From a9fd0a3b26eed1059aa82390b0addbc00e1d916d Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sun, 12 Oct 2025 18:21:14 -1000
Subject: [PATCH 01/16] fixed_vector, bluetooth services

---
 esphome/components/api/api.proto              |  4 +-
 esphome/components/api/api_options.proto      |  6 +++
 esphome/components/api/api_pb2.h              |  4 +-
 esphome/components/api/proto.h                | 26 +++++++++--
 .../bluetooth_proxy/bluetooth_connection.cpp  |  8 ++--
 esphome/core/helpers.h                        | 46 +++++++++++++++++++
 script/api_protobuf/api_protobuf.py           |  4 ++
 7 files changed, 85 insertions(+), 13 deletions(-)

diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 87f477799d..9b714d00f1 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -1519,7 +1519,7 @@ message BluetoothGATTCharacteristic {
   repeated uint64 uuid = 1 [(fixed_array_size) = 2, (fixed_array_skip_zero) = true];
   uint32 handle = 2;
   uint32 properties = 3;
-  repeated BluetoothGATTDescriptor descriptors = 4;
+  repeated BluetoothGATTDescriptor descriptors = 4 [(fixed_vector) = true];
 
   // New field for efficient UUID (v1.12+)
   // Only one of uuid or short_uuid will be set.
@@ -1531,7 +1531,7 @@ message BluetoothGATTCharacteristic {
 message BluetoothGATTService {
   repeated uint64 uuid = 1 [(fixed_array_size) = 2, (fixed_array_skip_zero) = true];
   uint32 handle = 2;
-  repeated BluetoothGATTCharacteristic characteristics = 3;
+  repeated BluetoothGATTCharacteristic characteristics = 3 [(fixed_vector) = true];
 
   // New field for efficient UUID (v1.12+)
   // Only one of uuid or short_uuid will be set.
diff --git a/esphome/components/api/api_options.proto b/esphome/components/api/api_options.proto
index 633f39b552..ead8ac0bbc 100644
--- a/esphome/components/api/api_options.proto
+++ b/esphome/components/api/api_options.proto
@@ -64,4 +64,10 @@ extend google.protobuf.FieldOptions {
     // This is typically done through methods returning const T& or special accessor
     // methods like get_options() or supported_modes_for_api_().
     optional string container_pointer = 50001;
+
+    // fixed_vector: Use FixedVector instead of std::vector for repeated fields
+    // When set, the repeated field will use FixedVector<T> which requires calling
+    // init(size) before adding elements. This eliminates std::vector template overhead
+    // and is ideal when the exact size is known before populating the array.
+    optional bool fixed_vector = 50013 [default=false];
 }
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index d9e68ece9b..1798458393 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1923,7 +1923,7 @@ class BluetoothGATTCharacteristic final : public ProtoMessage {
   std::array<uint64_t, 2> uuid{};
   uint32_t handle{0};
   uint32_t properties{0};
-  std::vector<BluetoothGATTDescriptor> descriptors{};
+  FixedVector<BluetoothGATTDescriptor> descriptors{};
   uint32_t short_uuid{0};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
@@ -1937,7 +1937,7 @@ class BluetoothGATTService final : public ProtoMessage {
  public:
   std::array<uint64_t, 2> uuid{};
   uint32_t handle{0};
-  std::vector<BluetoothGATTCharacteristic> characteristics{};
+  FixedVector<BluetoothGATTCharacteristic> characteristics{};
   uint32_t short_uuid{0};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index 9d780692ec..a6a09bf7c5 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -749,13 +749,29 @@ class ProtoSize {
   template<typename MessageType>
   inline void add_repeated_message(uint32_t field_id_size, const std::vector<MessageType> &messages) {
     // Skip if the vector is empty
-    if (messages.empty()) {
-      return;
+    if (!messages.empty()) {
+      // Use the force version for all messages in the repeated field
+      for (const auto &message : messages) {
+        add_message_object_force(field_id_size, message);
+      }
     }
+  }
 
-    // Use the force version for all messages in the repeated field
-    for (const auto &message : messages) {
-      add_message_object_force(field_id_size, message);
+  /**
+   * @brief Calculates and adds the sizes of all messages in a repeated field to the total message size (FixedVector
+   * version)
+   *
+   * @tparam MessageType The type of the nested messages in the FixedVector
+   * @param messages FixedVector of message objects
+   */
+  template<typename MessageType>
+  inline void add_repeated_message(uint32_t field_id_size, const FixedVector<MessageType> &messages) {
+    // Skip if the fixed vector is empty
+    if (!messages.empty()) {
+      // Use the force version for all messages in the repeated field
+      for (const auto &message : messages) {
+        add_message_object_force(field_id_size, message);
+      }
     }
   }
 };
diff --git a/esphome/components/bluetooth_proxy/bluetooth_connection.cpp b/esphome/components/bluetooth_proxy/bluetooth_connection.cpp
index cde82fbfb0..6f172b0bcf 100644
--- a/esphome/components/bluetooth_proxy/bluetooth_connection.cpp
+++ b/esphome/components/bluetooth_proxy/bluetooth_connection.cpp
@@ -230,8 +230,8 @@ void BluetoothConnection::send_service_for_discovery_() {
     service_resp.handle = service_result.start_handle;
 
     if (total_char_count > 0) {
-      // Reserve space and process characteristics
-      service_resp.characteristics.reserve(total_char_count);
+      // Initialize FixedVector with exact count and process characteristics
+      service_resp.characteristics.init(total_char_count);
       uint16_t char_offset = 0;
       esp_gattc_char_elem_t char_result;
       while (true) {  // characteristics
@@ -275,8 +275,8 @@ void BluetoothConnection::send_service_for_discovery_() {
           continue;
         }
 
