[web_server] Use ESPHOME_F for canHandle domain checks to reduce ESP8266 RAM (#13315)

Co-authored-by: Keith Burzinski <kbx81x@gmail.com>

esphome/codegen.py

@@ -69,7 +69,6 @@ from esphome.cpp_types import (  # noqa: F401
     JsonObjectConst,
     Parented,
     PollingComponent,
-    StringRef,
     arduino_json_ns,
     bool_,
     const_char_ptr,

esphome/components/fan/__init__.py

@@ -77,7 +77,7 @@ FanSpeedSetTrigger = fan_ns.class_(
     "FanSpeedSetTrigger", automation.Trigger.template(cg.int_)
 )
 FanPresetSetTrigger = fan_ns.class_(
-    "FanPresetSetTrigger", automation.Trigger.template(cg.StringRef)
+    "FanPresetSetTrigger", automation.Trigger.template(cg.std_string)
 )
 
 FanIsOnCondition = fan_ns.class_("FanIsOnCondition", automation.Condition.template())
@@ -287,7 +287,7 @@ async def setup_fan_core_(var, config):
         await automation.build_automation(trigger, [(cg.int_, "x")], conf)
     for conf in config.get(CONF_ON_PRESET_SET, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.StringRef, "x")], conf)
+        await automation.build_automation(trigger, [(cg.std_string, "x")], conf)
 
 
 async def register_fan(var, config):

esphome/components/fan/automation.h

@@ -208,7 +208,7 @@ class FanSpeedSetTrigger : public Trigger<int> {
   int last_speed_;
 };
 
-class FanPresetSetTrigger : public Trigger<StringRef> {
+class FanPresetSetTrigger : public Trigger<std::string> {
  public:
   FanPresetSetTrigger(Fan *state) {
     state->add_on_state_callback([this, state]() {
@@ -216,7 +216,7 @@ class FanPresetSetTrigger : public Trigger<StringRef> {
       auto should_trigger = preset_mode != this->last_preset_mode_;
       this->last_preset_mode_ = preset_mode;
       if (should_trigger) {
-        this->trigger(preset_mode);
+        this->trigger(std::string(preset_mode));
       }
     });
     this->last_preset_mode_ = state->get_preset_mode();

esphome/components/light/light_json_schema.cpp

@@ -1,4 +1,5 @@
 #include "light_json_schema.h"
+#include "color_mode.h"
 #include "light_output.h"
 #include "esphome/core/progmem.h"
 
@@ -8,29 +9,32 @@ namespace esphome::light {
 
 // See https://www.home-assistant.io/integrations/light.mqtt/#json-schema for documentation on the schema
 
-// Get JSON string for color mode using linear search (avoids large switch jump table)
-static const char *get_color_mode_json_str(ColorMode mode) {
-  // Parallel arrays: mode values and their corresponding strings
-  // Uses less RAM than a switch jump table on sparse enum values
-  static constexpr ColorMode MODES[] = {
-      ColorMode::ON_OFF,
-      ColorMode::BRIGHTNESS,
-      ColorMode::WHITE,
-      ColorMode::COLOR_TEMPERATURE,
-      ColorMode::COLD_WARM_WHITE,
-      ColorMode::RGB,
-      ColorMode::RGB_WHITE,
-      ColorMode::RGB_COLOR_TEMPERATURE,
-      ColorMode::RGB_COLD_WARM_WHITE,
-  };
-  static constexpr const char *STRINGS[] = {
-      "onoff", "brightness", "white", "color_temp", "cwww", "rgb", "rgbw", "rgbct", "rgbww",
-  };
-  for (size_t i = 0; i < sizeof(MODES) / sizeof(MODES[0]); i++) {
-    if (MODES[i] == mode)
-      return STRINGS[i];
+// Get JSON string for color mode.
+// ColorMode enum values are sparse bitmasks (0, 1, 3, 7, 11, 19, 35, 39, 47, 51) which would
+// generate a large jump table. Converting to bit index (0-9) allows a compact switch.
+static ProgmemStr get_color_mode_json_str(ColorMode mode) {
+  switch (ColorModeBitPolicy::to_bit(mode)) {
+    case 1:
+      return ESPHOME_F("onoff");
+    case 2:
+      return ESPHOME_F("brightness");
+    case 3:
+      return ESPHOME_F("white");
+    case 4:
+      return ESPHOME_F("color_temp");
+    case 5:
+      return ESPHOME_F("cwww");
+    case 6:
+      return ESPHOME_F("rgb");
+    case 7:
+      return ESPHOME_F("rgbw");
+    case 8:
+      return ESPHOME_F("rgbct");
+    case 9:
+      return ESPHOME_F("rgbww");
+    default:
+      return nullptr;
   }
-  return nullptr;
 }
 
 void LightJSONSchema::dump_json(LightState &state, JsonObject root) {
@@ -44,7 +48,7 @@ void LightJSONSchema::dump_json(LightState &state, JsonObject root) {
   auto values = state.remote_values;
 
