Merge branch 'api-proto-write-presized-buffer' into integration

# Conflicts:
#	esphome/components/api/proto.h

esphome/components/api/api_pb2.cpp

@@ -111,7 +111,7 @@ void DeviceInfoResponse::encode(ProtoWriteBuffer buffer) const {
   }
 #endif
 #ifdef USE_AREAS
-  buffer.encode_message(22, this->area);
+  buffer.encode_message(22, this->area, false);
 #endif
 #ifdef USE_ZWAVE_PROXY
   buffer.encode_uint32(23, this->zwave_proxy_feature_flags);
@@ -2435,7 +2435,7 @@ void VoiceAssistantRequest::encode(ProtoWriteBuffer buffer) const {
   buffer.encode_bool(1, this->start);
   buffer.encode_string(2, this->conversation_id);
   buffer.encode_uint32(3, this->flags);
-  buffer.encode_message(4, this->audio_settings);
+  buffer.encode_message(4, this->audio_settings, false);
   buffer.encode_string(5, this->wake_word_phrase);
 }
 void VoiceAssistantRequest::calculate_size(ProtoSize &size) const {

esphome/components/api/proto.cpp

@@ -70,6 +70,16 @@ uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size
   return count;
 }
 
+#ifdef ESPHOME_DEBUG_API
+void ProtoWriteBuffer::debug_check_bounds_(size_t bytes, const char *caller) {
+  if (this->pos_ + bytes > this->buffer_->data() + this->buffer_->size()) {
+    ESP_LOGE(TAG, "ProtoWriteBuffer bounds check failed in %s: bytes=%zu offset=%td buf_size=%zu", caller, bytes,
+             this->pos_ - this->buffer_->data(), this->buffer_->size());
+    abort();
+  }
+}
+#endif
+
 void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
   const uint8_t *ptr = buffer;
   const uint8_t *end = buffer + length;

esphome/components/api/proto.h

@@ -220,10 +220,6 @@ class ProtoWriteBuffer {
   ProtoWriteBuffer(std::vector<uint8_t> *buffer) : buffer_(buffer), pos_(buffer->data() + buffer->size()) {}
   ProtoWriteBuffer(std::vector<uint8_t> *buffer, size_t write_pos)
       : buffer_(buffer), pos_(buffer->data() + write_pos) {}
-  void write(uint8_t value) {
-    this->debug_check_bounds_(1);
-    *this->pos_++ = value;
-  }
   void encode_varint_raw(uint32_t value) {
     while (value > 0x7F) {
       this->debug_check_bounds_(1);
@@ -254,10 +250,7 @@ class ProtoWriteBuffer {
    *
    * Following https://protobuf.dev/programming-guides/encoding/#structure
    */
-  void encode_field_raw(uint32_t field_id, uint32_t type) {
-    uint32_t val = (field_id << 3) | (type & WIRE_TYPE_MASK);
-    this->encode_varint_raw(val);
-  }
+  void encode_field_raw(uint32_t field_id, uint32_t type) { this->encode_varint_raw((field_id << 3) | type); }
   void encode_string(uint32_t field_id, const char *string, size_t len, bool force = false) {
     if (len == 0 && !force)
       return;
@@ -298,15 +291,22 @@ class ProtoWriteBuffer {
     this->debug_check_bounds_(1);
     *this->pos_++ = value ? 0x01 : 0x00;
   }
-  void encode_fixed32(uint32_t field_id, uint32_t value, bool force = false) {
+  __attribute__((noinline)) void encode_fixed32(uint32_t field_id, uint32_t value, bool force = false) {
     if (value == 0 && !force)
       return;
 
