(this, 30);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentLight),
@@ -217,6 +218,7 @@ HASerializer* HALight::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -24,12 +24,13 @@ bool HALock::setState(const LockState state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
+    if (state == StateUnknown) {
+        return false;
    }

-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 void HALock::buildSerializer()
@@ -38,10 +39,11 @@ void HALock::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 11); // 11 - max properties nb
+    _serializer = new HASerializer(this, 20);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -73,7 +75,7 @@ HASerializer* HALock::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 11);
+    HASerializer* serializer = new HASerializer(this, 20);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentLock),
@@ -82,6 +84,7 @@ HASerializer* HALock::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -2,7 +2,9 @@
 #ifndef EX_ARDUINOHA_NUMBER

 #include "../HAMqtt.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"
+#include <string.h>

 HANumber::HANumber(const char* uniqueId, const NumberPrecision precision) :
    HABaseDeviceType(AHATOFSTR(HAComponentNumber), uniqueId),
@@ -17,23 +19,38 @@ HANumber::HANumber(const char* uniqueId, const NumberPrecision precision) :
    _maxValue(),
    _step(),
    _currentState(),
-    _commandCallback(nullptr)
+    _commandCallback(nullptr),
+    _commandTemplate(nullptr),
+    _valueTemplate(nullptr),
+    _payloadReset(nullptr)
 {

 }

+void HANumber::setValueTemplate(const char* valueTemplate)
+{
+    _valueTemplate = valueTemplate;
+}
+
+void HANumber::setCommandTemplate(const char* commandTemplate)
+{
+    _commandTemplate = commandTemplate;
+}
+
+void HANumber::setPayloadReset(const char* payloadReset)
+{
+    _payloadReset = payloadReset;
+}
+
 bool HANumber::setState(const HANumeric& state, const bool force)
 {
    if (!force && state == _currentState) {
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 void HANumber::updateMinMaxStep(const float min, const float max, const float step)
@@ -50,10 +67,11 @@ void HANumber::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 17); // 17 - max properties nb
+    _serializer = new HASerializer(this, 24);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
@@ -63,11 +81,27 @@ void HANumber::buildSerializer()
        getModeProperty(),
        HASerializer::ProgmemPropertyValue
    );
-    _serializer->set(
-        AHATOFSTR(HACommandTemplateProperty),
-        getCommandTemplate(),
-        HASerializer::ProgmemPropertyValue
-    );
+
+    if (nonEmptyString(_valueTemplate)) {
+        _serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_payloadReset)) {
+        _serializer->set(AHATOFSTR(HAPayloadResetProperty), _payloadReset);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        _serializer->set(
+            AHATOFSTR(HACommandTemplateProperty),
+            _commandTemplate
+        );
+    } else if (getBuiltInCommandTemplate()) {
+        _serializer->set(
+            AHATOFSTR(HACommandTemplateProperty),
+            getBuiltInCommandTemplate(),
+            HASerializer::ProgmemPropertyValue
+        );
+    }

    if (_minValue.isSet()) {
        _serializer->set(
@@ -121,7 +155,7 @@ HASerializer* HANumber::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 17);
+    HASerializer* serializer = new HASerializer(this, 24);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentNumber),
@@ -130,6 +164,7 @@ HASerializer* HANumber::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
@@ -139,11 +174,27 @@ HASerializer* HANumber::buildDeviceDiscoverySerializer()
        getModeProperty(),
        HASerializer::ProgmemPropertyValue
    );
-    serializer->set(
-        AHATOFSTR(HACommandTemplateProperty),
-        getCommandTemplate(),
-        HASerializer::ProgmemPropertyValue
-    );
+
+    if (nonEmptyString(_valueTemplate)) {
+        serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_payloadReset)) {
+        serializer->set(AHATOFSTR(HAPayloadResetProperty), _payloadReset);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        serializer->set(
+            AHATOFSTR(HACommandTemplateProperty),
+            _commandTemplate
+        );
+    } else if (getBuiltInCommandTemplate()) {
+        serializer->set(
+            AHATOFSTR(HACommandTemplateProperty),
+            getBuiltInCommandTemplate(),
+            HASerializer::ProgmemPropertyValue
+        );
+    }

    if (_minValue.isSet()) {
        serializer->set(
@@ -263,6 +314,23 @@ void HANumber::handleCommand(const uint8_t* cmd, const uint16_t length)
        return;
    }

+    if (
+        _payloadReset
+        && _payloadReset[0] != '\0'
+        && length == strlen(_payloadReset)
+        && memcmp(cmd, _payloadReset, length) == 0
+    ) {
+        if (_commandCallback) {
+            _commandCallback(HANumeric(), this);
+        }
+#if defined(ARDUINOHA_ENABLE_STDFUNCTION)
+        if (_commandStdCallback) {
+            _commandStdCallback(HANumeric(), this);
+        }
+#endif
+        return;
+    }
+
    if (memcmp_P(cmd, HAStateNone, length) == 0) {
        if (_commandCallback) {
            _commandCallback(HANumeric(), this);
@@ -302,7 +370,7 @@ const __FlashStringHelper* HANumber::getModeProperty() const
    }
 }

-const __FlashStringHelper* HANumber::getCommandTemplate()
+const __FlashStringHelper* HANumber::getBuiltInCommandTemplate() const
 {
    switch (_precision) {
    case PrecisionP1:
@@ -190,6 +190,10 @@ public:
     */
    void updateMinMaxStep(const float min, const float max, const float step);

+    void setValueTemplate(const char* valueTemplate);
+    void setCommandTemplate(const char* commandTemplate);
+    void setPayloadReset(const char* payloadReset);
+
    /**
     * Registers callback that will be called each time the number is changed in the HA panel.
     * Please note that it's not possible to register multiple callbacks for the same number.
@@ -254,9 +258,9 @@ private:
    const __FlashStringHelper* getModeProperty() const;

    /**
-     * Returns progmem string representing value template for the command.
+     * Built-in command template used for float precision (when no custom template is set).
     */
-    const __FlashStringHelper* getCommandTemplate();
+    const __FlashStringHelper* getBuiltInCommandTemplate() const;

    /// The precision of the number. By default it's `HANumber::PrecisionP0`.
    const NumberPrecision _precision;
@@ -294,6 +298,10 @@ private:
    /// The callback that will be called when the command is received from the HA.
    HANUMBER_CALLBACK(_commandCallback);

+    const char* _commandTemplate;
+    const char* _valueTemplate;
+    const char* _payloadReset;
+
 #if defined(ARDUINOHA_ENABLE_STDFUNCTION)
    /// The std::function callback that will be called when the command is received from the HA.
    std::function<void(HANumeric, HANumber*)> _commandStdCallback;
@@ -22,10 +22,11 @@ void HAScene::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 9); // 9 - max properties nb
+    _serializer = new HASerializer(this, 18);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -55,7 +56,7 @@ HASerializer* HAScene::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 9);
+    HASerializer* serializer = new HASerializer(this, 18);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentScene),
@@ -64,6 +65,7 @@ HASerializer* HAScene::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

@@ -2,6 +2,8 @@
 #ifndef EX_ARDUINOHA_SELECT

 #include "../HAMqtt.h"
+#include "../utils/HAUtils.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"

 HASelect::HASelect(const char* uniqueId) :
@@ -11,6 +13,8 @@ HASelect::HASelect(const char* uniqueId) :
    _icon(nullptr),
    _retain(false),
    _optimistic(false),
+    _valueTemplate(nullptr),
+    _commandTemplate(nullptr),
    _commandCallback(nullptr)
 #if defined(ARDUINOHA_ENABLE_STDFUNCTION)
    , _commandStdCallback()
@@ -35,13 +39,23 @@ HASelect::~HASelect()
    }
 }

+void HASelect::setValueTemplate(const char* valueTemplate)
+{
+    _valueTemplate = valueTemplate;
+}
+
+void HASelect::setCommandTemplate(const char* commandTemplate)
+{
+    _commandTemplate = commandTemplate;
+}
+
 void HASelect::setOptions(const char* options)
 {
    if (!options || _options) { // options can be set only once
        return;
    }

-    const uint16_t optionsNb = countOptionsInString(options);
+    const uint16_t optionsNb = HAUtils::countSemicolonSeparatedOptions(options);
    if (optionsNb == 0) {
        return;
    }
@@ -83,12 +97,13 @@ bool HASelect::setState(const int8_t state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
+    if (!_options || state >= _options->getItemsNb()) {
+        return false;
    }

-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 const char* HASelect::getCurrentOption() const
@@ -102,10 +117,11 @@ void HASelect::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 12); // 12 - max properties nb
+    _serializer = new HASerializer(this, 20);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
    _serializer->set(
@@ -114,6 +130,14 @@ void HASelect::buildSerializer()
        HASerializer::ArrayPropertyType
    );

+    if (nonEmptyString(_valueTemplate)) {
+        _serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        _serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    if (_retain) {
        _serializer->set(
            AHATOFSTR(HARetainProperty),
@@ -142,7 +166,7 @@ HASerializer* HASelect::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 12);
+    HASerializer* serializer = new HASerializer(this, 20);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentSelect),
@@ -151,6 +175,7 @@ HASerializer* HASelect::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
    serializer->set(
@@ -159,6 +184,14 @@ HASerializer* HASelect::buildDeviceDiscoverySerializer()
        HASerializer::ArrayPropertyType
    );

+    if (nonEmptyString(_valueTemplate)) {
+        serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    if (_retain) {
        serializer->set(
            AHATOFSTR(HARetainProperty),
@@ -256,25 +289,7 @@ bool HASelect::publishState(const int8_t state)

 uint8_t HASelect::countOptionsInString(const char* options) const
 {
-    // the given string is treated as a single option if there are no semicolons
-    uint8_t optionsNb = 1;
-    const uint16_t optionsLen = strlen(options);
-
-    if (optionsLen == 0) {
-        return 0;
-    }
-
-    for (uint16_t i = 0; i < optionsLen; i++) {
-        if (options[i] == ';') {
-            if (optionsNb == 255) {
-                break;
-            }
-
-            optionsNb++;
-        }
-    }
-
-    return optionsNb;
+    return HAUtils::countSemicolonSeparatedOptions(options);
 }

 #endif
@@ -105,6 +105,9 @@ public:
    inline void setOptimistic(const bool optimistic)
        { _optimistic = optimistic; }