   const auto color_mode = values.get_color_mode();
-  const char *mode_str = get_color_mode_json_str(color_mode);
+  const auto *mode_str = get_color_mode_json_str(color_mode);
   if (mode_str != nullptr) {
     root[ESPHOME_F("color_mode")] = mode_str;
   }

esphome/components/opentherm/opentherm.cpp

@@ -561,8 +561,9 @@ const char *OpenTherm::message_id_to_str(MessageId id) {
 }
 
 void OpenTherm::debug_data(OpenthermData &data) {
-  ESP_LOGD(TAG, "%s %s %s %s", format_bin(data.type).c_str(), format_bin(data.id).c_str(),
-           format_bin(data.valueHB).c_str(), format_bin(data.valueLB).c_str());
+  char type_buf[9], id_buf[9], hb_buf[9], lb_buf[9];
+  ESP_LOGD(TAG, "%s %s %s %s", format_bin_to(type_buf, data.type), format_bin_to(id_buf, data.id),
+           format_bin_to(hb_buf, data.valueHB), format_bin_to(lb_buf, data.valueLB));
   ESP_LOGD(TAG, "type: %s; id: %u; HB: %u; LB: %u; uint_16: %u; float: %f",
            this->message_type_to_str((MessageType) data.type), data.id, data.valueHB, data.valueLB, data.u16(),
            data.f88());

esphome/components/select/__init__.py

@@ -33,7 +33,7 @@ SelectPtr = Select.operator("ptr")
 # Triggers
 SelectStateTrigger = select_ns.class_(
     "SelectStateTrigger",
-    automation.Trigger.template(cg.StringRef, cg.size_t),
+    automation.Trigger.template(cg.std_string, cg.size_t),
 )
 
 # Actions
@@ -100,7 +100,7 @@ async def setup_select_core_(var, config, *, options: list[str]):
     for conf in config.get(CONF_ON_VALUE, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
         await automation.build_automation(
-            trigger, [(cg.StringRef, "x"), (cg.size_t, "i")], conf
+            trigger, [(cg.std_string, "x"), (cg.size_t, "i")], conf
         )
 
     if (mqtt_id := config.get(CONF_MQTT_ID)) is not None:

esphome/components/select/automation.h

@@ -6,11 +6,11 @@
 
 namespace esphome::select {
 
-class SelectStateTrigger : public Trigger<StringRef, size_t> {
+class SelectStateTrigger : public Trigger<std::string, size_t> {
  public:
   explicit SelectStateTrigger(Select *parent) : parent_(parent) {
     parent->add_on_state_callback(
-        [this](size_t index) { this->trigger(StringRef(this->parent_->option_at(index)), index); });
+        [this](size_t index) { this->trigger(std::string(this->parent_->option_at(index)), index); });
   }
 
  protected:

esphome/components/web_server/list_entities.cpp

@@ -143,7 +143,7 @@ bool ListEntitiesIterator::on_water_heater(water_heater::WaterHeater *obj) {
 
 #ifdef USE_INFRARED
 bool ListEntitiesIterator::on_infrared(infrared::Infrared *obj) {
-  // Infrared web_server support not yet implemented - this stub acknowledges the entity
+  this->events_->deferrable_send_state(obj, "state_detail_all", WebServer::infrared_all_json_generator);
   return true;
 }
 #endif

esphome/components/web_server/web_server.cpp

@@ -33,6 +33,10 @@
 #include "esphome/components/water_heater/water_heater.h"
 #endif
 
+#ifdef USE_INFRARED
+#include "esphome/components/infrared/infrared.h"
+#endif
+
 #ifdef USE_WEBSERVER_LOCAL
 #if USE_WEBSERVER_VERSION == 2
 #include "server_index_v2.h"
@@ -1952,6 +1956,110 @@ std::string WebServer::water_heater_json_(water_heater::WaterHeater *obj, JsonDe
 }
 #endif
 
