[core] Flatten single-callsite vector realloc functions (#13970)

esphome/components/api/api_connection.cpp

@@ -1864,6 +1864,8 @@ void APIConnection::on_fatal_error() {
   this->flags_.remove = true;
 }
 
+void __attribute__((flatten)) APIConnection::DeferredBatch::push_item(const BatchItem &item) { items.push_back(item); }
+
 void APIConnection::DeferredBatch::add_item(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
                                             uint8_t aux_data_index) {
   // Check if we already have a message of this type for this entity
@@ -1880,7 +1882,7 @@ void APIConnection::DeferredBatch::add_item(EntityBase *entity, uint8_t message_
     }
   }
   // No existing item found (or event), add new one
-  items.push_back({entity, message_type, estimated_size, aux_data_index});
+  this->push_item({entity, message_type, estimated_size, aux_data_index});
 }
 
 void APIConnection::DeferredBatch::add_item_front(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
@@ -1888,7 +1890,7 @@ void APIConnection::DeferredBatch::add_item_front(EntityBase *entity, uint8_t me
   // This avoids expensive vector::insert which shifts all elements
   // Note: We only ever have one high-priority message at a time (ping OR disconnect)
   // If we're disconnecting, pings are blocked, so this simple swap is sufficient
-  items.push_back({entity, message_type, estimated_size, AUX_DATA_UNUSED});
+  this->push_item({entity, message_type, estimated_size, AUX_DATA_UNUSED});
   if (items.size() > 1) {
     // Swap the new high-priority item to the front
     std::swap(items.front(), items.back());

esphome/components/api/api_connection.h

@@ -541,6 +541,8 @@ class APIConnection final : public APIServerConnectionBase {
                   uint8_t aux_data_index = AUX_DATA_UNUSED);
     // Add item to the front of the batch (for high priority messages like ping)
     void add_item_front(EntityBase *entity, uint8_t message_type, uint8_t estimated_size);
+    // Single push_back site to avoid duplicate _M_realloc_insert instantiation
+    void push_item(const BatchItem &item);
 
     // Clear all items
     void clear() {

esphome/components/api/api_server.cpp

@@ -195,7 +195,7 @@ void APIServer::remove_client_(size_t client_index) {
 #endif
 }
 
-void APIServer::accept_new_connections_() {
+void __attribute__((flatten)) APIServer::accept_new_connections_() {
   while (true) {
     struct sockaddr_storage source_addr;
     socklen_t addr_len = sizeof(source_addr);

esphome/components/wifi/wifi_component.cpp

@@ -487,6 +487,19 @@ bool WiFiComponent::matches_configured_network_(const char *ssid, const uint8_t
   return false;
 }
 
+void __attribute__((flatten)) WiFiComponent::set_sta_priority(bssid_t bssid, int8_t priority) {
+  for (auto &it : this->sta_priorities_) {
+    if (it.bssid == bssid) {
+      it.priority = priority;
+      return;
+    }
+  }
+  this->sta_priorities_.push_back(WiFiSTAPriority{
+      .bssid = bssid,
+      .priority = priority,
+  });
+}
+
 void WiFiComponent::log_discarded_scan_result_(const char *ssid, const uint8_t *bssid, int8_t rssi, uint8_t channel) {
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
   // Skip logging during roaming scans to avoid log buffer overflow

esphome/components/wifi/wifi_component.h

@@ -488,18 +488,7 @@ class WiFiComponent : public Component {
     }
     return 0;
   }
-  void set_sta_priority(const bssid_t bssid, int8_t priority) {
-    for (auto &it : this->sta_priorities_) {
-      if (it.bssid == bssid) {
-        it.priority = priority;
-        return;
-      }
-    }
-    this->sta_priorities_.push_back(WiFiSTAPriority{
-        .bssid = bssid,
-        .priority = priority,
-    });
-  }
+  void set_sta_priority(bssid_t bssid, int8_t priority);
 
   network::IPAddresses wifi_sta_ip_addresses();
   // Remove before 2026.9.0