[api] Fix missing ifdef guards for field_ifdef fields in protobuf base classes (#9693)

esphome/components/api/api_connection.h

@@ -301,8 +301,10 @@ class APIConnection : public APIServerConnection {
     if (entity->has_own_name())
       msg.name = entity->get_name();
 
-    // Set common EntityBase properties
+      // Set common EntityBase properties
+#ifdef USE_ENTITY_ICON
     msg.icon = entity->get_icon();
+#endif
     msg.disabled_by_default = entity->is_disabled_by_default();
     msg.entity_category = static_cast<enums::EntityCategory>(entity->get_entity_category());
 #ifdef USE_DEVICES

esphome/components/api/api_pb2.h

@@ -292,9 +292,13 @@ class InfoResponseProtoMessage : public ProtoMessage {
   uint32_t key{0};
   std::string name{};
   bool disabled_by_default{false};
+#ifdef USE_ENTITY_ICON
   std::string icon{};
+#endif
   enums::EntityCategory entity_category{};
+#ifdef USE_DEVICES
   uint32_t device_id{0};
+#endif
 
  protected:
 };
@@ -303,7 +307,9 @@ class StateResponseProtoMessage : public ProtoMessage {
  public:
   ~StateResponseProtoMessage() override = default;
   uint32_t key{0};
+#ifdef USE_DEVICES
   uint32_t device_id{0};
+#endif
 
  protected:
 };
@@ -312,7 +318,9 @@ class CommandProtoMessage : public ProtoDecodableMessage {
  public:
   ~CommandProtoMessage() override = default;
   uint32_t key{0};
+#ifdef USE_DEVICES
   uint32_t device_id{0};
+#endif
 
  protected:
 };

script/api_protobuf/api_protobuf.py

@@ -1491,6 +1491,28 @@ def find_common_fields(
     return common_fields
 
 
+def get_common_field_ifdef(
+    field_name: str, messages: list[descriptor.DescriptorProto]
+) -> str | None:
+    """Get the field_ifdef option if it's consistent across all messages.
+
+    Args:
+        field_name: Name of the field to check
+        messages: List of messages that contain this field
+
+    Returns:
+        The field_ifdef string if all messages have the same value, None otherwise
+    """
+    field_ifdefs = {
+        get_field_opt(field, pb.field_ifdef)
+        for msg in messages
+        if (field := next((f for f in msg.field if f.name == field_name), None))
+    }
+
+    # Return the ifdef only if all messages agree on the same value
+    return field_ifdefs.pop() if len(field_ifdefs) == 1 else None
+
+
 def build_base_class(
     base_class_name: str,
     common_fields: list[descriptor.FieldDescriptorProto],
@@ -1506,9 +1528,14 @@ def build_base_class(
     for field in common_fields:
         ti = create_field_type_info(field)
 
+        # Get field_ifdef if it's consistent across all messages
+        field_ifdef = get_common_field_ifdef(field.name, messages)
+
         # Only add field declarations, not encode/decode logic
-        protected_content.extend(ti.protected_content)
+        if ti.protected_content:
-        public_content.extend(ti.public_content)
+            protected_content.extend(wrap_with_ifdef(ti.protected_content, field_ifdef))
+        if ti.public_content:
+            public_content.extend(wrap_with_ifdef(ti.public_content, field_ifdef))
 
     # Determine if any message using this base class needs decoding
     needs_decode = any(