-        // Reserve space and process descriptors
-        characteristic_resp.descriptors.reserve(total_desc_count);
+        // Initialize FixedVector with exact count and process descriptors
+        characteristic_resp.descriptors.init(total_desc_count);
         uint16_t desc_offset = 0;
         esp_gattc_descr_elem_t desc_result;
         while (true) {  // descriptors
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index b5a0a1c8ac..2bdfcb4e2a 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -181,6 +181,31 @@ template<typename T> class FixedVector {
   FixedVector(const FixedVector &) = delete;
   FixedVector &operator=(const FixedVector &) = delete;
 
+  // Enable move semantics for use in containers
+  FixedVector(FixedVector &&other) noexcept : data_(other.data_), size_(other.size_), capacity_(other.capacity_) {
+    other.data_ = nullptr;
+    other.size_ = 0;
+    other.capacity_ = 0;
+  }
+
+  FixedVector &operator=(FixedVector &&other) noexcept {
+    if (this != &other) {
+      // Delete our current data
+      if (data_ != nullptr) {
+        delete[] data_;
+      }
+      // Take ownership of other's data
+      data_ = other.data_;
+      size_ = other.size_;
+      capacity_ = other.capacity_;
+      // Leave other in valid empty state
+      other.data_ = nullptr;
+      other.size_ = 0;
+      other.capacity_ = 0;
+    }
+    return *this;
+  }
+
   // Allocate capacity - can only be called once on empty vector
   void init(size_t n) {
     if (data_ == nullptr && n > 0) {
@@ -199,12 +224,33 @@ template<typename T> class FixedVector {
     }
   }
 
+  /// Construct element in place and return reference
+  /// Caller must ensure sufficient capacity was allocated via init()
+  T &emplace_back() {
+    if (size_ < capacity_) {
+      return data_[size_++];
+    }
+    // Should never happen with proper init() - return last element to avoid crash
+    return data_[capacity_ - 1];
+  }
+
+  /// Access last element
+  T &back() { return data_[size_ - 1]; }
+  const T &back() const { return data_[size_ - 1]; }
+
   size_t size() const { return size_; }
+  bool empty() const { return size_ == 0; }
 
   /// Access element without bounds checking (matches std::vector behavior)
   /// Caller must ensure index is valid (i < size())
   T &operator[](size_t i) { return data_[i]; }
   const T &operator[](size_t i) const { return data_[i]; }
+
+  /// Iterators for range-based for loops
+  T *begin() { return data_; }
+  T *end() { return data_ + size_; }
+  const T *begin() const { return data_; }
+  const T *end() const { return data_ + size_; }
 };
 
 ///@}
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 487c187372..9a55f1d136 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -1415,6 +1415,8 @@ class RepeatedTypeInfo(TypeInfo):
         # Check if this is a pointer field by looking for container_pointer option
         self._container_type = get_field_opt(field, pb.container_pointer, "")
         self._use_pointer = bool(self._container_type)
+        # Check if this should use FixedVector instead of std::vector
+        self._use_fixed_vector = get_field_opt(field, pb.fixed_vector, False)
 
         # For repeated fields, we need to get the base type info
         # but we can't call create_field_type_info as it would cause recursion
@@ -1438,6 +1440,8 @@ class RepeatedTypeInfo(TypeInfo):
             if "<" in self._container_type and ">" in self._container_type:
                 return f"const {self._container_type}*"
             return f"const {self._container_type}<{self._ti.cpp_type}>*"
+        if self._use_fixed_vector:
+            return f"FixedVector<{self._ti.cpp_type}>"
         return f"std::vector<{self._ti.cpp_type}>"
 
     @property

From 347501d895cb42d1a15633d4b2fd684ae6a2af6a Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sun, 12 Oct 2025 19:39:55 -1000
Subject: [PATCH 02/16] wifi fixed vector