+    void setValueTemplate(const char* valueTemplate);
+    void setCommandTemplate(const char* commandTemplate);
+
    /**
     * Registers callback that will be called each time the option is changed from the HA panel.
     * Please note that it's not possible to register multiple callbacks for the same select.
@@ -180,6 +183,9 @@ private:
    /// The optimistic mode of the select (`true` - enabled, `false` - disabled).
    bool _optimistic;

+    const char* _valueTemplate;
+    const char* _commandTemplate;
+
    /// The command callback that will be called when option is changed via the HA panel.
    HASELECT_CALLBACK(_commandCallback);

@@ -2,7 +2,11 @@
 #ifndef EX_ARDUINOHA_SENSOR

 #include "../HAMqtt.h"
+#include "../utils/HAUtils.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"
+#include "../utils/HASerializerArray.h"
+#include <string.h>

 HASensor::HASensor(const char* uniqueId, const uint16_t features) :
    HABaseDeviceType(AHATOFSTR(HAComponentSensor), uniqueId),
@@ -12,11 +16,99 @@ HASensor::HASensor(const char* uniqueId, const uint16_t features) :
    _forceUpdate(false),
    _icon(nullptr),
    _unitOfMeasurement(nullptr),
-    _expireAfter()
+    _expireAfter(),
+    _options(nullptr),
+    _suggestedDisplayPrecision(),
+    _valueTemplate(nullptr),
+    _jsonAttributesTemplate(nullptr),
+    _lastResetValueTemplate(nullptr)
 {

 }

+HASensor::~HASensor()
+{
+    if (_options) {
+        const uint8_t optionsNb = _options->getItemsNb();
+        const HASerializerArray::ItemType* options = _options->getItems();
+
+        if (optionsNb > 1) {
+            for (uint8_t i = 0; i < optionsNb; i++) {
+                delete options[i];
+            }
+        }
+
+        delete _options;
+    }
+}
+
+void HASensor::setSuggestedDisplayPrecision(uint8_t precision)
+{
+    _suggestedDisplayPrecision = HANumeric(static_cast<uint8_t>(precision), 0);
+}
+
+void HASensor::clearSuggestedDisplayPrecision()
+{
+    _suggestedDisplayPrecision.reset();
+}
+
+void HASensor::setOptions(const char* options)
+{
+    if (!options || _options) {
+        return;
+    }
+
+    const uint16_t optionsNb = HAUtils::countSemicolonSeparatedOptions(options);
+    if (optionsNb == 0) {
+        return;
+    }
+
+    const uint16_t optionsLen = strlen(options) + 1;
+    _options = new HASerializerArray(optionsNb, false);
+
+    if (optionsNb == 1) {
+        _options->add(options);
+        return;
+    }
+
+    uint16_t optionLen = 0;
+    for (uint16_t i = 0; i < optionsLen; i++) {
+        if (options[i] == ';' || options[i] == 0) {
+            if (optionLen == 0) {
+                break;
+            }
+
+            char* option = new char[optionLen + 1];
+            option[optionLen] = 0;
+            memcpy(option, &options[i - optionLen], optionLen);
+
+            if (!_options->add(option)) {
+                delete[] option;
+                break;
+            }
+            optionLen = 0;
+            continue;
+        }
+
+        optionLen++;
+    }
+}
+
+void HASensor::setValueTemplate(const char* valueTemplate)
+{
+    _valueTemplate = valueTemplate;
+}
+
+void HASensor::setJsonAttributesTemplate(const char* jsonAttributesTemplate)
+{
+    _jsonAttributesTemplate = jsonAttributesTemplate;
+}
+
+void HASensor::setLastResetValueTemplate(const char* lastResetValueTemplate)
+{
+    _lastResetValueTemplate = lastResetValueTemplate;
+}
+
 bool HASensor::setValue(const char* value)
 {
    if (!value) {
@@ -46,16 +138,44 @@ void HASensor::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 14); // 14 - max properties nb
+    _serializer = new HASerializer(this, 24);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HADeviceClassProperty), _deviceClass);
    _serializer->set(AHATOFSTR(HAStateClassProperty), _stateClass);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
    _serializer->set(AHATOFSTR(HAUnitOfMeasurementProperty), nonEmptyString(_unitOfMeasurement));

+    if (_suggestedDisplayPrecision.isSet()) {
+        _serializer->set(
+            AHATOFSTR(HASuggestedDisplayPrecisionProperty),
+            &_suggestedDisplayPrecision,
+            HASerializer::NumberPropertyType
+        );
+    }
+
+    if (nonEmptyString(_valueTemplate)) {
+        _serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_lastResetValueTemplate)) {
+        _serializer->set(
+            AHATOFSTR(HALastResetValueTemplateProperty),
+            _lastResetValueTemplate
+        );
+    }
+
+    if (_options) {
+        _serializer->set(
+            AHATOFSTR(HASensorOptionsProperty),
+            _options,
+            HASerializer::ArrayPropertyType
+        );
+    }
+
    if (_forceUpdate) {
        _serializer->set(
            AHATOFSTR(HAForceUpdateProperty),
@@ -74,6 +194,12 @@ void HASensor::buildSerializer()

    if (_features & JsonAttributesFeature) {
        _serializer->topic(AHATOFSTR(HAJsonAttributesTopic));
+        if (nonEmptyString(_jsonAttributesTemplate)) {
+            _serializer->set(
+                AHATOFSTR(HAJsonAttributesTemplateProperty),
+                _jsonAttributesTemplate
+            );
+        }
    }

    _serializer->set(HASerializer::WithDevice);
@@ -87,7 +213,7 @@ HASerializer* HASensor::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 14);
+    HASerializer* serializer = new HASerializer(this, 24);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentSensor),
@@ -96,12 +222,40 @@ HASerializer* HASensor::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HADeviceClassProperty), _deviceClass);
    serializer->set(AHATOFSTR(HAStateClassProperty), _stateClass);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
    serializer->set(AHATOFSTR(HAUnitOfMeasurementProperty), nonEmptyString(_unitOfMeasurement));

+    if (_suggestedDisplayPrecision.isSet()) {
+        serializer->set(
+            AHATOFSTR(HASuggestedDisplayPrecisionProperty),
+            &_suggestedDisplayPrecision,
+            HASerializer::NumberPropertyType
+        );
+    }
+
+    if (nonEmptyString(_valueTemplate)) {
+        serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_lastResetValueTemplate)) {
+        serializer->set(
+            AHATOFSTR(HALastResetValueTemplateProperty),
+            _lastResetValueTemplate
+        );
+    }
+
+    if (_options) {
+        serializer->set(
+            AHATOFSTR(HASensorOptionsProperty),
+            _options,
+            HASerializer::ArrayPropertyType
+        );
+    }
+
    if (_forceUpdate) {
        serializer->set(
            AHATOFSTR(HAForceUpdateProperty),
@@ -120,6 +274,12 @@ HASerializer* HASensor::buildDeviceDiscoverySerializer()

    if (_features & JsonAttributesFeature) {
        serializer->topic(AHATOFSTR(HAJsonAttributesTopic));
+        if (nonEmptyString(_jsonAttributesTemplate)) {
+            serializer->set(
+                AHATOFSTR(HAJsonAttributesTemplateProperty),
+                _jsonAttributesTemplate
+            );
+        }
    }

    serializer->set(HASerializer::WithAvailability);
@@ -4,6 +4,8 @@
 #include "HABaseDeviceType.h"
 #include "../utils/HANumeric.h"

+class HASerializerArray;
+
 #ifndef EX_ARDUINOHA_SENSOR

 /**
@@ -29,6 +31,8 @@ public:
     */
    HASensor(const char* uniqueId, const uint16_t features = DefaultFeatures);

+    virtual ~HASensor();
+
    /**
     * Publishes the MQTT message with the given value.
     * Unlike the other device types, the HASensor doesn't store the previous value that was set.
@@ -99,6 +103,18 @@ public:
    inline void setUnitOfMeasurement(const char* unitOfMeasurement)
        { _unitOfMeasurement = unitOfMeasurement; }

+    void setSuggestedDisplayPrecision(uint8_t precision);
+    void clearSuggestedDisplayPrecision();
+
+    /**
+     * Semicolon-separated options for device_class `enum`. Set only once.
+     */
+    void setOptions(const char* options);
+
+    void setValueTemplate(const char* valueTemplate);
+    void setJsonAttributesTemplate(const char* jsonAttributesTemplate);
+    void setLastResetValueTemplate(const char* lastResetValueTemplate);
+
 protected:
    virtual void buildSerializer() override final;
    virtual HASerializer* buildDeviceDiscoverySerializer() override;
@@ -127,6 +143,12 @@ private:

    /// It defines the number of seconds after the sensor’s state expires, if it’s not updated. By default the sensors state never expires.
    HANumeric _expireAfter;
+
+    HASerializerArray* _options;
+    HANumeric _suggestedDisplayPrecision;
+    const char* _valueTemplate;
+    const char* _jsonAttributesTemplate;
+    const char* _lastResetValueTemplate;
 };

 #endif
@@ -25,12 +25,9 @@ bool HASensorNumber::setValue(const HANumeric& value, const bool force)
        return true;
    }

-    if (publishValue(value)) {
-        _currentValue = value;
-        return true;
-    }
-
-    return false;
+    const bool published = publishValue(value);
+    _currentValue = value;
+    return published;
 }

 void HASensorNumber::onMqttConnected()
@@ -2,7 +2,25 @@
 #ifndef EX_ARDUINOHA_SWITCH

 #include "../HAMqtt.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"
+#include <string.h>
+
+static bool payloadEquals(
+    const uint8_t* data,
+    const uint16_t length,
+    const char* ram,
+    const __FlashStringHelper* flash
+)
+{
+    if (ram) {
+        const size_t n = strlen(ram);
+        return (length == n) && (memcmp(data, ram, length) == 0);
+    }
+
+    const size_t n = strlen_P(AHAFROMFSTR(flash));
+    return (length == n) && (memcmp_P(data, AHAFROMFSTR(flash), n) == 0);
+}

 HASwitch::HASwitch(const char* uniqueId) :
    HABaseDeviceType(AHATOFSTR(HAComponentSwitch), uniqueId),
@@ -11,23 +29,36 @@ HASwitch::HASwitch(const char* uniqueId) :
    _retain(false),
    _optimistic(false),
    _currentState(false),
+    _payloadOn(nullptr),
+    _payloadOff(nullptr),
+    _stateOn(nullptr),
+    _stateOff(nullptr),
+    _valueTemplate(nullptr),
+    _commandTemplate(nullptr),
    _commandCallback(nullptr)
 {

