Add tests for cg.templatable() auto FlashStringLiteral wrapping

Cover the new automatic ESPHOME_F() wrapping behavior: static strings
with std::string output_type, non-string values, None output_type,
to_exp callable/dict, and lambda passthrough.

esphome/analyze_memory/__init__.py

@@ -397,47 +397,38 @@ class MemoryAnalyzer:
             return pioenvs_dir
         return None
 
-    def _scan_cswtch_in_objects(
-        self, obj_dir: Path
-    ) -> dict[str, list[tuple[str, int]]]:
-        """Scan object files for CSWTCH symbols using a single nm invocation.
+    @staticmethod
+    def _parse_nm_cswtch_output(
+        output: str,
+        base_dir: Path | None,
+        cswtch_map: dict[str, list[tuple[str, int]]],
+    ) -> None:
+        """Parse nm output for CSWTCH symbols and add to cswtch_map.
 
-        Uses ``nm --print-file-name -S`` on all ``.o`` files at once.
-        Output format: ``/path/to/file.o:address size type name``
+        Handles both ``.o`` files and ``.a`` archives.
+
+        nm output formats::
+
+            .o files:  /path/file.o:hex_addr hex_size type name
+            .a files:  /path/lib.a:member.o:hex_addr hex_size type name
+
+        For ``.o`` files, paths are made relative to *base_dir* when possible.
+        For ``.a`` archives (detected by ``:`` in the file portion), paths are
+        formatted as ``archive_stem/member.o`` (e.g. ``liblwip2-536-feat/lwip-esp.o``).
 
         Args:
-            obj_dir: Directory containing object files (.pioenvs/<env>/)
-
-        Returns:
-            Dict mapping "CSWTCH$NNN:size" to list of (source_file, size) tuples.
+            output: Raw stdout from ``nm --print-file-name -S``.
+            base_dir: Base directory for computing relative paths of ``.o`` files.
+                      Pass ``None`` when scanning archives outside the build tree.
+            cswtch_map: Dict to populate, mapping ``"CSWTCH$N:size"`` to source list.
         """
-        cswtch_map: dict[str, list[tuple[str, int]]] = defaultdict(list)
-
-        if not self.nm_path:
-            return cswtch_map
-
-        # Find all .o files recursively, sorted for deterministic output
-        obj_files = sorted(obj_dir.rglob("*.o"))
-        if not obj_files:
-            return cswtch_map
-
-        _LOGGER.debug("Scanning %d object files for CSWTCH symbols", len(obj_files))
-
-        # Single nm call with --print-file-name for all object files
-        result = run_tool(
-            [self.nm_path, "--print-file-name", "-S"] + [str(f) for f in obj_files],
-            timeout=30,
-        )
-        if result is None or result.returncode != 0:
-            return cswtch_map
-
-        for line in result.stdout.splitlines():
+        for line in output.splitlines():
             if "CSWTCH$" not in line:
                 continue
 
             # Split on last ":" that precedes a hex address.
-            # nm --print-file-name format: filepath:hex_addr hex_size type name
-            # We split from the right: find the last colon followed by hex digits.
+            # For .o:  "filepath.o" : "hex_addr hex_size type name"
+            # For .a:  "filepath.a:member.o" : "hex_addr hex_size type name"
             parts_after_colon = line.rsplit(":", 1)
             if len(parts_after_colon) != 2:
                 continue
@@ -457,16 +448,89 @@ class MemoryAnalyzer:
             except ValueError:
                 continue
 
-            # Get relative path from obj_dir for readability
-            try:
-                rel_path = str(Path(file_path).relative_to(obj_dir))
-            except ValueError:
+            # Determine readable source path
+            # Use ".a:" to detect archive format (not bare ":" which matches
+            # Windows drive letters like "C:\...\file.o").
+            if ".a:" in file_path:
+                # Archive format: "archive.a:member.o" → "archive_stem/member.o"
+                archive_part, member = file_path.rsplit(":", 1)
+                archive_name = Path(archive_part).stem
+                rel_path = f"{archive_name}/{member}"
+            elif base_dir is not None:
+                try:
+                    rel_path = str(Path(file_path).relative_to(base_dir))
+                except ValueError:
+                    rel_path = file_path
+            else:
                 rel_path = file_path
 
             key = f"{sym_name}:{size}"
             cswtch_map[key].append((rel_path, size))
 
-        return cswtch_map
+    def _run_nm_cswtch_scan(
+        self,
+        files: list[Path],
+        base_dir: Path | None,
+        cswtch_map: dict[str, list[tuple[str, int]]],
+    ) -> None:
+        """Run nm on *files* and add any CSWTCH symbols to *cswtch_map*.
+
+        Args:
+            files: Object (``.o``) or archive (``.a``) files to scan.
+            base_dir: Base directory for relative path computation (see
+                      :meth:`_parse_nm_cswtch_output`).
+            cswtch_map: Dict to populate with results.
+        """
+        if not self.nm_path or not files:
+            return
+
+        _LOGGER.debug("Scanning %d files for CSWTCH symbols", len(files))
+
+        result = run_tool(
+            [self.nm_path, "--print-file-name", "-S"] + [str(f) for f in files],
+            timeout=30,
+        )
+        if result is None or result.returncode != 0:
+            _LOGGER.debug(
+                "nm failed or timed out scanning %d files for CSWTCH symbols",
+                len(files),
+            )
+            return
+
+        self._parse_nm_cswtch_output(result.stdout, base_dir, cswtch_map)
+
+    def _scan_cswtch_in_sdk_archives(
+        self, cswtch_map: dict[str, list[tuple[str, int]]]
+    ) -> None:
+        """Scan SDK library archives (.a) for CSWTCH symbols.
+
+        Prebuilt SDK libraries (e.g. lwip, bearssl) are not compiled from source,
+        so their CSWTCH symbols only exist inside ``.a`` archives.  Results are
+        merged into *cswtch_map* for keys not already found in ``.o`` files.
+
+        The same source file (e.g. ``lwip-esp.o``) often appears in multiple
+        library variants (``liblwip2-536.a``, ``liblwip2-1460-feat.a``, etc.),
+        so results are deduplicated by member name.
+        """
+        sdk_dirs = self._find_sdk_library_dirs()
+        if not sdk_dirs:
+            return
+
+        sdk_archives = sorted(a for sdk_dir in sdk_dirs for a in sdk_dir.glob("*.a"))
+
+        sdk_map: dict[str, list[tuple[str, int]]] = defaultdict(list)
+        self._run_nm_cswtch_scan(sdk_archives, None, sdk_map)
+
+        # Merge SDK results, deduplicating by member name.
+        for key, sources in sdk_map.items():
+            if key in cswtch_map:
+                continue
+            seen: dict[str, tuple[str, int]] = {}
+            for path, sz in sources:
+                member = Path(path).name
+                if member not in seen:
+                    seen[member] = (path, sz)
+            cswtch_map[key] = list(seen.values())
 
     def _source_file_to_component(self, source_file: str) -> str:
         """Map a source object file path to its component name.
@@ -505,17 +569,25 @@ class MemoryAnalyzer:
 
         CSWTCH symbols are compiler-generated lookup tables for switch statements.
         They are local symbols, so the same name can appear in different object files.
-        This method scans .o files to attribute them to their source components.
+        This method scans .o files and SDK archives to attribute them to their
+        source components.
         """
         obj_dir = self._find_object_files_dir()
         if obj_dir is None:
             _LOGGER.debug("No object files directory found, skipping CSWTCH analysis")
             return
 
-        # Scan object files for CSWTCH symbols
-        cswtch_map = self._scan_cswtch_in_objects(obj_dir)
+        # Scan build-dir object files for CSWTCH symbols
+        cswtch_map: dict[str, list[tuple[str, int]]] = defaultdict(list)
+        self._run_nm_cswtch_scan(sorted(obj_dir.rglob("*.o")), obj_dir, cswtch_map)
+
+        # Also scan SDK library archives (.a) for CSWTCH symbols.
+        # Prebuilt SDK libraries (e.g. lwip, bearssl) are not compiled from source
+        # so their symbols only exist inside .a archives, not as loose .o files.
+        self._scan_cswtch_in_sdk_archives(cswtch_map)
+
         if not cswtch_map:
-            _LOGGER.debug("No CSWTCH symbols found in object files")
+            _LOGGER.debug("No CSWTCH symbols found in object files or SDK archives")
             return
 
         # Collect CSWTCH symbols from the ELF (already parsed in sections)

esphome/codegen.py

@@ -11,6 +11,7 @@
 from esphome.cpp_generator import (  # noqa: F401
     ArrayInitializer,
     Expression,
+    FlashStringLiteral,
     LineComment,
     LogStringLiteral,
     MockObj,
@@ -87,6 +88,7 @@ from esphome.cpp_types import (  # noqa: F401
     size_t,
     std_ns,
     std_shared_ptr,
+    std_span,
     std_string,
     std_string_ref,
     std_vector,

esphome/components/api/__init__.py

@@ -524,24 +524,24 @@ async def homeassistant_service_to_code(
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, False)
-    templ = await cg.templatable(config[CONF_ACTION], args, None)
+    templ = await cg.templatable(config[CONF_ACTION], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
-        templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        templ = await cg.templatable(value, args, cg.std_string)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
-        templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        templ = await cg.templatable(value, args, cg.std_string)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
-        templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        templ = await cg.templatable(value, args, cg.std_string)
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     if on_error := config.get(CONF_ON_ERROR):
         cg.add_define("USE_API_HOMEASSISTANT_ACTION_RESPONSES")
@@ -609,24 +609,24 @@ async def homeassistant_event_to_code(config, action_id, template_arg, args):
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    templ = await cg.templatable(config[CONF_EVENT], args, None)
+    templ = await cg.templatable(config[CONF_EVENT], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
-        templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        templ = await cg.templatable(value, args, cg.std_string)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
-        templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        templ = await cg.templatable(value, args, cg.std_string)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
-        templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        templ = await cg.templatable(value, args, cg.std_string)
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     return var
 
@@ -649,11 +649,11 @@ async def homeassistant_tag_scanned_to_code(config, action_id, template_arg, arg
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    cg.add(var.set_service("esphome.tag_scanned"))
+    cg.add(var.set_service(cg.FlashStringLiteral("esphome.tag_scanned")))
     # Initialize FixedVector with exact size (1 data field)
     cg.add(var.init_data(1))
     templ = await cg.templatable(config[CONF_TAG], args, cg.std_string)
-    cg.add(var.add_data("tag_id", templ))
+    cg.add(var.add_data(cg.FlashStringLiteral("tag_id"), templ))
     return var
 
 

esphome/components/api/api_connection.cpp

@@ -283,7 +283,7 @@ void APIConnection::loop() {
 #endif
 }
 
-bool APIConnection::send_disconnect_response(const DisconnectRequest &msg) {
+bool APIConnection::send_disconnect_response() {
   // remote initiated disconnect_client
   // don't close yet, we still need to send the disconnect response
   // close will happen on next loop
@@ -292,7 +292,7 @@ bool APIConnection::send_disconnect_response(const DisconnectRequest &msg) {
   DisconnectResponse resp;
   return this->send_message(resp, DisconnectResponse::MESSAGE_TYPE);
 }
-void APIConnection::on_disconnect_response(const DisconnectResponse &value) {
+void APIConnection::on_disconnect_response() {
   this->helper_->close();
   this->flags_.remove = true;
 }
@@ -1095,7 +1095,7 @@ void APIConnection::on_get_time_response(const GetTimeResponse &value) {
 void APIConnection::subscribe_bluetooth_le_advertisements(const SubscribeBluetoothLEAdvertisementsRequest &msg) {
   bluetooth_proxy::global_bluetooth_proxy->subscribe_api_connection(this, msg.flags);
 }
-void APIConnection::unsubscribe_bluetooth_le_advertisements(const UnsubscribeBluetoothLEAdvertisementsRequest &msg) {
+void APIConnection::unsubscribe_bluetooth_le_advertisements() {
   bluetooth_proxy::global_bluetooth_proxy->unsubscribe_api_connection(this);
 }
 void APIConnection::bluetooth_device_request(const BluetoothDeviceRequest &msg) {
@@ -1121,8 +1121,7 @@ void APIConnection::bluetooth_gatt_notify(const BluetoothGATTNotifyRequest &msg)
   bluetooth_proxy::global_bluetooth_proxy->bluetooth_gatt_notify(msg);
 }
 
-bool APIConnection::send_subscribe_bluetooth_connections_free_response(
-    const SubscribeBluetoothConnectionsFreeRequest &msg) {
+bool APIConnection::send_subscribe_bluetooth_connections_free_response() {
   bluetooth_proxy::global_bluetooth_proxy->send_connections_free(this);
   return true;
 }
@@ -1491,12 +1490,12 @@ bool APIConnection::send_hello_response(const HelloRequest &msg) {
   return this->send_message(resp, HelloResponse::MESSAGE_TYPE);
 }
 
-bool APIConnection::send_ping_response(const PingRequest &msg) {
+bool APIConnection::send_ping_response() {
   PingResponse resp;
   return this->send_message(resp, PingResponse::MESSAGE_TYPE);
 }
 