+#ifdef USE_INFRARED
+void WebServer::handle_infrared_request(AsyncWebServerRequest *request, const UrlMatch &match) {
+  for (infrared::Infrared *obj : App.get_infrareds()) {
+    auto entity_match = match.match_entity(obj);
+    if (!entity_match.matched)
+      continue;
+
+    if (request->method() == HTTP_GET && entity_match.action_is_empty) {
+      auto detail = get_request_detail(request);
+      std::string data = this->infrared_json_(obj, detail);
+      request->send(200, ESPHOME_F("application/json"), data.c_str());
+      return;
+    }
+    if (!match.method_equals(ESPHOME_F("transmit"))) {
+      request->send(404);
+      return;
+    }
+
+    // Only allow transmit if the device supports it
+    if (!obj->has_transmitter()) {
+      request->send(400, ESPHOME_F("text/plain"), "Device does not support transmission");
+      return;
+    }
+
+    // Parse parameters
+    auto call = obj->make_call();
+
+    // Parse carrier frequency (optional)
+    if (request->hasParam(ESPHOME_F("carrier_frequency"))) {
+      auto value = parse_number<uint32_t>(request->getParam(ESPHOME_F("carrier_frequency"))->value().c_str());
+      if (value.has_value()) {
+        call.set_carrier_frequency(*value);
+      }
+    }
+
+    // Parse repeat count (optional, defaults to 1)
+    if (request->hasParam(ESPHOME_F("repeat_count"))) {
+      auto value = parse_number<uint32_t>(request->getParam(ESPHOME_F("repeat_count"))->value().c_str());
+      if (value.has_value()) {
+        call.set_repeat_count(*value);
+      }
+    }
+
+    // Parse base64url-encoded raw timings (required)
+    // Base64url is URL-safe: uses A-Za-z0-9-_ (no special characters needing escaping)
+    if (!request->hasParam(ESPHOME_F("data"))) {
+      request->send(400, ESPHOME_F("text/plain"), "Missing 'data' parameter");
+      return;
+    }
+
+    // .c_str() is required for Arduino framework where value() returns Arduino String instead of std::string
+    std::string encoded =
+        request->getParam(ESPHOME_F("data"))->value().c_str();  // NOLINT(readability-redundant-string-cstr)
+
+    // Validate base64url is not empty
+    if (encoded.empty()) {
+      request->send(400, ESPHOME_F("text/plain"), "Empty 'data' parameter");
+      return;
+    }
+
+#ifdef USE_ESP8266
+    // ESP8266 is single-threaded, call directly
+    call.set_raw_timings_base64url(encoded);
+    call.perform();
+#else
+    // Defer to main loop for thread safety. Move encoded string into lambda to ensure
+    // it outlives the call - set_raw_timings_base64url stores a pointer, so the string
+    // must remain valid until perform() completes.
+    this->defer([call, encoded = std::move(encoded)]() mutable {
+      call.set_raw_timings_base64url(encoded);
+      call.perform();
+    });
+#endif
+
+    request->send(200);
+    return;
+  }
+  request->send(404);
+}
+
+std::string WebServer::infrared_all_json_generator(WebServer *web_server, void *source) {
+  // NOLINTNEXTLINE(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
+  return web_server->infrared_json_(static_cast<infrared::Infrared *>(source), DETAIL_ALL);
+}
+
+std::string WebServer::infrared_json_(infrared::Infrared *obj, JsonDetail start_config) {
+  json::JsonBuilder builder;
+  JsonObject root = builder.root();
+
+  set_json_icon_state_value(root, obj, "infrared", "", 0, start_config);
+
+  auto traits = obj->get_traits();
+
+  root[ESPHOME_F("supports_transmitter")] = traits.get_supports_transmitter();
+  root[ESPHOME_F("supports_receiver")] = traits.get_supports_receiver();
+
+  if (start_config == DETAIL_ALL) {
+    this->add_sorting_info_(root, obj);
+  }
+
+  return builder.serialize();
+}
+#endif
+
 #ifdef USE_EVENT
 void WebServer::on_event(event::Event *obj) {
   if (!this->include_internal_ && obj->is_internal())
@@ -2083,24 +2191,21 @@ bool WebServer::canHandle(AsyncWebServerRequest *request) const {
   const auto &url = request->url();
   const auto method = request->method();
 
-  // Static URL checks
-  static const char *const STATIC_URLS[] = {
-    "/",
+  // Static URL checks - use ESPHOME_F to keep strings in flash on ESP8266
+  if (url == ESPHOME_F("/"))
+    return true;
 #if !defined(USE_ESP32) && defined(USE_ARDUINO)
-    "/events",
+  if (url == ESPHOME_F("/events"))
+    return true;
 #endif
 #ifdef USE_WEBSERVER_CSS_INCLUDE
-    "/0.css",
+  if (url == ESPHOME_F("/0.css"))
+    return true;
 #endif
 #ifdef USE_WEBSERVER_JS_INCLUDE
-    "/0.js",
+  if (url == ESPHOME_F("/0.js"))
+    return true;
 #endif
-  };
-
-  for (const auto &static_url : STATIC_URLS) {
-    if (url == static_url)
-      return true;
-  }
 
 #ifdef USE_WEBSERVER_PRIVATE_NETWORK_ACCESS
   if (method == HTTP_OPTIONS && request->hasHeader(ESPHOME_F("Access-Control-Request-Private-Network")))
@@ -2120,90 +2225,100 @@ bool WebServer::canHandle(AsyncWebServerRequest *request) const {
   if (!is_get_or_post)
     return false;
 