 }

+void HASwitch::setValueTemplate(const char* valueTemplate)
+{
+    _valueTemplate = valueTemplate;
+}
+
+void HASwitch::setCommandTemplate(const char* commandTemplate)
+{
+    _commandTemplate = commandTemplate;
+}
+
 bool HASwitch::setState(const bool state, const bool force)
 {
    if (!force && state == _currentState) {
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 void HASwitch::buildSerializer()
@@ -36,14 +67,39 @@ void HASwitch::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 12); // 12 - max properties nb
+    _serializer = new HASerializer(this, 24);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);

+    if (nonEmptyString(_payloadOn)) {
+        _serializer->set(AHATOFSTR(HAPayloadOnProperty), _payloadOn);
+    }
+
+    if (nonEmptyString(_payloadOff)) {
+        _serializer->set(AHATOFSTR(HAPayloadOffProperty), _payloadOff);
+    }
+
+    if (nonEmptyString(_stateOn)) {
+        _serializer->set(AHATOFSTR(HAStateOnDiscoveryProperty), _stateOn);
+    }
+
+    if (nonEmptyString(_stateOff)) {
+        _serializer->set(AHATOFSTR(HAStateOffDiscoveryProperty), _stateOff);
+    }
+
+    if (nonEmptyString(_valueTemplate)) {
+        _serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        _serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    // optional property
    if (_retain) {
        _serializer->set(
@@ -73,7 +129,7 @@ HASerializer* HASwitch::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 12);
+    HASerializer* serializer = new HASerializer(this, 24);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentSwitch),
@@ -82,10 +138,35 @@ HASerializer* HASwitch::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HADeviceClassProperty), _class);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);

+    if (nonEmptyString(_payloadOn)) {
+        serializer->set(AHATOFSTR(HAPayloadOnProperty), _payloadOn);
+    }
+
+    if (nonEmptyString(_payloadOff)) {
+        serializer->set(AHATOFSTR(HAPayloadOffProperty), _payloadOff);
+    }
+
+    if (nonEmptyString(_stateOn)) {
+        serializer->set(AHATOFSTR(HAStateOnDiscoveryProperty), _stateOn);
+    }
+
+    if (nonEmptyString(_stateOff)) {
+        serializer->set(AHATOFSTR(HAStateOffDiscoveryProperty), _stateOff);
+    }
+
+    if (nonEmptyString(_valueTemplate)) {
+        serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    if (_retain) {
        serializer->set(
            AHATOFSTR(HARetainProperty),
@@ -132,8 +213,6 @@ void HASwitch::onMqttMessage(
    const uint16_t length
 )
 {
-    (void)payload;
-
    const bool hasCommandCallback =
        _commandCallback
 #if defined(ARDUINOHA_ENABLE_STDFUNCTION)
@@ -146,7 +225,24 @@ void HASwitch::onMqttMessage(
        uniqueId(),
        AHATOFSTR(HACommandTopic)
    )) {
-        bool state = length == strlen_P(HAStateOn);
+        const bool isOn = payloadEquals(
+            payload,
+            length,
+            _payloadOn,
+            AHATOFSTR(HAStateOn)
+        );
+        const bool isOff = payloadEquals(
+            payload,
+            length,
+            _payloadOff,
+            AHATOFSTR(HAStateOff)
+        );
+
+        if (!isOn && !isOff) {
+            return;
+        }
+
+        const bool state = isOn;
        if (_commandCallback) {
            _commandCallback(state, this);
        }
@@ -160,9 +256,33 @@ void HASwitch::onMqttMessage(

 bool HASwitch::publishState(const bool state)
 {
+    if (state) {
+        if (nonEmptyString(_stateOn)) {
+            return publishOnDataTopic(
+                AHATOFSTR(HAStateTopic),
+                _stateOn,
+                true
+            );
+        }
+
+        return publishOnDataTopic(
+            AHATOFSTR(HAStateTopic),
+            AHATOFSTR(HAStateOn),
+            true
+        );
+    }
+
+    if (nonEmptyString(_stateOff)) {
+        return publishOnDataTopic(
+            AHATOFSTR(HAStateTopic),
+            _stateOff,
+            true
+        );
+    }
+
    return publishOnDataTopic(
        AHATOFSTR(HAStateTopic),
-        AHATOFSTR(state ? HAStateOn : HAStateOff),
+        AHATOFSTR(HAStateOff),
        true
    );
 }
@@ -103,6 +103,21 @@ public:
    inline void setOptimistic(const bool optimistic)
        { _optimistic = optimistic; }

+    inline void setPayloadOn(const char* payload)
+        { _payloadOn = payload; }
+
+    inline void setPayloadOff(const char* payload)
+        { _payloadOff = payload; }
+
+    inline void setStateOn(const char* state)
+        { _stateOn = state; }
+
+    inline void setStateOff(const char* state)
+        { _stateOff = state; }
+
+    void setValueTemplate(const char* valueTemplate);
+    void setCommandTemplate(const char* commandTemplate);
+
    /**
     * Registers callback that will be called each time the on/off command from HA is received.
     * Please note that it's not possible to register multiple callbacks for the same switch.
@@ -168,6 +183,13 @@ private:
    /// The current state of the switch. By default it's `false`.
    bool _currentState;

+    const char* _payloadOn;
+    const char* _payloadOff;
+    const char* _stateOn;
+    const char* _stateOff;
+    const char* _valueTemplate;
+    const char* _commandTemplate;
+
    /// The callback that will be called when switch command is received from the HA.
    HASWITCH_CALLBACK(_commandCallback);

@@ -2,6 +2,7 @@
 #ifndef EX_ARDUINOHA_TEXT

 #include "../HAMqtt.h"
+#include "../utils/HADictionary.h"
 #include "../utils/HASerializer.h"

 HAText::HAText(const char* uniqueId) :
@@ -13,6 +14,8 @@ HAText::HAText(const char* uniqueId) :
    _minValue(),
    _maxValue(),
    _pattern(nullptr),
+    _valueTemplate(nullptr),
+    _commandTemplate(nullptr),
    _currentState(nullptr),
    _commandCallback(nullptr)
 #if defined(ARDUINOHA_ENABLE_STDFUNCTION)
@@ -22,6 +25,16 @@ HAText::HAText(const char* uniqueId) :

 }

+void HAText::setValueTemplate(const char* valueTemplate)
+{
+    _valueTemplate = valueTemplate;
+}
+
+void HAText::setCommandTemplate(const char* commandTemplate)
+{
+    _commandTemplate = commandTemplate;
+}
+
 bool HAText::setState(const char* state, const bool force)
 {
    if (!state) {
@@ -36,12 +49,9 @@ bool HAText::setState(const char* state, const bool force)
        return true;
    }

-    if (publishState(state)) {
-        _currentState = state;
-        return true;
-    }
-
-    return false;
+    const bool published = publishState(state);
+    _currentState = state;
+    return published;
 }

 void HAText::buildSerializer()
@@ -50,10 +60,11 @@ void HAText::buildSerializer()
        return;
    }

-    _serializer = new HASerializer(this, 15); // 15 - max properties nb
+    _serializer = new HASerializer(this, 22);
    _serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(_serializer);
    _serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(_serializer);
    _serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    _serializer->set(AHATOFSTR(HAIconProperty), _icon);
    _serializer->set(
@@ -63,6 +74,14 @@ void HAText::buildSerializer()
    );
    _serializer->set(AHATOFSTR(HAPatternProperty), _pattern);

+    if (nonEmptyString(_valueTemplate)) {
+        _serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        _serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    if (_minValue.isSet()) {
        _serializer->set(
            AHATOFSTR(HAMinProperty),
@@ -107,7 +126,7 @@ HASerializer* HAText::buildDeviceDiscoverySerializer()
        return nullptr;
    }

-    HASerializer* serializer = new HASerializer(this, 15);
+    HASerializer* serializer = new HASerializer(this, 22);
    serializer->set(
        AHATOFSTR(HAPlatformProperty),
        AHATOFSTR(HAComponentText),
@@ -116,6 +135,7 @@ HASerializer* HAText::buildDeviceDiscoverySerializer()
    serializer->set(AHATOFSTR(HANameProperty), _name);
    setEntityIdProperty(serializer);
    serializer->set(HASerializer::WithUniqueId);
+    applyCommonEntityProperties(serializer);
    serializer->set(AHATOFSTR(HAStateEntityCategory), nonEmptyString(_entityCategory));
    serializer->set(AHATOFSTR(HAIconProperty), _icon);
    serializer->set(
@@ -125,6 +145,14 @@ HASerializer* HAText::buildDeviceDiscoverySerializer()
    );
    serializer->set(AHATOFSTR(HAPatternProperty), _pattern);

+    if (nonEmptyString(_valueTemplate)) {
+        serializer->set(AHATOFSTR(HAValueTemplateProperty), _valueTemplate);
+    }
+
+    if (nonEmptyString(_commandTemplate)) {
+        serializer->set(AHATOFSTR(HACommandTemplateProperty), _commandTemplate);
+    }
+
    if (_minValue.isSet()) {
        serializer->set(
            AHATOFSTR(HAMinProperty),
@@ -121,6 +121,9 @@ public:
    inline void setPattern(const char* pattern)
        { _pattern = pattern; }

+    void setValueTemplate(const char* valueTemplate);
+    void setCommandTemplate(const char* commandTemplate);
+
    /**
     * Registers callback that will be called each time text command from HA is received.
     * Please note that it's not possible to register multiple callbacks for the same text entity.
@@ -197,6 +200,9 @@ private:
    /// Regular expression pattern accepted by Home Assistant. It can be nullptr.
    const char* _pattern;

+    const char* _valueTemplate;
+    const char* _commandTemplate;
+
    /// The current state of the text. It can be nullptr if state wasn't set.
    const char* _currentState;

@@ -14,7 +14,8 @@ PubSubClientMock::PubSubClientMock() :
    _subscriptions(nullptr),
    _subscriptionsNb(0),
    _insideCallback(false),
-    _publishCallsFromCallbackNb(0),
+    _failNextBeginPublish(false),
+    _failNextEndPublish(false),
    callback(nullptr)
 {