-bool APIConnection::send_device_info_response(const DeviceInfoRequest &msg) {
+bool APIConnection::send_device_info_response() {
   DeviceInfoResponse resp{};
   resp.name = StringRef(App.get_name());
   resp.friendly_name = StringRef(App.get_friendly_name());
@@ -1746,9 +1745,7 @@ bool APIConnection::send_noise_encryption_set_key_response(const NoiseEncryption
 }
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
-void APIConnection::subscribe_home_assistant_states(const SubscribeHomeAssistantStatesRequest &msg) {
-  state_subs_at_ = 0;
-}
+void APIConnection::subscribe_home_assistant_states() { state_subs_at_ = 0; }
 #endif
 bool APIConnection::try_to_clear_buffer(bool log_out_of_space) {
   if (this->flags_.remove)

esphome/components/api/api_connection.h

@@ -127,7 +127,7 @@ class APIConnection final : public APIServerConnection {
 #endif  // USE_API_HOMEASSISTANT_SERVICES
 #ifdef USE_BLUETOOTH_PROXY
   void subscribe_bluetooth_le_advertisements(const SubscribeBluetoothLEAdvertisementsRequest &msg) override;
-  void unsubscribe_bluetooth_le_advertisements(const UnsubscribeBluetoothLEAdvertisementsRequest &msg) override;
+  void unsubscribe_bluetooth_le_advertisements() override;
 
   void bluetooth_device_request(const BluetoothDeviceRequest &msg) override;
   void bluetooth_gatt_read(const BluetoothGATTReadRequest &msg) override;
@@ -136,7 +136,7 @@ class APIConnection final : public APIServerConnection {
   void bluetooth_gatt_write_descriptor(const BluetoothGATTWriteDescriptorRequest &msg) override;
   void bluetooth_gatt_get_services(const BluetoothGATTGetServicesRequest &msg) override;
   void bluetooth_gatt_notify(const BluetoothGATTNotifyRequest &msg) override;
-  bool send_subscribe_bluetooth_connections_free_response(const SubscribeBluetoothConnectionsFreeRequest &msg) override;
+  bool send_subscribe_bluetooth_connections_free_response() override;
   void bluetooth_scanner_set_mode(const BluetoothScannerSetModeRequest &msg) override;
 
 #endif
@@ -187,8 +187,8 @@ class APIConnection final : public APIServerConnection {
   void update_command(const UpdateCommandRequest &msg) override;
 #endif
 
-  void on_disconnect_response(const DisconnectResponse &value) override;
-  void on_ping_response(const PingResponse &value) override {
+  void on_disconnect_response() override;
+  void on_ping_response() override {
     // we initiated ping
     this->flags_.sent_ping = false;
   }
@@ -199,11 +199,11 @@ class APIConnection final : public APIServerConnection {
   void on_get_time_response(const GetTimeResponse &value) override;
 #endif
   bool send_hello_response(const HelloRequest &msg) override;
-  bool send_disconnect_response(const DisconnectRequest &msg) override;
-  bool send_ping_response(const PingRequest &msg) override;
-  bool send_device_info_response(const DeviceInfoRequest &msg) override;
-  void list_entities(const ListEntitiesRequest &msg) override { this->begin_iterator_(ActiveIterator::LIST_ENTITIES); }
-  void subscribe_states(const SubscribeStatesRequest &msg) override {
+  bool send_disconnect_response() override;
+  bool send_ping_response() override;
+  bool send_device_info_response() override;
+  void list_entities() override { this->begin_iterator_(ActiveIterator::LIST_ENTITIES); }
+  void subscribe_states() override {
     this->flags_.state_subscription = true;
     // Start initial state iterator only if no iterator is active
     // If list_entities is running, we'll start initial_state when it completes
@@ -217,12 +217,10 @@ class APIConnection final : public APIServerConnection {
       App.schedule_dump_config();
   }
 #ifdef USE_API_HOMEASSISTANT_SERVICES
-  void subscribe_homeassistant_services(const SubscribeHomeassistantServicesRequest &msg) override {
-    this->flags_.service_call_subscription = true;
-  }
+  void subscribe_homeassistant_services() override { this->flags_.service_call_subscription = true; }
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
-  void subscribe_home_assistant_states(const SubscribeHomeAssistantStatesRequest &msg) override;
+  void subscribe_home_assistant_states() override;
 #endif
 #ifdef USE_API_USER_DEFINED_ACTIONS
   void execute_service(const ExecuteServiceRequest &msg) override;

esphome/components/api/api_pb2_service.cpp

@@ -15,6 +15,9 @@ void APIServerConnectionBase::log_receive_message_(const LogString *name, const
   DumpBuffer dump_buf;
   ESP_LOGVV(TAG, "%s: %s", LOG_STR_ARG(name), msg.dump_to(dump_buf));
 }
+void APIServerConnectionBase::log_receive_message_(const LogString *name) {
+  ESP_LOGVV(TAG, "%s: {}", LOG_STR_ARG(name));
+}
 #endif
 
 void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) {
@@ -29,66 +32,52 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
       break;
     }
     case DisconnectRequest::MESSAGE_TYPE: {
-      DisconnectRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_disconnect_request"), msg);
+      this->log_receive_message_(LOG_STR("on_disconnect_request"));
 #endif
-      this->on_disconnect_request(msg);
+      this->on_disconnect_request();
       break;
     }
     case DisconnectResponse::MESSAGE_TYPE: {
-      DisconnectResponse msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_disconnect_response"), msg);
+      this->log_receive_message_(LOG_STR("on_disconnect_response"));
 #endif
-      this->on_disconnect_response(msg);
+      this->on_disconnect_response();
       break;
     }
     case PingRequest::MESSAGE_TYPE: {
-      PingRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_ping_request"), msg);
+      this->log_receive_message_(LOG_STR("on_ping_request"));
 #endif
-      this->on_ping_request(msg);
+      this->on_ping_request();
       break;
     }
     case PingResponse::MESSAGE_TYPE: {
-      PingResponse msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_ping_response"), msg);
+      this->log_receive_message_(LOG_STR("on_ping_response"));
 #endif
-      this->on_ping_response(msg);
+      this->on_ping_response();
       break;
     }
     case DeviceInfoRequest::MESSAGE_TYPE: {
-      DeviceInfoRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_device_info_request"), msg);
+      this->log_receive_message_(LOG_STR("on_device_info_request"));
 #endif
-      this->on_device_info_request(msg);
+      this->on_device_info_request();
       break;
     }
     case ListEntitiesRequest::MESSAGE_TYPE: {
-      ListEntitiesRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_list_entities_request"), msg);
+      this->log_receive_message_(LOG_STR("on_list_entities_request"));
 #endif
-      this->on_list_entities_request(msg);
+      this->on_list_entities_request();
       break;
     }
     case SubscribeStatesRequest::MESSAGE_TYPE: {
-      SubscribeStatesRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_subscribe_states_request"), msg);
+      this->log_receive_message_(LOG_STR("on_subscribe_states_request"));
 #endif
-      this->on_subscribe_states_request(msg);
+      this->on_subscribe_states_request();
       break;
     }
     case SubscribeLogsRequest::MESSAGE_TYPE: {
@@ -146,12 +135,10 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
 #endif
 #ifdef USE_API_HOMEASSISTANT_SERVICES
     case SubscribeHomeassistantServicesRequest::MESSAGE_TYPE: {
-      SubscribeHomeassistantServicesRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_subscribe_homeassistant_services_request"), msg);
+      this->log_receive_message_(LOG_STR("on_subscribe_homeassistant_services_request"));
 #endif
-      this->on_subscribe_homeassistant_services_request(msg);
+      this->on_subscribe_homeassistant_services_request();
       break;
     }
 #endif
@@ -166,12 +153,10 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
     }
 #ifdef USE_API_HOMEASSISTANT_STATES
     case SubscribeHomeAssistantStatesRequest::MESSAGE_TYPE: {
-      SubscribeHomeAssistantStatesRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_subscribe_home_assistant_states_request"), msg);
+      this->log_receive_message_(LOG_STR("on_subscribe_home_assistant_states_request"));
 #endif
-      this->on_subscribe_home_assistant_states_request(msg);
+      this->on_subscribe_home_assistant_states_request();
       break;
     }
 #endif
@@ -375,23 +360,19 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
 #endif
 #ifdef USE_BLUETOOTH_PROXY
     case SubscribeBluetoothConnectionsFreeRequest::MESSAGE_TYPE: {
-      SubscribeBluetoothConnectionsFreeRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_subscribe_bluetooth_connections_free_request"), msg);
+      this->log_receive_message_(LOG_STR("on_subscribe_bluetooth_connections_free_request"));
 #endif
-      this->on_subscribe_bluetooth_connections_free_request(msg);
+      this->on_subscribe_bluetooth_connections_free_request();
       break;
     }
 #endif
 #ifdef USE_BLUETOOTH_PROXY
     case UnsubscribeBluetoothLEAdvertisementsRequest::MESSAGE_TYPE: {
-      UnsubscribeBluetoothLEAdvertisementsRequest msg;
-      // Empty message: no decode needed
 #ifdef HAS_PROTO_MESSAGE_DUMP
-      this->log_receive_message_(LOG_STR("on_unsubscribe_bluetooth_le_advertisements_request"), msg);
+      this->log_receive_message_(LOG_STR("on_unsubscribe_bluetooth_le_advertisements_request"));
 #endif
-      this->on_unsubscribe_bluetooth_le_advertisements_request(msg);
+      this->on_unsubscribe_bluetooth_le_advertisements_request();
       break;
     }
 #endif
@@ -647,36 +628,29 @@ void APIServerConnection::on_hello_request(const HelloRequest &msg) {
     this->on_fatal_error();
   }
 }
-void APIServerConnection::on_disconnect_request(const DisconnectRequest &msg) {
-  if (!this->send_disconnect_response(msg)) {
+void APIServerConnection::on_disconnect_request() {
+  if (!this->send_disconnect_response()) {
     this->on_fatal_error();
   }
 }
-void APIServerConnection::on_ping_request(const PingRequest &msg) {
-  if (!this->send_ping_response(msg)) {
+void APIServerConnection::on_ping_request() {
+  if (!this->send_ping_response()) {
     this->on_fatal_error();
   }
 }
-void APIServerConnection::on_device_info_request(const DeviceInfoRequest &msg) {
-  if (!this->send_device_info_response(msg)) {
+void APIServerConnection::on_device_info_request() {
+  if (!this->send_device_info_response()) {
     this->on_fatal_error();
   }
 }
-void APIServerConnection::on_list_entities_request(const ListEntitiesRequest &msg) { this->list_entities(msg); }
-void APIServerConnection::on_subscribe_states_request(const SubscribeStatesRequest &msg) {
-  this->subscribe_states(msg);
-}
+void APIServerConnection::on_list_entities_request() { this->list_entities(); }
+void APIServerConnection::on_subscribe_states_request() { this->subscribe_states(); }
 void APIServerConnection::on_subscribe_logs_request(const SubscribeLogsRequest &msg) { this->subscribe_logs(msg); }
 #ifdef USE_API_HOMEASSISTANT_SERVICES
-void APIServerConnection::on_subscribe_homeassistant_services_request(
-    const SubscribeHomeassistantServicesRequest &msg) {
-  this->subscribe_homeassistant_services(msg);
-}
+void APIServerConnection::on_subscribe_homeassistant_services_request() { this->subscribe_homeassistant_services(); }
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
-void APIServerConnection::on_subscribe_home_assistant_states_request(const SubscribeHomeAssistantStatesRequest &msg) {
-  this->subscribe_home_assistant_states(msg);
-}
+void APIServerConnection::on_subscribe_home_assistant_states_request() { this->subscribe_home_assistant_states(); }
 #endif
 #ifdef USE_API_USER_DEFINED_ACTIONS
 void APIServerConnection::on_execute_service_request(const ExecuteServiceRequest &msg) { this->execute_service(msg); }
@@ -793,17 +767,15 @@ void APIServerConnection::on_bluetooth_gatt_notify_request(const BluetoothGATTNo
 }
 #endif
 #ifdef USE_BLUETOOTH_PROXY
-void APIServerConnection::on_subscribe_bluetooth_connections_free_request(
-    const SubscribeBluetoothConnectionsFreeRequest &msg) {
-  if (!this->send_subscribe_bluetooth_connections_free_response(msg)) {
+void APIServerConnection::on_subscribe_bluetooth_connections_free_request() {
+  if (!this->send_subscribe_bluetooth_connections_free_response()) {
     this->on_fatal_error();
   }
 }
 #endif
 #ifdef USE_BLUETOOTH_PROXY
-void APIServerConnection::on_unsubscribe_bluetooth_le_advertisements_request(
-    const UnsubscribeBluetoothLEAdvertisementsRequest &msg) {
-  this->unsubscribe_bluetooth_le_advertisements(msg);
+void APIServerConnection::on_unsubscribe_bluetooth_le_advertisements_request() {
+  this->unsubscribe_bluetooth_le_advertisements();
 }
 #endif
 #ifdef USE_BLUETOOTH_PROXY

esphome/components/api/api_pb2_service.h

@@ -14,6 +14,7 @@ class APIServerConnectionBase : public ProtoService {
  protected:
   void log_send_message_(const char *name, const char *dump);
   void log_receive_message_(const LogString *name, const ProtoMessage &msg);
+  void log_receive_message_(const LogString *name);
 
  public:
 #endif
@@ -28,15 +29,15 @@ class APIServerConnectionBase : public ProtoService {
 
   virtual void on_hello_request(const HelloRequest &value){};
 
