Several string formatting helpers that returned std::string are now soft-deprecated in favor of stack-based alternatives. This prevents heap fragmentation on long-running ESP devices.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The USE_ESP_IDF C++ define and related Python APIs are deprecated. Since Arduino-ESP32 is built on ESP-IDF, all IDF APIs are available on ESP32 regardless of framework selection.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The light component’s callback system has been refactored to use a listener interface pattern with lazy allocation. This replaces the previous CallbackManager<void()> approach with explicit listener interfaces that only allocate memory when callbacks are actually registered.
This is a breaking change for external components that register light state callbacks in ESPHome 2025.12.0 and later.
The network::get_use_address() function has been optimized to return const char* instead of const std::string& to reduce memory overhead. This eliminates unnecessary string object storage when accessing the device’s network address.
This is a breaking change for external components that call network::get_use_address() in ESPHome 2025.11.0 and later.
ESPHome 2025.11.0 introduces significant memory optimizations to the Climate entity class that affect external components implementing custom climate devices.
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