---
 esphome/components/wifi/wifi_component.cpp    |  2 +-
 esphome/components/wifi/wifi_component.h      |  4 +-
 .../wifi/wifi_component_esp8266.cpp           |  8 ++++
 .../wifi/wifi_component_esp_idf.cpp           |  5 +-
 .../wifi/wifi_component_libretiny.cpp         |  2 +-
 esphome/core/helpers.h                        | 46 +++++++++++++++----
 6 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/esphome/components/wifi/wifi_component.cpp b/esphome/components/wifi/wifi_component.cpp
index 2e083d4c68..1bb2674ad7 100644
--- a/esphome/components/wifi/wifi_component.cpp
+++ b/esphome/components/wifi/wifi_component.cpp
@@ -552,7 +552,7 @@ void WiFiComponent::start_scanning() {
 // Using insertion sort instead of std::stable_sort saves flash memory
 // by avoiding template instantiations (std::rotate, std::stable_sort, lambdas)
 // IMPORTANT: This sort is stable (preserves relative order of equal elements)
-static void insertion_sort_scan_results(std::vector<WiFiScanResult> &results) {
+static void insertion_sort_scan_results(FixedVector<WiFiScanResult> &results) {
   const size_t size = results.size();
   for (size_t i = 1; i < size; i++) {
     // Make a copy to avoid issues with move semantics during comparison
diff --git a/esphome/components/wifi/wifi_component.h b/esphome/components/wifi/wifi_component.h
index ee62ec1a69..e1c3d6df88 100644
--- a/esphome/components/wifi/wifi_component.h
+++ b/esphome/components/wifi/wifi_component.h
@@ -278,7 +278,7 @@ class WiFiComponent : public Component {
   std::string get_use_address() const;
   void set_use_address(const std::string &use_address);
 
-  const std::vector<WiFiScanResult> &get_scan_result() const { return scan_result_; }
+  const FixedVector<WiFiScanResult> &get_scan_result() const { return scan_result_; }
 
   network::IPAddress wifi_soft_ap_ip();
 
@@ -385,7 +385,7 @@ class WiFiComponent : public Component {
   std::string use_address_;
   std::vector<WiFiAP> sta_;
   std::vector<WiFiSTAPriority> sta_priorities_;
-  std::vector<WiFiScanResult> scan_result_;
+  FixedVector<WiFiScanResult> scan_result_;
   WiFiAP selected_ap_;
   WiFiAP ap_;
   optional<float> output_power_;
diff --git a/esphome/components/wifi/wifi_component_esp8266.cpp b/esphome/components/wifi/wifi_component_esp8266.cpp
index 3b3b4b139c..59909b2cb5 100644
--- a/esphome/components/wifi/wifi_component_esp8266.cpp
+++ b/esphome/components/wifi/wifi_component_esp8266.cpp
@@ -696,7 +696,15 @@ void WiFiComponent::wifi_scan_done_callback_(void *arg, STATUS status) {
     this->retry_connect();
     return;
   }
+
+  // Count the number of results first
   auto *head = reinterpret_cast<bss_info *>(arg);
+  size_t count = 0;
+  for (bss_info *it = head; it != nullptr; it = STAILQ_NEXT(it, next)) {
+    count++;
+  }
+
+  this->scan_result_.init(count);
   for (bss_info *it = head; it != nullptr; it = STAILQ_NEXT(it, next)) {
     WiFiScanResult res({it->bssid[0], it->bssid[1], it->bssid[2], it->bssid[3], it->bssid[4], it->bssid[5]},
                        std::string(reinterpret_cast<char *>(it->ssid), it->ssid_len), it->channel, it->rssi,
diff --git a/esphome/components/wifi/wifi_component_esp_idf.cpp b/esphome/components/wifi/wifi_component_esp_idf.cpp
index ccec800205..4c719ef4c3 100644
--- a/esphome/components/wifi/wifi_component_esp_idf.cpp
+++ b/esphome/components/wifi/wifi_component_esp_idf.cpp
@@ -763,8 +763,9 @@ void WiFiComponent::wifi_process_event_(IDFWiFiEvent *data) {
     const auto &it = data->data.sta_scan_done;
     ESP_LOGV(TAG, "Scan done: status=%" PRIu32 " number=%u scan_id=%u", it.status, it.number, it.scan_id);
 
-    scan_result_.clear();
     this->scan_done_ = true;
+    scan_result_.clear();
+
     if (it.status != 0) {
       // scan error
       return;
@@ -784,7 +785,7 @@ void WiFiComponent::wifi_process_event_(IDFWiFiEvent *data) {
     }
     records.resize(number);
 
-    scan_result_.reserve(number);
+    scan_result_.init(number);
     for (int i = 0; i < number; i++) {
       auto &record = records[i];
       bssid_t bssid;
diff --git a/esphome/components/wifi/wifi_component_libretiny.cpp b/esphome/components/wifi/wifi_component_libretiny.cpp
index b15f710150..cb179d9022 100644
--- a/esphome/components/wifi/wifi_component_libretiny.cpp
+++ b/esphome/components/wifi/wifi_component_libretiny.cpp
@@ -411,7 +411,7 @@ void WiFiComponent::wifi_scan_done_callback_() {
   if (num < 0)
     return;
 
-  this->scan_result_.reserve(static_cast<unsigned int>(num));
+  this->scan_result_.init(static_cast<unsigned int>(num));
   for (int i = 0; i < num; i++) {
     String ssid = WiFi.SSID(i);
     wifi_auth_mode_t authmode = WiFi.encryptionType(i);
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index b5a0a1c8ac..12e921e3be 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -168,34 +168,54 @@ template<typename T> class FixedVector {
   size_t size_{0};
   size_t capacity_{0};
 