-  // Use lookup tables for domain checks
-  static const char *const GET_ONLY_DOMAINS[] = {
+  // Check GET-only domains - use ESPHOME_F to keep strings in flash on ESP8266
+  if (is_get) {
 #ifdef USE_SENSOR
-      "sensor",
+    if (match.domain_equals(ESPHOME_F("sensor")))
+      return true;
 #endif
 #ifdef USE_BINARY_SENSOR
-      "binary_sensor",
+    if (match.domain_equals(ESPHOME_F("binary_sensor")))
+      return true;
 #endif
 #ifdef USE_TEXT_SENSOR
-      "text_sensor",
+    if (match.domain_equals(ESPHOME_F("text_sensor")))
+      return true;
 #endif
 #ifdef USE_EVENT
-      "event",
+    if (match.domain_equals(ESPHOME_F("event")))
+      return true;
 #endif
-  };
-
-  static const char *const GET_POST_DOMAINS[] = {
-#ifdef USE_SWITCH
-      "switch",
-#endif
-#ifdef USE_BUTTON
-      "button",
-#endif
-#ifdef USE_FAN
-      "fan",
-#endif
-#ifdef USE_LIGHT
-      "light",
-#endif
-#ifdef USE_COVER
-      "cover",
-#endif
-#ifdef USE_NUMBER
-      "number",
-#endif
-#ifdef USE_DATETIME_DATE
-      "date",
-#endif
-#ifdef USE_DATETIME_TIME
-      "time",
-#endif
-#ifdef USE_DATETIME_DATETIME
-      "datetime",
-#endif
-#ifdef USE_TEXT
-      "text",
-#endif
-#ifdef USE_SELECT
-      "select",
-#endif
-#ifdef USE_CLIMATE
-      "climate",
-#endif
-#ifdef USE_LOCK
-      "lock",
-#endif
-#ifdef USE_VALVE
-      "valve",
-#endif
-#ifdef USE_ALARM_CONTROL_PANEL
-      "alarm_control_panel",
-#endif
-#ifdef USE_UPDATE
-      "update",
-#endif
-#ifdef USE_WATER_HEATER
-      "water_heater",
-#endif
-  };
-
-  // Check GET-only domains
-  if (is_get) {
-    for (const auto &domain : GET_ONLY_DOMAINS) {
-      if (match.domain_equals(domain))
-        return true;
-    }
   }
 
   // Check GET+POST domains
   if (is_get_or_post) {
-    for (const auto &domain : GET_POST_DOMAINS) {
-      if (match.domain_equals(domain))
-        return true;
-    }
+#ifdef USE_SWITCH
+    if (match.domain_equals(ESPHOME_F("switch")))
+      return true;
+#endif
+#ifdef USE_BUTTON
+    if (match.domain_equals(ESPHOME_F("button")))
+      return true;
+#endif
+#ifdef USE_FAN
+    if (match.domain_equals(ESPHOME_F("fan")))
+      return true;
+#endif
+#ifdef USE_LIGHT
+    if (match.domain_equals(ESPHOME_F("light")))
+      return true;
+#endif
+#ifdef USE_COVER
+    if (match.domain_equals(ESPHOME_F("cover")))
+      return true;
+#endif
+#ifdef USE_NUMBER
+    if (match.domain_equals(ESPHOME_F("number")))
+      return true;
+#endif
+#ifdef USE_DATETIME_DATE
+    if (match.domain_equals(ESPHOME_F("date")))
+      return true;
+#endif
+#ifdef USE_DATETIME_TIME
+    if (match.domain_equals(ESPHOME_F("time")))
+      return true;
+#endif
+#ifdef USE_DATETIME_DATETIME
+    if (match.domain_equals(ESPHOME_F("datetime")))
+      return true;
+#endif
+#ifdef USE_TEXT
+    if (match.domain_equals(ESPHOME_F("text")))
+      return true;
+#endif
+#ifdef USE_SELECT
+    if (match.domain_equals(ESPHOME_F("select")))
+      return true;
+#endif
+#ifdef USE_CLIMATE
+    if (match.domain_equals(ESPHOME_F("climate")))
+      return true;
+#endif
+#ifdef USE_LOCK
+    if (match.domain_equals(ESPHOME_F("lock")))
+      return true;
+#endif
+#ifdef USE_VALVE
+    if (match.domain_equals(ESPHOME_F("valve")))
+      return true;
+#endif
+#ifdef USE_ALARM_CONTROL_PANEL
+    if (match.domain_equals(ESPHOME_F("alarm_control_panel")))
+      return true;
+#endif
+#ifdef USE_UPDATE
+    if (match.domain_equals(ESPHOME_F("update")))
+      return true;
+#endif
+#ifdef USE_WATER_HEATER
+    if (match.domain_equals(ESPHOME_F("water_heater")))
+      return true;
+#endif
+#ifdef USE_INFRARED
+    if (match.domain_equals(ESPHOME_F("infrared")))
+      return true;
+#endif
   }
 
   return false;
@@ -2352,6 +2467,11 @@ void WebServer::handleRequest(AsyncWebServerRequest *request) {
   else if (match.domain_equals(ESPHOME_F("water_heater"))) {
     this->handle_water_heater_request(request, match);
   }
+#endif
+#ifdef USE_INFRARED
+  else if (match.domain_equals(ESPHOME_F("infrared"))) {
+    this->handle_infrared_request(request, match);
+  }
 #endif
   else {
     // No matching handler found - send 404

esphome/components/web_server/web_server.h

@@ -460,6 +460,13 @@ class WebServer : public Controller,
   static std::string water_heater_all_json_generator(WebServer *web_server, void *source);
 #endif
 
+#ifdef USE_INFRARED
+  /// Handle an infrared request under '/infrared/<id>/transmit'.
+  void handle_infrared_request(AsyncWebServerRequest *request, const UrlMatch &match);
+
+  static std::string infrared_all_json_generator(WebServer *web_server, void *source);
+#endif
+
 #ifdef USE_EVENT
   void on_event(event::Event *obj) override;
 
