[light] Use bitmask instead of std::set for color modes

esphome/components/api/api.proto

@@ -506,7 +506,7 @@ message ListEntitiesLightResponse {
   string name = 3;
   reserved 4; // Deprecated: was string unique_id
 
-  repeated ColorMode supported_color_modes = 12 [(container_pointer) = "std::set<light::ColorMode>"];
+  repeated ColorMode supported_color_modes = 12 [(fixed_vector) = true];
   // next four supports_* are for legacy clients, newer clients should use color modes
   // Deprecated in API version 1.6
   bool legacy_supports_brightness = 5 [deprecated=true];

esphome/components/api/api_connection.cpp

@@ -477,7 +477,11 @@ uint16_t APIConnection::try_send_light_info(EntityBase *entity, APIConnection *c
   auto *light = static_cast<light::LightState *>(entity);
   ListEntitiesLightResponse msg;
   auto traits = light->get_traits();
-  msg.supported_color_modes = &traits.get_supported_color_modes_for_api_();
+  const auto &color_modes_mask = traits.get_supported_color_modes();
+  msg.supported_color_modes.init(color_modes_mask.size());
+  for (auto mode : color_modes_mask) {
+    msg.supported_color_modes.push_back(static_cast<enums::ColorMode>(mode));
+  }
   if (traits.supports_color_capability(light::ColorCapability::COLOR_TEMPERATURE) ||
       traits.supports_color_capability(light::ColorCapability::COLD_WARM_WHITE)) {
     msg.min_mireds = traits.get_min_mireds();

esphome/components/api/api_pb2.cpp

@@ -471,7 +471,7 @@ void ListEntitiesLightResponse::encode(ProtoWriteBuffer buffer) const {
   buffer.encode_string(1, this->object_id_ref_);
   buffer.encode_fixed32(2, this->key);
   buffer.encode_string(3, this->name_ref_);
-  for (const auto &it : *this->supported_color_modes) {
+  for (auto &it : this->supported_color_modes) {
     buffer.encode_uint32(12, static_cast<uint32_t>(it), true);
   }
   buffer.encode_float(9, this->min_mireds);
@@ -492,8 +492,8 @@ void ListEntitiesLightResponse::calculate_size(ProtoSize &size) const {
   size.add_length(1, this->object_id_ref_.size());
   size.add_fixed32(1, this->key);
   size.add_length(1, this->name_ref_.size());
-  if (!this->supported_color_modes->empty()) {
-    for (const auto &it : *this->supported_color_modes) {
+  if (!this->supported_color_modes.empty()) {
+    for (const auto &it : this->supported_color_modes) {
       size.add_uint32_force(1, static_cast<uint32_t>(it));
     }
   }

esphome/components/api/api_pb2.h

@@ -790,7 +790,7 @@ class ListEntitiesLightResponse final : public InfoResponseProtoMessage {
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "list_entities_light_response"; }
 #endif
-  const std::set<light::ColorMode> *supported_color_modes{};
+  FixedVector<enums::ColorMode> supported_color_modes{};
   float min_mireds{0.0f};
   float max_mireds{0.0f};
   std::vector<std::string> effects{};

esphome/components/api/api_pb2_dump.cpp

@@ -913,7 +913,7 @@ void ListEntitiesLightResponse::dump_to(std::string &out) const {
   dump_field(out, "object_id", this->object_id_ref_);
   dump_field(out, "key", this->key);
   dump_field(out, "name", this->name_ref_);
-  for (const auto &it : *this->supported_color_modes) {
+  for (const auto &it : this->supported_color_modes) {
     dump_field(out, "supported_color_modes", static_cast<enums::ColorMode>(it), 4);
   }
   dump_field(out, "min_mireds", this->min_mireds);

esphome/components/light/color_mode.h

@@ -104,5 +104,132 @@ constexpr ColorModeHelper operator|(ColorModeHelper lhs, ColorMode rhs) {
   return static_cast<ColorMode>(static_cast<uint8_t>(lhs) | static_cast<uint8_t>(rhs));
 }
 