+  // Helper to destroy elements and free memory
+  void cleanup_() {
+    if (data_ != nullptr) {
+      // Manually destroy all elements
+      for (size_t i = 0; i < size_; i++) {
+        data_[i].~T();
+      }
+      // Free raw memory
+      ::operator delete(data_);
+    }
+  }
+
  public:
   FixedVector() = default;
 
-  ~FixedVector() {
-    if (data_ != nullptr) {
-      delete[] data_;
-    }
-  }
+  ~FixedVector() { cleanup_(); }
 
   // Disable copy to avoid accidental copies
   FixedVector(const FixedVector &) = delete;
   FixedVector &operator=(const FixedVector &) = delete;
 
-  // Allocate capacity - can only be called once on empty vector
+  // Allocate capacity - can be called multiple times to reinit
   void init(size_t n) {
-    if (data_ == nullptr && n > 0) {
-      data_ = new T[n];
+    cleanup_();
+    data_ = nullptr;
+    capacity_ = 0;
+    size_ = 0;
+    if (n > 0) {
+      // Allocate raw memory without calling constructors
+      data_ = static_cast<T *>(::operator new(n * sizeof(T)));
       capacity_ = n;
-      size_ = 0;
     }
   }
 
+  // Clear the vector (reset size to 0, keep capacity)
+  void clear() { size_ = 0; }
+
+  // Check if vector is empty
+  bool empty() const { return size_ == 0; }
+
   /// Add element without bounds checking
   /// Caller must ensure sufficient capacity was allocated via init()
   /// Silently ignores pushes beyond capacity (no exception or assertion)
   void push_back(const T &value) {
     if (size_ < capacity_) {
-      data_[size_++] = value;
+      // Use placement new to construct the object in pre-allocated memory
+      new (&data_[size_]) T(value);
+      size_++;
     }
   }
 
@@ -205,6 +225,12 @@ template<typename T> class FixedVector {
   /// Caller must ensure index is valid (i < size())
   T &operator[](size_t i) { return data_[i]; }
   const T &operator[](size_t i) const { return data_[i]; }
+
+  // Iterator support for range-based for loops
+  T *begin() { return data_; }
+  T *end() { return data_ + size_; }
+  const T *begin() const { return data_; }
+  const T *end() const { return data_ + size_; }
 };
 
 ///@}

From c652aa375a402a9888821955699bf1c93fb9de1f Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Mon, 13 Oct 2025 13:10:46 -1000
Subject: [PATCH 03/16] Bump pylint from 3.3.9 to 4.0.0 (#11211)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
---
 requirements_test.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/requirements_test.txt b/requirements_test.txt
index 51b8e6f8ed..c4227fdbde 100644
--- a/requirements_test.txt
+++ b/requirements_test.txt
@@ -1,4 +1,4 @@
-pylint==3.3.9
+pylint==4.0.0
 flake8==7.3.0  # also change in .pre-commit-config.yaml when updating
 ruff==0.14.0  # also change in .pre-commit-config.yaml when updating
 pyupgrade==3.21.0  # also change in .pre-commit-config.yaml when updating

From fe07c342467b4d42388ff2eeafff338d5e03f20b Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Tue, 14 Oct 2025 00:00:45 +0000
Subject: [PATCH 04/16] Bump aioesphomeapi from 41.14.0 to 41.16.0 (#11215)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
---
 requirements.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/requirements.txt b/requirements.txt
index 9937709c1c..1142c587b6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,7 +12,7 @@ platformio==6.1.18  # When updating platformio, also update /docker/Dockerfile
 esptool==5.1.0
 click==8.1.7
 esphome-dashboard==20251013.0
-aioesphomeapi==41.14.0
+aioesphomeapi==41.16.0
 zeroconf==0.148.0
 puremagic==1.30
 ruamel.yaml==0.18.15 # dashboard_import

From 22370c0ad178ad9931cf4d54197a9edf52f04759 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:03:08 -1000
Subject: [PATCH 05/16] merge

---
 esphome/core/helpers.h | 42 +++++++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 11 deletions(-)

diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 80ce21af57..084ad28882 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -168,14 +168,22 @@ template<typename T> class FixedVector {
   size_t size_{0};
   size_t capacity_{0};
 
+  // Helper to destroy elements and free memory
+  void cleanup_() {
+    if (data_ != nullptr) {
+      // Manually destroy all elements
+      for (size_t i = 0; i < size_; i++) {
+        data_[i].~T();
+      }
+      // Free raw memory
+      ::operator delete(data_);
+    }
+  }
+
  public:
   FixedVector() = default;
 
-  ~FixedVector() {
-    if (data_ != nullptr) {
-      delete[] data_;
-    }
-  }
+  ~FixedVector() { cleanup_(); }
 
