[fan] Use FixedVector for preset modes, preserve config order (breaking)

esphome/components/api/api.proto

@@ -425,7 +425,7 @@ message ListEntitiesFanResponse {
   bool disabled_by_default = 9;
   string icon = 10 [(field_ifdef) = "USE_ENTITY_ICON"];
   EntityCategory entity_category = 11;
-  repeated string supported_preset_modes = 12 [(container_pointer) = "std::set"];
+  repeated string supported_preset_modes = 12 [(container_pointer) = "FixedVector"];
   uint32 device_id = 13 [(field_ifdef) = "USE_DEVICES"];
 }
 // Deprecated in API version 1.6 - only used in deprecated fields

esphome/components/api/api_pb2.h

@@ -725,7 +725,7 @@ class ListEntitiesFanResponse final : public InfoResponseProtoMessage {
   bool supports_speed{false};
   bool supports_direction{false};
   int32_t supported_speed_count{0};
-  const std::set<std::string> *supported_preset_modes{};
+  const FixedVector<std::string> *supported_preset_modes{};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
 #ifdef HAS_PROTO_MESSAGE_DUMP

esphome/components/fan/fan.cpp

@@ -39,7 +39,7 @@ void FanCall::perform() {
 }
 
 void FanCall::validate_() {
-  auto traits = this->parent_.get_traits();
+  const auto &traits = this->parent_.get_traits();
 
   if (this->speed_.has_value()) {
     this->speed_ = clamp(*this->speed_, 1, traits.supported_speed_count());
@@ -51,7 +51,15 @@ void FanCall::validate_() {
 
   if (!this->preset_mode_.empty()) {
     const auto &preset_modes = traits.supported_preset_modes();
-    if (preset_modes.find(this->preset_mode_) == preset_modes.end()) {
+    // Linear search is efficient for small preset mode lists (typically 2-5 items)
+    bool found = false;
+    for (const auto &mode : preset_modes) {
+      if (mode == this->preset_mode_) {
+        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();
     }
@@ -96,7 +104,7 @@ FanCall FanRestoreState::to_call(Fan &fan) {
     // Use stored preset index to get preset name
     const auto &preset_modes = fan.get_traits().supported_preset_modes();
     if (this->preset_mode < preset_modes.size()) {
-      call.set_preset_mode(*std::next(preset_modes.begin(), this->preset_mode));
+      call.set_preset_mode(preset_modes[this->preset_mode]);
     }
   }
   return call;
@@ -111,7 +119,7 @@ void FanRestoreState::apply(Fan &fan) {
     // Use stored preset index to get preset name
     const auto &preset_modes = fan.get_traits().supported_preset_modes();
     if (this->preset_mode < preset_modes.size()) {
-      fan.preset_mode = *std::next(preset_modes.begin(), this->preset_mode);
+      fan.preset_mode = preset_modes[this->preset_mode];
     }
   }
   fan.publish_state();
@@ -124,7 +132,7 @@ FanCall Fan::make_call() { return FanCall(*this); }
 
 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();
+  const auto &traits = this->get_traits();
 
   ESP_LOGD(TAG, "'%s' - Sending state:", this->name_.c_str());
   ESP_LOGD(TAG, "  State: %s", ONOFF(this->state));
@@ -190,17 +198,20 @@ void Fan::save_state_() {
 
   if (this->get_traits().supports_preset_modes() && !this->preset_mode.empty()) {
     const auto &preset_modes = this->get_traits().supported_preset_modes();
-    // Store index of current preset mode
-    auto preset_iterator = preset_modes.find(this->preset_mode);
-    if (preset_iterator != preset_modes.end())
-      state.preset_mode = std::distance(preset_modes.begin(), preset_iterator);
+    // Store index of current preset mode - linear search is efficient for small lists
+    for (size_t i = 0; i < preset_modes.size(); i++) {
+      if (preset_modes[i] == this->preset_mode) {
+        state.preset_mode = i;
+        break;
+      }
+    }
   }
 
   this->rtc_.save(&state);
 }
 
 void Fan::dump_traits_(const char *tag, const char *prefix) {
-  auto traits = this->get_traits();
+  const auto &traits = this->get_traits();
 
   if (traits.supports_speed()) {
     ESP_LOGCONFIG(tag,

esphome/components/fan/fan.h

@@ -127,7 +127,7 @@ class Fan : public EntityBase {
 
   void publish_state();
 
