[fan] Remove duplicate preset mode storage to save RAM (#11632)

esphome/components/api/api_connection.cpp

@@ -410,8 +410,8 @@ uint16_t APIConnection::try_send_fan_state(EntityBase *entity, APIConnection *co
   }
   if (traits.supports_direction())
     msg.direction = static_cast<enums::FanDirection>(fan->direction);
-  if (traits.supports_preset_modes())
+  if (traits.supports_preset_modes() && fan->has_preset_mode())
-    msg.set_preset_mode(StringRef(fan->preset_mode));
+    msg.set_preset_mode(StringRef(fan->get_preset_mode()));
   return fill_and_encode_entity_state(fan, msg, FanStateResponse::MESSAGE_TYPE, conn, remaining_size, is_single);
 }
 uint16_t APIConnection::try_send_fan_info(EntityBase *entity, APIConnection *conn, uint32_t remaining_size,

esphome/components/copy/fan/copy_fan.cpp

@@ -12,7 +12,7 @@ void CopyFan::setup() {
     this->oscillating = source_->oscillating;
     this->speed = source_->speed;
     this->direction = source_->direction;
-    this->preset_mode = source_->preset_mode;
+    this->set_preset_mode_(source_->get_preset_mode());
     this->publish_state();
   });
 
@@ -20,7 +20,7 @@ void CopyFan::setup() {
   this->oscillating = source_->oscillating;
   this->speed = source_->speed;
   this->direction = source_->direction;
-  this->preset_mode = source_->preset_mode;
+  this->set_preset_mode_(source_->get_preset_mode());
   this->publish_state();
 }
 
@@ -49,7 +49,7 @@ void CopyFan::control(const fan::FanCall &call) {
     call2.set_speed(*call.get_speed());
   if (call.get_direction().has_value())
     call2.set_direction(*call.get_direction());
-  if (!call.get_preset_mode().empty())
+  if (call.has_preset_mode())
     call2.set_preset_mode(call.get_preset_mode());
   call2.perform();
 }

esphome/components/fan/automation.h

@@ -212,18 +212,19 @@ class FanPresetSetTrigger : public Trigger<std::string> {
  public:
   FanPresetSetTrigger(Fan *state) {
     state->add_on_state_callback([this, state]() {
-      auto preset_mode = state->preset_mode;
+      const auto *preset_mode = state->get_preset_mode();
       auto should_trigger = preset_mode != this->last_preset_mode_;
       this->last_preset_mode_ = preset_mode;
       if (should_trigger) {
-        this->trigger(preset_mode);
+        // Trigger with empty string when nullptr to maintain backward compatibility
+        this->trigger(preset_mode != nullptr ? preset_mode : "");
       }
     });
-    this->last_preset_mode_ = state->preset_mode;
+    this->last_preset_mode_ = state->get_preset_mode();
   }
 
  protected:
-  std::string last_preset_mode_;
+  const char *last_preset_mode_{nullptr};
 };
 
 }  // namespace fan

esphome/components/fan/fan.cpp

@@ -17,6 +17,27 @@ const LogString *fan_direction_to_string(FanDirection direction) {
   }
 }
 
+FanCall &FanCall::set_preset_mode(const std::string &preset_mode) { return this->set_preset_mode(preset_mode.c_str()); }
+
+FanCall &FanCall::set_preset_mode(const char *preset_mode) {
+  if (preset_mode == nullptr || strlen(preset_mode) == 0) {
+    this->preset_mode_ = nullptr;
+    return *this;
+  }
+
+  // Find and validate pointer from traits immediately
+  auto traits = this->parent_.get_traits();
+  const char *validated_mode = traits.find_preset_mode(preset_mode);
+  if (validated_mode != nullptr) {
+    this->preset_mode_ = validated_mode;  // Store pointer from traits
+  } else {
+    // Preset mode not found in traits - log warning and don't set
+    ESP_LOGW(TAG, "%s: Preset mode '%s' not supported", this->parent_.get_name().c_str(), preset_mode);
+    this->preset_mode_ = nullptr;
+  }
+  return *this;
+}
+
 void FanCall::perform() {
   ESP_LOGD(TAG, "'%s' - Setting:", this->parent_.get_name().c_str());
   this->validate_();
@@ -32,8 +53,8 @@ void FanCall::perform() {
   if (this->direction_.has_value()) {
     ESP_LOGD(TAG, "  Direction: %s", LOG_STR_ARG(fan_direction_to_string(*this->direction_)));
   }
-  if (!this->preset_mode_.empty()) {
+  if (this->has_preset_mode()) {
-    ESP_LOGD(TAG, "  Preset Mode: %s", this->preset_mode_.c_str());
+    ESP_LOGD(TAG, "  Preset Mode: %s", this->preset_mode_);
   }
   this->parent_.control(*this);
 }
@@ -46,30 +67,15 @@ void FanCall::validate_() {
 
