CallbackManager and LazyCallbackManager now use a lightweight 8-byte Callback struct instead of std::function (16 bytes). External components that define their own callback registration methods using std::function should update to templates for optimal performance.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
Custom mode vectors (custom_fan_modes, custom_presets for climate; preset_modes for fan) are now stored on the entity base class instead of being rebuilt inside traits on every call. The old ClimateTraits and FanTraits setter methods are deprecated.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
The FlushResult enum introduced in ESPHome 2026.3.0 has been renamed to UARTFlushResult with prefixed enum values to follow ESPHome’s naming conventions and avoid macro collisions.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
Shared helper functions and types have been moved from modbus_controller to modbus::helpers to enable reuse by other modbus-based components. Deprecated shims keep the old names working until ESPHome 2026.10.0.
This is a developer breaking change for external components in ESPHome 2026.4.0 and later.
Direct access to the sensor .raw_state member is now deprecated. Use get_raw_state() instead. The .raw_state member will be removed in ESPHome 2026.10.0.
This is a breaking change for external components in ESPHome 2026.4.0 and later.
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