[api] Make ProtoDecodableMessage::decode() non-virtual (#15076)

esphome/components/api/api_pb2.h

@@ -1253,7 +1253,7 @@ class ExecuteServiceArgument final : public ProtoDecodableMessage {
   FixedVector<int32_t> int_array{};
   FixedVector<float> float_array{};
   FixedVector<std::string> string_array{};
-  void decode(const uint8_t *buffer, size_t length) override;
+  void decode(const uint8_t *buffer, size_t length);
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *dump_to(DumpBuffer &out) const override;
 #endif
@@ -1278,7 +1278,7 @@ class ExecuteServiceRequest final : public ProtoDecodableMessage {
 #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES
   bool return_response{false};
 #endif
-  void decode(const uint8_t *buffer, size_t length) override;
+  void decode(const uint8_t *buffer, size_t length);
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *dump_to(DumpBuffer &out) const override;
 #endif

esphome/components/api/proto.h

@@ -152,8 +152,7 @@ class ProtoVarInt {
 #endif
 };
 
-// Forward declarations for decode_to_message and related encoding helpers
-class ProtoDecodableMessage;
+// Forward declarations for encoding helpers
 class ProtoMessage;
 class ProtoSize;
 
@@ -166,16 +165,9 @@ class ProtoLengthDelimited {
   const uint8_t *data() const { return this->value_; }
   size_t size() const { return this->length_; }
 
-  /**
-   * Decode the length-delimited data into an existing ProtoDecodableMessage instance.
-   *
-   * This method allows decoding without templates, enabling use in contexts
-   * where the message type is not known at compile time. The ProtoDecodableMessage's
-   * decode() method will be called with the raw data and length.
-   *
-   * @param msg The ProtoDecodableMessage instance to decode into
-   */
-  void decode_to_message(ProtoDecodableMessage &msg) const;
+  /// Decode the length-delimited data into a message instance.
+  /// Template preserves concrete type so decode() resolves statically.
+  template<typename T> void decode_to_message(T &msg) const;
 
  protected:
   const uint8_t *const value_;
@@ -468,7 +460,7 @@ class ProtoMessage {
 // Base class for messages that support decoding
 class ProtoDecodableMessage : public ProtoMessage {
  public:
-  virtual void decode(const uint8_t *buffer, size_t length);
+  void decode(const uint8_t *buffer, size_t length);
 
   /**
    * Count occurrences of a repeated field in a protobuf buffer.
@@ -704,8 +696,8 @@ template<typename T> inline void ProtoWriteBuffer::encode_optional_sub_message(u
   this->encode_optional_sub_message(field_id, value.calculate_size(), &value, &proto_encode_msg<T>);
 }
 
-// Implementation of decode_to_message - must be after ProtoDecodableMessage is defined
-inline void ProtoLengthDelimited::decode_to_message(ProtoDecodableMessage &msg) const {
+// Template decode_to_message - preserves concrete type so decode() resolves statically
+template<typename T> void ProtoLengthDelimited::decode_to_message(T &msg) const {
   msg.decode(this->value_, this->length_);
 }
 

script/api_protobuf/api_protobuf.py

@@ -2275,7 +2275,7 @@ def build_message_type(
         o += "}\n"
         cpp += o
         # Generate the decode() declaration in header (public method)
-        prot = "void decode(const uint8_t *buffer, size_t length) override;"
+        prot = "void decode(const uint8_t *buffer, size_t length);"
         public_content.append(prot)
 
     # Only generate encode method if this message needs encoding and has fields