   // Enable move semantics for use in containers
   FixedVector(FixedVector &&other) noexcept : data_(other.data_), size_(other.size_), capacity_(other.capacity_) {
@@ -202,21 +210,33 @@ template<typename T> class FixedVector {
     return *this;
   }
 
-  // Allocate capacity - can only be called once on empty vector
+  // Allocate capacity - can be called multiple times to reinit
   void init(size_t n) {
-    if (data_ == nullptr && n > 0) {
-      data_ = new T[n];
+    cleanup_();
+    data_ = nullptr;
+    capacity_ = 0;
+    size_ = 0;
+    if (n > 0) {
+      // Allocate raw memory without calling constructors
+      data_ = static_cast<T *>(::operator new(n * sizeof(T)));
       capacity_ = n;
-      size_ = 0;
     }
   }
 
+  // Clear the vector (reset size to 0, keep capacity)
+  void clear() { size_ = 0; }
+
+  // Check if vector is empty
+  bool empty() const { return size_ == 0; }
+
   /// Add element without bounds checking
   /// Caller must ensure sufficient capacity was allocated via init()
   /// Silently ignores pushes beyond capacity (no exception or assertion)
   void push_back(const T &value) {
     if (size_ < capacity_) {
-      data_[size_++] = value;
+      // Use placement new to construct the object in pre-allocated memory
+      new (&data_[size_]) T(value);
+      size_++;
     }
   }
 
@@ -242,7 +262,7 @@ template<typename T> class FixedVector {
   T &operator[](size_t i) { return data_[i]; }
   const T &operator[](size_t i) const { return data_[i]; }
 
-  /// Iterators for range-based for loops
+  // Iterator support for range-based for loops
   T *begin() { return data_; }
   T *end() { return data_ + size_; }
   const T *begin() const { return data_; }

From fbef9b126403ca49999b589ba5670fbe980b7c9e Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:03:59 -1000
Subject: [PATCH 06/16] revert

---
 .../components/bluetooth_proxy/bluetooth_connection.cpp   | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/esphome/components/bluetooth_proxy/bluetooth_connection.cpp b/esphome/components/bluetooth_proxy/bluetooth_connection.cpp
index 6f172b0bcf..cde82fbfb0 100644
--- a/esphome/components/bluetooth_proxy/bluetooth_connection.cpp
+++ b/esphome/components/bluetooth_proxy/bluetooth_connection.cpp
@@ -230,8 +230,8 @@ void BluetoothConnection::send_service_for_discovery_() {
     service_resp.handle = service_result.start_handle;
 
     if (total_char_count > 0) {
-      // Initialize FixedVector with exact count and process characteristics
-      service_resp.characteristics.init(total_char_count);
+      // Reserve space and process characteristics
+      service_resp.characteristics.reserve(total_char_count);
       uint16_t char_offset = 0;
       esp_gattc_char_elem_t char_result;
       while (true) {  // characteristics
@@ -275,8 +275,8 @@ void BluetoothConnection::send_service_for_discovery_() {
           continue;
         }
 
-        // Initialize FixedVector with exact count and process descriptors
-        characteristic_resp.descriptors.init(total_desc_count);
+        // Reserve space and process descriptors
+        characteristic_resp.descriptors.reserve(total_desc_count);
         uint16_t desc_offset = 0;
         esp_gattc_descr_elem_t desc_result;
         while (true) {  // descriptors

From ddf6e0a7b61ac09db7bfdafc17362cf4804b189f Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:04:15 -1000
Subject: [PATCH 07/16] revert

---
 esphome/components/api/api.proto         |  4 ++--
 esphome/components/api/api_options.proto |  6 ------
 esphome/components/api/api_pb2.h         |  4 ++--
 esphome/components/api/proto.h           | 26 +++++-------------------
 4 files changed, 9 insertions(+), 31 deletions(-)

diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 9b714d00f1..87f477799d 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -1519,7 +1519,7 @@ message BluetoothGATTCharacteristic {
   repeated uint64 uuid = 1 [(fixed_array_size) = 2, (fixed_array_skip_zero) = true];
   uint32 handle = 2;
   uint32 properties = 3;
-  repeated BluetoothGATTDescriptor descriptors = 4 [(fixed_vector) = true];
+  repeated BluetoothGATTDescriptor descriptors = 4;
 
   // New field for efficient UUID (v1.12+)
   // Only one of uuid or short_uuid will be set.
@@ -1531,7 +1531,7 @@ message BluetoothGATTCharacteristic {
 message BluetoothGATTService {
   repeated uint64 uuid = 1 [(fixed_array_size) = 2, (fixed_array_skip_zero) = true];
   uint32 handle = 2;
-  repeated BluetoothGATTCharacteristic characteristics = 3 [(fixed_vector) = true];
+  repeated BluetoothGATTCharacteristic characteristics = 3;
 