@@ -662,6 +669,9 @@ class WebServer : public Controller,
 #ifdef USE_WATER_HEATER
   std::string water_heater_json_(water_heater::WaterHeater *obj, JsonDetail start_config);
 #endif
+#ifdef USE_INFRARED
+  std::string infrared_json_(infrared::Infrared *obj, JsonDetail start_config);
+#endif
 #ifdef USE_UPDATE
   std::string update_json_(update::UpdateEntity *obj, JsonDetail start_config);
 #endif

esphome/core/helpers.cpp

@@ -404,15 +404,31 @@ std::string format_hex_pretty(const std::string &data, char separator, bool show
   return format_hex_pretty_uint8(reinterpret_cast<const uint8_t *>(data.data()), data.length(), separator, show_length);
 }
 
+char *format_bin_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length) {
+  if (buffer_size == 0) {
+    return buffer;
+  }
+  // Calculate max bytes we can format: each byte needs 8 chars
+  size_t max_bytes = (buffer_size - 1) / 8;
+  if (max_bytes == 0 || length == 0) {
+    buffer[0] = '\0';
+    return buffer;
+  }
+  size_t bytes_to_format = std::min(length, max_bytes);
+
+  for (size_t byte_idx = 0; byte_idx < bytes_to_format; byte_idx++) {
+    for (size_t bit_idx = 0; bit_idx < 8; bit_idx++) {
+      buffer[byte_idx * 8 + bit_idx] = ((data[byte_idx] >> (7 - bit_idx)) & 1) + '0';
+    }
+  }
+  buffer[bytes_to_format * 8] = '\0';
+  return buffer;
+}
+
 std::string format_bin(const uint8_t *data, size_t length) {
   std::string result;
   result.resize(length * 8);
-  for (size_t byte_idx = 0; byte_idx < length; byte_idx++) {
-    for (size_t bit_idx = 0; bit_idx < 8; bit_idx++) {
-      result[byte_idx * 8 + bit_idx] = ((data[byte_idx] >> (7 - bit_idx)) & 1) + '0';
-    }
-  }
-
+  format_bin_to(&result[0], length * 8 + 1, data, length);
   return result;
 }
 

esphome/core/helpers.h

@@ -1096,9 +1096,66 @@ std::string format_hex_pretty(T val, char separator = '.', bool show_length = tr
   return format_hex_pretty(reinterpret_cast<uint8_t *>(&val), sizeof(T), separator, show_length);
 }
 
+/// Calculate buffer size needed for format_bin_to: "01234567...\0" = bytes * 8 + 1
+constexpr size_t format_bin_size(size_t byte_count) { return byte_count * 8 + 1; }
+
+/** Format byte array as binary string to buffer.
+ *
+ * Each byte is formatted as 8 binary digits (MSB first).
+ * Truncates output if data exceeds buffer capacity.
+ *
+ * @param buffer Output buffer to write to.
+ * @param buffer_size Size of the output buffer.
+ * @param data Pointer to the byte array to format.
+ * @param length Number of bytes in the array.
+ * @return Pointer to buffer.
+ *
+ * Buffer size needed: length * 8 + 1 (use format_bin_size()).
+ *
+ * Example:
+ * @code
+ * char buf[9];  // format_bin_size(1)
+ * format_bin_to(buf, sizeof(buf), data, 1);  // "10101011"
+ * @endcode
+ */
+char *format_bin_to(char *buffer, size_t buffer_size, const uint8_t *data, size_t length);
+
+/// Format byte array as binary to buffer. Automatically deduces buffer size.
+template<size_t N> inline char *format_bin_to(char (&buffer)[N], const uint8_t *data, size_t length) {
+  static_assert(N >= 9, "Buffer must hold at least one binary byte (9 chars)");
+  return format_bin_to(buffer, N, data, length);
+}
+
+/** Format an unsigned integer in binary to buffer, MSB first.
+ *
+ * @tparam N Buffer size (must be >= sizeof(T) * 8 + 1).
+ * @tparam T Unsigned integer type.
+ * @param buffer Output buffer to write to.
+ * @param val The unsigned integer value to format.
+ * @return Pointer to buffer.
+ *
+ * Example:
+ * @code
+ * char buf[9];  // format_bin_size(sizeof(uint8_t))
+ * format_bin_to(buf, uint8_t{0xAA});  // "10101010"
+ * char buf16[17];  // format_bin_size(sizeof(uint16_t))
+ * format_bin_to(buf16, uint16_t{0x1234});  // "0001001000110100"
+ * @endcode
+ */
+template<size_t N, typename T, enable_if_t<std::is_unsigned<T>::value, int> = 0>
+inline char *format_bin_to(char (&buffer)[N], T val) {
+  static_assert(N >= sizeof(T) * 8 + 1, "Buffer too small for type");
+  val = convert_big_endian(val);
+  return format_bin_to(buffer, reinterpret_cast<const uint8_t *>(&val), sizeof(T));
+}
+
 /// Format the byte array \p data of length \p len in binary.
+/// @warning Allocates heap memory. Use format_bin_to() with a stack buffer instead.
+/// Causes heap fragmentation on long-running devices.
 std::string format_bin(const uint8_t *data, size_t length);
 /// Format an unsigned integer in binary, starting with the most significant byte.
+/// @warning Allocates heap memory. Use format_bin_to() with a stack buffer instead.
+/// Causes heap fragmentation on long-running devices.
 template<typename T, enable_if_t<std::is_unsigned<T>::value, int> = 0> std::string format_bin(T val) {
   val = convert_big_endian(val);
   return format_bin(reinterpret_cast<uint8_t *>(&val), sizeof(T));