     // https://developers.home-assistant.io/docs/core/entity/fan/#preset-modes
     // "Manually setting a speed must disable any set preset mode"
-    this->preset_mode_.clear();
+    this->preset_mode_ = nullptr;
-  }
-
-  if (!this->preset_mode_.empty()) {
-    const auto &preset_modes = traits.supported_preset_modes();
-    bool found = false;
-    for (const auto &mode : preset_modes) {
-      if (strcmp(mode, this->preset_mode_.c_str()) == 0) {
-        found = true;
-        break;
-      }
-    }
-    if (!found) {
-      ESP_LOGW(TAG, "%s: Preset mode '%s' not supported", this->parent_.get_name().c_str(), this->preset_mode_.c_str());
-      this->preset_mode_.clear();
-    }
   }
 
   // when turning on...
   if (!this->parent_.state && this->binary_state_.has_value() &&
       *this->binary_state_
       // ..,and no preset mode will be active...
-      && this->preset_mode_.empty() &&
+      && !this->has_preset_mode() &&
-      this->parent_.preset_mode.empty()
+      this->parent_.get_preset_mode() == nullptr
       // ...and neither current nor new speed is available...
       && traits.supports_speed() && this->parent_.speed == 0 && !this->speed_.has_value()) {
     // ...set speed to 100%
@@ -117,12 +123,13 @@ void FanRestoreState::apply(Fan &fan) {
 
   auto traits = fan.get_traits();
   if (traits.supports_preset_modes()) {
-    // Use stored preset index to get preset name
+    // Use stored preset index to get preset name from traits
     const auto &preset_modes = traits.supported_preset_modes();
     if (this->preset_mode < preset_modes.size()) {
-      fan.preset_mode = preset_modes[this->preset_mode];
+      fan.set_preset_mode_(preset_modes[this->preset_mode]);
     }
   }
+
   fan.publish_state();
 }
 
@@ -131,6 +138,29 @@ FanCall Fan::turn_off() { return this->make_call().set_state(false); }
 FanCall Fan::toggle() { return this->make_call().set_state(!this->state); }
 FanCall Fan::make_call() { return FanCall(*this); }
 
+const char *Fan::find_preset_mode_(const char *preset_mode) { return this->get_traits().find_preset_mode(preset_mode); }
+
+bool Fan::set_preset_mode_(const char *preset_mode) {
+  if (preset_mode == nullptr) {
+    // Treat nullptr as clearing the preset mode
+    if (this->preset_mode_ == nullptr) {
+      return false;  // No change
+    }
+    this->clear_preset_mode_();
+    return true;
+  }
+  const char *validated = this->find_preset_mode_(preset_mode);
+  if (validated == nullptr || this->preset_mode_ == validated) {
+    return false;  // Preset mode not supported or no change
+  }
+  this->preset_mode_ = validated;
+  return true;
+}
+
+bool Fan::set_preset_mode_(const std::string &preset_mode) { return this->set_preset_mode_(preset_mode.c_str()); }
+
+void Fan::clear_preset_mode_() { this->preset_mode_ = nullptr; }
+
 void Fan::add_on_state_callback(std::function<void()> &&callback) { this->state_callback_.add(std::move(callback)); }
 void Fan::publish_state() {
   auto traits = this->get_traits();
@@ -146,8 +176,9 @@ void Fan::publish_state() {
   if (traits.supports_direction()) {
     ESP_LOGD(TAG, "  Direction: %s", LOG_STR_ARG(fan_direction_to_string(this->direction)));
   }
-  if (traits.supports_preset_modes() && !this->preset_mode.empty()) {
+  const char *preset = this->get_preset_mode();
-    ESP_LOGD(TAG, "  Preset Mode: %s", this->preset_mode.c_str());
+  if (preset != nullptr) {
+    ESP_LOGD(TAG, "  Preset Mode: %s", preset);
   }
   this->state_callback_.call();
   this->save_state_();
@@ -199,16 +230,15 @@ void Fan::save_state_() {
   state.speed = this->speed;
   state.direction = this->direction;
 
-  if (traits.supports_preset_modes() && !this->preset_mode.empty()) {
+  const char *preset = this->get_preset_mode();
+  if (preset != nullptr) {
     const auto &preset_modes = traits.supported_preset_modes();
-    // Store index of current preset mode
+    // Find index of current preset mode (pointer comparison is safe since preset is from traits)
-    size_t i = 0;
+    for (size_t i = 0; i < preset_modes.size(); i++) {
-    for (const auto &mode : preset_modes) {
+      if (preset_modes[i] == preset) {
-      if (strcmp(mode, this->preset_mode.c_str()) == 0) {
         state.preset_mode = i;
         break;
       }
-      i++;
     }
   }
 

esphome/components/fan/fan.h

@@ -70,11 +70,10 @@ class FanCall {
     return *this;
   }
   optional<FanDirection> get_direction() const { return this->direction_; }
-  FanCall &set_preset_mode(const std::string &preset_mode) {
+  FanCall &set_preset_mode(const std::string &preset_mode);
-    this->preset_mode_ = preset_mode;
+  FanCall &set_preset_mode(const char *preset_mode);
-    return *this;
+  const char *get_preset_mode() const { return this->preset_mode_; }
-  }
+  bool has_preset_mode() const { return this->preset_mode_ != nullptr; }
-  std::string get_preset_mode() const { return this->preset_mode_; }
 
   void perform();
 