   // New field for efficient UUID (v1.12+)
   // Only one of uuid or short_uuid will be set.
diff --git a/esphome/components/api/api_options.proto b/esphome/components/api/api_options.proto
index ead8ac0bbc..633f39b552 100644
--- a/esphome/components/api/api_options.proto
+++ b/esphome/components/api/api_options.proto
@@ -64,10 +64,4 @@ extend google.protobuf.FieldOptions {
     // This is typically done through methods returning const T& or special accessor
     // methods like get_options() or supported_modes_for_api_().
     optional string container_pointer = 50001;
-
-    // fixed_vector: Use FixedVector instead of std::vector for repeated fields
-    // When set, the repeated field will use FixedVector<T> which requires calling
-    // init(size) before adding elements. This eliminates std::vector template overhead
-    // and is ideal when the exact size is known before populating the array.
-    optional bool fixed_vector = 50013 [default=false];
 }
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 1798458393..d9e68ece9b 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1923,7 +1923,7 @@ class BluetoothGATTCharacteristic final : public ProtoMessage {
   std::array<uint64_t, 2> uuid{};
   uint32_t handle{0};
   uint32_t properties{0};
-  FixedVector<BluetoothGATTDescriptor> descriptors{};
+  std::vector<BluetoothGATTDescriptor> descriptors{};
   uint32_t short_uuid{0};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
@@ -1937,7 +1937,7 @@ class BluetoothGATTService final : public ProtoMessage {
  public:
   std::array<uint64_t, 2> uuid{};
   uint32_t handle{0};
-  FixedVector<BluetoothGATTCharacteristic> characteristics{};
+  std::vector<BluetoothGATTCharacteristic> characteristics{};
   uint32_t short_uuid{0};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index a6a09bf7c5..9d780692ec 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -749,29 +749,13 @@ class ProtoSize {
   template<typename MessageType>
   inline void add_repeated_message(uint32_t field_id_size, const std::vector<MessageType> &messages) {
     // Skip if the vector is empty
-    if (!messages.empty()) {
-      // Use the force version for all messages in the repeated field
-      for (const auto &message : messages) {
-        add_message_object_force(field_id_size, message);
-      }
+    if (messages.empty()) {
+      return;
     }
-  }
 
-  /**
-   * @brief Calculates and adds the sizes of all messages in a repeated field to the total message size (FixedVector
-   * version)
-   *
-   * @tparam MessageType The type of the nested messages in the FixedVector
-   * @param messages FixedVector of message objects
-   */
-  template<typename MessageType>
-  inline void add_repeated_message(uint32_t field_id_size, const FixedVector<MessageType> &messages) {
-    // Skip if the fixed vector is empty
-    if (!messages.empty()) {
-      // Use the force version for all messages in the repeated field
-      for (const auto &message : messages) {
-        add_message_object_force(field_id_size, message);
-      }
+    // Use the force version for all messages in the repeated field
+    for (const auto &message : messages) {
+      add_message_object_force(field_id_size, message);
     }
   }
 };

From d5234e335709e63eb022240c98c9c885994b247f Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:04:39 -1000
Subject: [PATCH 08/16] merge

---
 esphome/components/wifi/wifi_component_esp_idf.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/esphome/components/wifi/wifi_component_esp_idf.cpp b/esphome/components/wifi/wifi_component_esp_idf.cpp
index 4c719ef4c3..e45b873e8d 100644
--- a/esphome/components/wifi/wifi_component_esp_idf.cpp
+++ b/esphome/components/wifi/wifi_component_esp_idf.cpp
@@ -763,8 +763,8 @@ void WiFiComponent::wifi_process_event_(IDFWiFiEvent *data) {
     const auto &it = data->data.sta_scan_done;
     ESP_LOGV(TAG, "Scan done: status=%" PRIu32 " number=%u scan_id=%u", it.status, it.number, it.scan_id);
 
-    this->scan_done_ = true;
     scan_result_.clear();
+    this->scan_done_ = true;
 
     if (it.status != 0) {
       // scan error

From ce46f1630859861534f91ed15e03a3ae5c335855 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:05:19 -1000
Subject: [PATCH 09/16] merge

---
 esphome/components/wifi/wifi_component_esp_idf.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/esphome/components/wifi/wifi_component_esp_idf.cpp b/esphome/components/wifi/wifi_component_esp_idf.cpp
index e45b873e8d..951f5803a6 100644
--- a/esphome/components/wifi/wifi_component_esp_idf.cpp
+++ b/esphome/components/wifi/wifi_component_esp_idf.cpp
@@ -765,7 +765,6 @@ void WiFiComponent::wifi_process_event_(IDFWiFiEvent *data) {
 
     scan_result_.clear();
     this->scan_done_ = true;
-
     if (it.status != 0) {
       // scan error
       return;

From 7792a115c26d93b7d18cb112008457a30dfad2ea Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:05:31 -1000
Subject: [PATCH 10/16] merge

---
 script/api_protobuf/api_protobuf.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 9a55f1d136..487c187372 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -1415,8 +1415,6 @@ class RepeatedTypeInfo(TypeInfo):
         # Check if this is a pointer field by looking for container_pointer option
         self._container_type = get_field_opt(field, pb.container_pointer, "")
         self._use_pointer = bool(self._container_type)
-        # Check if this should use FixedVector instead of std::vector
-        self._use_fixed_vector = get_field_opt(field, pb.fixed_vector, False)
 