     this->encode_field_raw(field_id, 5);  // type 5: 32-bit fixed32
-    this->write((value >> 0) & 0xFF);
-    this->write((value >> 8) & 0xFF);
-    this->write((value >> 16) & 0xFF);
-    this->write((value >> 24) & 0xFF);
+    this->debug_check_bounds_(4);
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    // Protobuf fixed32 is little-endian, so direct copy works
+    std::memcpy(this->pos_, &value, 4);
+    this->pos_ += 4;
+#else
+    *this->pos_++ = (value >> 0) & 0xFF;
+    *this->pos_++ = (value >> 8) & 0xFF;
+    *this->pos_++ = (value >> 16) & 0xFF;
+    *this->pos_++ = (value >> 24) & 0xFF;
+#endif
   }
   // NOTE: Wire type 1 (64-bit fixed: double, fixed64, sfixed64) is intentionally
   // not supported to reduce overhead on embedded systems. All ESPHome devices are
@@ -342,15 +342,17 @@ class ProtoWriteBuffer {
   }
   /// Encode a packed repeated sint32 field (zero-copy from vector)
   void encode_packed_sint32(uint32_t field_id, const std::vector<int32_t> &values);
-  void encode_message(uint32_t field_id, const ProtoMessage &value);
+  /// Encode a nested message field (force=true for repeated, false for singular)
+  void encode_message(uint32_t field_id, const ProtoMessage &value, bool force = true);
   std::vector<uint8_t> *get_buffer() const { return buffer_; }
 
  protected:
-  void debug_check_bounds_([[maybe_unused]] size_t bytes) {
 #ifdef ESPHOME_DEBUG_API
-    assert(this->pos_ + bytes <= this->buffer_->data() + this->buffer_->size());
+  void debug_check_bounds_(size_t bytes, const char *caller = __builtin_FUNCTION());
+#else
+  void debug_check_bounds_(size_t bytes, const char *caller = __builtin_FUNCTION()) {}
 #endif
-  }
+
   std::vector<uint8_t> *buffer_;
   uint8_t *pos_;
 };
@@ -921,14 +923,19 @@ inline void ProtoWriteBuffer::encode_packed_sint32(uint32_t field_id, const std:
 }
 
 // Implementation of encode_message - must be after ProtoMessage is defined
-inline void ProtoWriteBuffer::encode_message(uint32_t field_id, const ProtoMessage &value) {
-  this->encode_field_raw(field_id, 2);  // type 2: Length-delimited message
-
+inline void ProtoWriteBuffer::encode_message(uint32_t field_id, const ProtoMessage &value, bool force) {
   // Calculate the message size first
   ProtoSize msg_size;
   value.calculate_size(msg_size);
   uint32_t msg_length_bytes = msg_size.get_size();
 
+  // Skip empty singular messages (matches add_message_field which skips when nested_size == 0)
+  // Repeated messages (force=true) are always encoded since an empty item is meaningful
+  if (msg_length_bytes == 0 && !force)
+    return;
+
+  this->encode_field_raw(field_id, 2);  // type 2: Length-delimited message
+
   // Write the length varint directly through pos_
   this->encode_varint_raw(msg_length_bytes);
 
@@ -936,6 +943,7 @@ inline void ProtoWriteBuffer::encode_message(uint32_t field_id, const ProtoMessa
   // The copy writes msg_length_bytes bytes starting from our current pos_.
   // We then advance our pos_ by the known message size.
   value.encode(*this);
+  this->debug_check_bounds_(msg_length_bytes);
   this->pos_ += msg_length_bytes;
 }
 

script/api_protobuf/api_protobuf.py

@@ -689,6 +689,14 @@ class MessageType(TypeInfo):
     def encode_func(self) -> str:
         return "encode_message"
 
+    @property
+    def encode_content(self) -> str:
+        # Singular message fields pass force=false (skip empty messages)
+        # The default for encode_nested_message is force=true (for repeated fields)
+        return (
+            f"buffer.{self.encode_func}({self.number}, this->{self.field_name}, false);"
+        )
+
     @property
     def decode_length(self) -> str:
         # Override to return None for message types because we can't use template-based