Replace 14 TemplatableValue fields with a per-field union that stores
either a constant value or a callable pointer in the same 4 bytes
(on 32-bit targets). A 2-bit-per-field type tag in a uint32_t tracks
field state (unset/constant/stateless lambda/stateful lambda).
Reduces LightControlAction from 128 to 76 bytes per instance on ESP32.
For a config with 8 light actions, this saves 416 bytes of RAM and
476 bytes of flash (from eliminated TemplatableValue template
instantiations).
Regression tests for #15040 using a single compiled binary with two
cwww lights to verify:
- constant_brightness: true maintains constant total CW+WW power
output across all color temperatures with gamma correction
- constant_brightness: false correctly varies total power (higher
at mid-range where both channels contribute)
TextSaver::save() returned false for both unchanged values and
values that are too long, causing a misleading warning on every
duplicate save. Return true early when the value hasn't changed.
Add integration test for template text save/restore persistence.
The scheduler was already managing SchedulerItem lifecycle explicitly
through its object pool (recycle_item_main_loop_ / get_item_from_pool_locked_).
The unique_ptr wrapper added overhead (11 destructor call sites on the hot path)
without providing safety — if a lifecycle path was missed, the unique_ptr would
silently delete the item and cause needless heap allocations instead of pool reuse.
Replace unique_ptr<SchedulerItem, SchedulerItemDeleter> with raw SchedulerItem*
throughout. Every item is now explicitly recycled to the pool or deleted via
delete_item_(). This eliminates all 11 unique_ptr destructor calls from the hot
path and saves ~256 bytes of firmware.
Add debug leak detection under ESPHOME_DEBUG_SCHEDULER: a live-item counter
verified at the end of every call() cycle asserts that all allocated items are
accounted for in items_, to_add_, defer_queue_, or the pool. This turns silent
heap churn from missed lifecycle management into an immediate assert failure
caught by integration tests.
Also moves the retry-cancelled check before item allocation in set_timer_common_
to avoid needless alloc+delete on the cold retry path, and fixes a thread-safety
issue where recycle_item_main_loop_ (main-loop-only) was called from
set_timer_common_ which can run on non-main-loop threads.
Enable debug_scheduler: true in all 18 scheduler integration test fixtures.
Add inject_to_rx_buffer_delayed() to uart_mock which stages bytes
that aren't visible to available() until the delay elapses. This
simulates USB packet delivery latency.
The test uses a 40ms delay which is:
- Greater than the old ~2ms timeout (fails without fix)
- Less than the new 50ms fallback timeout (passes with fix)
- Add test fixture simulating USB UART (no rx_full_threshold set)
with a 20ms gap between response chunks
- Make rx_full_threshold optional in uart_mock
- Extract MODBUS_BITS_PER_CHAR and MS_PER_SEC constexprs
J. Nick Koston