The GPIOPin::dump_summary() virtual method now writes to a caller-provided buffer instead of returning std::string. This eliminates heap allocations during configuration dumps.
This is a breaking change for external components that implement custom GPIO pins in ESPHome 2026.1.0 and later.
The OTA component now uses a listener interface instead of std::function callbacks. The alarm control panel component has removed per-state callback methods in favor of a unified state callback.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
The Socket class virtual methods getpeername() and getsockname() that returned std::string have been removed. The ClientInfo struct no longer contains std::string fields.
This is a breaking change for external components in ESPHome 2026.1.0 and later.
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.
Several entity component getters now return StringRef instead of const char* or std::string. This improves safety by eliminating null pointer crashes and provides a modern C++ API.
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.
ESPHome 2025.11.0 introduces memory optimizations to the Event entity class that reduce heap usage and store event type strings in flash. These changes affect external components implementing custom event devices.