-  virtual FanTraits get_traits() = 0;
+  virtual const FanTraits &get_traits() = 0;
 
   /// Set the restore mode of this fan.
   void set_restore_mode(FanRestoreMode restore_mode) { this->restore_mode_ = restore_mode; }

esphome/components/fan/fan_traits.h

@@ -1,5 +1,5 @@
-#include <set>
 #include <utility>
+#include "esphome/core/helpers.h"
 
 #pragma once
 
@@ -36,9 +36,18 @@ class FanTraits {
   /// Set whether this fan supports changing direction
   void set_direction(bool direction) { this->direction_ = direction; }
   /// Return the preset modes supported by the fan.
-  std::set<std::string> supported_preset_modes() const { return this->preset_modes_; }
-  /// Set the preset modes supported by the fan.
-  void set_supported_preset_modes(const std::set<std::string> &preset_modes) { this->preset_modes_ = preset_modes; }
+  const FixedVector<std::string> &supported_preset_modes() const { return this->preset_modes_; }
+  /// Set the preset modes supported by the fan (from initializer list).
+  void set_supported_preset_modes(const std::initializer_list<std::string> &preset_modes) {
+    this->preset_modes_ = preset_modes;
+  }
+  /// Set the preset modes supported by the fan (from FixedVector).
+  template<typename T> void set_supported_preset_modes(const T &preset_modes) {
+    this->preset_modes_.init(preset_modes.size());
+    for (const auto &mode : preset_modes) {
+      this->preset_modes_.push_back(mode);
+    }
+  }
   /// Return if preset modes are supported
   bool supports_preset_modes() const { return !this->preset_modes_.empty(); }
 
@@ -46,17 +55,17 @@ class FanTraits {
 #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 preset modes set.
+  // This method returns a reference to the internal preset modes.
   // 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<std::string> &supported_preset_modes_for_api_() const { return this->preset_modes_; }
+  const FixedVector<std::string> &supported_preset_modes_for_api_() const { return this->preset_modes_; }
 #endif
   bool oscillation_{false};
   bool speed_{false};
   bool direction_{false};
   int speed_count_{};
-  std::set<std::string> preset_modes_{};
+  FixedVector<std::string> preset_modes_{};
 };
 
 }  // namespace fan

esphome/components/hbridge/fan/hbridge_fan.cpp

@@ -36,7 +36,8 @@ void HBridgeFan::setup() {
 
   // Construct traits
   this->traits_ = fan::FanTraits(this->oscillating_ != nullptr, true, true, this->speed_count_);
-  this->traits_.set_supported_preset_modes(this->preset_modes_);
+  if (!this->preset_modes_.empty())
+    this->traits_.set_supported_preset_modes(this->preset_modes_);
 }
 
 void HBridgeFan::dump_config() {

esphome/components/hbridge/fan/hbridge_fan.h

@@ -1,8 +1,7 @@
 #pragma once
 
-#include <set>
-
 #include "esphome/core/automation.h"
+#include "esphome/core/helpers.h"
 #include "esphome/components/output/binary_output.h"
 #include "esphome/components/output/float_output.h"
 #include "esphome/components/fan/fan.h"
@@ -22,11 +21,11 @@ class HBridgeFan : public Component, public fan::Fan {
   void set_pin_a(output::FloatOutput *pin_a) { pin_a_ = pin_a; }
   void set_pin_b(output::FloatOutput *pin_b) { pin_b_ = pin_b; }
   void set_enable_pin(output::FloatOutput *enable) { enable_ = enable; }
-  void set_preset_modes(const std::set<std::string> &presets) { preset_modes_ = presets; }
+  void set_preset_modes(const std::initializer_list<std::string> &presets) { preset_modes_ = presets; }
 
   void setup() override;
   void dump_config() override;
-  fan::FanTraits get_traits() override { return this->traits_; }
+  const fan::FanTraits &get_traits() override { return this->traits_; }
 
   fan::FanCall brake();
 