@@ -121,8 +122,8 @@ bool PubSubClientMock::beginPublish(
        return false;
    }

-    if (_insideCallback) {
-        _publishCallsFromCallbackNb++;
+    if (_failNextBeginPublish) {
+        _failNextBeginPublish = false;
        return false;
    }

@@ -178,6 +179,11 @@ int PubSubClientMock::endPublish()
        return 0;
    }

+    if (_failNextEndPublish) {
+        _failNextEndPublish = false;
+        return 0;
+    }
+
    size_t messageSize = _pendingMessage->bufferSize;
    uint8_t index = _flushedMessagesNb;

@@ -169,11 +169,11 @@ public:
    inline bool isInsideCallback() const
        { return _insideCallback; }

-    inline uint16_t getPublishCallsFromCallbackNb() const
-        { return _publishCallsFromCallbackNb; }
+    inline void failNextBeginPublish()
+        { _failNextBeginPublish = true; }

-    inline void resetPublishCallsFromCallbackNb()
-        { _publishCallsFromCallbackNb = 0; }
+    inline void failNextEndPublish()
+        { _failNextEndPublish = true; }

    void clearFlushedMessages();
    void clearSubscriptions();
@@ -194,7 +194,8 @@ private:
    MqttConnection _connection;
    MqttWill _lastWill;
    bool _insideCallback;
-    uint16_t _publishCallsFromCallbackNb;
+    bool _failNextBeginPublish;
+    bool _failNextEndPublish;
    MQTT_CALLBACK_SIGNATURE;
 };

@@ -0,0 +1,194 @@
+#include <Arduino.h>
+#include <string.h>
+#include "HAAvailabilityConfig.h"
+#include "HADictionary.h"
+
+static uint16_t jsonEscapedStringSize(const char* s)
+{
+    if (!s) {
+        return 0;
+    }
+    return 2 * strlen_P(HASerializerJsonEscapeChar) + strlen(s);
+}
+
+static void appendEscapedString(char* buf, const char* s)
+{
+    strcat_P(buf, HASerializerJsonEscapeChar);
+    strcat(buf, s);
+    strcat_P(buf, HASerializerJsonEscapeChar);
+}
+
+HAAvailabilityConfig::HAAvailabilityConfig() :
+    _count(0)
+{
+    memset(_entries, 0, sizeof(_entries));
+}
+
+HAAvailabilityConfig::~HAAvailabilityConfig()
+{
+    clear();
+}
+
+char* HAAvailabilityConfig::duplicateString(const char* value) const
+{
+    if (!value || value[0] == '\0') {
+        return nullptr;
+    }
+
+    const size_t len = strlen(value);
+    char* copy = new char[len + 1];
+    memcpy(copy, value, len + 1);
+    return copy;
+}
+
+void HAAvailabilityConfig::clearEntry(Entry& entry)
+{
+    delete[] entry.topic;
+    delete[] entry.valueTemplate;
+    delete[] entry.payloadAvailable;
+    delete[] entry.payloadNotAvailable;
+    entry.topic = nullptr;
+    entry.valueTemplate = nullptr;
+    entry.payloadAvailable = nullptr;
+    entry.payloadNotAvailable = nullptr;
+}
+
+bool HAAvailabilityConfig::add(
+    const char* topic,
+    const char* valueTemplate,
+    const char* payloadAvailable,
+    const char* payloadNotAvailable
+)
+{
+    if (!topic || topic[0] == '\0' || _count >= MaxEntries) {
+        return false;
+    }
+
+    Entry entry = {};
+    entry.topic = duplicateString(topic);
+    if (!entry.topic) {
+        return false;
+    }
+
+    entry.valueTemplate = duplicateString(valueTemplate);
+    entry.payloadAvailable = duplicateString(payloadAvailable);
+    entry.payloadNotAvailable = duplicateString(payloadNotAvailable);
+
+    _entries[_count] = entry;
+    _count++;
+    return true;
+}
+
+void HAAvailabilityConfig::clear()
+{
+    for (uint8_t i = 0; i < _count; i++) {
+        clearEntry(_entries[i]);
+    }
+
+    _count = 0;
+}
+
+uint16_t HAAvailabilityConfig::calculateJsonSize() const
+{
+    uint16_t size =
+        strlen_P(HASerializerJsonArrayPrefix) +
+        strlen_P(HASerializerJsonArraySuffix);
+
+    if (_count == 0) {
+        return size;
+    }
+
+    size += (_count - 1) * strlen_P(HASerializerJsonPropertiesSeparator);
+
+    for (uint8_t i = 0; i < _count; i++) {
+        const Entry& e = _entries[i];
+        // {"t":"topic" ... }
+        size += strlen_P(HASerializerJsonDataPrefix);
+        size += strlen_P(HASerializerJsonDataSuffix);
+
+        // "t":"..."
+        size +=
+            strlen_P(HASerializerJsonPropertyPrefix) +
+            strlen_P(HATopic) +
+            strlen_P(HASerializerJsonPropertySuffix) +
+            jsonEscapedStringSize(e.topic);
+
+        if (e.valueTemplate && e.valueTemplate[0] != '\0') {
+            size += strlen_P(HASerializerJsonPropertiesSeparator);
+            size +=
+                strlen_P(HASerializerJsonPropertyPrefix) +
+                strlen_P(HAValueTemplateProperty) +
+                strlen_P(HASerializerJsonPropertySuffix) +
+                jsonEscapedStringSize(e.valueTemplate);
+        }
+        if (e.payloadAvailable && e.payloadAvailable[0] != '\0') {
+            size += strlen_P(HASerializerJsonPropertiesSeparator);
+            size +=
+                strlen_P(HASerializerJsonPropertyPrefix) +
+                strlen_P(HAPayloadAvailableProperty) +
+                strlen_P(HASerializerJsonPropertySuffix) +
+                jsonEscapedStringSize(e.payloadAvailable);
+        }
+        if (e.payloadNotAvailable && e.payloadNotAvailable[0] != '\0') {
+            size += strlen_P(HASerializerJsonPropertiesSeparator);
+            size +=
+                strlen_P(HASerializerJsonPropertyPrefix) +
+                strlen_P(HAPayloadNotAvailableProperty) +
+                strlen_P(HASerializerJsonPropertySuffix) +
+                jsonEscapedStringSize(e.payloadNotAvailable);
+        }
+    }
+
+    return size;
+}
+
+bool HAAvailabilityConfig::serialize(char* output) const
+{
+    if (!output) {
+        return false;
+    }
+
+    output[0] = 0;
+    strcat_P(output, HASerializerJsonArrayPrefix);
+
+    for (uint8_t i = 0; i < _count; i++) {
+        if (i > 0) {
+            strcat_P(output, HASerializerJsonPropertiesSeparator);
+        }
+
+        strcat_P(output, HASerializerJsonDataPrefix);
+
+        strcat_P(output, HASerializerJsonPropertyPrefix);
+        strcat_P(output, HATopic);
+        strcat_P(output, HASerializerJsonPropertySuffix);
+        appendEscapedString(output, _entries[i].topic);
+
+        const Entry& e = _entries[i];
+        if (e.valueTemplate && e.valueTemplate[0] != '\0') {
+            strcat_P(output, HASerializerJsonPropertiesSeparator);
+            strcat_P(output, HASerializerJsonPropertyPrefix);
+            strcat_P(output, HAValueTemplateProperty);
+            strcat_P(output, HASerializerJsonPropertySuffix);
+            appendEscapedString(output, e.valueTemplate);
+        }
+        if (e.payloadAvailable && e.payloadAvailable[0] != '\0') {
+            strcat_P(output, HASerializerJsonPropertiesSeparator);
+            strcat_P(output, HASerializerJsonPropertyPrefix);
+            strcat_P(output, HAPayloadAvailableProperty);
+            strcat_P(output, HASerializerJsonPropertySuffix);
+            appendEscapedString(output, e.payloadAvailable);
+        }
+        if (e.payloadNotAvailable && e.payloadNotAvailable[0] != '\0') {
+            strcat_P(output, HASerializerJsonPropertiesSeparator);
+            strcat_P(output, HASerializerJsonPropertyPrefix);
+            strcat_P(output, HAPayloadNotAvailableProperty);
+            strcat_P(output, HASerializerJsonPropertySuffix);
+            appendEscapedString(output, e.payloadNotAvailable);
+        }
+
+        strcat_P(output, HASerializerJsonDataSuffix);
+    }
+
+    strcat_P(output, HASerializerJsonArraySuffix);
+    return true;
+}
@@ -0,0 +1,62 @@
+#ifndef AHA_HAAVAILABILITYCONFIG_H
+#define AHA_HAAVAILABILITYCONFIG_H
+
+#include <stdint.h>
+
+/**
+ * Holds up to four MQTT availability entries for discovery JSON (`avty`).
+ * Topic strings must remain valid for the lifetime of the config (same pattern as other ArduinoHA setters).
+ */
+class HAAvailabilityConfig
+{
+public:
+    static const uint8_t MaxEntries = 4;
+
+    struct Entry {
+        const char* topic;
+        const char* valueTemplate;
+        const char* payloadAvailable;
+        const char* payloadNotAvailable;
+    };
+
+    HAAvailabilityConfig();
+    ~HAAvailabilityConfig();
+
+    /**
+     * Adds an availability entry. `topic` must be a full MQTT topic string.
+     * @return false when full or topic is null/empty.
+     */
+    bool add(
+        const char* topic,
+        const char* valueTemplate = nullptr,
+        const char* payloadAvailable = nullptr,
+        const char* payloadNotAvailable = nullptr
+    );
+
+    void clear();
+
+    inline uint8_t count() const
+        { return _count; }
+
+    inline const Entry& getEntry(const uint8_t index) const
+        { return _entries[index]; }
+
+    /**
+     * Size of the JSON array only, including `[` and `]`, excluding property name and separators.
+     */
+    uint16_t calculateJsonSize() const;
+
+    /**
+     * Writes the JSON array into `output` (must be at least calculateJsonSize()+1 bytes).
+     */
+    bool serialize(char* output) const;
+
+private:
+    void clearEntry(Entry& entry);
+    char* duplicateString(const char* value) const;
+
+    Entry _entries[MaxEntries];
+    uint8_t _count;
+};
+
+#endif
@@ -83,7 +83,32 @@ const char HASwingModesProperty[] PROGMEM = {"swing_modes"};
 const char HAModesProperty[] PROGMEM = {"modes"};
 const char HATemperatureCommandTemplateProperty[] PROGMEM = {"temp_cmd_tpl"};
 const char HAPayloadOnProperty[] PROGMEM = {"pl_on"};
+const char HAPayloadOffProperty[] PROGMEM = {"pl_off"};
+const char HAPayloadAvailableProperty[] PROGMEM = {"pl_avail"};
+const char HAPayloadNotAvailableProperty[] PROGMEM = {"pl_not_avail"};
+const char HAAvailabilityListProperty[] PROGMEM = {"avty"};
+const char HAAvailabilityModeProperty[] PROGMEM = {"avty_mode"};
 const char HAExpireAfterProperty[] PROGMEM = {"exp_aft"};
+const char HAOffDelayProperty[] PROGMEM = {"off_dly"};
+const char HAEnabledByDefaultProperty[] PROGMEM = {"en"};
+const char HAEntityPictureProperty[] PROGMEM = {"ent_pic"};
+const char HAQosProperty[] PROGMEM = {"qos"};
+const char HAStateOnDiscoveryProperty[] PROGMEM = {"stat_on"};
+const char HAStateOffDiscoveryProperty[] PROGMEM = {"stat_off"};
+const char HASuggestedDisplayPrecisionProperty[] PROGMEM = {"sug_dsp_prc"};
+const char HAJsonAttributesTemplateProperty[] PROGMEM = {"json_attr_tpl"};
+const char HASensorOptionsProperty[] PROGMEM = {"ops"};
+const char HALastResetValueTemplateProperty[] PROGMEM = {"lrst_val_tpl"};
+const char HAPayloadResetProperty[] PROGMEM = {"pl_rst"};
+const char HAPayloadPressProperty[] PROGMEM = {"pl_prs"};
+
+const char HADeviceModelIdProperty[] PROGMEM = {"mdl_id"};
+const char HADeviceHwVersionProperty[] PROGMEM = {"hw"};
+const char HADeviceSerialNumberProperty[] PROGMEM = {"sn"};
+const char HADeviceSuggestedAreaProperty[] PROGMEM = {"sa"};
+const char HADeviceViaDeviceProperty[] PROGMEM = {"via_device"};
+const char HADeviceConnectionsProperty[] PROGMEM = {"cns"};
+const char HAOriginSupportUrlProperty[] PROGMEM = {"url"};