+/// Bitmask for storing a set of ColorMode values efficiently.
+/// Replaces std::set<ColorMode> to eliminate red-black tree overhead (~586 bytes).
+class ColorModeMask {
+ public:
+  constexpr ColorModeMask() = default;
+
+  /// Support initializer list syntax: {ColorMode::RGB, ColorMode::WHITE}
+  constexpr ColorModeMask(std::initializer_list<ColorMode> modes) {
+    for (auto mode : modes) {
+      this->add(mode);
+    }
+  }
+
+  constexpr void add(ColorMode mode) { this->mask_ |= (1 << mode_to_bit(mode)); }
+
+  constexpr bool contains(ColorMode mode) const { return (this->mask_ & (1 << mode_to_bit(mode))) != 0; }
+
+  constexpr size_t size() const {
+    // Count set bits
+    uint16_t n = this->mask_;
+    size_t count = 0;
+    while (n) {
+      count += n & 1;
+      n >>= 1;
+    }
+    return count;
+  }
+
+  /// Iterator support for API encoding
+  class Iterator {
+   public:
+    using iterator_category = std::forward_iterator_tag;
+    using value_type = ColorMode;
+    using difference_type = std::ptrdiff_t;
+    using pointer = const ColorMode *;
+    using reference = ColorMode;
+
+    constexpr Iterator(uint16_t mask, int bit) : mask_(mask), bit_(bit) { advance_to_next_set_bit(); }
+
+    constexpr ColorMode operator*() const { return bit_to_mode(bit_); }
+
+    constexpr Iterator &operator++() {
+      ++bit_;
+      advance_to_next_set_bit();
+      return *this;
+    }
+
+    constexpr bool operator==(const Iterator &other) const { return bit_ == other.bit_; }
+
+    constexpr bool operator!=(const Iterator &other) const { return !(*this == other); }
+
+   private:
+    constexpr void advance_to_next_set_bit() {
+      while (bit_ < 16 && !(mask_ & (1 << bit_))) {
+        ++bit_;
+      }
+    }
+
+    uint16_t mask_;
+    int bit_;
+  };
+
+  constexpr Iterator begin() const { return Iterator(mask_, 0); }
+  constexpr Iterator end() const { return Iterator(mask_, 16); }
+
+ private:
+  uint16_t mask_{0};
+
+  /// Map ColorMode enum values to bit positions (0-9)
+  static constexpr int mode_to_bit(ColorMode mode) {
+    // Using switch instead of lookup table to avoid RAM usage on ESP8266
+    // The compiler optimizes this efficiently
+    switch (mode) {
+      case ColorMode::UNKNOWN:
+        return 0;
+      case ColorMode::ON_OFF:
+        return 1;
+      case ColorMode::BRIGHTNESS:
+        return 2;
+      case ColorMode::WHITE:
+        return 3;
+      case ColorMode::COLOR_TEMPERATURE:
+        return 4;
+      case ColorMode::COLD_WARM_WHITE:
+        return 5;
+      case ColorMode::RGB:
+        return 6;
+      case ColorMode::RGB_WHITE:
+        return 7;
+      case ColorMode::RGB_COLOR_TEMPERATURE:
+        return 8;
+      case ColorMode::RGB_COLD_WARM_WHITE:
+        return 9;
+      default:
+        return 0;
+    }
+  }
+
+  static constexpr ColorMode bit_to_mode(int bit) {
+    // Using switch instead of lookup table to avoid RAM usage on ESP8266
+    switch (bit) {
+      case 0:
+        return ColorMode::UNKNOWN;
+      case 1:
+        return ColorMode::ON_OFF;
+      case 2:
+        return ColorMode::BRIGHTNESS;
+      case 3:
+        return ColorMode::WHITE;
+      case 4:
+        return ColorMode::COLOR_TEMPERATURE;
+      case 5:
+        return ColorMode::COLD_WARM_WHITE;
+      case 6:
+        return ColorMode::RGB;
+      case 7:
+        return ColorMode::RGB_WHITE;
+      case 8:
+        return ColorMode::RGB_COLOR_TEMPERATURE;
+      case 9:
+        return ColorMode::RGB_COLD_WARM_WHITE;
+      default:
+        return ColorMode::UNKNOWN;
+    }
+  }
+};
+
 }  // namespace light
 }  // namespace esphome

esphome/components/light/light_call.cpp

@@ -425,10 +425,10 @@ ColorMode LightCall::compute_color_mode_() {
   // If no color mode is specified, we try to guess the color mode. This is needed for backward compatibility to
   // pre-colormode clients and automations, but also for the MQTT API, where HA doesn't let us know which color mode
   // was used for some reason.
-  std::set<ColorMode> suitable_modes = this->get_suitable_color_modes_();
+  ColorModeMask suitable_modes = this->get_suitable_color_modes_();
 