-  virtual void on_disconnect_request(const DisconnectRequest &value){};
-  virtual void on_disconnect_response(const DisconnectResponse &value){};
-  virtual void on_ping_request(const PingRequest &value){};
-  virtual void on_ping_response(const PingResponse &value){};
-  virtual void on_device_info_request(const DeviceInfoRequest &value){};
+  virtual void on_disconnect_request(){};
+  virtual void on_disconnect_response(){};
+  virtual void on_ping_request(){};
+  virtual void on_ping_response(){};
+  virtual void on_device_info_request(){};
 
-  virtual void on_list_entities_request(const ListEntitiesRequest &value){};
+  virtual void on_list_entities_request(){};
 
-  virtual void on_subscribe_states_request(const SubscribeStatesRequest &value){};
+  virtual void on_subscribe_states_request(){};
 
 #ifdef USE_COVER
   virtual void on_cover_command_request(const CoverCommandRequest &value){};
@@ -61,14 +62,14 @@ class APIServerConnectionBase : public ProtoService {
 #endif
 
 #ifdef USE_API_HOMEASSISTANT_SERVICES
-  virtual void on_subscribe_homeassistant_services_request(const SubscribeHomeassistantServicesRequest &value){};
+  virtual void on_subscribe_homeassistant_services_request(){};
 #endif
 
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
   virtual void on_homeassistant_action_response(const HomeassistantActionResponse &value){};
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
-  virtual void on_subscribe_home_assistant_states_request(const SubscribeHomeAssistantStatesRequest &value){};
+  virtual void on_subscribe_home_assistant_states_request(){};
 #endif
 
 #ifdef USE_API_HOMEASSISTANT_STATES
@@ -147,12 +148,11 @@ class APIServerConnectionBase : public ProtoService {
 #endif
 
 #ifdef USE_BLUETOOTH_PROXY
-  virtual void on_subscribe_bluetooth_connections_free_request(const SubscribeBluetoothConnectionsFreeRequest &value){};
+  virtual void on_subscribe_bluetooth_connections_free_request(){};
 #endif
 
 #ifdef USE_BLUETOOTH_PROXY
-  virtual void on_unsubscribe_bluetooth_le_advertisements_request(
-      const UnsubscribeBluetoothLEAdvertisementsRequest &value){};
+  virtual void on_unsubscribe_bluetooth_le_advertisements_request(){};
 #endif
 
 #ifdef USE_BLUETOOTH_PROXY
@@ -231,17 +231,17 @@ class APIServerConnectionBase : public ProtoService {
 class APIServerConnection : public APIServerConnectionBase {
  public:
   virtual bool send_hello_response(const HelloRequest &msg) = 0;
-  virtual bool send_disconnect_response(const DisconnectRequest &msg) = 0;
-  virtual bool send_ping_response(const PingRequest &msg) = 0;
-  virtual bool send_device_info_response(const DeviceInfoRequest &msg) = 0;
-  virtual void list_entities(const ListEntitiesRequest &msg) = 0;
-  virtual void subscribe_states(const SubscribeStatesRequest &msg) = 0;
+  virtual bool send_disconnect_response() = 0;
+  virtual bool send_ping_response() = 0;
+  virtual bool send_device_info_response() = 0;
+  virtual void list_entities() = 0;
+  virtual void subscribe_states() = 0;
   virtual void subscribe_logs(const SubscribeLogsRequest &msg) = 0;
 #ifdef USE_API_HOMEASSISTANT_SERVICES
-  virtual void subscribe_homeassistant_services(const SubscribeHomeassistantServicesRequest &msg) = 0;
+  virtual void subscribe_homeassistant_services() = 0;
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
-  virtual void subscribe_home_assistant_states(const SubscribeHomeAssistantStatesRequest &msg) = 0;
+  virtual void subscribe_home_assistant_states() = 0;
 #endif
 #ifdef USE_API_USER_DEFINED_ACTIONS
   virtual void execute_service(const ExecuteServiceRequest &msg) = 0;
@@ -331,11 +331,10 @@ class APIServerConnection : public APIServerConnectionBase {
   virtual void bluetooth_gatt_notify(const BluetoothGATTNotifyRequest &msg) = 0;
 #endif
 #ifdef USE_BLUETOOTH_PROXY
-  virtual bool send_subscribe_bluetooth_connections_free_response(
-      const SubscribeBluetoothConnectionsFreeRequest &msg) = 0;
+  virtual bool send_subscribe_bluetooth_connections_free_response() = 0;
 #endif
 #ifdef USE_BLUETOOTH_PROXY
-  virtual void unsubscribe_bluetooth_le_advertisements(const UnsubscribeBluetoothLEAdvertisementsRequest &msg) = 0;
+  virtual void unsubscribe_bluetooth_le_advertisements() = 0;
 #endif
 #ifdef USE_BLUETOOTH_PROXY
   virtual void bluetooth_scanner_set_mode(const BluetoothScannerSetModeRequest &msg) = 0;
@@ -363,17 +362,17 @@ class APIServerConnection : public APIServerConnectionBase {
 #endif
  protected:
   void on_hello_request(const HelloRequest &msg) override;
-  void on_disconnect_request(const DisconnectRequest &msg) override;
-  void on_ping_request(const PingRequest &msg) override;
-  void on_device_info_request(const DeviceInfoRequest &msg) override;
-  void on_list_entities_request(const ListEntitiesRequest &msg) override;
-  void on_subscribe_states_request(const SubscribeStatesRequest &msg) override;
+  void on_disconnect_request() override;
+  void on_ping_request() override;
+  void on_device_info_request() override;
+  void on_list_entities_request() override;
+  void on_subscribe_states_request() override;
   void on_subscribe_logs_request(const SubscribeLogsRequest &msg) override;
 #ifdef USE_API_HOMEASSISTANT_SERVICES
-  void on_subscribe_homeassistant_services_request(const SubscribeHomeassistantServicesRequest &msg) override;
+  void on_subscribe_homeassistant_services_request() override;
 #endif
 #ifdef USE_API_HOMEASSISTANT_STATES
-  void on_subscribe_home_assistant_states_request(const SubscribeHomeAssistantStatesRequest &msg) override;
+  void on_subscribe_home_assistant_states_request() override;
 #endif
 #ifdef USE_API_USER_DEFINED_ACTIONS
   void on_execute_service_request(const ExecuteServiceRequest &msg) override;
@@ -463,11 +462,10 @@ class APIServerConnection : public APIServerConnectionBase {
   void on_bluetooth_gatt_notify_request(const BluetoothGATTNotifyRequest &msg) override;
 #endif
 #ifdef USE_BLUETOOTH_PROXY
-  void on_subscribe_bluetooth_connections_free_request(const SubscribeBluetoothConnectionsFreeRequest &msg) override;
+  void on_subscribe_bluetooth_connections_free_request() override;
 #endif
 #ifdef USE_BLUETOOTH_PROXY
-  void on_unsubscribe_bluetooth_le_advertisements_request(
-      const UnsubscribeBluetoothLEAdvertisementsRequest &msg) override;
+  void on_unsubscribe_bluetooth_le_advertisements_request() override;
 #endif
 #ifdef USE_BLUETOOTH_PROXY
   void on_bluetooth_scanner_set_mode_request(const BluetoothScannerSetModeRequest &msg) override;

esphome/components/api/homeassistant_service.h

@@ -126,6 +126,20 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
     this->add_kv_(this->variables_, key, std::forward<V>(value));
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, ESPHOME_F() returns __FlashStringHelper* (PROGMEM pointer).
+  // Store as const char* — populate_service_map copies from PROGMEM at play() time.
+  template<typename V> void add_data(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_data_template(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_template_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_variable(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->variables_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+#endif
+
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
   template<typename T> void set_response_template(T response_template) {
     this->response_template_ = response_template;
@@ -217,7 +231,31 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
                                    Ts... x) {
     dest.init(source.size());
 
-    // Count non-static strings to allocate exact storage needed
+#ifdef USE_ESP8266
+    // On ESP8266, keys may be in PROGMEM (from ESPHOME_F in codegen) and
+    // FLASH_STRING values need copying via _P functions.
+    // Allocate storage for all keys + all values (2 entries per source item).
+    // strlen_P/memcpy_P handle both RAM and PROGMEM pointers safely.
+    value_storage.init(source.size() * 2);
+
+    for (auto &it : source) {
+      auto &kv = dest.emplace_back();
+
+      // Key: copy from possible PROGMEM
+      {
+        size_t key_len = strlen_P(it.key);
+        value_storage.push_back(std::string(key_len, '\0'));
+        memcpy_P(value_storage.back().data(), it.key, key_len);
+        kv.key = StringRef(value_storage.back());
+      }
+
+      // Value: value() handles FLASH_STRING via _P functions internally
+      value_storage.push_back(it.value.value(x...));
+      kv.value = StringRef(value_storage.back());
+    }
+#else
+    // On non-ESP8266, strings are directly readable from flash-mapped memory.
+    // Count non-static strings to allocate exact storage needed.
     size_t lambda_count = 0;
     for (const auto &it : source) {
       if (!it.value.is_static_string()) {
@@ -231,14 +269,15 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
       kv.key = StringRef(it.key);
 
       if (it.value.is_static_string()) {
-        // Static string from YAML - zero allocation
+        // Static string — pointer directly readable, zero allocation
         kv.value = StringRef(it.value.get_static_string());
       } else {
-        // Lambda evaluation - store result, reference it
+        // Lambda — evaluate and store result
         value_storage.push_back(it.value.value(x...));
         kv.value = StringRef(value_storage.back());
       }
     }
+#endif
   }
 
   APIServer *parent_;

esphome/components/api/proto.h

@@ -112,8 +112,12 @@ class ProtoVarInt {
     uint64_t result = buffer[0] & 0x7F;
     uint8_t bitpos = 7;
 
+    // A 64-bit varint is at most 10 bytes (ceil(64/7)). Reject overlong encodings
+    // to avoid undefined behavior from shifting uint64_t by >= 64 bits.
+    uint32_t max_len = std::min(len, uint32_t(10));
+
     // Start from the second byte since we've already processed the first
-    for (uint32_t i = 1; i < len; i++) {
+    for (uint32_t i = 1; i < max_len; i++) {
       uint8_t val = buffer[i];
       result |= uint64_t(val & 0x7F) << uint64_t(bitpos);
       bitpos += 7;

esphome/components/e131/e131.cpp

@@ -55,7 +55,6 @@ void E131Component::setup() {
 }
 
 void E131Component::loop() {
-  std::vector<uint8_t> payload;
   E131Packet packet;
   int universe = 0;
   uint8_t buf[1460];
@@ -64,11 +63,9 @@ void E131Component::loop() {
   if (len == -1) {
     return;
   }
-  payload.resize(len);
-  memmove(&payload[0], buf, len);
 
-  if (!this->packet_(payload, universe, packet)) {
-    ESP_LOGV(TAG, "Invalid packet received of size %zu.", payload.size());
+  if (!this->packet_(buf, (size_t) len, universe, packet)) {
+    ESP_LOGV(TAG, "Invalid packet received of size %zd.", len);
     return;
   }
 

esphome/components/e131/e131.h

@@ -38,7 +38,7 @@ class E131Component : public esphome::Component {
   void set_method(E131ListenMethod listen_method) { this->listen_method_ = listen_method; }
 
  protected:
-  bool packet_(const std::vector<uint8_t> &data, int &universe, E131Packet &packet);
+  bool packet_(const uint8_t *data, size_t len, int &universe, E131Packet &packet);
   bool process_(int universe, const E131Packet &packet);
   bool join_igmp_groups_();
   void join_(int universe);

esphome/components/e131/e131_packet.cpp

@@ -116,11 +116,11 @@ void E131Component::leave_(int universe) {
   ESP_LOGD(TAG, "Left %d universe for E1.31.", universe);
 }
 
-bool E131Component::packet_(const std::vector<uint8_t> &data, int &universe, E131Packet &packet) {
-  if (data.size() < E131_MIN_PACKET_SIZE)
+bool E131Component::packet_(const uint8_t *data, size_t len, int &universe, E131Packet &packet) {
+  if (len < E131_MIN_PACKET_SIZE)
     return false;
 