         # For repeated fields, we need to get the base type info
         # but we can't call create_field_type_info as it would cause recursion
@@ -1440,8 +1438,6 @@ class RepeatedTypeInfo(TypeInfo):
             if "<" in self._container_type and ">" in self._container_type:
                 return f"const {self._container_type}*"
             return f"const {self._container_type}<{self._ti.cpp_type}>*"
-        if self._use_fixed_vector:
-            return f"FixedVector<{self._ti.cpp_type}>"
         return f"std::vector<{self._ti.cpp_type}>"
 
     @property

From bb2f568f3d4971b536a6c5a59bb25bb59fc45365 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:07:52 -1000
Subject: [PATCH 11/16] merge

---
 esphome/core/helpers.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 084ad28882..6b04af3c7c 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -226,9 +226,6 @@ template<typename T> class FixedVector {
   // Clear the vector (reset size to 0, keep capacity)
   void clear() { size_ = 0; }
 
-  // Check if vector is empty
-  bool empty() const { return size_ == 0; }
-
   /// Add element without bounds checking
   /// Caller must ensure sufficient capacity was allocated via init()
   /// Silently ignores pushes beyond capacity (no exception or assertion)

From c9a1664398e8a4a9c8f9a3c38d5e67dadf5c6303 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:08:27 -1000
Subject: [PATCH 12/16] merge

---
 esphome/core/helpers.h | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 084ad28882..6b04af3c7c 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -226,9 +226,6 @@ template<typename T> class FixedVector {
   // Clear the vector (reset size to 0, keep capacity)
   void clear() { size_ = 0; }
 
-  // Check if vector is empty
-  bool empty() const { return size_ == 0; }
-
   /// Add element without bounds checking
   /// Caller must ensure sufficient capacity was allocated via init()
   /// Silently ignores pushes beyond capacity (no exception or assertion)

From b878aa0270c2faaedee25342d1a15b69c43dbad6 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:09:44 -1000
Subject: [PATCH 13/16] fix

---
 esphome/core/helpers.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 6b04af3c7c..a3c0447a8d 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -226,6 +226,14 @@ template<typename T> class FixedVector {
   // Clear the vector (reset size to 0, keep capacity)
   void clear() { size_ = 0; }
 
+  // Shrink capacity to fit current size (frees all memory)
+  void shrink_to_fit() {
+    cleanup_();
+    data_ = nullptr;
+    capacity_ = 0;
+    size_ = 0;
+  }
+
   /// Add element without bounds checking
   /// Caller must ensure sufficient capacity was allocated via init()
   /// Silently ignores pushes beyond capacity (no exception or assertion)

From de10d781259fb73b605fed83d5c14812997234b8 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:10:41 -1000
Subject: [PATCH 14/16] dry

---
 esphome/core/helpers.h | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index a3c0447a8d..e838c82f3e 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -180,6 +180,13 @@ template<typename T> class FixedVector {
     }
   }
 
+  // Helper to reset pointers after cleanup
+  void reset_() {
+    data_ = nullptr;
+    capacity_ = 0;
+    size_ = 0;
+  }
+
  public:
   FixedVector() = default;
 
@@ -187,25 +194,19 @@ template<typename T> class FixedVector {
 
   // Enable move semantics for use in containers
   FixedVector(FixedVector &&other) noexcept : data_(other.data_), size_(other.size_), capacity_(other.capacity_) {
-    other.data_ = nullptr;
-    other.size_ = 0;
-    other.capacity_ = 0;
+    other.reset_();
   }
 
   FixedVector &operator=(FixedVector &&other) noexcept {
     if (this != &other) {
       // Delete our current data
-      if (data_ != nullptr) {
-        delete[] data_;
-      }
+      cleanup_();
       // Take ownership of other's data
       data_ = other.data_;
       size_ = other.size_;
       capacity_ = other.capacity_;
       // Leave other in valid empty state
-      other.data_ = nullptr;
-      other.size_ = 0;
-      other.capacity_ = 0;
+      other.reset_();
     }
     return *this;
   }
@@ -213,9 +214,7 @@ template<typename T> class FixedVector {
   // Allocate capacity - can be called multiple times to reinit
   void init(size_t n) {
     cleanup_();
-    data_ = nullptr;
-    capacity_ = 0;
-    size_ = 0;
+    reset_();
     if (n > 0) {
       // Allocate raw memory without calling constructors
       data_ = static_cast<T *>(::operator new(n * sizeof(T)));
@@ -229,9 +228,7 @@ template<typename T> class FixedVector {
   // Shrink capacity to fit current size (frees all memory)
   void shrink_to_fit() {
     cleanup_();
-    data_ = nullptr;
-    capacity_ = 0;
-    size_ = 0;
+    reset_();
   }
 
   /// Add element without bounds checking

From 453ab0adb8ec9f6da7af1d84590e1a2d309711e7 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:10:56 -1000
Subject: [PATCH 15/16] backmerge