@@ -86,7 +85,7 @@ class FanCall {
   optional<bool> oscillating_;
   optional<int> speed_;
   optional<FanDirection> direction_{};
-  std::string preset_mode_{};
+  const char *preset_mode_{nullptr};  // Pointer to string in traits (after validation)
 };
 
 struct FanRestoreState {
@@ -112,8 +111,6 @@ class Fan : public EntityBase {
   int speed{0};
   /// The current direction of the fan
   FanDirection direction{FanDirection::FORWARD};
-  // The current preset mode of the fan
-  std::string preset_mode{};
 
   FanCall turn_on();
   FanCall turn_off();
@@ -130,8 +127,15 @@ class Fan : public EntityBase {
   /// Set the restore mode of this fan.
   void set_restore_mode(FanRestoreMode restore_mode) { this->restore_mode_ = restore_mode; }
 
+  /// Get the current preset mode (returns pointer to string stored in traits, or nullptr if not set)
+  const char *get_preset_mode() const { return this->preset_mode_; }
+
+  /// Check if a preset mode is currently active
+  bool has_preset_mode() const { return this->preset_mode_ != nullptr; }
+
  protected:
   friend FanCall;
+  friend struct FanRestoreState;
 
   virtual void control(const FanCall &call) = 0;
 
@@ -140,9 +144,21 @@ class Fan : public EntityBase {
 
   void dump_traits_(const char *tag, const char *prefix);
 
+  /// Set the preset mode (finds and stores pointer from traits). Returns true if changed.
+  bool set_preset_mode_(const char *preset_mode);
+  /// Set the preset mode (finds and stores pointer from traits). Returns true if changed.
+  bool set_preset_mode_(const std::string &preset_mode);
+  /// Clear the preset mode
+  void clear_preset_mode_();
+  /// Find and return the matching preset mode pointer from traits, or nullptr if not found.
+  const char *find_preset_mode_(const char *preset_mode);
+
   CallbackManager<void()> state_callback_{};
   ESPPreferenceObject rtc_;
   FanRestoreMode restore_mode_;
+
+ private:
+  const char *preset_mode_{nullptr};
 };
 
 }  // namespace fan

esphome/components/fan/fan_traits.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstring>
 #include <vector>
 #include <initializer_list>
 
@@ -44,6 +45,17 @@ class FanTraits {
 
   /// Return if preset modes are supported
   bool supports_preset_modes() const { return !this->preset_modes_.empty(); }
+  /// Find and return the matching preset mode pointer from supported modes, or nullptr if not found.
+  const char *find_preset_mode(const char *preset_mode) const {
+    if (preset_mode == nullptr)
+      return nullptr;
+    for (const char *mode : this->preset_modes_) {
+      if (strcmp(mode, preset_mode) == 0) {
+        return mode;  // Return pointer from traits
+      }
+    }
+    return nullptr;
+  }
 
  protected:
   bool oscillation_{false};

esphome/components/hbridge/fan/hbridge_fan.cpp

@@ -57,7 +57,7 @@ void HBridgeFan::control(const fan::FanCall &call) {
     this->oscillating = *call.get_oscillating();
   if (call.get_direction().has_value())
     this->direction = *call.get_direction();
-  this->preset_mode = call.get_preset_mode();
+  this->set_preset_mode_(call.get_preset_mode());
 
   this->write_state_();
   this->publish_state();

esphome/components/speed/fan/speed_fan.cpp

@@ -29,7 +29,7 @@ void SpeedFan::control(const fan::FanCall &call) {
     this->oscillating = *call.get_oscillating();
   if (call.get_direction().has_value())
     this->direction = *call.get_direction();
-  this->preset_mode = call.get_preset_mode();
+  this->set_preset_mode_(call.get_preset_mode());
 
   this->write_state_();
   this->publish_state();

esphome/components/template/fan/template_fan.cpp

@@ -29,7 +29,7 @@ void TemplateFan::control(const fan::FanCall &call) {
     this->oscillating = *call.get_oscillating();
   if (call.get_direction().has_value() && this->has_direction_)
     this->direction = *call.get_direction();
-  this->preset_mode = call.get_preset_mode();
+  this->set_preset_mode_(call.get_preset_mode());
 
   this->publish_state();
 }