 // topics
 const char HAConfigTopic[] PROGMEM = {"config"};
@@ -83,7 +83,33 @@ extern const char HASwingModesProperty[];
 extern const char HAModesProperty[];
 extern const char HATemperatureCommandTemplateProperty[];
 extern const char HAPayloadOnProperty[];
+extern const char HAPayloadOffProperty[];
+extern const char HAPayloadAvailableProperty[];
+extern const char HAPayloadNotAvailableProperty[];
+extern const char HAAvailabilityListProperty[];
+extern const char HAAvailabilityModeProperty[];
 extern const char HAExpireAfterProperty[];
+extern const char HAOffDelayProperty[];
+extern const char HAEnabledByDefaultProperty[];
+extern const char HAEntityPictureProperty[];
+extern const char HAQosProperty[];
+extern const char HAStateOnDiscoveryProperty[];
+extern const char HAStateOffDiscoveryProperty[];
+extern const char HASuggestedDisplayPrecisionProperty[];
+extern const char HAJsonAttributesTemplateProperty[];
+extern const char HASensorOptionsProperty[];
+extern const char HALastResetValueTemplateProperty[];
+extern const char HAPayloadResetProperty[];
+extern const char HAPayloadPressProperty[];
+
+// device (discovery `dev` object)
+extern const char HADeviceModelIdProperty[];
+extern const char HADeviceHwVersionProperty[];
+extern const char HADeviceSerialNumberProperty[];
+extern const char HADeviceSuggestedAreaProperty[];
+extern const char HADeviceViaDeviceProperty[];
+extern const char HADeviceConnectionsProperty[];
+extern const char HAOriginSupportUrlProperty[];

 // topics
 extern const char HAConfigTopic[];
@@ -11,6 +11,7 @@
 #include "../HAMqtt.h"
 #include "../utils/HAUtils.h"
 #include "../utils/HANumeric.h"
+#include "../utils/HAAvailabilityConfig.h"
 #include "../device-types/HABaseDeviceType.h"

 uint16_t HASerializer::calculateConfigTopicLength(
@@ -196,20 +197,9 @@ void HASerializer::set(const FlagType flag)
        entry->property = nullptr;
        entry->value = nullptr;
    } else if (flag == WithAvailability) {
-        HAMqtt* mqtt = HAMqtt::instance();
-        const bool isSharedAvailability = mqtt->getDevice()->isSharedAvailabilityEnabled();
-        const bool isAvailabilityConfigured = _deviceType->isAvailabilityConfigured();
-
-        if (!isSharedAvailability && !isAvailabilityConfigured) {
-            return; // not configured
+        if (_deviceType) {
+            _deviceType->configureAvailabilityEntries(this);
        }
-
-        SerializerEntry* entry = addEntry();
-        entry->type = TopicEntryType;
-        entry->property = AHATOFSTR(HAAvailabilityTopic);
-        entry->value = isSharedAvailability
-            ? mqtt->getDevice()->getAvailabilityTopic()
-            : nullptr;
    }
 }

@@ -290,6 +280,9 @@ uint16_t HASerializer::calculateEntrySize(const SerializerEntry* entry) const
    case TopicEntryType:
        return calculateTopicEntrySize(entry);

+    case AvailabilityArrayEntryType:
+        return calculateAvailabilityArrayEntrySize(entry);
+
    case FlagEntryType:
        return calculateFlagSize(
            static_cast<FlagType>(entry->subtype)
@@ -332,6 +325,25 @@ uint16_t HASerializer::calculateTopicEntrySize(
    return size;
 }

+uint16_t HASerializer::calculateAvailabilityArrayEntrySize(
+    const SerializerEntry* entry
+) const
+{
+    if (!entry->value) {
+        return 0;
+    }
+
+    const HAAvailabilityConfig* cfg = static_cast<const HAAvailabilityConfig*>(
+        entry->value
+    );
+
+    return
+        strlen_P(HASerializerJsonPropertyPrefix) +
+        strlen_P(AHAFROMFSTR(entry->property)) +
+        strlen_P(HASerializerJsonPropertySuffix) +
+        cfg->calculateJsonSize();
+}
+
 uint16_t HASerializer::calculateFlagSize(const FlagType flag) const
 {
    const HAMqtt* mqtt = HAMqtt::instance();
@@ -400,6 +412,11 @@ uint16_t HASerializer::calculatePropertyValueSize(
        return array->calculateSize();
    }

+    case JsonLiteralPropertyValue: {
+        const char* value = static_cast<const char*>(entry->value);
+        return value ? strlen(value) : 0;
+    }
+
    default:
        return 0;
    }
@@ -421,6 +438,9 @@ bool HASerializer::flushEntry(const SerializerEntry* entry) const
    case TopicEntryType:
        return flushTopic(entry);

+    case AvailabilityArrayEntryType:
+        return flushAvailabilityArray(entry);
+
    case FlagEntryType:
        return flushFlag(entry);

@@ -480,6 +500,16 @@ bool HASerializer::flushEntryValue(const SerializerEntry* entry) const
        return true;
    }

+    case JsonLiteralPropertyValue: {
+        const char* value = static_cast<const char*>(entry->value);
+        if (!value) {
+            return false;
+        }
+
+        mqtt->writePayload(value, strlen(value));
+        return true;
+    }
+
    default:
        return false;
    }
@@ -523,6 +553,35 @@ bool HASerializer::flushTopic(const SerializerEntry* entry) const
    return true;
 }

+bool HASerializer::flushAvailabilityArray(const SerializerEntry* entry) const
+{
+    HAMqtt* mqtt = HAMqtt::instance();
+    if (!entry->value) {
+        return false;
+    }
+
+    const HAAvailabilityConfig* cfg = static_cast<const HAAvailabilityConfig*>(
+        entry->value
+    );
+
+    mqtt->writePayload(AHATOFSTR(HASerializerJsonPropertyPrefix));
+    mqtt->writePayload(entry->property);
+    mqtt->writePayload(AHATOFSTR(HASerializerJsonPropertySuffix));
+
+    const uint16_t jsonSize = cfg->calculateJsonSize();
+    if (jsonSize >= 512) {
+        return false;
+    }
+
+    char buf[512];
+    if (!cfg->serialize(buf)) {
+        return false;
+    }
+
+    mqtt->writePayload(buf, jsonSize);
+    return true;
+}
+
 bool HASerializer::flushFlag(const SerializerEntry* entry) const
 {
    HAMqtt* mqtt = HAMqtt::instance();
@@ -23,7 +23,8 @@ public:
        UnknownEntryType = 0,
        PropertyEntryType,
        TopicEntryType,
-        FlagEntryType
+        FlagEntryType,
+        AvailabilityArrayEntryType
    };

    /// The type of a flag for a FlagEntryType.
@@ -40,7 +41,9 @@ public:
        ProgmemPropertyValue,
        BoolPropertyType,
        NumberPropertyType,
-        ArrayPropertyType
+        ArrayPropertyType,
+        /// Raw JSON fragment (no quoting); value is a null-terminated RAM string.
+        JsonLiteralPropertyValue
    };

    /// Representation of a single entry in the object.
@@ -198,6 +201,8 @@ public:
     */
    bool flush() const;

+    friend class HABaseDeviceType;
+
 private:
    /// Pointer to the device type that owns the serializer.
    HABaseDeviceType* _deviceType;
@@ -229,6 +234,10 @@ private:
     */
    uint16_t calculateTopicEntrySize(const SerializerEntry* entry) const;

+    uint16_t calculateAvailabilityArrayEntrySize(
+        const SerializerEntry* entry
+    ) const;
+
    /**
     * Calculates the size of the entry of type `FlagEntryType`.
     */
@@ -261,6 +270,8 @@ private:
     */
    bool flushTopic(const SerializerEntry* entry) const;

+    bool flushAvailabilityArray(const SerializerEntry* entry) const;
+
    /**
     * Flushes the entry of type `FlagEntryType` to the MQTT.
     */
@@ -3,6 +3,7 @@
 #endif

