From 15fca7dea86061178d18a47fc3f69525c7f4d07b Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 16 Aug 2025 09:35:12 -0400
Subject: [PATCH] Avoid object_id string allocations for all entity info API
 messages

---
 esphome/components/api/api_connection.h | 12 +++++++++---
 esphome/core/entity_base.cpp            | 10 ++++++++++
 esphome/core/entity_base.h              | 11 +++++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/esphome/components/api/api_connection.h b/esphome/components/api/api_connection.h
index 076dccfad7..7524d43299 100644
--- a/esphome/components/api/api_connection.h
+++ b/esphome/components/api/api_connection.h
@@ -301,9 +301,15 @@ class APIConnection : public APIServerConnection {
                                               APIConnection *conn, uint32_t remaining_size, bool is_single) {
     // Set common fields that are shared by all entity types
     msg.key = entity->get_object_id_hash();
-    // IMPORTANT: get_object_id() may return a temporary std::string
-    std::string object_id = entity->get_object_id();
-    msg.set_object_id(StringRef(object_id));
+    // Try to use static reference first to avoid allocation
+    StringRef static_ref = entity->get_object_id_ref_for_api_();
+    if (!static_ref.empty()) {
+      msg.set_object_id(static_ref);
+    } else {
+      // Dynamic case - need to allocate
+      std::string object_id = entity->get_object_id();
+      msg.set_object_id(StringRef(object_id));
+    }
 
     if (entity->has_own_name()) {
       msg.set_name(entity->get_name());
diff --git a/esphome/core/entity_base.cpp b/esphome/core/entity_base.cpp
index 2ea9c77a3e..97bf7147b5 100644
--- a/esphome/core/entity_base.cpp
+++ b/esphome/core/entity_base.cpp
@@ -1,6 +1,7 @@
 #include "esphome/core/entity_base.h"
 #include "esphome/core/application.h"
 #include "esphome/core/helpers.h"
+#include "esphome/core/string_ref.h"
 
 namespace esphome {
 
@@ -58,6 +59,15 @@ std::string EntityBase::get_object_id() const {
     return this->object_id_c_str_;
   }
 }
+StringRef EntityBase::get_object_id_ref_for_api_() const {
+  static constexpr auto EMPTY_STRING_REF = StringRef::from_lit("");
+  // Return empty for dynamic case (MAC suffix)
+  if (!this->flags_.has_own_name && App.is_name_add_mac_suffix_enabled()) {
+    return EMPTY_STRING_REF;
+  }
+  // For static case, return the string or empty if null
+  return this->object_id_c_str_ == nullptr ? EMPTY_STRING_REF : StringRef(this->object_id_c_str_);
+}
 void EntityBase::set_object_id(const char *object_id) {
   this->object_id_c_str_ = object_id;
   this->calc_object_id_();
diff --git a/esphome/core/entity_base.h b/esphome/core/entity_base.h
index e60e0728bc..68163ce8c3 100644
--- a/esphome/core/entity_base.h
+++ b/esphome/core/entity_base.h
@@ -12,6 +12,11 @@
 
 namespace esphome {
 
+// Forward declaration for friend access
+namespace api {
+class APIConnection;
+}  // namespace api
+
 enum EntityCategory : uint8_t {
   ENTITY_CATEGORY_NONE = 0,
   ENTITY_CATEGORY_CONFIG = 1,
@@ -81,6 +86,12 @@ class EntityBase {
   void set_has_state(bool state) { this->flags_.has_state = state; }
 
  protected:
+  friend class api::APIConnection;
+
+  // Get object_id as StringRef when it's static (for API usage)
+  // Returns empty StringRef if object_id is dynamic (needs allocation)
+  StringRef get_object_id_ref_for_api_() const;
+
   /// The hash_base() function has been deprecated. It is kept in this
   /// class for now, to prevent external components from not compiling.
   virtual uint32_t hash_base() { return 0L; }