-  auto *sbuff = reinterpret_cast<const E131RawPacket *>(&data[0]);
+  auto *sbuff = reinterpret_cast<const E131RawPacket *>(data);
 
   if (memcmp(sbuff->acn_id, ACN_ID, sizeof(sbuff->acn_id)) != 0)
     return false;

esphome/components/epaper_spi/colorconv.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <cstdint>
+#include <algorithm>
+#include "esphome/core/color.h"
+
+/* Utility for converting internal \a Color RGB representation to supported IC hardware color keys
+ *
+ * Focus in driver layer is on efficiency.
+ * For optimum output quality on RGB inputs consider offline color keying/dithering.
+ * Also see e.g. Image component.
+ */
+
+namespace esphome::epaper_spi {
+
+/** Delta for when to regard as gray */
+static constexpr uint8_t COLORCONV_GRAY_THRESHOLD = 50;
+
+/** Map RGB color to discrete BWYR hex 4 color key
+ *
+ * @tparam NATIVE_COLOR  Type of native hardware color values
+ * @param color     RGB color to convert from
+ * @param hw_black  Native value for black
+ * @param hw_white  Native value for white
+ * @param hw_yellow Native value for yellow
+ * @param hw_red    Native value for red
+ * @return          Converted native hardware color value
+ * @internal Constexpr. Does not depend on side effects ("pure").
+ */
+template<typename NATIVE_COLOR>
+constexpr NATIVE_COLOR color_to_bwyr(Color color, NATIVE_COLOR hw_black, NATIVE_COLOR hw_white, NATIVE_COLOR hw_yellow,
+                                     NATIVE_COLOR hw_red) {
+  // --- Step 1: Check for Grayscale (Black or White) ---
+  // We define "grayscale" as a color where the min and max components
+  // are close to each other.
+
+  const auto [min_rgb, max_rgb] = std::minmax({color.r, color.g, color.b});
+
+  if ((max_rgb - min_rgb) < COLORCONV_GRAY_THRESHOLD) {
+    // It's a shade of gray. Map to BLACK or WHITE.
+    // We split the luminance at the halfway point (382 = (255*3)/2)
+    if ((static_cast<int>(color.r) + color.g + color.b) > 382) {
+      return hw_white;
+    }
+    return hw_black;
+  }
+
+  // --- Step 2: Check for Primary/Secondary Colors ---
+  // If it's not gray, it's a color. We check which components are
+  // "on" (over 128) vs "off". This divides the RGB cube into 8 corners.
+  const bool r_on = (color.r > 128);
+  const bool g_on = (color.g > 128);
+  const bool b_on = (color.b > 128);
+
+  if (r_on) {
+    if (!b_on) {
+      return g_on ? hw_yellow : hw_red;
+    }
+
+    // At least red+blue high (but not gray) -> White
+    return hw_white;
+  } else {
+    return (b_on && g_on) ? hw_white : hw_black;
+  }
+}
+
+}  // namespace esphome::epaper_spi

esphome/components/epaper_spi/epaper_spi_jd79660.cpp

@@ -0,0 +1,227 @@
+#include "epaper_spi_jd79660.h"
+#include "colorconv.h"
+
+#include "esphome/core/log.h"
+
+namespace esphome::epaper_spi {
+static constexpr const char *const TAG = "epaper_spi.jd79660";
+
+/** Pixel color as 2bpp. Must match IC LUT values. */
+enum JD79660Color : uint8_t {
+  BLACK = 0b00,
+  WHITE = 0b01,
+  YELLOW = 0b10,
+  RED = 0b11,
+};
+
+/** Map RGB color to JD79660 BWYR hex color keys */
+static JD79660Color HOT color_to_hex(Color color) {
+  return color_to_bwyr(color, JD79660Color::BLACK, JD79660Color::WHITE, JD79660Color::YELLOW, JD79660Color::RED);
+}
+
+void EPaperJD79660::fill(Color color) {
+  // If clipping is active, fall back to base implementation
+  if (this->get_clipping().is_set()) {
+    EPaperBase::fill(color);
+    return;
+  }
+
+  const auto pixel_color = color_to_hex(color);
+
+  // We store 4 pixels per byte
+  this->buffer_.fill(pixel_color | (pixel_color << 2) | (pixel_color << 4) | (pixel_color << 6));
+}
+
+void HOT EPaperJD79660::draw_pixel_at(int x, int y, Color color) {
+  if (!this->rotate_coordinates_(x, y))
+    return;
+  const auto pixel_bits = color_to_hex(color);
+  const uint32_t pixel_position = x + y * this->get_width_internal();
+  // We store 4 pixels per byte at LSB offsets 6, 4, 2, 0
+  const uint32_t byte_position = pixel_position / 4;
+  const uint32_t bit_offset = 6 - ((pixel_position % 4) * 2);
+  const auto original = this->buffer_[byte_position];
+
+  this->buffer_[byte_position] = (original & (~(0b11 << bit_offset))) |  // mask old 2bpp
+                                 (pixel_bits << bit_offset);             // add new 2bpp
+}
+
+bool EPaperJD79660::reset() {
+  // On entry state RESET set step, next state will be RESET_END
+  if (this->state_ == EPaperState::RESET) {
+    this->step_ = FSMState::RESET_STEP0_H;
+  }
+
+  switch (this->step_) {
+    case FSMState::RESET_STEP0_H:
+      // Step #0: Reset H for some settle time.
+
+      ESP_LOGVV(TAG, "reset #0");
+      this->reset_pin_->digital_write(true);
+
+      this->reset_duration_ = SLEEP_MS_RESET0;
+      this->step_ = FSMState::RESET_STEP1_L;
+      return false;  // another loop: step #1 below
+
+    case FSMState::RESET_STEP1_L:
+      // Step #1: Reset L pulse for slightly >1.5ms.
+      // This is actual reset trigger.
+
+      ESP_LOGVV(TAG, "reset #1");
+
+      // As commented on SLEEP_MS_RESET1: Reset pulse must happen within time window.
+      // So do not use FSM loop, and avoid other calls/logs during pulse below.
+      this->reset_pin_->digital_write(false);
+      delay(SLEEP_MS_RESET1);
+      this->reset_pin_->digital_write(true);
+
+      this->reset_duration_ = SLEEP_MS_RESET2;
+      this->step_ = FSMState::RESET_STEP2_IDLECHECK;
+      return false;  // another loop: step #2 below
+
+    case FSMState::RESET_STEP2_IDLECHECK:
+      // Step #2: Basically finished. Check sanity, and move FSM to INITIALISE state
+      ESP_LOGVV(TAG, "reset #2");
+
+      if (!this->is_idle_()) {
+        // Expectation: Idle after reset + settle time.
+        // Improperly connected/unexpected hardware?
+        // Error path reproducable e.g. with disconnected VDD/... pins
+        // (optimally while busy_pin configured with local pulldown).
+        // -> Mark failed to avoid followup problems.
+        this->mark_failed(LOG_STR("Busy after reset"));
+      }
+      break;  // End state loop below
+
+    default:
+      // Unexpected step = bug?
+      this->mark_failed();
+  }
+
+  this->step_ = FSMState::INIT_STEP0_REGULARINIT;  // reset for initialize state
+  return true;
+}
+
+bool EPaperJD79660::initialise(bool partial) {
+  switch (this->step_) {
+    case FSMState::INIT_STEP0_REGULARINIT:
+      // Step #0: Regular init sequence
+      ESP_LOGVV(TAG, "init #0");
+      if (!EPaperBase::initialise(partial)) {  // Call parent impl
+        return false;                          // If parent should request another loop, do so
+      }
+
+      // Fast init requested + supported?
+      if (partial && (this->fast_update_length_ > 0)) {
+        this->step_ = FSMState::INIT_STEP1_FASTINIT;
+        this->wait_for_idle_(true);  // Must wait for idle before fastinit sequence in next loop
+        return false;                // another loop: step #1 below
+      }
+
+      break;  // End state loop below
+
+    case FSMState::INIT_STEP1_FASTINIT:
+      // Step #1: Fast init sequence
+      ESP_LOGVV(TAG, "init #1");
+      this->write_fastinit_();
+      break;  // End state loop below
+
+    default:
+      // Unexpected step = bug?
+      this->mark_failed();
+  }
+
+  this->step_ = FSMState::NONE;
+  return true;  // Finished: State transition waits for idle
+}
+
+bool EPaperJD79660::transfer_buffer_chunks_() {
+  size_t buf_idx = 0;
+  uint8_t bytes_to_send[MAX_TRANSFER_SIZE];
+  const uint32_t start_time = App.get_loop_component_start_time();
+  const auto buffer_length = this->buffer_length_;
+  while (this->current_data_index_ != buffer_length) {
+    bytes_to_send[buf_idx++] = this->buffer_[this->current_data_index_++];
+
+    if (buf_idx == sizeof bytes_to_send) {
+      this->start_data_();
+      this->write_array(bytes_to_send, buf_idx);
+      this->disable();
+      ESP_LOGVV(TAG, "Wrote %zu bytes at %ums", buf_idx, (unsigned) millis());
+      buf_idx = 0;
+
+      if (millis() - start_time > MAX_TRANSFER_TIME) {
+        // Let the main loop run and come back next loop
+        return false;
+      }
+    }
+  }
+
+  // Finished the entire dataset
+  if (buf_idx != 0) {
+    this->start_data_();
+    this->write_array(bytes_to_send, buf_idx);
+    this->disable();
+    ESP_LOGVV(TAG, "Wrote %zu bytes at %ums", buf_idx, (unsigned) millis());
+  }
+  // Cleanup for next transfer
+  this->current_data_index_ = 0;
+
+  // Finished with all buffer chunks
+  return true;
+}
+
+void EPaperJD79660::write_fastinit_() {
+  // Undocumented register sequence in vendor register range.
+  // Related to Fast Init/Update.
+  // Should likely happen after regular init seq and power on, but before refresh.
+  // Might only work for some models with certain factory MTP.
+  // Please do not change without knowledge to avoid breakage.
+
+  this->send_init_sequence_(this->fast_update_, this->fast_update_length_);
+}
+
+bool EPaperJD79660::transfer_data() {
+  // For now always send full frame buffer in chunks.
+  // JD79660 might support partial window transfers. But sample code missing.
+  // And likely minimal impact, solely on SPI transfer time into RAM.
+
+  if (this->current_data_index_ == 0) {
+    this->command(CMD_TRANSFER);
+  }
+
+  return this->transfer_buffer_chunks_();
+}
+
+void EPaperJD79660::refresh_screen([[maybe_unused]] bool partial) {
+  ESP_LOGV(TAG, "Refresh");
+  this->cmd_data(CMD_REFRESH, {(uint8_t) 0x00});
+}
+
+void EPaperJD79660::power_off() {
+  ESP_LOGV(TAG, "Power off");
+  this->cmd_data(CMD_POWEROFF, {(uint8_t) 0x00});
+}
+
+void EPaperJD79660::deep_sleep() {
+  ESP_LOGV(TAG, "Deep sleep");
+  // "Deepsleep between update": Ensure EPD sleep to avoid early hardware wearout!
+  this->cmd_data(CMD_DEEPSLEEP, {(uint8_t) 0xA5});
+
+  // Notes:
+  // - VDD: Some boards (Waveshare) with "clever reset logic" would allow switching off
+  //   EPD VDD by pulling reset pin low for longer time.
+  //   However, a) not all boards have this, b) reliable sequence timing is difficult,
+  //   c) saving is not worth it after deepsleep command above.
+  //   If needed: Better option is to drive VDD via MOSFET with separate enable pin.
+  //
+  // - Possible safe shutdown:
+  //   EPaperBase::on_safe_shutdown() may also trigger deep_sleep() again.
+  //   Regularly, in IDLE state, this does not make sense for this "deepsleep between update" model,
+  //   but SPI sequence should simply be ignored by sleeping receiver.
+  //   But if triggering during lengthy update, this quick SPI sleep sequence may have benefit.
+  //   Optimally, EPDs should even be set all white for longer storage.
+  //   But full sequence (>15s) not possible w/o app logic.
+}
+
+}  // namespace esphome::epaper_spi