 #include <Arduino.h>
+#include <string.h>
 #include "HAUtils.h"
 #include "HADictionary.h"

@@ -46,3 +47,29 @@ char* HAUtils::byteArrayToStr(

    return dst;
 }
+
+uint8_t HAUtils::countSemicolonSeparatedOptions(const char* options)
+{
+    if (!options) {
+        return 0;
+    }
+
+    uint8_t optionsNb = 1;
+    const uint16_t optionsLen = strlen(options);
+
+    if (optionsLen == 0) {
+        return 0;
+    }
+
+    for (uint16_t i = 0; i < optionsLen; i++) {
+        if (options[i] == ';') {
+            if (optionsNb == 255) {
+                break;
+            }
+
+            optionsNb++;
+        }
+    }
+
+    return optionsNb;
+}
@@ -47,6 +47,12 @@ public:
        const byte* src,
        const uint16_t length
    );
+
+    /**
+     * Counts semicolon-separated segments (e.g. select/sensor options string).
+     * Empty string yields 0; a string without semicolons yields 1.
+     */
+    static uint8_t countSemicolonSeparatedOptions(const char* options);
 };

 #endif
@@ -19,6 +19,7 @@ static TestCase tests[] = {
    TEST_ENTRY(test_BinarySensorTest_publish_initial_state),
    TEST_ENTRY(test_BinarySensorTest_publish_state_debounce),
    TEST_ENTRY(test_BinarySensorTest_publish_state_debounce_skip),
+    TEST_ENTRY(test_BinarySensorTest_disconnected_state_updates_local_shadow),
    TEST_ENTRY(test_BinarySensorTest_publish_state_off),
    TEST_ENTRY(test_BinarySensorTest_publish_state_on),
    TEST_ENTRY(test_ButtonTest_availability),
@@ -57,6 +58,7 @@ static TestCase tests[] = {
    TEST_ENTRY(test_SensorNumberTest_publish_p3_zero_signed),
    TEST_ENTRY(test_SensorNumberTest_publish_p3_zero_unsigned),
    TEST_ENTRY(test_SensorNumberTest_publish_precision_mismatch),
+    TEST_ENTRY(test_SensorNumberTest_disconnected_value_updates_local_shadow),
    TEST_ENTRY(test_SensorNumberTest_publish_uint16),
    TEST_ENTRY(test_SensorNumberTest_publish_uint32),
    TEST_ENTRY(test_SensorNumberTest_publish_uint8),
@@ -85,7 +87,7 @@ static TestCase tests[] = {
    TEST_ENTRY(test_SwitchTest_command_off),
    TEST_ENTRY(test_SwitchTest_command_on),
    TEST_ENTRY(test_SwitchTest_command_subscription),
-    TEST_ENTRY(test_SwitchTest_callback_publish_attempt_is_rejected),
+    TEST_ENTRY(test_SwitchTest_callback_publish_is_deferred_until_after_dispatch),
    TEST_ENTRY(test_SwitchTest_current_state_setter),
    TEST_ENTRY(test_SwitchTest_default_entity_id_setter),
    TEST_ENTRY(test_SwitchTest_default_params),
@@ -121,7 +123,7 @@ static TestCase tests[] = {
    TEST_ENTRY(test_TextTest_publish_nothing_if_retained),
    TEST_ENTRY(test_TextTest_publish_state),
    TEST_ENTRY(test_TextTest_publish_state_debounce),
-    TEST_ENTRY(test_TextTest_callback_publish_attempt_is_rejected),
+    TEST_ENTRY(test_TextTest_callback_publish_is_deferred_until_after_dispatch),
    TEST_ENTRY(test_TextTest_retain_setter),
 };

@@ -29,6 +29,7 @@ extern void test_BinarySensorTest_object_id_setter(void);
 extern void test_BinarySensorTest_publish_initial_state(void);
 extern void test_BinarySensorTest_publish_state_debounce(void);
 extern void test_BinarySensorTest_publish_state_debounce_skip(void);
+extern void test_BinarySensorTest_disconnected_state_updates_local_shadow(void);
 extern void test_BinarySensorTest_publish_state_off(void);
 extern void test_BinarySensorTest_publish_state_on(void);
 extern void test_ButtonTest_availability(void);
@@ -67,6 +68,7 @@ extern void test_SensorNumberTest_publish_p3_smaller(void);
 extern void test_SensorNumberTest_publish_p3_zero_signed(void);
 extern void test_SensorNumberTest_publish_p3_zero_unsigned(void);
 extern void test_SensorNumberTest_publish_precision_mismatch(void);
+extern void test_SensorNumberTest_disconnected_value_updates_local_shadow(void);
 extern void test_SensorNumberTest_publish_uint16(void);
 extern void test_SensorNumberTest_publish_uint32(void);
 extern void test_SensorNumberTest_publish_uint8(void);
@@ -113,7 +115,7 @@ extern void test_SwitchTest_publish_nothing_if_retained(void);
 extern void test_SwitchTest_publish_state_off(void);
 extern void test_SwitchTest_publish_state_on(void);
 extern void test_SwitchTest_retain_setter(void);
-extern void test_SwitchTest_callback_publish_attempt_is_rejected(void);
+extern void test_SwitchTest_callback_publish_is_deferred_until_after_dispatch(void);
 extern void test_TextTest_availability(void);
 extern void test_TextTest_command_callback(void);
 extern void test_TextTest_command_subscription(void);
@@ -132,6 +134,6 @@ extern void test_TextTest_publish_nothing_if_retained(void);
 extern void test_TextTest_publish_state(void);
 extern void test_TextTest_publish_state_debounce(void);
 extern void test_TextTest_retain_setter(void);
-extern void test_TextTest_callback_publish_attempt_is_rejected(void);
+extern void test_TextTest_callback_publish_is_deferred_until_after_dispatch(void);

 #endif
@@ -281,3 +281,13 @@ void test_BinarySensorTest_publish_state_debounce_skip(void) {
    TEST_ASSERT_TRUE(result);
 }

+void test_BinarySensorTest_disconnected_state_updates_local_shadow(void) {
+    initMqttTest(testDeviceId)
+
+    HABinarySensor sensor(testUniqueId);
+
+    TEST_ASSERT_FALSE(sensor.setState(true));
+    TEST_ASSERT_TRUE(sensor.getCurrentState());
+    TEST_ASSERT_EQUAL(0, mock->getFlushedMessagesNb());
+}
+
@@ -676,3 +676,14 @@ void test_SensorNumberTest_publish_precision_mismatch(void) {
    TEST_ASSERT_EQUAL(mock->getFlushedMessagesNb(), 0);
 }

+void test_SensorNumberTest_disconnected_value_updates_local_shadow(void) {
+    initMqttTest(testDeviceId)
+
+    HASensorNumber sensor(testUniqueId, HASensorNumber::PrecisionP1);
+
+    TEST_ASSERT_FALSE(sensor.setValue(27.5f));
+    TEST_ASSERT_TRUE(sensor.getCurrentValue().isSet());
+    AHA_ASSERT_NEAR_FLOAT(27.5f, sensor.getCurrentValue().toFloat(), 0.1f);
+    TEST_ASSERT_EQUAL(0, mock->getFlushedMessagesNb());
+}
+
@@ -42,9 +42,9 @@ void onCommandReceived(bool state, HASwitch* caller)
    lastCommandCallbackCall.caller = caller;
 }

-void onCommandPublishAttempt(bool state, HASwitch* caller)
+void onCommandDeferredPublish(bool state, HASwitch* caller)
 {
-    TEST_ASSERT_FALSE(caller->setState(state));
+    TEST_ASSERT_TRUE(caller->setState(state));
 }

 void test_SwitchTest_invalid_unique_id(void) {
@@ -393,17 +393,19 @@ void test_SwitchTest_command_off(void) {
    assertCommandCallbackCalled(false, &testSwitch)
 }

-void test_SwitchTest_callback_publish_attempt_is_rejected(void) {
+void test_SwitchTest_callback_publish_is_deferred_until_after_dispatch(void) {
    prepareTest

    mock->connectDummy();
+    mqtt.resetDeferredPublishTestCounters();
    HASwitch testSwitch(testUniqueId);
-    testSwitch.onCommand(onCommandPublishAttempt);
+    testSwitch.onCommand(onCommandDeferredPublish);

    mock->fakeMessage(AHATOFSTR(CommandTopic), F("ON"));

-    TEST_ASSERT_EQUAL(1, mock->getPublishCallsFromCallbackNb());
-    TEST_ASSERT_EQUAL(0, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    AHA_ASSERT_MQTT_MESSAGE(mock, 0, AHATOFSTR(StateTopic), "ON", true);
 }

 void test_SwitchTest_different_switch_command(void) {
@@ -46,9 +46,9 @@ void onCommandReceived(const char* value, HAText* caller)
    lastCommandCallbackCall.caller = caller;
 }

-void onCommandPublishAttempt(const char* value, HAText* caller)
+void onCommandDeferredPublish(const char* value, HAText* caller)
 {
-    TEST_ASSERT_FALSE(caller->setState(value));
+    TEST_ASSERT_TRUE(caller->setState(value));
 }

 void test_TextTest_invalid_unique_id(void) {
@@ -328,17 +328,19 @@ void test_TextTest_command_callback(void) {
    assertCommandCallbackCalled("hello", &text)
 }

-void test_TextTest_callback_publish_attempt_is_rejected(void) {
+void test_TextTest_callback_publish_is_deferred_until_after_dispatch(void) {
    prepareTest

    mock->connectDummy();
+    mqtt.resetDeferredPublishTestCounters();
    HAText text(testUniqueId);
-    text.onCommand(onCommandPublishAttempt);
+    text.onCommand(onCommandDeferredPublish);

    mock->fakeMessage(AHATOFSTR(CommandTopic), F("hello"));