esphome/core/progmem.h

@@ -12,6 +12,8 @@
 #define ESPHOME_strncpy_P strncpy_P
 #define ESPHOME_strncat_P strncat_P
 #define ESPHOME_snprintf_P snprintf_P
+// Type for pointers to PROGMEM strings (for use with ESPHOME_F return values)
+using ProgmemStr = const __FlashStringHelper *;
 #else
 #define ESPHOME_F(string_literal) (string_literal)
 #define ESPHOME_PGM_P const char *
@@ -19,4 +21,6 @@
 #define ESPHOME_strncpy_P strncpy
 #define ESPHOME_strncat_P strncat
 #define ESPHOME_snprintf_P snprintf
+// Type for pointers to strings (no PROGMEM on non-ESP8266 platforms)
+using ProgmemStr = const char *;
 #endif

esphome/core/string_ref.h

@@ -72,7 +72,6 @@ class StringRef {
 
   constexpr const char *c_str() const { return base_; }
   constexpr size_type size() const { return len_; }
-  constexpr size_type length() const { return len_; }
   constexpr bool empty() const { return len_ == 0; }
   constexpr const_reference operator[](size_type pos) const { return *(base_ + pos); }
 
@@ -81,32 +80,6 @@ class StringRef {
 
   operator std::string() const { return str(); }
 
-  /// Find first occurrence of substring, returns std::string::npos if not found.
-  /// Note: Requires the underlying string to be null-terminated.
-  size_type find(const char *s, size_type pos = 0) const {
-    if (pos >= len_)
-      return std::string::npos;
-    const char *result = std::strstr(base_ + pos, s);
-    // Verify entire match is within bounds (strstr searches to null terminator)
-    if (result && result + std::strlen(s) <= base_ + len_)
-      return static_cast<size_type>(result - base_);
-    return std::string::npos;
-  }
-  size_type find(char c, size_type pos = 0) const {
-    if (pos >= len_)
-      return std::string::npos;
-    const void *result = std::memchr(base_ + pos, static_cast<unsigned char>(c), len_ - pos);
-    return result ? static_cast<size_type>(static_cast<const char *>(result) - base_) : std::string::npos;
-  }
-
-  /// Return substring as std::string
-  std::string substr(size_type pos = 0, size_type count = std::string::npos) const {
-    if (pos >= len_)
-      return std::string();
-    size_type actual_count = (count == std::string::npos || pos + count > len_) ? len_ - pos : count;
-    return std::string(base_ + pos, actual_count);
-  }
-
  private:
   const char *base_;
   size_type len_;
@@ -187,43 +160,6 @@ inline std::string operator+(const std::string &lhs, const StringRef &rhs) {
   str.append(rhs.c_str(), rhs.size());
   return str;
 }
-// String conversion functions for ADL compatibility (allows stoi(x) where x is StringRef)
-// Must be in esphome namespace for ADL to find them. Uses strtol/strtod directly to avoid heap allocation.
-namespace internal {
-// NOLINTBEGIN(google-runtime-int)
-template<typename R, typename F> inline R parse_number(const StringRef &str, size_t *pos, F conv) {
-  char *end;
-  R result = conv(str.c_str(), &end);
-  // Set pos to 0 on conversion failure (when no characters consumed), otherwise index after number
-  if (pos)
-    *pos = (end == str.c_str()) ? 0 : static_cast<size_t>(end - str.c_str());
-  return result;
-}
-template<typename R, typename F> inline R parse_number(const StringRef &str, size_t *pos, int base, F conv) {
-  char *end;
-  R result = conv(str.c_str(), &end, base);
-  // Set pos to 0 on conversion failure (when no characters consumed), otherwise index after number
-  if (pos)
-    *pos = (end == str.c_str()) ? 0 : static_cast<size_t>(end - str.c_str());
-  return result;
-}
-// NOLINTEND(google-runtime-int)
-}  // namespace internal
-// NOLINTBEGIN(readability-identifier-naming,google-runtime-int)
-inline int stoi(const StringRef &str, size_t *pos = nullptr, int base = 10) {
-  return static_cast<int>(internal::parse_number<long>(str, pos, base, std::strtol));
-}
-inline long stol(const StringRef &str, size_t *pos = nullptr, int base = 10) {
-  return internal::parse_number<long>(str, pos, base, std::strtol);
-}
-inline float stof(const StringRef &str, size_t *pos = nullptr) {
-  return internal::parse_number<float>(str, pos, std::strtof);
-}
-inline double stod(const StringRef &str, size_t *pos = nullptr) {
-  return internal::parse_number<double>(str, pos, std::strtod);
-}
-// NOLINTEND(readability-identifier-naming,google-runtime-int)
-
 #ifdef USE_JSON
 // NOLINTNEXTLINE(readability-identifier-naming)
 inline void convertToJson(const StringRef &src, JsonVariant dst) { dst.set(src.c_str()); }

