drop double copy

esphome/components/api/api.proto

@@ -1143,7 +1143,7 @@ message ListEntitiesSelectResponse {
   reserved 4; // Deprecated: was string unique_id
 
   string icon = 5 [(field_ifdef) = "USE_ENTITY_ICON"];
-  repeated string options = 6 [(container_pointer) = "std::vector"];
+  repeated string options = 6 [(container_pointer) = "FixedVector"];
   bool disabled_by_default = 7;
   EntityCategory entity_category = 8;
   uint32 device_id = 9 [(field_ifdef) = "USE_DEVICES"];

esphome/components/api/api_pb2.h

@@ -1534,7 +1534,7 @@ class ListEntitiesSelectResponse final : public InfoResponseProtoMessage {
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "list_entities_select_response"; }
 #endif
-  const std::vector<std::string> *options{};
+  const FixedVector<std::string> *options{};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
 #ifdef HAS_PROTO_MESSAGE_DUMP

esphome/components/copy/select/copy_select.cpp

@@ -9,7 +9,7 @@ static const char *const TAG = "copy.select";
 void CopySelect::setup() {
   source_->add_on_state_callback([this](const std::string &value, size_t index) { this->publish_state(value); });
 
-  traits.set_options(source_->traits.get_options());
+  this->traits.copy_options(source_->traits.get_options());
 
   if (source_->has_state())
     this->publish_state(source_->state);

esphome/components/lvgl/lvgl_esphome.cpp

@@ -286,26 +286,24 @@ std::string LvSelectable::get_selected_text() {
   return this->options_[selected];
 }
 
-static std::string join_string(std::vector<std::string> options) {
-  return std::accumulate(
-      options.begin(), options.end(), std::string(),
-      [](const std::string &a, const std::string &b) -> std::string { return a + (!a.empty() ? "\n" : "") + b; });
-}
-
 void LvSelectable::set_selected_text(const std::string &text, lv_anim_enable_t anim) {
-  auto index = std::find(this->options_.begin(), this->options_.end(), text);
+  auto *index = std::find(this->options_.begin(), this->options_.end(), text);
   if (index != this->options_.end()) {
     this->set_selected_index(index - this->options_.begin(), anim);
     lv_event_send(this->obj, lv_api_event, nullptr);
   }
 }
 
-void LvSelectable::set_options(std::vector<std::string> options) {
+void LvSelectable::set_options(const std::initializer_list<std::string> &options) {
   auto index = this->get_selected_index();
   if (index >= options.size())
     index = options.size() - 1;
-  this->options_ = std::move(options);
-  this->set_option_string(join_string(this->options_).c_str());
+  // Join strings directly from initializer_list to avoid double iteration
+  std::string joined = std::accumulate(
+      options.begin(), options.end(), std::string(),
+      [](const std::string &a, const std::string &b) -> std::string { return a + (!a.empty() ? "\n" : "") + b; });
+  this->options_ = options;
+  this->set_option_string(joined.c_str());
   lv_event_send(this->obj, LV_EVENT_REFRESH, nullptr);
   this->set_selected_index(index, LV_ANIM_OFF);
 }

esphome/components/lvgl/lvgl_esphome.h

@@ -358,12 +358,12 @@ class LvSelectable : public LvCompound {
   virtual void set_selected_index(size_t index, lv_anim_enable_t anim) = 0;
   void set_selected_text(const std::string &text, lv_anim_enable_t anim);
   std::string get_selected_text();
-  std::vector<std::string> get_options() { return this->options_; }
-  void set_options(std::vector<std::string> options);
+  const FixedVector<std::string> &get_options() { return this->options_; }
+  void set_options(const std::initializer_list<std::string> &options);
 
  protected:
   virtual void set_option_string(const char *options) = 0;
-  std::vector<std::string> options_{};
+  FixedVector<std::string> options_{};
 };
 
 #ifdef USE_LVGL_DROPDOWN

esphome/components/lvgl/select/lvgl_select.h

@@ -53,7 +53,10 @@ class LVGLSelect : public select::Select, public Component {
     this->widget_->set_selected_text(value, this->anim_);
     this->publish();
   }
-  void set_options_() { this->traits.set_options(this->widget_->get_options()); }
+  void set_options_() {
+    // Copy options from lvgl widget to select traits
+    this->traits.copy_options(this->widget_->get_options());
+  }
 
   LvSelectable *widget_;
   lv_anim_enable_t anim_;

esphome/components/select/select_traits.cpp

@@ -3,9 +3,9 @@
 namespace esphome {
 namespace select {
 
-void SelectTraits::set_options(std::vector<std::string> options) { this->options_ = std::move(options); }
+void SelectTraits::set_options(const std::initializer_list<std::string> &options) { this->options_ = options; }
 
