[core] Use StringRef for get_comment and get_compilation_time to avoid allocations

esphome/components/mqtt/mqtt_component.cpp

@@ -154,7 +154,7 @@ bool MQTTComponent::send_discovery_() {
         device_info[MQTT_DEVICE_MANUFACTURER] =
             model == nullptr ? ESPHOME_PROJECT_NAME : std::string(ESPHOME_PROJECT_NAME, model - ESPHOME_PROJECT_NAME);
 #else
-        device_info[MQTT_DEVICE_SW_VERSION] = ESPHOME_VERSION " (" + App.get_compilation_time() + ")";
+        device_info[MQTT_DEVICE_SW_VERSION] = ESPHOME_VERSION " (" + App.get_compilation_time_ref() + ")";
         device_info[MQTT_DEVICE_MODEL] = ESPHOME_BOARD;
 #if defined(USE_ESP8266) || defined(USE_ESP32)
         device_info[MQTT_DEVICE_MANUFACTURER] = "Espressif";

esphome/components/sen5x/sen5x.cpp

@@ -157,7 +157,7 @@ void SEN5XComponent::setup() {
         // Hash with compilation time and serial number
         // This ensures the baseline storage is cleared after OTA
         // Serial numbers are unique to each sensor, so mulitple sensors can be used without conflict
-        uint32_t hash = fnv1_hash(App.get_compilation_time() + std::to_string(combined_serial));
+        uint32_t hash = fnv1_hash(App.get_compilation_time_ref() + std::to_string(combined_serial).c_str());
         this->pref_ = global_preferences->make_preference<Sen5xBaselines>(hash, true);
 
         if (this->pref_.load(&this->voc_baselines_storage_)) {

esphome/components/sgp30/sgp30.cpp

@@ -75,7 +75,7 @@ void SGP30Component::setup() {
   // Hash with compilation time and serial number
   // This ensures the baseline storage is cleared after OTA
   // Serial numbers are unique to each sensor, so mulitple sensors can be used without conflict
-  uint32_t hash = fnv1_hash(App.get_compilation_time() + std::to_string(this->serial_number_));
+  uint32_t hash = fnv1_hash(App.get_compilation_time_ref() + std::to_string(this->serial_number_).c_str());
   this->pref_ = global_preferences->make_preference<SGP30Baselines>(hash, true);
 
   if (this->store_baseline_ && this->pref_.load(&this->baselines_storage_)) {

esphome/components/sgp4x/sgp4x.cpp

@@ -59,7 +59,7 @@ void SGP4xComponent::setup() {
     // Hash with compilation time and serial number
     // This ensures the baseline storage is cleared after OTA
     // Serial numbers are unique to each sensor, so mulitple sensors can be used without conflict
-    uint32_t hash = fnv1_hash(App.get_compilation_time() + std::to_string(this->serial_number_));
+    uint32_t hash = fnv1_hash(App.get_compilation_time_ref() + std::to_string(this->serial_number_).c_str());
     this->pref_ = global_preferences->make_preference<SGP4xBaselines>(hash, true);
 
     if (this->pref_.load(&this->voc_baselines_storage_)) {

esphome/components/version/version_text_sensor.cpp

@@ -13,7 +13,7 @@ void VersionTextSensor::setup() {
   if (this->hide_timestamp_) {
     this->publish_state(ESPHOME_VERSION);
   } else {
-    this->publish_state(str_sprintf(ESPHOME_VERSION " %s", App.get_compilation_time().c_str()));
+    this->publish_state(str_sprintf(ESPHOME_VERSION " %s", App.get_compilation_time_ref().c_str()));
   }
 }
 float VersionTextSensor::get_setup_priority() const { return setup_priority::DATA; }

esphome/components/web_server/web_server.cpp

@@ -283,7 +283,7 @@ std::string WebServer::get_config_json() {
   JsonObject root = builder.root();
 
   root["title"] = App.get_friendly_name().empty() ? App.get_name() : App.get_friendly_name();
-  root["comment"] = App.get_comment();
+  root["comment"] = App.get_comment_ref();
 #if defined(USE_WEBSERVER_OTA_DISABLED) || !defined(USE_WEBSERVER_OTA)
   root["ota"] = false;  // Note: USE_WEBSERVER_OTA_DISABLED only affects web_server, not captive_portal
 #else

esphome/components/wifi/wifi_component.cpp

@@ -360,7 +360,7 @@ void WiFiComponent::start() {
                 get_mac_address_pretty_into_buffer(mac_s));
   this->last_connected_ = millis();
 
-  uint32_t hash = this->has_sta() ? fnv1_hash(App.get_compilation_time()) : 88491487UL;
+  uint32_t hash = this->has_sta() ? fnv1_hash(App.get_compilation_time_ref()) : 88491487UL;
 
   this->pref_ = global_preferences->make_preference<wifi::SavedWifiSettings>(hash, true);
 #ifdef USE_WIFI_FAST_CONNECT

esphome/core/application.h

@@ -256,6 +256,8 @@ class Application {
 
   /// Get the comment of this Application set by pre_setup().
   std::string get_comment() const { return this->comment_; }
+  /// Get the comment as StringRef (avoids allocation)
+  StringRef get_comment_ref() const { return StringRef::from_maybe_nullptr(this->comment_); }
 
   bool is_name_add_mac_suffix_enabled() const { return this->name_add_mac_suffix_; }
 

esphome/core/helpers.h

@@ -380,6 +380,7 @@ uint16_t crc16be(const uint8_t *data, uint16_t len, uint16_t crc = 0, uint16_t p
 /// Calculate a FNV-1 hash of \p str.
 uint32_t fnv1_hash(const char *str);
 inline uint32_t fnv1_hash(const std::string &str) { return fnv1_hash(str.c_str()); }
+inline uint32_t fnv1_hash(const StringRef &str) { return fnv1_hash(str.c_str()); }
 
 /// Return a random 32-bit unsigned integer.
 uint32_t random_uint32();