esphome/cpp_types.py

@@ -44,4 +44,3 @@ gpio_Flags = gpio_ns.enum("Flags", is_class=True)
 EntityCategory = esphome_ns.enum("EntityCategory")
 Parented = esphome_ns.class_("Parented")
 ESPTime = esphome_ns.struct("ESPTime")
-StringRef = esphome_ns.class_("StringRef")

script/ci-custom.py

@@ -682,6 +682,7 @@ def lint_trailing_whitespace(fname, match):
 # Heap-allocating helpers that cause fragmentation on long-running embedded devices.
 # These return std::string and should be replaced with stack-based alternatives.
 HEAP_ALLOCATING_HELPERS = {
+    "format_bin": "format_bin_to() with a stack buffer",
     "format_hex": "format_hex_to() with a stack buffer",
     "format_hex_pretty": "format_hex_pretty_to() with a stack buffer",
     "format_mac_address_pretty": "format_mac_addr_upper() with a stack buffer",
@@ -699,6 +700,7 @@ HEAP_ALLOCATING_HELPERS = {
     # get_mac_address(?!_) ensures we don't match get_mac_address_into_buffer, etc.
     # CPP_RE_EOL captures rest of line so NOLINT comments are detected
     r"[^\w]("
+    r"format_bin(?!_)|"
     r"format_hex(?!_)|"
     r"format_hex_pretty(?!_)|"
     r"format_mac_address_pretty|"

tests/integration/fixtures/select_stringref_trigger.yaml

@@ -1,85 +0,0 @@
-esphome:
-  name: select-stringref-test
-  friendly_name: Select StringRef Test
-
-host:
-
-logger:
-  level: DEBUG
-
-api:
-
-select:
-  - platform: template
-    name: "Test Select"
-    id: test_select
-    optimistic: true
-    options:
-      - "Option A"
-      - "Option B"
-      - "Option C"
-    initial_option: "Option A"
-    on_value:
-      then:
-        # Test 1: Log the value directly (StringRef -> const char* via c_str())
-        - logger.log:
-            format: "Select value: %s"
-            args: ['x.c_str()']
-        # Test 2: String concatenation (StringRef + const char* -> std::string)
-        - lambda: |-
-            std::string with_suffix = x + " selected";
-            ESP_LOGI("test", "Concatenated: %s", with_suffix.c_str());
-        # Test 3: Comparison (StringRef == const char*)
-        - lambda: |-
-            if (x == "Option B") {
-              ESP_LOGI("test", "Option B was selected");
-            }
-        # Test 4: Use index parameter (variable name is 'i')
-        - lambda: |-
-            ESP_LOGI("test", "Select index: %d", (int)i);
-        # Test 5: StringRef.length() method
-        - lambda: |-
-            ESP_LOGI("test", "Length: %d", (int)x.length());
-        # Test 6: StringRef.find() method with substring
-        - lambda: |-
-            if (x.find("Option") != std::string::npos) {
-              ESP_LOGI("test", "Found 'Option' in value");
-            }
-        # Test 7: StringRef.find() method with character
-        - lambda: |-
-            size_t space_pos = x.find(' ');
-            if (space_pos != std::string::npos) {
-              ESP_LOGI("test", "Space at position: %d", (int)space_pos);
-            }
-        # Test 8: StringRef.substr() method
-        - lambda: |-
-            std::string prefix = x.substr(0, 6);
-            ESP_LOGI("test", "Substr prefix: %s", prefix.c_str());
-
-  # Second select with numeric options to test ADL functions
-  - platform: template
-    name: "Baud Rate"
-    id: baud_select
-    optimistic: true
-    options:
-      - "9600"
-      - "115200"
-    initial_option: "9600"
-    on_value:
-      then:
-        # Test 9: stoi via ADL
-        - lambda: |-
-            int baud = stoi(x);
-            ESP_LOGI("test", "stoi result: %d", baud);
-        # Test 10: stol via ADL
-        - lambda: |-
-            long baud_long = stol(x);
-            ESP_LOGI("test", "stol result: %ld", baud_long);
-        # Test 11: stof via ADL
-        - lambda: |-
-            float baud_float = stof(x);
-            ESP_LOGI("test", "stof result: %.0f", baud_float);
-        # Test 12: stod via ADL
-        - lambda: |-
-            double baud_double = stod(x);
-            ESP_LOGI("test", "stod result: %.0f", baud_double);

