From 0bc18a82814ea7cfec35facd143e1316fd6414a1 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 5 Jul 2025 23:34:55 -0500
Subject: [PATCH] Eliminate API component guard variable to save 8 bytes RAM
 (#9341)

---
 esphome/components/api/api_server.cpp |  8 ++++++++
 esphome/components/api/api_server.h   | 12 ++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/esphome/components/api/api_server.cpp b/esphome/components/api/api_server.cpp
index 0fd9c1a228..4dc6fe2390 100644
--- a/esphome/components/api/api_server.cpp
+++ b/esphome/components/api/api_server.cpp
@@ -24,6 +24,14 @@ static const char *const TAG = "api";
 // APIServer
 APIServer *global_api_server = nullptr;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
+#ifndef USE_API_YAML_SERVICES
+// Global empty vector to avoid guard variables (saves 8 bytes)
+// This is initialized at program startup before any threads
+static const std::vector<UserServiceDescriptor *> empty_user_services{};
+
+const std::vector<UserServiceDescriptor *> &get_empty_user_services_instance() { return empty_user_services; }
+#endif
+
 APIServer::APIServer() {
   global_api_server = this;
   // Pre-allocate shared write buffer
diff --git a/esphome/components/api/api_server.h b/esphome/components/api/api_server.h
index 9dc2b4b7d6..f34fd55974 100644
--- a/esphome/components/api/api_server.h
+++ b/esphome/components/api/api_server.h
@@ -25,6 +25,11 @@ struct SavedNoisePsk {
 } PACKED;  // NOLINT
 #endif
 
+#ifndef USE_API_YAML_SERVICES
+// Forward declaration of helper function
+const std::vector<UserServiceDescriptor *> &get_empty_user_services_instance();
+#endif
+
 class APIServer : public Component, public Controller {
  public:
   APIServer();
@@ -151,8 +156,11 @@ class APIServer : public Component, public Controller {
 #ifdef USE_API_YAML_SERVICES
     return this->user_services_;
 #else
-    static const std::vector<UserServiceDescriptor *> EMPTY;
-    return this->user_services_ ? *this->user_services_ : EMPTY;
+    if (this->user_services_) {
+      return *this->user_services_;
+    }
+    // Return reference to global empty instance (no guard needed)
+    return get_empty_user_services_instance();
 #endif
   }