DFTE/docs/CONFIGURATION.md

Configuration and memory limits

DFTE has a stable public object layout. TemplateContext owns its rendering stack and read buffer at runtime, so choosing capacities cannot make a consumer and the compiled library disagree about object size.

// Keep each context alive for the full response that uses it.
TemplateContext standard;            // Default: 16 stack frames, 512-byte buffer.
TemplateContext pageContext(6, 128); // Known shallow response, smaller allocation.

void setup() {
    if (!standard.isReady() || !pageContext.isReady()) {
        // Allocation failed; do not start a response with either context.
    }
}

The context allocates its stack and read buffer when it is constructed. Its approximate heap use is maxDepth * sizeof(RenderingContext) + bufferSize, plus allocator overhead; its fixed 24-byte placeholder-token storage is part of the stable context object. Allocate one context per concurrently streaming request; use explicit small capacities for bounded pages rather than changing global definitions. Nested template expansion normally consumes two stack frames per level.

Setting	Default	Meaning
DFTE_MAX_STACK_DEPTH	16	Default depth passed by the no-argument TemplateContext constructor
DFTE_BUFFER_SIZE	512	Default read-buffer size passed by the no-argument constructor
DFTE_MAX_ITERATIONS	50	Safety cap for one renderer call
DFTE_PROGMEM_CHUNK_SIZE	512	Source-copy window for flash data
DFTE_RAM_CHUNK_SIZE	128	Source-copy window for RAM data
DFTE_MAX_PLACEHOLDERS_DEFAULT	16	Default PlaceholderRegistry capacity

The first two are constructor defaults, not layout controls: a consuming translation unit can choose them without an ABI mismatch. The source-copy and iteration settings change renderer behaviour, so set them consistently for a whole PlatformIO build. DFTE_PLACEHOLDER_NAME_SIZE is no longer a supported setting; placeholder tokens have a fixed ABI-stable capacity of 23 characters plus the terminator.

DFTE_MAX_PLACEHOLDERS_DEFAULT is only a constructor default; pass an explicit registry capacity where a device needs more.

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