---
 esphome/core/helpers.h | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index 6b04af3c7c..e838c82f3e 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -180,6 +180,13 @@ template<typename T> class FixedVector {
     }
   }
 
+  // Helper to reset pointers after cleanup
+  void reset_() {
+    data_ = nullptr;
+    capacity_ = 0;
+    size_ = 0;
+  }
+
  public:
   FixedVector() = default;
 
@@ -187,25 +194,19 @@ template<typename T> class FixedVector {
 
   // Enable move semantics for use in containers
   FixedVector(FixedVector &&other) noexcept : data_(other.data_), size_(other.size_), capacity_(other.capacity_) {
-    other.data_ = nullptr;
-    other.size_ = 0;
-    other.capacity_ = 0;
+    other.reset_();
   }
 
   FixedVector &operator=(FixedVector &&other) noexcept {
     if (this != &other) {
       // Delete our current data
-      if (data_ != nullptr) {
-        delete[] data_;
-      }
+      cleanup_();
       // Take ownership of other's data
       data_ = other.data_;
       size_ = other.size_;
       capacity_ = other.capacity_;
       // Leave other in valid empty state
-      other.data_ = nullptr;
-      other.size_ = 0;
-      other.capacity_ = 0;
+      other.reset_();
     }
     return *this;
   }
@@ -213,9 +214,7 @@ template<typename T> class FixedVector {
   // Allocate capacity - can be called multiple times to reinit
   void init(size_t n) {
     cleanup_();
-    data_ = nullptr;
-    capacity_ = 0;
-    size_ = 0;
+    reset_();
     if (n > 0) {
       // Allocate raw memory without calling constructors
       data_ = static_cast<T *>(::operator new(n * sizeof(T)));
@@ -226,6 +225,12 @@ template<typename T> class FixedVector {
   // Clear the vector (reset size to 0, keep capacity)
   void clear() { size_ = 0; }
 
+  // Shrink capacity to fit current size (frees all memory)
+  void shrink_to_fit() {
+    cleanup_();
+    reset_();
+  }
+
   /// Add element without bounds checking
   /// Caller must ensure sufficient capacity was allocated via init()
   /// Silently ignores pushes beyond capacity (no exception or assertion)

From 7b5a86e4df1a90f2521b283d7ec8a17c5c5e2359 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 13 Oct 2025 14:15:37 -1000
Subject: [PATCH 16/16] fixes

---
 esphome/components/wifi/wifi_component.cpp |  2 +-
 esphome/components/wifi/wifi_component.h   | 12 ++++++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/esphome/components/wifi/wifi_component.cpp b/esphome/components/wifi/wifi_component.cpp
index 3cdc034be6..8308421220 100644
--- a/esphome/components/wifi/wifi_component.cpp
+++ b/esphome/components/wifi/wifi_component.cpp
@@ -554,7 +554,7 @@ void WiFiComponent::start_scanning() {
 // Using insertion sort instead of std::stable_sort saves flash memory
 // by avoiding template instantiations (std::rotate, std::stable_sort, lambdas)
 // IMPORTANT: This sort is stable (preserves relative order of equal elements)
-static void insertion_sort_scan_results(FixedVector<WiFiScanResult> &results) {
+template<typename VectorType> static void insertion_sort_scan_results(VectorType &results) {
   const size_t size = results.size();
   for (size_t i = 1; i < size; i++) {
     // Make a copy to avoid issues with move semantics during comparison
diff --git a/esphome/components/wifi/wifi_component.h b/esphome/components/wifi/wifi_component.h
index e1c3d6df88..bbb4649027 100644
--- a/esphome/components/wifi/wifi_component.h
+++ b/esphome/components/wifi/wifi_component.h
@@ -121,6 +121,14 @@ struct EAPAuth {
 
 using bssid_t = std::array<uint8_t, 6>;
 
+// Use std::vector for RP2040 since scan count is unknown (callback-based)
+// Use FixedVector for other platforms where count is queried first
+#ifdef USE_RP2040
+template<typename T> using wifi_scan_vector_t = std::vector<T>;
+#else
+template<typename T> using wifi_scan_vector_t = FixedVector<T>;
+#endif
+
 class WiFiAP {
  public:
   void set_ssid(const std::string &ssid);
@@ -278,7 +286,7 @@ class WiFiComponent : public Component {
   std::string get_use_address() const;
   void set_use_address(const std::string &use_address);
 
-  const FixedVector<WiFiScanResult> &get_scan_result() const { return scan_result_; }
+  const wifi_scan_vector_t<WiFiScanResult> &get_scan_result() const { return scan_result_; }
 
   network::IPAddress wifi_soft_ap_ip();
 
@@ -385,7 +393,7 @@ class WiFiComponent : public Component {
   std::string use_address_;
   std::vector<WiFiAP> sta_;
   std::vector<WiFiSTAPriority> sta_priorities_;
-  FixedVector<WiFiScanResult> scan_result_;
+  wifi_scan_vector_t<WiFiScanResult> scan_result_;
   WiFiAP selected_ap_;
   WiFiAP ap_;
   optional<float> output_power_;