esphome/components/epaper_spi/epaper_spi_jd79660.h

@@ -0,0 +1,145 @@
+#pragma once
+
+#include "epaper_spi.h"
+
+namespace esphome::epaper_spi {
+
+/**
+ * JD7966x IC driver implementation
+ *
+ * Currently tested with:
+ * - JD79660 (max res: 200x200)
+ *
+ * May also work for other JD7966x chipset family members with minimal adaptations.
+ *
+ * Capabilities:
+ * - HW frame buffer layout:
+ *   4 colors (gray0..3, commonly BWYR). Bytes consist of 4px/2bpp.
+ *   Width must be rounded to multiple of 4.
+ * - Fast init/update (shorter wave forms): Yes. Controlled by CONF_FULL_UPDATE_EVERY.
+ *   Needs undocumented fastinit sequence, based on likely vendor specific MTP content.
+ * - Partial transfer (transfer only changed window): No. Maybe possible by HW.
+ * - Partial refresh (refresh only changed window): No. Likely HW limit.
+ *
+ * @internal \c final saves few bytes by devirtualization. Remove \c final when subclassing.
+ */
+class EPaperJD79660 final : public EPaperBase {
+ public:
+  EPaperJD79660(const char *name, uint16_t width, uint16_t height, const uint8_t *init_sequence,
+                size_t init_sequence_length, const uint8_t *fast_update, uint16_t fast_update_length)
+      : EPaperBase(name, width, height, init_sequence, init_sequence_length, DISPLAY_TYPE_COLOR),
+        fast_update_(fast_update),
+        fast_update_length_(fast_update_length) {
+    this->row_width_ = (width + 3) / 4;  // Fix base class calc (2bpp instead of 1bpp)
+    this->buffer_length_ = this->row_width_ * height;
+  }
+
+  void fill(Color color) override;
+
+ protected:
+  /** Draw colored pixel into frame buffer */
+  void draw_pixel_at(int x, int y, Color color) override;
+
+  /** Reset (multistep sequence)
+   * @pre this->reset_pin_ != nullptr // cv.Required check
+   * @post Should be idle on successful reset. Can mark failures.
+   */
+  bool reset() override;
+
+  /** Initialise (multistep sequence) */
+  bool initialise(bool partial) override;
+
+  /** Buffer transfer */
+  bool transfer_data() override;
+
+  /** Power on: Already part of init sequence (likely needed there before transferring buffers).
+   * So nothing to do in FSM state.
+   */
+  void power_on() override {}
+
+  /** Refresh screen
+   * @param partial Ignored: Needed earlier in \a ::initialize
+   * @pre Must be idle.
+   * @post Should return to idle later after processing.
+   */
+  void refresh_screen([[maybe_unused]] bool partial) override;
+
+  /** Power off
+   * @pre Must be idle.
+   * @post Should return to idle later after processing.
+   *       (latter will take long period like ~15-20s on actual refresh!)
+   */
+  void power_off() override;
+
+  /** Deepsleep: Must be used to avoid hardware wearout!
+   * @pre Must be idle.
+   * @post Will go busy, and not return idle till ::reset!
+   */
+  void deep_sleep() override;
+
+  /** Internal: Send fast init sequence via undocumented vendor registers
+   * @pre Must be directly after regular ::initialise sequence, before ::transfer_data
+   * @pre Must be idle.
+   * @post Should return to idle later after processing.
+   */
+  void write_fastinit_();
+
+  /** Internal: Send raw buffer in chunks
+   * \retval true Finished
+   * \retval false Loop time elapsed. Need to call again next loop.
+   */
+  bool transfer_buffer_chunks_();
+
+  /** @name IC commands @{ */
+  static constexpr uint8_t CMD_POWEROFF = 0x02;
+  static constexpr uint8_t CMD_DEEPSLEEP = 0x07;
+  static constexpr uint8_t CMD_TRANSFER = 0x10;
+  static constexpr uint8_t CMD_REFRESH = 0x12;
+  /** @} */
+
+  /** State machine constants for \a step_ */
+  enum class FSMState : uint8_t {
+    NONE = 0,  //!< Initial/default value: Unused
+
+    /* Reset state steps */
+    RESET_STEP0_H,
+    RESET_STEP1_L,
+    RESET_STEP2_IDLECHECK,
+
+    /* Init state steps */
+    INIT_STEP0_REGULARINIT,
+    INIT_STEP1_FASTINIT,
+  };
+
+  /** Wait time (millisec) for first reset phase: High
+   *
+   * Wait via FSM loop.
+   */
+  static constexpr uint16_t SLEEP_MS_RESET0 = 200;
+
+  /** Wait time (millisec) for second reset phase: Low
+   *
+   * Holding Reset Low too long may trigger "clever reset" logic
+   * of e.g. Waveshare Rev2 boards: VDD is shut down via MOSFET, and IC
+   * will not report idle anymore!
+   * FSM loop may spuriously increase delay, e.g. >16ms.
+   * Therefore, sync wait below, as allowed (code rule "delays > 10ms not permitted"),
+   * yet only slightly exceeding known IC min req of >1.5ms.
+   */
+  static constexpr uint16_t SLEEP_MS_RESET1 = 2;
+
+  /** Wait time (millisec) for third reset phase: High
+   *
+   * Wait via FSM loop.
+   */
+  static constexpr uint16_t SLEEP_MS_RESET2 = 200;
+
+  // properties initialised in the constructor
+  const uint8_t *const fast_update_{};
+  const uint16_t fast_update_length_{};
+
+  /** Counter for tracking substeps within FSM state */
+  FSMState step_{FSMState::NONE};
+};
+
+}  // namespace esphome::epaper_spi

esphome/components/epaper_spi/epaper_spi_spectra_e6.h

@@ -4,7 +4,7 @@
 
 namespace esphome::epaper_spi {
 
-class EPaperSpectraE6 : public EPaperBase {
+class EPaperSpectraE6 final : public EPaperBase {
  public:
   EPaperSpectraE6(const char *name, uint16_t width, uint16_t height, const uint8_t *init_sequence,
                   size_t init_sequence_length)

esphome/components/epaper_spi/epaper_waveshare.h

@@ -6,7 +6,7 @@ namespace esphome::epaper_spi {
 /**
  * An epaper display that needs LUTs to be sent to it.
  */
-class EpaperWaveshare : public EPaperMono {
+class EpaperWaveshare final : public EPaperMono {
  public:
   EpaperWaveshare(const char *name, uint16_t width, uint16_t height, const uint8_t *init_sequence,
                   size_t init_sequence_length, const uint8_t *lut, size_t lut_length, const uint8_t *partial_lut,

esphome/components/epaper_spi/models/jd79660.py

@@ -0,0 +1,86 @@
+import esphome.codegen as cg
+from esphome.components.mipi import flatten_sequence
+import esphome.config_validation as cv
+from esphome.const import CONF_BUSY_PIN, CONF_RESET_PIN
+from esphome.core import ID
+
+from ..display import CONF_INIT_SEQUENCE_ID
+from . import EpaperModel
+
+
+class JD79660(EpaperModel):
+    def __init__(self, name, class_name="EPaperJD79660", fast_update=None, **kwargs):
+        super().__init__(name, class_name, **kwargs)
+        self.fast_update = fast_update
+
+    def option(self, name, fallback=cv.UNDEFINED) -> cv.Optional | cv.Required:
+        # Validate required pins, as C++ code will assume existence
+        if name in (CONF_RESET_PIN, CONF_BUSY_PIN):
+            return cv.Required(name)
+
+        # Delegate to parent
+        return super().option(name, fallback)
+
+    def get_constructor_args(self, config) -> tuple:
+        # Resembles init_sequence handling for fast_update config
+        if self.fast_update is None:
+            fast_update = cg.nullptr, 0
+        else:
+            flat_fast_update = flatten_sequence(self.fast_update)
+            fast_update = (
+                cg.static_const_array(
+                    ID(
+                        config[CONF_INIT_SEQUENCE_ID].id + "_fast_update", type=cg.uint8
+                    ),
+                    flat_fast_update,
+                ),
+                len(flat_fast_update),
+            )
+        return (*fast_update,)
+
+
+jd79660 = JD79660(
+    "jd79660",
+    # Specified refresh times are ~20s (full) or ~15s (fast) due to BWRY.
+    # So disallow low update intervals (with safety margin), to avoid e.g. FSM update loops.
+    # Even less frequent intervals (min/h) highly recommended to optimize lifetime!
+    minimum_update_interval="30s",
+    # SPI rate: From spec comparisons, IC should allow SCL write cycles up to 10MHz rate.
+    # Existing code samples also prefer 10MHz. So justifies as default.
+    # Decrease value further in user config if needed (e.g. poor cabling).
+    data_rate="10MHz",
+    # No need to set optional reset_duration:
+    # Code requires multistep reset sequence with precise timings
+    # according to data sheet or samples.
+)
+
+# Waveshare 1.54-G
+#
+# Device may have specific factory provisioned MTP content to facilitate vendor register features like fast init.
+# Vendor specific init derived from vendor sample code
+# <https://github.com/waveshareteam/e-Paper/blob/master/E-paper_Separate_Program/1in54_e-Paper_G/ESP32/EPD_1in54g.cpp>
+# Compatible MIT license, see esphome/LICENSE file.
+#
+# fmt: off
+jd79660.extend(
+    "Waveshare-1.54in-G",
+    width=200,
+    height=200,
+
+    initsequence=(
+        (0x4D, 0x78,),
+        (0x00, 0x0F, 0x29,),
+        (0x06, 0x0d, 0x12, 0x30, 0x20, 0x19, 0x2a, 0x22,),
+        (0x50, 0x37,),
+        (0x61, 200 // 256, 200 % 256, 200 // 256, 200 % 256,),  # RES: 200x200 fixed
+        (0xE9, 0x01,),
+        (0x30, 0x08,),
+        # Power On (0x04): Must be early part of init seq = Disabled later!
+        (0x04,),
+    ),
+    fast_update=(
+        (0xE0, 0x02,),
+        (0xE6, 0x5D,),
+        (0xA5, 0x00,),
+    ),
+)

esphome/components/ld2412/ld2412.cpp

@@ -310,19 +310,8 @@ void LD2412Component::restart_and_read_all_info() {
 }
 
 void LD2412Component::loop() {
-  // Read all available bytes in batches to reduce UART call overhead.
-  int avail = this->available();
-  uint8_t buf[MAX_LINE_LENGTH];
-  while (avail > 0) {
-    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
-    if (!this->read_array(buf, to_read)) {
-      break;
-    }
-    avail -= to_read;
-
-    for (size_t i = 0; i < to_read; i++) {
-      this->readline_(buf[i]);
-    }
+  while (this->available()) {
+    this->readline_(this->read());
   }
 }
 

esphome/components/logger/logger_zephyr.cpp

@@ -68,7 +68,7 @@ void HOT Logger::write_msg_(const char *msg, uint16_t len) {
 #ifdef CONFIG_PRINTK
   // Requires the debug component and an active SWD connection.
   // It is used for pyocd rtt -t nrf52840
-  k_str_out(const_cast<char *>(msg), len);
+  printk("%.*s", static_cast<int>(len), msg);
 #endif
   if (this->uart_dev_ == nullptr) {
     return;

esphome/components/lps22/lps22.cpp

@@ -38,22 +38,29 @@ void LPS22Component::dump_config() {
   LOG_UPDATE_INTERVAL(this);
 }
 
+static constexpr uint32_t INTERVAL_READ = 0;
+
 void LPS22Component::update() {
   uint8_t value = 0x00;
   this->read_register(CTRL_REG2, &value, 1);
   value |= CTRL_REG2_ONE_SHOT_MASK;
   this->write_register(CTRL_REG2, &value, 1);
-  this->set_retry(READ_INTERVAL, READ_ATTEMPTS, [this](uint8_t _) { return this->try_read_(); });
+  this->read_attempts_remaining_ = READ_ATTEMPTS;
+  this->set_interval(INTERVAL_READ, READ_INTERVAL, [this]() { this->try_read_(); });
 }
 
-RetryResult LPS22Component::try_read_() {
+void LPS22Component::try_read_() {
   uint8_t value = 0x00;
   this->read_register(STATUS, &value, 1);
   const uint8_t expected_status_mask = STATUS_T_DA_MASK | STATUS_P_DA_MASK;
   if ((value & expected_status_mask) != expected_status_mask) {
     ESP_LOGD(TAG, "STATUS not ready: %x", value);
-    return RetryResult::RETRY;
+    if (--this->read_attempts_remaining_ == 0) {
+      this->cancel_interval(INTERVAL_READ);
+    }
+    return;
   }
+  this->cancel_interval(INTERVAL_READ);
 
   if (this->temperature_sensor_ != nullptr) {
     uint8_t t_buf[2]{0};
@@ -68,7 +75,6 @@ RetryResult LPS22Component::try_read_() {
     uint32_t p_lsb = encode_uint24(p_buf[2], p_buf[1], p_buf[0]);
     this->pressure_sensor_->publish_state(PRESSURE_SCALE * static_cast<float>(p_lsb));
   }
-  return RetryResult::DONE;
 }
 
 }  // namespace lps22

esphome/components/lps22/lps22.h

@@ -17,10 +17,11 @@ class LPS22Component : public sensor::Sensor, public PollingComponent, public i2
   void dump_config() override;
 
  protected:
+  void try_read_();
+
   sensor::Sensor *temperature_sensor_{nullptr};
   sensor::Sensor *pressure_sensor_{nullptr};
-
-  RetryResult try_read_();
+  uint8_t read_attempts_remaining_{0};
 };
 
 }  // namespace lps22

esphome/components/lvgl/schemas.py

@@ -436,6 +436,7 @@ def container_schema(widget_type: WidgetType, extras=None):
     schema = schema.extend(widget_type.schema)
 
     def validator(value):
+        value = value or {}
         return append_layout_schema(schema, value)(value)
 
     return validator

esphome/components/mqtt/mqtt_component.cpp

@@ -34,10 +34,7 @@ inline char *append_char(char *p, char c) {
 // MQTT_COMPONENT_TYPE_MAX_LEN, MQTT_SUFFIX_MAX_LEN, and MQTT_DEFAULT_TOPIC_MAX_LEN are in mqtt_component.h.
 // ESPHOME_DEVICE_NAME_MAX_LEN and OBJECT_ID_MAX_LEN are defined in entity_base.h.
 // This ensures the stack buffers below are always large enough.
-static constexpr size_t DISCOVERY_PREFIX_MAX_LEN = 64;  // Validated in Python: cv.Length(max=64)
-// Format: prefix + "/" + type + "/" + name + "/" + object_id + "/config" + null
-static constexpr size_t DISCOVERY_TOPIC_MAX_LEN = DISCOVERY_PREFIX_MAX_LEN + 1 + MQTT_COMPONENT_TYPE_MAX_LEN + 1 +
-                                                  ESPHOME_DEVICE_NAME_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 7 + 1;
+// MQTT_DISCOVERY_PREFIX_MAX_LEN and MQTT_DISCOVERY_TOPIC_MAX_LEN are defined in mqtt_component.h
 