   // Don't change if the current mode is suitable.
-  if (suitable_modes.count(current_mode) > 0) {
+  if (suitable_modes.contains(current_mode)) {
     ESP_LOGI(TAG, "'%s': color mode not specified; retaining %s", this->parent_->get_name().c_str(),
              LOG_STR_ARG(color_mode_to_human(current_mode)));
     return current_mode;
@@ -436,7 +436,7 @@ ColorMode LightCall::compute_color_mode_() {
 
   // Use the preferred suitable mode.
   for (auto mode : suitable_modes) {
-    if (supported_modes.count(mode) == 0)
+    if (!supported_modes.contains(mode))
       continue;
 
     ESP_LOGI(TAG, "'%s': color mode not specified; using %s", this->parent_->get_name().c_str(),
@@ -451,7 +451,7 @@ ColorMode LightCall::compute_color_mode_() {
            LOG_STR_ARG(color_mode_to_human(color_mode)));
   return color_mode;
 }
-std::set<ColorMode> LightCall::get_suitable_color_modes_() {
+ColorModeMask LightCall::get_suitable_color_modes_() {
   bool has_white = this->has_white() && this->white_ > 0.0f;
   bool has_ct = this->has_color_temperature();
   bool has_cwww =

esphome/components/light/light_call.h

@@ -1,7 +1,6 @@
 #pragma once
 
 #include "light_color_values.h"
-#include <set>
 
 namespace esphome {
 
@@ -187,7 +186,7 @@ class LightCall {
   //// Compute the color mode that should be used for this call.
   ColorMode compute_color_mode_();
   /// Get potential color modes for this light call.
-  std::set<ColorMode> get_suitable_color_modes_();
+  ColorModeMask get_suitable_color_modes_();
   /// Some color modes also can be set using non-native parameters, transform those calls.
   void transform_parameters_();
 

esphome/components/light/light_traits.h

@@ -2,7 +2,6 @@
 
 #include "esphome/core/helpers.h"
 #include "color_mode.h"
-#include <set>
 
 namespace esphome {
 
@@ -19,12 +18,15 @@ class LightTraits {
  public:
   LightTraits() = default;
 
-  const std::set<ColorMode> &get_supported_color_modes() const { return this->supported_color_modes_; }
-  void set_supported_color_modes(std::set<ColorMode> supported_color_modes) {
-    this->supported_color_modes_ = std::move(supported_color_modes);
+  const ColorModeMask &get_supported_color_modes() const { return this->supported_color_modes_; }
+  void set_supported_color_modes(ColorModeMask supported_color_modes) {
+    this->supported_color_modes_ = supported_color_modes;
+  }
+  void set_supported_color_modes(std::initializer_list<ColorMode> modes) {
+    this->supported_color_modes_ = ColorModeMask(modes);
   }
 
-  bool supports_color_mode(ColorMode color_mode) const { return this->supported_color_modes_.count(color_mode); }
+  bool supports_color_mode(ColorMode color_mode) const { return this->supported_color_modes_.contains(color_mode); }
   bool supports_color_capability(ColorCapability color_capability) const {
     for (auto mode : this->supported_color_modes_) {
       if (mode & color_capability)
@@ -59,17 +61,7 @@ class LightTraits {
   void set_max_mireds(float max_mireds) { this->max_mireds_ = max_mireds; }
 
  protected:
-#ifdef USE_API
-  // The API connection is a friend class to access internal methods
-  friend class api::APIConnection;
-  // This method returns a reference to the internal color modes set.
-  // It is used by the API to avoid copying data when encoding messages.
-  // Warning: Do not use this method outside of the API connection code.
-  // It returns a reference to internal data that can be invalidated.
-  const std::set<ColorMode> &get_supported_color_modes_for_api_() const { return this->supported_color_modes_; }
-#endif
-
-  std::set<ColorMode> supported_color_modes_{};
+  ColorModeMask supported_color_modes_{};
   float min_mireds_{0};
   float max_mireds_{0};
 };