-const std::vector<std::string> &SelectTraits::get_options() const { return this->options_; }
+const FixedVector<std::string> &SelectTraits::get_options() const { return this->options_; }
 
 }  // namespace select
 }  // namespace esphome

esphome/components/select/select_traits.h

@@ -1,18 +1,21 @@
 #pragma once
 
-#include <vector>
 #include <string>
+#include <initializer_list>
+#include "esphome/core/helpers.h"
 
 namespace esphome {
 namespace select {
 
 class SelectTraits {
  public:
-  void set_options(std::vector<std::string> options);
-  const std::vector<std::string> &get_options() const;
+  void set_options(const std::initializer_list<std::string> &options);
+  const FixedVector<std::string> &get_options() const;
+  /// Copy options from another SelectTraits (for copy_select, lvgl)
+  void copy_options(const FixedVector<std::string> &other) { this->options_.copy_from(other); }
 
  protected:
-  std::vector<std::string> options_;
+  FixedVector<std::string> options_;
 };
 
 }  // namespace select

esphome/core/helpers.h

@@ -194,12 +194,8 @@ template<typename T> class FixedVector {
     size_ = 0;
   }
 
- public:
-  FixedVector() = default;
-
-  /// Constructor from initializer list - allocates exact size needed
-  /// This enables brace initialization: FixedVector<int> v = {1, 2, 3};
-  FixedVector(std::initializer_list<T> init_list) {
+  // Helper to assign from initializer list (shared by constructor and assignment operator)
+  void assign_from_initializer_list_(std::initializer_list<T> init_list) {
     init(init_list.size());
     size_t idx = 0;
     for (const auto &item : init_list) {
@@ -209,9 +205,17 @@ template<typename T> class FixedVector {
     size_ = init_list.size();
   }
 
+ public:
+  FixedVector() = default;
+
+  /// Constructor from initializer list - allocates exact size needed
+  /// This enables brace initialization: FixedVector<int> v = {1, 2, 3};
+  FixedVector(std::initializer_list<T> init_list) { assign_from_initializer_list_(init_list); }
+
   ~FixedVector() { cleanup_(); }
 
   // Disable copy operations (avoid accidental expensive copies)
+  // Use copy_from() for explicit copying when needed (e.g., copy_select)
   FixedVector(const FixedVector &) = delete;
   FixedVector &operator=(const FixedVector &) = delete;
 
@@ -234,6 +238,28 @@ template<typename T> class FixedVector {
     return *this;
   }
 
+  /// Assignment from initializer list - avoids temporary and move overhead
+  /// This enables: FixedVector<int> v; v = {1, 2, 3};
+  FixedVector &operator=(std::initializer_list<T> init_list) {
+    cleanup_();
+    reset_();
+    assign_from_initializer_list_(init_list);
+    return *this;
+  }
+
+  /// Explicitly copy another FixedVector
+  /// This method exists instead of operator= to make copying intentional and visible.
+  /// Copying is expensive on embedded systems, so we require explicit opt-in.
+  /// Use cases: copy_select (copying source options), lvgl (copying widget options)
+  void copy_from(const FixedVector &other) {
+    cleanup_();
+    reset_();
+    init(other.size());
+    for (const auto &item : other) {
+      push_back(item);
+    }
+  }
+
   // Allocate capacity - can be called multiple times to reinit
   void init(size_t n) {
     cleanup_();
@@ -292,6 +318,11 @@ template<typename T> class FixedVector {
     return data_[size_ - 1];
   }
 
+  /// Access first element (no bounds checking - matches std::vector behavior)
+  /// Caller must ensure vector is not empty (size() > 0)
+  T &front() { return data_[0]; }
+  const T &front() const { return data_[0]; }
+
   /// Access last element (no bounds checking - matches std::vector behavior)
   /// Caller must ensure vector is not empty (size() > 0)
   T &back() { return data_[size_ - 1]; }
@@ -305,6 +336,12 @@ template<typename T> class FixedVector {
   T &operator[](size_t i) { return data_[i]; }
   const T &operator[](size_t i) const { return data_[i]; }
 
+  /// Access element with bounds checking (matches std::vector behavior)
+  /// Returns reference to element at index i
+  /// Behavior for out of bounds access matches std::vector::at() (undefined on embedded)
+  T &at(size_t i) { return data_[i]; }
+  const T &at(size_t i) const { return data_[i]; }
+
   // Iterator support for range-based for loops
   T *begin() { return data_; }
   T *end() { return data_ + size_; }