 // Function implementation of LOG_MQTT_COMPONENT macro to reduce code size
 void log_mqtt_component(const char *tag, MQTTComponent *obj, bool state_topic, bool command_topic) {
@@ -54,15 +51,15 @@ void MQTTComponent::set_subscribe_qos(uint8_t qos) { this->subscribe_qos_ = qos;
 
 void MQTTComponent::set_retain(bool retain) { this->retain_ = retain; }
 
-std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discovery_info) const {
+StringRef MQTTComponent::get_discovery_topic_to_(std::span<char, MQTT_DISCOVERY_TOPIC_MAX_LEN> buf,
+                                                 const MQTTDiscoveryInfo &discovery_info) const {
   char sanitized_name[ESPHOME_DEVICE_NAME_MAX_LEN + 1];
   str_sanitize_to(sanitized_name, App.get_name().c_str());
   const char *comp_type = this->component_type();
   char object_id_buf[OBJECT_ID_MAX_LEN];
   StringRef object_id = this->get_default_object_id_to_(object_id_buf);
 
-  char buf[DISCOVERY_TOPIC_MAX_LEN];
-  char *p = buf;
+  char *p = buf.data();
 
   p = append_str(p, discovery_info.prefix.data(), discovery_info.prefix.size());
   p = append_char(p, '/');
@@ -72,8 +69,9 @@ std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discove
   p = append_char(p, '/');
   p = append_str(p, object_id.c_str(), object_id.size());
   p = append_str(p, "/config", 7);
+  *p = '\0';
 
-  return std::string(buf, p - buf);
+  return StringRef(buf.data(), p - buf.data());
 }
 
 StringRef MQTTComponent::get_default_topic_for_to_(std::span<char, MQTT_DEFAULT_TOPIC_MAX_LEN> buf, const char *suffix,
@@ -182,16 +180,19 @@ bool MQTTComponent::publish_json(const char *topic, const json::json_build_t &f)
 bool MQTTComponent::send_discovery_() {
   const MQTTDiscoveryInfo &discovery_info = global_mqtt_client->get_discovery_info();
 
+  char discovery_topic_buf[MQTT_DISCOVERY_TOPIC_MAX_LEN];
+  StringRef discovery_topic = this->get_discovery_topic_to_(discovery_topic_buf, discovery_info);
+
   if (discovery_info.clean) {
     ESP_LOGV(TAG, "'%s': Cleaning discovery", this->friendly_name_().c_str());
-    return global_mqtt_client->publish(this->get_discovery_topic_(discovery_info), "", 0, this->qos_, true);
+    return global_mqtt_client->publish(discovery_topic.c_str(), "", 0, this->qos_, true);
   }
 
   ESP_LOGV(TAG, "'%s': Sending discovery", this->friendly_name_().c_str());
 
   // NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
   return global_mqtt_client->publish_json(
-      this->get_discovery_topic_(discovery_info),
+      discovery_topic.c_str(),
       [this](JsonObject root) {
         SendDiscoveryConfig config;
         config.state_topic = true;
@@ -204,7 +205,7 @@ bool MQTTComponent::send_discovery_() {
         }
 
         // Fields from EntityBase
-        root[MQTT_NAME] = this->get_entity()->has_own_name() ? this->friendly_name_() : "";
+        root[MQTT_NAME] = this->get_entity()->has_own_name() ? this->friendly_name_() : StringRef();
 
         if (this->is_disabled_by_default_())
           root[MQTT_ENABLED_BY_DEFAULT] = false;
@@ -248,7 +249,7 @@ bool MQTTComponent::send_discovery_() {
         if (discovery_info.unique_id_generator == MQTT_MAC_ADDRESS_UNIQUE_ID_GENERATOR) {
           char friendly_name_hash[9];
           buf_append_printf(friendly_name_hash, sizeof(friendly_name_hash), 0, "%08" PRIx32,
-                            fnv1_hash(this->friendly_name_()));
+                            fnv1_hash(this->friendly_name_().c_str()));
           // Format: mac-component_type-hash (e.g. "aabbccddeeff-sensor-12345678")
           // MAC (12) + "-" (1) + domain (max 20) + "-" (1) + hash (8) + null (1) = 43
           char unique_id[MAC_ADDRESS_BUFFER_SIZE + ESPHOME_DOMAIN_MAX_LEN + 11];
@@ -414,7 +415,7 @@ void MQTTComponent::schedule_resend_state() { this->resend_state_ = true; }
 bool MQTTComponent::is_connected_() const { return global_mqtt_client->is_connected(); }
 
 // Pull these properties from EntityBase if not overridden
-std::string MQTTComponent::friendly_name_() const { return this->get_entity()->get_name(); }
+const StringRef &MQTTComponent::friendly_name_() const { return this->get_entity()->get_name(); }
 StringRef MQTTComponent::get_default_object_id_to_(std::span<char, OBJECT_ID_MAX_LEN> buf) const {
   return this->get_entity()->get_object_id_to(buf);
 }

esphome/components/mqtt/mqtt_component.h

@@ -32,6 +32,10 @@ static constexpr size_t MQTT_TOPIC_PREFIX_MAX_LEN = 64;  // Validated in Python:
 // Format: prefix + "/" + type + "/" + object_id + "/" + suffix + null
 static constexpr size_t MQTT_DEFAULT_TOPIC_MAX_LEN =
     MQTT_TOPIC_PREFIX_MAX_LEN + 1 + MQTT_COMPONENT_TYPE_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 1 + MQTT_SUFFIX_MAX_LEN + 1;
+static constexpr size_t MQTT_DISCOVERY_PREFIX_MAX_LEN = 64;  // Validated in Python: cv.Length(max=64)
+// Format: prefix + "/" + type + "/" + name + "/" + object_id + "/config" + null
+static constexpr size_t MQTT_DISCOVERY_TOPIC_MAX_LEN = MQTT_DISCOVERY_PREFIX_MAX_LEN + 1 + MQTT_COMPONENT_TYPE_MAX_LEN +
+                                                       1 + ESPHOME_DEVICE_NAME_MAX_LEN + 1 + OBJECT_ID_MAX_LEN + 7 + 1;
 
 class MQTTComponent;  // Forward declaration
 void log_mqtt_component(const char *tag, MQTTComponent *obj, bool state_topic, bool command_topic);
@@ -263,8 +267,9 @@ class MQTTComponent : public Component {
   void subscribe_json(const std::string &topic, const mqtt_json_callback_t &callback, uint8_t qos = 0);
 
  protected:
-  /// Helper method to get the discovery topic for this component.
-  std::string get_discovery_topic_(const MQTTDiscoveryInfo &discovery_info) const;
+  /// Helper method to get the discovery topic for this component into a buffer.
+  StringRef get_discovery_topic_to_(std::span<char, MQTT_DISCOVERY_TOPIC_MAX_LEN> buf,
+                                    const MQTTDiscoveryInfo &discovery_info) const;
 
   /** Get this components state/command/... topic into a buffer.
    *
@@ -288,7 +293,7 @@ class MQTTComponent : public Component {
   virtual const EntityBase *get_entity() const = 0;
 
   /// Get the friendly name of this MQTT component.
-  std::string friendly_name_() const;
+  const StringRef &friendly_name_() const;
 
   /// Get the icon field of this component as StringRef
   StringRef get_icon_ref_() const;

esphome/components/packet_transport/packet_transport.cpp

@@ -396,9 +396,9 @@ static bool process_rolling_code(Provider &provider, PacketDecoder &decoder) {
 /**
  * Process a received packet
  */
-void PacketTransport::process_(const std::vector<uint8_t> &data) {
+void PacketTransport::process_(std::span<const uint8_t> data) {
   auto ping_key_seen = !this->ping_pong_enable_;
-  PacketDecoder decoder((data.data()), data.size());
+  PacketDecoder decoder(data.data(), data.size());
   char namebuf[256]{};
   uint8_t byte;
   FuData rdata{};

esphome/components/packet_transport/packet_transport.h

@@ -9,8 +9,9 @@
 #include "esphome/components/binary_sensor/binary_sensor.h"
 #endif
 
-#include <vector>
 #include <map>
+#include <span>
+#include <vector>
 
 /**
  * Providing packet encoding functions for exchanging data with a remote host.
@@ -113,7 +114,7 @@ class PacketTransport : public PollingComponent {
   virtual bool should_send() { return true; }
 
   // to be called by child classes when a data packet is received.
-  void process_(const std::vector<uint8_t> &data);
+  void process_(std::span<const uint8_t> data);
   void send_data_(bool all);
   void flush_();
   void add_data_(uint8_t key, const char *id, float data);

esphome/components/template/water_heater/__init__.py

@@ -46,6 +46,7 @@ CONFIG_SCHEMA = (
                 RESTORE_MODES, upper=True
             ),
             cv.Optional(CONF_CURRENT_TEMPERATURE): cv.returning_lambda,
+            cv.Optional(CONF_TARGET_TEMPERATURE): cv.returning_lambda,
             cv.Optional(CONF_MODE): cv.returning_lambda,
             cv.Optional(CONF_SUPPORTED_MODES): cv.ensure_list(
                 water_heater.validate_water_heater_mode
@@ -78,6 +79,14 @@ async def to_code(config: ConfigType) -> None:
         )
         cg.add(var.set_current_temperature_lambda(template_))
 
+    if CONF_TARGET_TEMPERATURE in config:
+        template_ = await cg.process_lambda(
+            config[CONF_TARGET_TEMPERATURE],
+            [],
+            return_type=cg.optional.template(cg.float_),
+        )
+        cg.add(var.set_target_temperature_lambda(template_))
+
     if CONF_MODE in config:
         template_ = await cg.process_lambda(
             config[CONF_MODE],

esphome/components/template/water_heater/template_water_heater.cpp

@@ -16,7 +16,8 @@ void TemplateWaterHeater::setup() {
       restore->perform();
     }
   }
-  if (!this->current_temperature_f_.has_value() && !this->mode_f_.has_value())
+  if (!this->current_temperature_f_.has_value() && !this->target_temperature_f_.has_value() &&
+      !this->mode_f_.has_value())
     this->disable_loop();
 }
 
@@ -28,6 +29,9 @@ water_heater::WaterHeaterTraits TemplateWaterHeater::traits() {
   }
 
   traits.set_supports_current_temperature(true);
+  if (this->target_temperature_f_.has_value()) {
+    traits.add_feature_flags(water_heater::WATER_HEATER_SUPPORTS_TARGET_TEMPERATURE);
+  }
   return traits;
 }
 
@@ -42,6 +46,14 @@ void TemplateWaterHeater::loop() {
     }
   }
 
+  auto target_temp = this->target_temperature_f_.call();
+  if (target_temp.has_value()) {
+    if (*target_temp != this->target_temperature_) {
+      this->target_temperature_ = *target_temp;
+      changed = true;
+    }
+  }
+
   auto new_mode = this->mode_f_.call();
   if (new_mode.has_value()) {
     if (*new_mode != this->mode_) {

esphome/components/template/water_heater/template_water_heater.h

@@ -20,6 +20,9 @@ class TemplateWaterHeater : public Component, public water_heater::WaterHeater {
   template<typename F> void set_current_temperature_lambda(F &&f) {
     this->current_temperature_f_.set(std::forward<F>(f));
   }
+  template<typename F> void set_target_temperature_lambda(F &&f) {
+    this->target_temperature_f_.set(std::forward<F>(f));
+  }
   template<typename F> void set_mode_lambda(F &&f) { this->mode_f_.set(std::forward<F>(f)); }
 
   void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
@@ -44,6 +47,7 @@ class TemplateWaterHeater : public Component, public water_heater::WaterHeater {
   // Ordered to minimize padding on 32-bit: 4-byte members first, then smaller
   Trigger<> set_trigger_;
   TemplateLambda<float> current_temperature_f_;
+  TemplateLambda<float> target_temperature_f_;
   TemplateLambda<water_heater::WaterHeaterMode> mode_f_;
   TemplateWaterHeaterRestoreMode restore_mode_{WATER_HEATER_NO_RESTORE};
   water_heater::WaterHeaterModeMask supported_modes_;

esphome/components/udp/__init__.py

@@ -13,7 +13,7 @@ from esphome.components.packet_transport import (
 import esphome.config_validation as cv
 from esphome.const import CONF_DATA, CONF_ID, CONF_PORT, CONF_TRIGGER_ID
 from esphome.core import ID
-from esphome.cpp_generator import literal
+from esphome.cpp_generator import MockObj
 
 CODEOWNERS = ["@clydebarrow"]
 DEPENDENCIES = ["network"]
@@ -23,8 +23,12 @@ MULTI_CONF = True
 udp_ns = cg.esphome_ns.namespace("udp")
 UDPComponent = udp_ns.class_("UDPComponent", cg.Component)
 UDPWriteAction = udp_ns.class_("UDPWriteAction", automation.Action)
-trigger_args = cg.std_vector.template(cg.uint8)
 trigger_argname = "data"
+# Listener callback type (non-owning span from UDP component)
+listener_args = cg.std_span.template(cg.uint8.operator("const"))
+listener_argtype = [(listener_args, trigger_argname)]
+# Automation/trigger type (owned vector, safe for deferred actions like delay)
+trigger_args = cg.std_vector.template(cg.uint8)
 trigger_argtype = [(trigger_args, trigger_argname)]
 