-    TEST_ASSERT_EQUAL(1, mock->getPublishCallsFromCallbackNb());
-    TEST_ASSERT_EQUAL(0, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    AHA_ASSERT_MQTT_MESSAGE(mock, 0, AHATOFSTR(StateTopic), "hello", true);
 }

 void test_TextTest_different_text_command(void) {
@@ -13,7 +13,7 @@ static TestCase tests[] = {
    TEST_ENTRY(test_NumberTest_command_number_unsigned),
    TEST_ENTRY(test_NumberTest_command_number_zero),
    TEST_ENTRY(test_NumberTest_command_subscription),
-    TEST_ENTRY(test_NumberTest_callback_publish_attempt_is_rejected),
+    TEST_ENTRY(test_NumberTest_callback_publish_is_deferred_until_after_dispatch),
    TEST_ENTRY(test_NumberTest_current_state_setter_getter_float),
    TEST_ENTRY(test_NumberTest_current_state_setter_getter_int16),
    TEST_ENTRY(test_NumberTest_current_state_setter_getter_int32),
@@ -227,7 +227,7 @@ static TestCase tests[] = {
    TEST_ENTRY(test_SelectTest_publish_state_only),
    TEST_ENTRY(test_SelectTest_retain_setter),
    TEST_ENTRY(test_SelectTest_single_option),
-    TEST_ENTRY(test_SelectTest_callback_publish_attempt_is_rejected),
+    TEST_ENTRY(test_SelectTest_callback_publish_is_deferred_until_after_dispatch),
 };

 static const size_t TEST_COUNT = sizeof(tests) / sizeof(tests[0]);
@@ -23,7 +23,7 @@ extern void test_NumberTest_command_number_signed(void);
 extern void test_NumberTest_command_number_unsigned(void);
 extern void test_NumberTest_command_number_zero(void);
 extern void test_NumberTest_command_subscription(void);
-extern void test_NumberTest_callback_publish_attempt_is_rejected(void);
+extern void test_NumberTest_callback_publish_is_deferred_until_after_dispatch(void);
 extern void test_NumberTest_current_state_setter_getter_float(void);
 extern void test_NumberTest_current_state_setter_getter_int16(void);
 extern void test_NumberTest_current_state_setter_getter_int32(void);
@@ -237,6 +237,6 @@ extern void test_SelectTest_publish_state_none(void);
 extern void test_SelectTest_publish_state_only(void);
 extern void test_SelectTest_retain_setter(void);
 extern void test_SelectTest_single_option(void);
-extern void test_SelectTest_callback_publish_attempt_is_rejected(void);
+extern void test_SelectTest_callback_publish_is_deferred_until_after_dispatch(void);

 #endif
@@ -42,9 +42,9 @@ void onCommandReceived(HANumeric number, HANumber* caller)
    lastCommandCallbackCall.caller = caller;
 }

-void onCommandPublishAttempt(HANumeric value, HANumber* caller)
+void onCommandDeferredPublish(HANumeric value, HANumber* caller)
 {
-    TEST_ASSERT_FALSE(caller->setState(value));
+    TEST_ASSERT_TRUE(caller->setState(value));
 }

 void test_NumberTest_invalid_unique_id(void) {
@@ -1015,17 +1015,19 @@ void test_NumberTest_command_number_float_p3(void) {
    assertCommandCallbackCalled(HANumeric(-1.234f, 3), &number)
 }

-void test_NumberTest_callback_publish_attempt_is_rejected(void) {
+void test_NumberTest_callback_publish_is_deferred_until_after_dispatch(void) {
    prepareTest

    mock->connectDummy();
+    mqtt.resetDeferredPublishTestCounters();
    HANumber number(testUniqueId);
-    number.onCommand(onCommandPublishAttempt);
+    number.onCommand(onCommandDeferredPublish);

    mock->fakeMessage(AHATOFSTR(CommandTopic), F("1234"));

-    TEST_ASSERT_EQUAL(1, mock->getPublishCallsFromCallbackNb());
-    TEST_ASSERT_EQUAL(0, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    AHA_ASSERT_MQTT_MESSAGE(mock, 0, AHATOFSTR(StateTopic), "1234", true);
 }

 void test_NumberTest_command_number_invalid(void) {
@@ -41,9 +41,9 @@ void onCommandReceived(int8_t index, HASelect* caller)
    lastCommandCallbackCall.caller = caller;
 }

-void onCommandPublishAttempt(int8_t index, HASelect* caller)
+void onCommandDeferredPublish(int8_t index, HASelect* caller)
 {
-    TEST_ASSERT_FALSE(caller->setState(index));
+    TEST_ASSERT_TRUE(caller->setState(index));
 }

 void test_SelectTest_invalid_unique_id(void) {
@@ -482,18 +482,20 @@ void test_SelectTest_command_option_non_existing(void) {
    assertCommandCallbackNotCalled()
 }

-void test_SelectTest_callback_publish_attempt_is_rejected(void) {
+void test_SelectTest_callback_publish_is_deferred_until_after_dispatch(void) {
    prepareTest

    mock->connectDummy();
+    mqtt.resetDeferredPublishTestCounters();
    HASelect select(testUniqueId);
    select.setOptions("Option A;B;C");
-    select.onCommand(onCommandPublishAttempt);
+    select.onCommand(onCommandDeferredPublish);

    mock->fakeMessage(AHATOFSTR(CommandTopic), F("B"));

-    TEST_ASSERT_EQUAL(1, mock->getPublishCallsFromCallbackNb());
-    TEST_ASSERT_EQUAL(0, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    AHA_ASSERT_MQTT_MESSAGE(mock, 0, AHATOFSTR(StateTopic), "B", true);
 }

 void test_SelectTest_different_select_command(void) {
@@ -7,7 +7,13 @@ static TestCase tests[] = {
    TEST_ENTRY(test_MqttTest_reconnect_interval_default_value),
    TEST_ENTRY(test_MqttTest_reconnect_interval_setter),
    TEST_ENTRY(test_MqttTest_reconnect_interval_throttles_attempts),
-    TEST_ENTRY(test_MqttTest_publish_attempt_from_message_callback_is_rejected),
+    TEST_ENTRY(test_MqttTest_publish_from_message_callback_is_deferred_and_flushed),
+    TEST_ENTRY(test_MqttTest_deferred_publish_order_is_preserved),
+    TEST_ENTRY(test_MqttTest_processing_message_flag_only_wraps_inbound_dispatch),
+    TEST_ENTRY(test_MqttTest_streaming_publish_from_message_callback_is_deferred_and_flushed),
+    TEST_ENTRY(test_MqttTest_deferred_publish_is_kept_across_disconnect_and_retried_from_loop),
+    TEST_ENTRY(test_MqttTest_failed_deferred_flush_keeps_queue_and_retries_in_order),
+    TEST_ENTRY(test_MqttTest_mixed_deferred_publish_order_is_preserved),

    TEST_ENTRY(test_DeviceTest_default_unique_id),
    TEST_ENTRY(test_DeviceTest_unique_id_constructor_char),
@@ -17,7 +17,13 @@ extern void test_MqttTest_maximum_number_of_device_types(void);
 extern void test_MqttTest_reconnect_interval_default_value(void);
 extern void test_MqttTest_reconnect_interval_setter(void);
 extern void test_MqttTest_reconnect_interval_throttles_attempts(void);
-extern void test_MqttTest_publish_attempt_from_message_callback_is_rejected(void);
+extern void test_MqttTest_publish_from_message_callback_is_deferred_and_flushed(void);
+extern void test_MqttTest_deferred_publish_order_is_preserved(void);
+extern void test_MqttTest_processing_message_flag_only_wraps_inbound_dispatch(void);
+extern void test_MqttTest_streaming_publish_from_message_callback_is_deferred_and_flushed(void);
+extern void test_MqttTest_deferred_publish_is_kept_across_disconnect_and_retried_from_loop(void);
+extern void test_MqttTest_failed_deferred_flush_keeps_queue_and_retries_in_order(void);
+extern void test_MqttTest_mixed_deferred_publish_order_is_preserved(void);

 extern void test_DeviceTest_default_unique_id(void);
 extern void test_DeviceTest_unique_id_constructor_char(void);
@@ -5,7 +5,9 @@
 static const char* testDeviceId = "testDevice";
 static const char* testUniqueId = "uniqueId";
 static HAMqtt* activeMqtt = nullptr;
+static PubSubClientMock* activeMock = nullptr;
 static bool messageCallbackCalled = false;
+static bool processingFlagSeenDuringCallback = false;

 const char ComponentNameStr[] PROGMEM = {"componentName"};

@@ -22,7 +24,7 @@ protected:
    }
 };

-void onMessagePublishAttempt(const char* topic, const uint8_t* payload, uint16_t length)
+void onMessageDeferredPublish(const char* topic, const uint8_t* payload, uint16_t length)
 {
    (void)topic;
    (void)payload;
@@ -30,7 +32,78 @@ void onMessagePublishAttempt(const char* topic, const uint8_t* payload, uint16_t

    messageCallbackCalled = true;
    TEST_ASSERT_NOT_NULL(activeMqtt);
-    TEST_ASSERT_FALSE(activeMqtt->publish("testData/testDevice/echo", "1", false));
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/echo", "1", false));
+}
+
+void onMessageQueueOrderedPublishes(const char* topic, const uint8_t* payload, uint16_t length)
+{
+    (void)topic;
+    (void)payload;
+    (void)length;
+
+    TEST_ASSERT_NOT_NULL(activeMqtt);
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/a", "1", false));
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/b", "2", false));
+}
+
+void onMessageInspectProcessingState(const char* topic, const uint8_t* payload, uint16_t length)
+{
+    (void)topic;
+    (void)payload;
+    (void)length;
+
+    TEST_ASSERT_NOT_NULL(activeMqtt);
+    processingFlagSeenDuringCallback = activeMqtt->isProcessingMessage();
+}
+
+void onMessageDeferredStreamingPublish(const char* topic, const uint8_t* payload, uint16_t length)
+{
+    (void)topic;
+    (void)payload;
+    (void)length;
+
+    TEST_ASSERT_NOT_NULL(activeMqtt);
+    TEST_ASSERT_TRUE(activeMqtt->beginPublish("testData/testDevice/stream", 2, false));
+    activeMqtt->writePayload("O", 1);
+    activeMqtt->writePayload("K", 1);
+    TEST_ASSERT_TRUE(activeMqtt->endPublish());
+}
+
+void onMessageDeferredPublishThenDisconnect(const char* topic, const uint8_t* payload, uint16_t length)
+{
+    (void)topic;
+    (void)payload;
+    (void)length;
+
+    TEST_ASSERT_NOT_NULL(activeMqtt);
+    TEST_ASSERT_NOT_NULL(activeMock);
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/retry", "1", false));
+    activeMock->disconnect();
+}
+
+void onMessageDeferredPublishesForFailedFlush(const char* topic, const uint8_t* payload, uint16_t length)
+{
+    (void)topic;
+    (void)payload;
+    (void)length;
+
+    TEST_ASSERT_NOT_NULL(activeMqtt);
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/a", "1", false));
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/b", "2", false));
+}
+
+void onMessageMixedDeferredPublishesPreserveOrder(const char* topic, const uint8_t* payload, uint16_t length)
+{
+    (void)topic;
+    (void)payload;
+    (void)length;
+
+    TEST_ASSERT_NOT_NULL(activeMqtt);
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/a", "1", false));
+    TEST_ASSERT_TRUE(activeMqtt->beginPublish("testData/testDevice/b", 1, false));
+    activeMqtt->writePayload("2", 1);
+    TEST_ASSERT_TRUE(activeMqtt->endPublish());
+    TEST_ASSERT_TRUE(activeMqtt->publish("testData/testDevice/c", "3", false));
 }

 void test_MqttTest_maximum_number_of_device_types(void)
@@ -84,7 +157,7 @@ void test_MqttTest_reconnect_interval_throttles_attempts(void)
    TEST_ASSERT_EQUAL_UINT16(2, mock->getConnectCallsNb());
 }

