[fan] Fix preset_mode not restored on boot (#14002)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

esphome/components/fan/fan.cpp

@@ -221,12 +221,17 @@ void Fan::publish_state() {
 }
 
 // Random 32-bit value, change this every time the layout of the FanRestoreState struct changes.
-constexpr uint32_t RESTORE_STATE_VERSION = 0x71700ABA;
+constexpr uint32_t RESTORE_STATE_VERSION = 0x71700ABB;
 optional<FanRestoreState> Fan::restore_state_() {
   FanRestoreState recovered{};
   this->rtc_ = this->make_entity_preference<FanRestoreState>(RESTORE_STATE_VERSION);
   bool restored = this->rtc_.load(&recovered);
 
+  if (!restored) {
+    // No valid saved data; ensure preset_mode sentinel is set
+    recovered.preset_mode = FanRestoreState::NO_PRESET;
+  }
+
   switch (this->restore_mode_) {
     case FanRestoreMode::NO_RESTORE:
       return {};
@@ -264,6 +269,7 @@ void Fan::save_state_() {
   state.oscillating = this->oscillating;
   state.speed = this->speed;
   state.direction = this->direction;
+  state.preset_mode = FanRestoreState::NO_PRESET;
 
   if (this->has_preset_mode()) {
     const auto &preset_modes = traits.supported_preset_modes();

esphome/components/fan/fan.h

@@ -91,11 +91,13 @@ class FanCall {
 };
 
 struct FanRestoreState {
+  static constexpr uint8_t NO_PRESET = UINT8_MAX;
+
   bool state;
   int speed;
   bool oscillating;
   FanDirection direction;
-  uint8_t preset_mode;
+  uint8_t preset_mode{NO_PRESET};
 
   /// Convert this struct to a fan call that can be performed.
   FanCall to_call(Fan &fan);

esphome/components/hbridge/fan/hbridge_fan.cpp

@@ -28,15 +28,15 @@ fan::FanCall HBridgeFan::brake() {
 }
 
 void HBridgeFan::setup() {
+  // Construct traits before restore so preset modes can be looked up by index
+  this->traits_ = fan::FanTraits(this->oscillating_ != nullptr, true, true, this->speed_count_);
+  this->traits_.set_supported_preset_modes(this->preset_modes_);
+
   auto restore = this->restore_state_();
   if (restore.has_value()) {
     restore->apply(*this);
     this->write_state_();
   }
-
-  // Construct traits
-  this->traits_ = fan::FanTraits(this->oscillating_ != nullptr, true, true, this->speed_count_);
-  this->traits_.set_supported_preset_modes(this->preset_modes_);
 }
 
 void HBridgeFan::dump_config() {

esphome/components/speed/fan/speed_fan.cpp

@@ -7,15 +7,15 @@ namespace speed {
 static const char *const TAG = "speed.fan";
 
 void SpeedFan::setup() {
+  // Construct traits before restore so preset modes can be looked up by index
+  this->traits_ = fan::FanTraits(this->oscillating_ != nullptr, true, this->direction_ != nullptr, this->speed_count_);
+  this->traits_.set_supported_preset_modes(this->preset_modes_);
+
   auto restore = this->restore_state_();
   if (restore.has_value()) {
     restore->apply(*this);
     this->write_state_();
   }
-
-  // Construct traits
-  this->traits_ = fan::FanTraits(this->oscillating_ != nullptr, true, this->direction_ != nullptr, this->speed_count_);
-  this->traits_.set_supported_preset_modes(this->preset_modes_);
 }
 
 void SpeedFan::dump_config() { LOG_FAN("", "Speed Fan", this); }

esphome/components/template/fan/template_fan.cpp

@@ -6,15 +6,15 @@ namespace esphome::template_ {
 static const char *const TAG = "template.fan";
 
 void TemplateFan::setup() {
+  // Construct traits before restore so preset modes can be looked up by index
+  this->traits_ =
+      fan::FanTraits(this->has_oscillating_, this->speed_count_ > 0, this->has_direction_, this->speed_count_);
+  this->traits_.set_supported_preset_modes(this->preset_modes_);
+
   auto restore = this->restore_state_();
   if (restore.has_value()) {
     restore->apply(*this);
   }
-
-  // Construct traits
-  this->traits_ =
-      fan::FanTraits(this->has_oscillating_, this->speed_count_ > 0, this->has_direction_, this->speed_count_);
-  this->traits_.set_supported_preset_modes(this->preset_modes_);
 }
 
 void TemplateFan::dump_config() { LOG_FAN("", "Template Fan", this); }