 CONF_ADDRESSES = "addresses"
@@ -118,7 +122,13 @@ async def to_code(config):
             trigger_id, trigger_argtype, on_receive
         )
         trigger_lambda = await cg.process_lambda(
-            trigger.trigger(literal(trigger_argname)), trigger_argtype
+            trigger.trigger(
+                cg.std_vector.template(cg.uint8)(
+                    MockObj(trigger_argname).begin(),
+                    MockObj(trigger_argname).end(),
+                )
+            ),
+            listener_argtype,
         )
         cg.add(var.add_listener(trigger_lambda))
         cg.add(var.set_should_listen())

esphome/components/udp/packet_transport/udp_transport.cpp

@@ -12,7 +12,7 @@ bool UDPTransport::should_send() { return network::is_connected(); }
 void UDPTransport::setup() {
   PacketTransport::setup();
   if (!this->providers_.empty() || this->is_encrypted_()) {
-    this->parent_->add_listener([this](std::vector<uint8_t> &buf) { this->process_(buf); });
+    this->parent_->add_listener([this](std::span<const uint8_t> data) { this->process_(data); });
   }
 }
 

esphome/components/udp/udp_component.cpp

@@ -103,8 +103,8 @@ void UDPComponent::setup() {
 }
 
 void UDPComponent::loop() {
-  auto buf = std::vector<uint8_t>(MAX_PACKET_SIZE);
   if (this->should_listen_) {
+    std::array<uint8_t, MAX_PACKET_SIZE> buf;
     for (;;) {
 #if defined(USE_SOCKET_IMPL_BSD_SOCKETS) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
       auto len = this->listen_socket_->read(buf.data(), buf.size());
@@ -116,9 +116,9 @@ void UDPComponent::loop() {
 #endif
       if (len <= 0)
         break;
-      buf.resize(len);
-      ESP_LOGV(TAG, "Received packet of length %zu", len);
-      this->packet_listeners_.call(buf);
+      size_t packet_len = static_cast<size_t>(len);
+      ESP_LOGV(TAG, "Received packet of length %zu", packet_len);
+      this->packet_listeners_.call(std::span<const uint8_t>(buf.data(), packet_len));
     }
   }
 }

esphome/components/udp/udp_component.h

@@ -10,7 +10,9 @@
 #ifdef USE_SOCKET_IMPL_LWIP_TCP
 #include <WiFiUdp.h>
 #endif
+#include <array>
 #include <initializer_list>
+#include <span>
 #include <vector>
 
 namespace esphome::udp {
@@ -26,7 +28,7 @@ class UDPComponent : public Component {
   void set_broadcast_port(uint16_t port) { this->broadcast_port_ = port; }
   void set_should_broadcast() { this->should_broadcast_ = true; }
   void set_should_listen() { this->should_listen_ = true; }
-  void add_listener(std::function<void(std::vector<uint8_t> &)> &&listener) {
+  void add_listener(std::function<void(std::span<const uint8_t>)> &&listener) {
     this->packet_listeners_.add(std::move(listener));
   }
   void setup() override;
@@ -41,7 +43,7 @@ class UDPComponent : public Component {
   uint16_t broadcast_port_{};
   bool should_broadcast_{};
   bool should_listen_{};
-  CallbackManager<void(std::vector<uint8_t> &)> packet_listeners_{};
+  CallbackManager<void(std::span<const uint8_t>)> packet_listeners_{};
 
 #if defined(USE_SOCKET_IMPL_BSD_SOCKETS) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
   std::unique_ptr<socket::Socket> broadcast_socket_ = nullptr;

esphome/components/water_heater/water_heater.cpp

@@ -65,6 +65,7 @@ WaterHeaterCall &WaterHeaterCall::set_away(bool away) {
   } else {
     this->state_ &= ~WATER_HEATER_STATE_AWAY;
   }
+  this->state_mask_ |= WATER_HEATER_STATE_AWAY;
   return *this;
 }
 
@@ -74,6 +75,7 @@ WaterHeaterCall &WaterHeaterCall::set_on(bool on) {
   } else {
     this->state_ &= ~WATER_HEATER_STATE_ON;
   }
+  this->state_mask_ |= WATER_HEATER_STATE_ON;
   return *this;
 }
 
@@ -92,11 +94,11 @@ void WaterHeaterCall::perform() {
   if (!std::isnan(this->target_temperature_high_)) {
     ESP_LOGD(TAG, "  Target Temperature High: %.2f", this->target_temperature_high_);
   }
-  if (this->state_ & WATER_HEATER_STATE_AWAY) {
-    ESP_LOGD(TAG, "  Away: YES");
+  if (this->state_mask_ & WATER_HEATER_STATE_AWAY) {
+    ESP_LOGD(TAG, "  Away: %s", (this->state_ & WATER_HEATER_STATE_AWAY) ? "YES" : "NO");
   }
-  if (this->state_ & WATER_HEATER_STATE_ON) {
-    ESP_LOGD(TAG, "  On: YES");
+  if (this->state_mask_ & WATER_HEATER_STATE_ON) {
+    ESP_LOGD(TAG, "  On: %s", (this->state_ & WATER_HEATER_STATE_ON) ? "YES" : "NO");
   }
   this->parent_->control(*this);
 }
@@ -137,13 +139,17 @@ void WaterHeaterCall::validate_() {
       this->target_temperature_high_ = NAN;
     }
   }
-  if ((this->state_ & WATER_HEATER_STATE_AWAY) && !traits.get_supports_away_mode()) {
-    ESP_LOGW(TAG, "'%s' - Away mode not supported", this->parent_->get_name().c_str());
+  if (!traits.get_supports_away_mode()) {
+    if (this->state_ & WATER_HEATER_STATE_AWAY) {
+      ESP_LOGW(TAG, "'%s' - Away mode not supported", this->parent_->get_name().c_str());
+    }
     this->state_ &= ~WATER_HEATER_STATE_AWAY;
+    this->state_mask_ &= ~WATER_HEATER_STATE_AWAY;
   }
   // If ON/OFF not supported, device is always on - clear the flag silently
   if (!traits.has_feature_flags(WATER_HEATER_SUPPORTS_ON_OFF)) {
     this->state_ &= ~WATER_HEATER_STATE_ON;
+    this->state_mask_ &= ~WATER_HEATER_STATE_ON;
   }
 }
 

esphome/components/water_heater/water_heater.h

@@ -91,6 +91,8 @@ class WaterHeaterCall {
   float get_target_temperature_high() const { return this->target_temperature_high_; }
   /// Get state flags value
   uint32_t get_state() const { return this->state_; }
+  /// Get mask of state flags that are being changed
+  uint32_t get_state_mask() const { return this->state_mask_; }
 
  protected:
   void validate_();
@@ -100,6 +102,7 @@ class WaterHeaterCall {
   float target_temperature_low_{NAN};
   float target_temperature_high_{NAN};
   uint32_t state_{0};
+  uint32_t state_mask_{0};
 };
 
 struct WaterHeaterCallInternal : public WaterHeaterCall {
@@ -111,6 +114,7 @@ struct WaterHeaterCallInternal : public WaterHeaterCall {
     this->target_temperature_low_ = restore.target_temperature_low_;
     this->target_temperature_high_ = restore.target_temperature_high_;
     this->state_ = restore.state_;
+    this->state_mask_ = restore.state_mask_;
     return *this;
   }
 };

esphome/components/web_server_idf/multipart.cpp

@@ -6,8 +6,7 @@
 #include <cstring>
 #include "multipart_parser.h"
 
-namespace esphome {
-namespace web_server_idf {
+namespace esphome::web_server_idf {
 
 static const char *const TAG = "multipart";
 
@@ -249,6 +248,5 @@ std::string str_trim(const std::string &str) {
   return str.substr(start, end - start + 1);
 }
 
-}  // namespace web_server_idf
-}  // namespace esphome
+}  // namespace esphome::web_server_idf
 #endif  // defined(USE_ESP32) && defined(USE_WEBSERVER_OTA)

esphome/components/web_server_idf/multipart.h

@@ -10,8 +10,7 @@
 #include <string>
 #include <utility>
 
-namespace esphome {
-namespace web_server_idf {
+namespace esphome::web_server_idf {
 
 // Wrapper around zorxx/multipart-parser for ESP-IDF OTA uploads
 class MultipartReader {
@@ -81,6 +80,5 @@ bool parse_multipart_boundary(const char *content_type, const char **boundary_st
 // Trim whitespace from both ends of a string
 std::string str_trim(const std::string &str);
 
-}  // namespace web_server_idf
-}  // namespace esphome
+}  // namespace esphome::web_server_idf
 #endif  // defined(USE_ESP32) && defined(USE_WEBSERVER_OTA)

esphome/components/web_server_idf/utils.cpp

@@ -8,8 +8,7 @@
 
 #include "utils.h"
 
-namespace esphome {
-namespace web_server_idf {
+namespace esphome::web_server_idf {
 
 static const char *const TAG = "web_server_idf_utils";
 
@@ -119,6 +118,5 @@ const char *stristr(const char *haystack, const char *needle) {
   return nullptr;
 }
 
-}  // namespace web_server_idf
-}  // namespace esphome
+}  // namespace esphome::web_server_idf
 #endif  // USE_ESP32

esphome/components/web_server_idf/utils.h

@@ -5,8 +5,7 @@
 #include <string>
 #include "esphome/core/helpers.h"
 
-namespace esphome {
-namespace web_server_idf {
+namespace esphome::web_server_idf {
 
 /// Decode URL-encoded string in-place (e.g., %20 -> space, + -> space)
 /// Returns the new length of the decoded string
@@ -29,6 +28,5 @@ bool str_ncmp_ci(const char *s1, const char *s2, size_t n);
 // Case-insensitive string search (like strstr but case-insensitive)
 const char *stristr(const char *haystack, const char *needle);
 
-}  // namespace web_server_idf
-}  // namespace esphome
+}  // namespace esphome::web_server_idf
 #endif  // USE_ESP32

esphome/components/web_server_idf/web_server_idf.cpp

@@ -30,8 +30,7 @@
 #include <cerrno>
 #include <sys/socket.h>
 
-namespace esphome {
-namespace web_server_idf {
+namespace esphome::web_server_idf {
 
 #ifndef HTTPD_409
 #define HTTPD_409 "409 Conflict"
@@ -258,8 +257,6 @@ StringRef AsyncWebServerRequest::url_to(std::span<char, URL_BUF_SIZE> buffer) co
   return StringRef(buffer.data(), decoded_len);
 }
 
-std::string AsyncWebServerRequest::host() const { return this->get_header("Host").value(); }
-
 void AsyncWebServerRequest::send(AsyncWebServerResponse *response) {
   httpd_resp_send(*this, response->get_content_data(), response->get_content_size());
 }
@@ -897,7 +894,6 @@ esp_err_t AsyncWebServer::handle_multipart_upload_(httpd_req_t *r, const char *c
 }
 #endif  // USE_WEBSERVER_OTA
 
-}  // namespace web_server_idf
-}  // namespace esphome
+}  // namespace esphome::web_server_idf
 
 #endif  // !defined(USE_ESP32)

esphome/components/web_server_idf/web_server_idf.h

@@ -121,7 +121,6 @@ class AsyncWebServerRequest {
     char buffer[URL_BUF_SIZE];
     return std::string(this->url_to(buffer));
   }
-  std::string host() const;
   // NOLINTNEXTLINE(readability-identifier-naming)
   size_t contentLength() const { return this->req_->content_len; }
 

esphome/core/automation.h

@@ -4,6 +4,7 @@
 #include "esphome/core/defines.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/preferences.h"
+#include "esphome/core/progmem.h"
 #include "esphome/core/string_ref.h"
 #include <concepts>
 #include <functional>
@@ -56,6 +57,16 @@ template<typename T, typename... X> class TemplatableValue {
     this->static_str_ = str;
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, __FlashStringHelper* is a distinct type from const char*.
+  // ESPHOME_F(s) expands to F(s) which returns __FlashStringHelper* pointing to PROGMEM.
+  // Store as FLASH_STRING — value()/is_empty()/ref_or_copy_to() use _P functions
+  // to access the PROGMEM pointer safely.
+  TemplatableValue(const __FlashStringHelper *str) requires std::same_as<T, std::string> : type_(FLASH_STRING) {
+    this->static_str_ = reinterpret_cast<const char *>(str);
+  }
+#endif
+
   template<typename F> TemplatableValue(F value) requires(!std::invocable<F, X...>) : type_(VALUE) {
     if constexpr (USE_HEAP_STORAGE) {
       this->value_ = new T(std::move(value));
@@ -89,7 +100,7 @@ template<typename T, typename... X> class TemplatableValue {
       this->f_ = new std::function<T(X...)>(*other.f_);
     } else if (this->type_ == STATELESS_LAMBDA) {
       this->stateless_f_ = other.stateless_f_;
-    } else if (this->type_ == STATIC_STRING) {
+    } else if (this->type_ == STATIC_STRING || this->type_ == FLASH_STRING) {
       this->static_str_ = other.static_str_;
     }
   }
@@ -108,7 +119,7 @@ template<typename T, typename... X> class TemplatableValue {
       other.f_ = nullptr;
     } else if (this->type_ == STATELESS_LAMBDA) {
       this->stateless_f_ = other.stateless_f_;
-    } else if (this->type_ == STATIC_STRING) {
+    } else if (this->type_ == STATIC_STRING || this->type_ == FLASH_STRING) {
       this->static_str_ = other.static_str_;
     }
     other.type_ = NONE;
@@ -141,7 +152,7 @@ template<typename T, typename... X> class TemplatableValue {
     } else if (this->type_ == LAMBDA) {
       delete this->f_;
     }
-    // STATELESS_LAMBDA/STATIC_STRING/NONE: no cleanup needed (pointers, not heap-allocated)
+    // STATELESS_LAMBDA/STATIC_STRING/FLASH_STRING/NONE: no cleanup needed (pointers, not heap-allocated)
   }
 
   bool has_value() const { return this->type_ != NONE; }
@@ -165,6 +176,17 @@ template<typename T, typename... X> class TemplatableValue {
           return std::string(this->static_str_);
         }
         __builtin_unreachable();
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        // PROGMEM pointer — must use _P functions to access on ESP8266
+        if constexpr (std::same_as<T, std::string>) {
+          size_t len = strlen_P(this->static_str_);
+          std::string result(len, '\0');
+          memcpy_P(result.data(), this->static_str_, len);
+          return result;
+        }
+        __builtin_unreachable();
+#endif
       case NONE:
       default:
         return T{};
@@ -186,9 +208,12 @@ template<typename T, typename... X> class TemplatableValue {
   }
 