tests/integration/test_select_stringref_trigger.py

@@ -1,143 +0,0 @@
-"""Integration test for select on_value trigger with StringRef parameter."""
-
-from __future__ import annotations
-
-import asyncio
-import re
-
-import pytest
-
-from .types import APIClientConnectedFactory, RunCompiledFunction
-
-
-@pytest.mark.asyncio
-async def test_select_stringref_trigger(
-    yaml_config: str,
-    run_compiled: RunCompiledFunction,
-    api_client_connected: APIClientConnectedFactory,
-) -> None:
-    """Test select on_value trigger passes StringRef that works with string operations."""
-    loop = asyncio.get_running_loop()
-
-    # Track log messages to verify StringRef operations work
-    value_logged_future = loop.create_future()
-    concatenated_future = loop.create_future()
-    comparison_future = loop.create_future()
-    index_logged_future = loop.create_future()
-    length_future = loop.create_future()
-    find_substr_future = loop.create_future()
-    find_char_future = loop.create_future()
-    substr_future = loop.create_future()
-    # ADL functions
-    stoi_future = loop.create_future()
-    stol_future = loop.create_future()
-    stof_future = loop.create_future()
-    stod_future = loop.create_future()
-
-    # Patterns to match in logs
-    value_pattern = re.compile(r"Select value: Option B")
-    concatenated_pattern = re.compile(r"Concatenated: Option B selected")
-    comparison_pattern = re.compile(r"Option B was selected")
-    index_pattern = re.compile(r"Select index: 1")
-    length_pattern = re.compile(r"Length: 8")  # "Option B" is 8 chars
-    find_substr_pattern = re.compile(r"Found 'Option' in value")
-    find_char_pattern = re.compile(r"Space at position: 6")  # space at index 6
-    substr_pattern = re.compile(r"Substr prefix: Option")
-    # ADL function patterns (115200 from baud rate select)
-    stoi_pattern = re.compile(r"stoi result: 115200")
-    stol_pattern = re.compile(r"stol result: 115200")
-    stof_pattern = re.compile(r"stof result: 115200")
-    stod_pattern = re.compile(r"stod result: 115200")
-
-    def check_output(line: str) -> None:
-        """Check log output for expected messages."""
-        if not value_logged_future.done() and value_pattern.search(line):
-            value_logged_future.set_result(True)
-        if not concatenated_future.done() and concatenated_pattern.search(line):
-            concatenated_future.set_result(True)
-        if not comparison_future.done() and comparison_pattern.search(line):
-            comparison_future.set_result(True)
-        if not index_logged_future.done() and index_pattern.search(line):
-            index_logged_future.set_result(True)
-        if not length_future.done() and length_pattern.search(line):
-            length_future.set_result(True)
-        if not find_substr_future.done() and find_substr_pattern.search(line):
-            find_substr_future.set_result(True)
-        if not find_char_future.done() and find_char_pattern.search(line):
-            find_char_future.set_result(True)
-        if not substr_future.done() and substr_pattern.search(line):
-            substr_future.set_result(True)
-        # ADL functions
-        if not stoi_future.done() and stoi_pattern.search(line):
-            stoi_future.set_result(True)
-        if not stol_future.done() and stol_pattern.search(line):
-            stol_future.set_result(True)
-        if not stof_future.done() and stof_pattern.search(line):
-            stof_future.set_result(True)
-        if not stod_future.done() and stod_pattern.search(line):
-            stod_future.set_result(True)
-
-    async with (
-        run_compiled(yaml_config, line_callback=check_output),
-        api_client_connected() as client,
-    ):
-        # Verify device info
-        device_info = await client.device_info()
-        assert device_info is not None
-        assert device_info.name == "select-stringref-test"
-
-        # List entities to find our select
-        entities, _ = await client.list_entities_services()
-
-        select_entity = next(
-            (e for e in entities if hasattr(e, "options") and e.name == "Test Select"),
-            None,
-        )
-        assert select_entity is not None, "Test Select entity not found"
-
-        baud_entity = next(
-            (e for e in entities if hasattr(e, "options") and e.name == "Baud Rate"),
-            None,
-        )
-        assert baud_entity is not None, "Baud Rate entity not found"
-
-        # Change select to Option B - this should trigger on_value with StringRef
-        client.select_command(select_entity.key, "Option B")
-        # Change baud to 115200 - this tests ADL functions (stoi, stol, stof, stod)
-        client.select_command(baud_entity.key, "115200")
-
-        # Wait for all log messages confirming StringRef operations work
-        try:
-            await asyncio.wait_for(
-                asyncio.gather(
-                    value_logged_future,
-                    concatenated_future,
-                    comparison_future,
-                    index_logged_future,
-                    length_future,
-                    find_substr_future,
-                    find_char_future,
-                    substr_future,
-                    stoi_future,
-                    stol_future,
-                    stof_future,
-                    stod_future,
-                ),
-                timeout=5.0,
-            )
-        except TimeoutError:
-            results = {
-                "value_logged": value_logged_future.done(),
-                "concatenated": concatenated_future.done(),
-                "comparison": comparison_future.done(),
-                "index_logged": index_logged_future.done(),
-                "length": length_future.done(),
-                "find_substr": find_substr_future.done(),
-                "find_char": find_char_future.done(),
-                "substr": substr_future.done(),
-                "stoi": stoi_future.done(),
-                "stol": stol_future.done(),
-                "stof": stof_future.done(),
-                "stod": stod_future.done(),
-            }
-            pytest.fail(f"StringRef operations failed - received: {results}")