-void test_MqttTest_publish_attempt_from_message_callback_is_rejected(void)
+void test_MqttTest_publish_from_message_callback_is_deferred_and_flushed(void)
 {
    PubSubClientMock* mock = new PubSubClientMock();
    HADevice device(testDeviceId);
@@ -95,14 +168,186 @@ void test_MqttTest_publish_attempt_from_message_callback_is_rejected(void)

    activeMqtt = &mqtt;
    messageCallbackCalled = false;
-    mock->resetPublishCallsFromCallbackNb();
-    mqtt.onMessage(onMessagePublishAttempt);
+    mqtt.resetDeferredPublishTestCounters();
+    mqtt.onMessage(onMessageDeferredPublish);

    mock->fakeMessage("testData/testDevice/input", "1");

    TEST_ASSERT_TRUE(messageCallbackCalled);
-    TEST_ASSERT_EQUAL_UINT16(1, mock->getPublishCallsFromCallbackNb());
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/echo", mock->getFlushedMessages()[0]->topic);
+    TEST_ASSERT_EQUAL_STRING("1", mock->getFlushedMessages()[0]->buffer);
+
+    activeMqtt = nullptr;
+}
+
+void test_MqttTest_deferred_publish_order_is_preserved(void)
+{
+    PubSubClientMock* mock = new PubSubClientMock();
+    HADevice device(testDeviceId);
+    HAMqtt mqtt(mock, device);
+    mqtt.setDataPrefix("testData");
+    mqtt.begin("testHost", "testUser", "testPass");
+    mock->connectDummy();
+
+    activeMqtt = &mqtt;
+    mqtt.resetDeferredPublishTestCounters();
+    mqtt.onMessage(onMessageQueueOrderedPublishes);
+
+    mock->fakeMessage("testData/testDevice/input", "x");
+
+    TEST_ASSERT_EQUAL_UINT16(2, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(2, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/a", mock->getFlushedMessages()[0]->topic);
+    TEST_ASSERT_EQUAL_STRING("1", mock->getFlushedMessages()[0]->buffer);
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/b", mock->getFlushedMessages()[1]->topic);
+    TEST_ASSERT_EQUAL_STRING("2", mock->getFlushedMessages()[1]->buffer);
+
+    activeMqtt = nullptr;
+}
+
+void test_MqttTest_processing_message_flag_only_wraps_inbound_dispatch(void)
+{
+    PubSubClientMock* mock = new PubSubClientMock();
+    HADevice device(testDeviceId);
+    HAMqtt mqtt(mock, device);
+    mqtt.setDataPrefix("testData");
+    mqtt.begin("testHost", "testUser", "testPass");
+    mock->connectDummy();
+
+    activeMqtt = &mqtt;
+    processingFlagSeenDuringCallback = false;
+    TEST_ASSERT_FALSE(mqtt.isProcessingMessage());
+    mqtt.onMessage(onMessageInspectProcessingState);
+
+    mock->fakeMessage("testData/testDevice/input", "1");
+
+    TEST_ASSERT_TRUE(processingFlagSeenDuringCallback);
+    TEST_ASSERT_FALSE(mqtt.isProcessingMessage());
+
+    activeMqtt = nullptr;
+}
+
+void test_MqttTest_streaming_publish_from_message_callback_is_deferred_and_flushed(void)
+{
+    PubSubClientMock* mock = new PubSubClientMock();
+    HADevice device(testDeviceId);
+    HAMqtt mqtt(mock, device);
+    mqtt.setDataPrefix("testData");
+    mqtt.begin("testHost", "testUser", "testPass");
+    mock->connectDummy();
+
+    activeMqtt = &mqtt;
+    mqtt.resetDeferredPublishTestCounters();
+    mqtt.onMessage(onMessageDeferredStreamingPublish);
+
+    mock->fakeMessage("testData/testDevice/input", "1");
+
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(0, mqtt.getPendingDeferredPublishesForTest());
+    TEST_ASSERT_FALSE(mqtt.hasDeferredFlushFailureForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/stream", mock->getFlushedMessages()[0]->topic);
+    TEST_ASSERT_EQUAL_STRING("OK", mock->getFlushedMessages()[0]->buffer);
+
+    activeMqtt = nullptr;
+}
+
+void test_MqttTest_deferred_publish_is_kept_across_disconnect_and_retried_from_loop(void)
+{
+    PubSubClientMock* mock = new PubSubClientMock();
+    HADevice device(testDeviceId);
+    HAMqtt mqtt(mock, device);
+    mqtt.setDataPrefix("testData");
+    mqtt.begin("testHost", "testUser", "testPass");
+    mock->connectDummy();
+
+    activeMqtt = &mqtt;
+    activeMock = mock;
+    mqtt.resetDeferredPublishTestCounters();
+    mqtt.onMessage(onMessageDeferredPublishThenDisconnect);
+
+    mock->fakeMessage("testData/testDevice/input", "1");
+
+    TEST_ASSERT_EQUAL_UINT16(1, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mqtt.getPendingDeferredPublishesForTest());
+    TEST_ASSERT_TRUE(mqtt.hasDeferredFlushFailureForTest());
+    TEST_ASSERT_TRUE(mqtt.didDeferredFlushFailDueToDisconnectForTest());
    TEST_ASSERT_EQUAL_UINT8(0, mock->getFlushedMessagesNb());
+
+    mock->connectDummy();
+    mqtt.loop();
+
+    TEST_ASSERT_EQUAL_UINT8(0, mqtt.getPendingDeferredPublishesForTest());
+    TEST_ASSERT_FALSE(mqtt.hasDeferredFlushFailureForTest());
+    TEST_ASSERT_EQUAL_UINT8(1, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/retry", mock->getFlushedMessages()[0]->topic);
+    TEST_ASSERT_EQUAL_STRING("1", mock->getFlushedMessages()[0]->buffer);
+
+    activeMock = nullptr;
+    activeMqtt = nullptr;
+}
+
+void test_MqttTest_failed_deferred_flush_keeps_queue_and_retries_in_order(void)
+{
+    PubSubClientMock* mock = new PubSubClientMock();
+    HADevice device(testDeviceId);
+    HAMqtt mqtt(mock, device);
+    mqtt.setDataPrefix("testData");
+    mqtt.begin("testHost", "testUser", "testPass");
+    mock->connectDummy();
+
+    activeMqtt = &mqtt;
+    mqtt.resetDeferredPublishTestCounters();
+    mqtt.onMessage(onMessageDeferredPublishesForFailedFlush);
+    mock->failNextEndPublish();
+
+    mock->fakeMessage("testData/testDevice/input", "1");
+
+    TEST_ASSERT_EQUAL_UINT16(2, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(2, mqtt.getPendingDeferredPublishesForTest());
+    TEST_ASSERT_TRUE(mqtt.hasDeferredFlushFailureForTest());
+    TEST_ASSERT_TRUE(mqtt.didDeferredFlushFailAtEndPublishForTest());
+    TEST_ASSERT_EQUAL_UINT8(0, mock->getFlushedMessagesNb());
+
+    mqtt.loop();
+
+    TEST_ASSERT_EQUAL_UINT8(0, mqtt.getPendingDeferredPublishesForTest());
+    TEST_ASSERT_FALSE(mqtt.hasDeferredFlushFailureForTest());
+    TEST_ASSERT_EQUAL_UINT8(2, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/a", mock->getFlushedMessages()[0]->topic);
+    TEST_ASSERT_EQUAL_STRING("1", mock->getFlushedMessages()[0]->buffer);
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/b", mock->getFlushedMessages()[1]->topic);
+    TEST_ASSERT_EQUAL_STRING("2", mock->getFlushedMessages()[1]->buffer);
+
+    activeMqtt = nullptr;
+}
+
+void test_MqttTest_mixed_deferred_publish_order_is_preserved(void)
+{
+    PubSubClientMock* mock = new PubSubClientMock();
+    HADevice device(testDeviceId);
+    HAMqtt mqtt(mock, device);
+    mqtt.setDataPrefix("testData");
+    mqtt.begin("testHost", "testUser", "testPass");
+    mock->connectDummy();
+
+    activeMqtt = &mqtt;
+    mqtt.resetDeferredPublishTestCounters();
+    mqtt.onMessage(onMessageMixedDeferredPublishesPreserveOrder);
+
+    mock->fakeMessage("testData/testDevice/input", "1");
+
+    TEST_ASSERT_EQUAL_UINT16(3, mqtt.getDeferredPublishEnqueueCountForTest());
+    TEST_ASSERT_EQUAL_UINT8(0, mqtt.getPendingDeferredPublishesForTest());
+    TEST_ASSERT_EQUAL_UINT8(3, mock->getFlushedMessagesNb());
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/a", mock->getFlushedMessages()[0]->topic);
+    TEST_ASSERT_EQUAL_STRING("1", mock->getFlushedMessages()[0]->buffer);
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/b", mock->getFlushedMessages()[1]->topic);
+    TEST_ASSERT_EQUAL_STRING("2", mock->getFlushedMessages()[1]->buffer);
+    TEST_ASSERT_EQUAL_STRING("testData/testDevice/c", mock->getFlushedMessages()[2]->topic);
+    TEST_ASSERT_EQUAL_STRING("3", mock->getFlushedMessages()[2]->buffer);

    activeMqtt = nullptr;
 }