@@ -38,7 +37,7 @@ class HBridgeFan : public Component, public fan::Fan {
   int speed_count_{};
   DecayMode decay_mode_{DECAY_MODE_SLOW};
   fan::FanTraits traits_;
-  std::set<std::string> preset_modes_{};
+  FixedVector<std::string> preset_modes_{};
 
   void control(const fan::FanCall &call) override;
   void write_state_();

esphome/components/speed/fan/speed_fan.cpp

@@ -15,7 +15,8 @@ void SpeedFan::setup() {
 
   // 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_);
+  if (!this->preset_modes_.empty())
+    this->traits_.set_supported_preset_modes(this->preset_modes_);
 }
 
 void SpeedFan::dump_config() { LOG_FAN("", "Speed Fan", this); }

esphome/components/speed/fan/speed_fan.h

@@ -1,8 +1,7 @@
 #pragma once
 
-#include <set>
-
 #include "esphome/core/component.h"
+#include "esphome/core/helpers.h"
 #include "esphome/components/output/binary_output.h"
 #include "esphome/components/output/float_output.h"
 #include "esphome/components/fan/fan.h"
@@ -18,8 +17,8 @@ class SpeedFan : public Component, public fan::Fan {
   void set_output(output::FloatOutput *output) { this->output_ = output; }
   void set_oscillating(output::BinaryOutput *oscillating) { this->oscillating_ = oscillating; }
   void set_direction(output::BinaryOutput *direction) { this->direction_ = direction; }
-  void set_preset_modes(const std::set<std::string> &presets) { this->preset_modes_ = presets; }
-  fan::FanTraits get_traits() override { return this->traits_; }
+  void set_preset_modes(const std::initializer_list<std::string> &presets) { this->preset_modes_ = presets; }
+  const fan::FanTraits &get_traits() override { return this->traits_; }
 
  protected:
   void control(const fan::FanCall &call) override;
@@ -30,7 +29,7 @@ class SpeedFan : public Component, public fan::Fan {
   output::BinaryOutput *direction_{nullptr};
   int speed_count_{};
   fan::FanTraits traits_;
-  std::set<std::string> preset_modes_{};
+  FixedVector<std::string> preset_modes_{};
 };
 
 }  // namespace speed

esphome/components/template/fan/template_fan.cpp

@@ -15,7 +15,8 @@ void TemplateFan::setup() {
   // 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_);
+  if (!this->preset_modes_.empty())
+    this->traits_.set_supported_preset_modes(this->preset_modes_);
 }
 
 void TemplateFan::dump_config() { LOG_FAN("", "Template Fan", this); }

esphome/components/template/fan/template_fan.h

@@ -1,8 +1,7 @@
 #pragma once
 
-#include <set>
-
 #include "esphome/core/component.h"
+#include "esphome/core/helpers.h"
 #include "esphome/components/fan/fan.h"
 
 namespace esphome {
@@ -16,8 +15,8 @@ class TemplateFan : public Component, public fan::Fan {
   void set_has_direction(bool has_direction) { this->has_direction_ = has_direction; }
   void set_has_oscillating(bool has_oscillating) { this->has_oscillating_ = has_oscillating; }
   void set_speed_count(int count) { this->speed_count_ = count; }
-  void set_preset_modes(const std::set<std::string> &presets) { this->preset_modes_ = presets; }
-  fan::FanTraits get_traits() override { return this->traits_; }
+  void set_preset_modes(const std::initializer_list<std::string> &presets) { this->preset_modes_ = presets; }
+  const fan::FanTraits &get_traits() override { return this->traits_; }
 
  protected:
   void control(const fan::FanCall &call) override;
@@ -26,7 +25,7 @@ class TemplateFan : public Component, public fan::Fan {
   bool has_direction_{false};
   int speed_count_{0};
   fan::FanTraits traits_;
-  std::set<std::string> preset_modes_{};
+  FixedVector<std::string> preset_modes_{};
 };
 
 }  // namespace template_

tests/components/fan/common.yaml

@@ -0,0 +1,11 @@
+fan:
+  - platform: template
+    id: test_fan
+    name: "Test Fan"
+    preset_modes:
+      - Eco
+      - Sleep
+      - Turbo
+    has_oscillating: true
+    has_direction: true
+    speed_count: 3

tests/components/fan/test.esp8266-ard.yaml

@@ -0,0 +1 @@
+<<: !include common.yaml