   /// Check if this holds a static string (const char* stored without allocation)
+  /// The pointer is always directly readable (RAM or flash-mapped).
+  /// Returns false for FLASH_STRING (PROGMEM on ESP8266, requires _P functions).
   bool is_static_string() const { return this->type_ == STATIC_STRING; }
 
   /// Get the static string pointer (only valid if is_static_string() returns true)
+  /// The pointer is always directly readable — FLASH_STRING uses a separate type.
   const char *get_static_string() const { return this->static_str_; }
 
   /// Check if the string value is empty without allocating (for std::string specialization).
@@ -200,6 +225,12 @@ template<typename T, typename... X> class TemplatableValue {
         return true;
       case STATIC_STRING:
         return this->static_str_ == nullptr || this->static_str_[0] == '\0';
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        // PROGMEM pointer — must use progmem_read_byte on ESP8266
+        return this->static_str_ == nullptr ||
+               progmem_read_byte(reinterpret_cast<const uint8_t *>(this->static_str_)) == '\0';
+#endif
       case VALUE:
         return this->value_->empty();
       default:  // LAMBDA/STATELESS_LAMBDA - must call value()
@@ -209,8 +240,9 @@ template<typename T, typename... X> class TemplatableValue {
 
   /// Get a StringRef to the string value without heap allocation when possible.
   /// For STATIC_STRING/VALUE, returns reference to existing data (no allocation).
+  /// For FLASH_STRING (ESP8266 PROGMEM), copies to provided buffer via _P functions.
   /// For LAMBDA/STATELESS_LAMBDA, calls value(), copies to provided buffer, returns ref to buffer.
-  /// @param lambda_buf Buffer used only for lambda case (must remain valid while StringRef is used).
+  /// @param lambda_buf Buffer used only for copy cases (must remain valid while StringRef is used).
   /// @param lambda_buf_size Size of the buffer.
   /// @return StringRef pointing to the string data.
   StringRef ref_or_copy_to(char *lambda_buf, size_t lambda_buf_size) const requires std::same_as<T, std::string> {
@@ -221,6 +253,19 @@ template<typename T, typename... X> class TemplatableValue {
         if (this->static_str_ == nullptr)
           return StringRef();
         return StringRef(this->static_str_, strlen(this->static_str_));
+#ifdef USE_ESP8266
+      case FLASH_STRING:
+        if (this->static_str_ == nullptr)
+          return StringRef();
+        {
+          // PROGMEM pointer — copy to buffer via _P functions
+          size_t len = strlen_P(this->static_str_);
+          size_t copy_len = std::min(len, lambda_buf_size - 1);
+          memcpy_P(lambda_buf, this->static_str_, copy_len);
+          lambda_buf[copy_len] = '\0';
+          return StringRef(lambda_buf, copy_len);
+        }
+#endif
       case VALUE:
         return StringRef(this->value_->data(), this->value_->size());
       default: {  // LAMBDA/STATELESS_LAMBDA - must call value() and copy
@@ -239,6 +284,7 @@ template<typename T, typename... X> class TemplatableValue {
    LAMBDA,
    STATELESS_LAMBDA,
    STATIC_STRING,  // For const char* when T is std::string - avoids heap allocation
+   FLASH_STRING,   // PROGMEM pointer on ESP8266; never set on other platforms
  } type_;
   // For std::string, use heap pointer to minimize union size (4 bytes vs 12+).
   // For other types, store value inline as before.
@@ -247,7 +293,7 @@ template<typename T, typename... X> class TemplatableValue {
     ValueStorage value_;  // T for inline storage, T* for heap storage
     std::function<T(X...)> *f_;
     T (*stateless_f_)(X...);
-    const char *static_str_;  // For STATIC_STRING type
+    const char *static_str_;  // For STATIC_STRING and FLASH_STRING types
   };
 };
 

esphome/cpp_generator.py

@@ -247,6 +247,23 @@ class LogStringLiteral(Literal):
         return f"LOG_STR({cpp_string_escape(self.string)})"
 
 
+class FlashStringLiteral(Literal):
+    """A string literal wrapped in ESPHOME_F() for PROGMEM storage on ESP8266.
+
+    On ESP8266, ESPHOME_F(s) expands to F(s) which stores the string in flash (PROGMEM).
+    On other platforms, ESPHOME_F(s) expands to plain s (no-op).
+    """
+
+    __slots__ = ("string",)
+
+    def __init__(self, string: str) -> None:
+        super().__init__()
+        self.string = string
+
+    def __str__(self) -> str:
+        return f"ESPHOME_F({cpp_string_escape(self.string)})"
+
+
 class IntLiteral(Literal):
     __slots__ = ("i",)
 
@@ -761,6 +778,10 @@ async def templatable(
     if is_template(value):
         return await process_lambda(value, args, return_type=output_type)
     if to_exp is None:
+        # Automatically wrap static strings in ESPHOME_F() for PROGMEM storage on ESP8266.
+        # On other platforms ESPHOME_F() is a no-op returning const char*.
+        if isinstance(value, str) and str(output_type) == "std::string":
+            return FlashStringLiteral(value)
         return value
     if isinstance(to_exp, dict):
         return to_exp[value]

esphome/cpp_types.py

@@ -12,6 +12,7 @@ std_shared_ptr = std_ns.class_("shared_ptr")
 std_string = std_ns.class_("string")
 std_string_ref = std_ns.namespace("string &")
 std_vector = std_ns.class_("vector")
+std_span = std_ns.class_("span")
 uint8 = global_ns.namespace("uint8_t")
 uint16 = global_ns.namespace("uint16_t")
 uint32 = global_ns.namespace("uint32_t")

esphome/dashboard/web_server.py

@@ -317,6 +317,7 @@ class EsphomeCommandWebSocket(CheckOriginMixin, tornado.websocket.WebSocketHandl
             # Check if the proc was not forcibly closed
             _LOGGER.info("Process exited with return code %s", returncode)
             self.write_message({"event": "exit", "code": returncode})
+            self.close()
 
     def on_close(self) -> None:
         # Check if proc exists (if 'start' has been run)
@@ -1053,17 +1054,26 @@ class DownloadBinaryRequestHandler(BaseHandler):
         # fallback to type=, but prioritize file=
         file_name = self.get_argument("type", None)
         file_name = self.get_argument("file", file_name)
-        if file_name is None:
+        if file_name is None or not file_name.strip():
             self.send_error(400)
             return
-        file_name = file_name.replace("..", "").lstrip("/")
         # get requested download name, or build it based on filename
         download_name = self.get_argument(
             "download",
             f"{storage_json.name}-{file_name}",
         )
 
-        path = storage_json.firmware_bin_path.parent.joinpath(file_name)
+        if storage_json.firmware_bin_path is None:
+            self.send_error(404)
+            return
+
+        base_dir = storage_json.firmware_bin_path.parent.resolve()
+        path = base_dir.joinpath(file_name).resolve()
+        try:
+            path.relative_to(base_dir)
+        except ValueError:
+            self.send_error(403)
+            return
 
         if not path.is_file():
             args = ["esphome", "idedata", settings.rel_path(configuration)]
@@ -1077,7 +1087,7 @@ class DownloadBinaryRequestHandler(BaseHandler):
 
             found = False
             for image in idedata.extra_flash_images:
-                if image.path.endswith(file_name):
+                if image.path.as_posix().endswith(file_name):
                     path = image.path
                     download_name = file_name
                     found = True

esphome/wizard.py

@@ -1,6 +1,5 @@
 import base64
 from pathlib import Path
-import random
 import secrets
 import string
 from typing import Literal, NotRequired, TypedDict, Unpack
@@ -130,7 +129,7 @@ def wizard_file(**kwargs: Unpack[WizardFileKwargs]) -> str:
     if len(ap_name) > 32:
         ap_name = ap_name_base
     kwargs["fallback_name"] = ap_name
-    kwargs["fallback_psk"] = "".join(random.choice(letters) for _ in range(12))
+    kwargs["fallback_psk"] = "".join(secrets.choice(letters) for _ in range(12))
 
     base = BASE_CONFIG_FRIENDLY if kwargs.get("friendly_name") else BASE_CONFIG
 

script/api_protobuf/api_protobuf.py

@@ -2270,10 +2270,13 @@ SOURCE_NAMES = {
     SOURCE_CLIENT: "SOURCE_CLIENT",
 }
 
-RECEIVE_CASES: dict[int, tuple[str, str | None]] = {}
+RECEIVE_CASES: dict[int, tuple[str, str | None, str]] = {}
 
 ifdefs: dict[str, str] = {}
 
+# Track messages with no fields (empty messages) for parameter elision
+EMPTY_MESSAGES: set[str] = set()
+
 
 def get_opt(
     desc: descriptor.DescriptorProto,
@@ -2504,26 +2507,26 @@ def build_service_message_type(
         # Only add ifdef when we're actually generating content
         if ifdef is not None:
             hout += f"#ifdef {ifdef}\n"
-        # Generate receive
+        # Generate receive handler and switch case
         func = f"on_{snake}"
-        hout += f"virtual void {func}(const {mt.name} &value){{}};\n"
-        case = ""
-        case += f"{mt.name} msg;\n"
-        # Check if this message has any fields (excluding deprecated ones)
         has_fields = any(not field.options.deprecated for field in mt.field)
-        if has_fields:
-            # Normal case: decode the message
+        is_empty = not has_fields
+        if is_empty:
+            EMPTY_MESSAGES.add(mt.name)
+        hout += f"virtual void {func}({'' if is_empty else f'const {mt.name} &value'}){{}};\n"
+        case = ""
+        if not is_empty:
+            case += f"{mt.name} msg;\n"
             case += "msg.decode(msg_data, msg_size);\n"
-        else:
-            # Empty message optimization: skip decode since there are no fields
-            case += "// Empty message: no decode needed\n"
         if log:
             case += "#ifdef HAS_PROTO_MESSAGE_DUMP\n"
-            case += f'this->log_receive_message_(LOG_STR("{func}"), msg);\n'
+            if is_empty:
+                case += f'this->log_receive_message_(LOG_STR("{func}"));\n'
+            else:
+                case += f'this->log_receive_message_(LOG_STR("{func}"), msg);\n'
             case += "#endif\n"
-        case += f"this->{func}(msg);\n"
+        case += f"this->{func}({'msg' if not is_empty else ''});\n"
         case += "break;"
-        # Store the message name and ifdef with the case for later use
         RECEIVE_CASES[id_] = (case, ifdef, mt.name)
 
         # Only close ifdef if we opened it
@@ -2839,6 +2842,7 @@ static const char *const TAG = "api.service";
     hpp += (
         "  void log_receive_message_(const LogString *name, const ProtoMessage &msg);\n"
     )
+    hpp += "  void log_receive_message_(const LogString *name);\n"
     hpp += " public:\n"
     hpp += "#endif\n\n"
 
@@ -2862,6 +2866,9 @@ static const char *const TAG = "api.service";
     cpp += "  DumpBuffer dump_buf;\n"
     cpp += '  ESP_LOGVV(TAG, "%s: %s", LOG_STR_ARG(name), msg.dump_to(dump_buf));\n'
     cpp += "}\n"
+    cpp += f"void {class_name}::log_receive_message_(const LogString *name) {{\n"
+    cpp += '  ESP_LOGVV(TAG, "%s: {}", LOG_STR_ARG(name));\n'
+    cpp += "}\n"
     cpp += "#endif\n\n"
 
     for mt in file.message_type:
@@ -2929,22 +2936,22 @@ static const char *const TAG = "api.service";
             hpp_protected += f"#ifdef {ifdef}\n"
             cpp += f"#ifdef {ifdef}\n"
 
-        hpp_protected += f"  void {on_func}(const {inp} &msg) override;\n"
+        is_empty = inp in EMPTY_MESSAGES
+        param = "" if is_empty else f"const {inp} &msg"
+        arg = "" if is_empty else "msg"
 
-        # For non-void methods, generate a send_ method instead of return-by-value
+        hpp_protected += f"  void {on_func}({param}) override;\n"
         if is_void:
-            hpp += f"  virtual void {func}(const {inp} &msg) = 0;\n"
+            hpp += f"  virtual void {func}({param}) = 0;\n"
         else:
-            hpp += f"  virtual bool send_{func}_response(const {inp} &msg) = 0;\n"
+            hpp += f"  virtual bool send_{func}_response({param}) = 0;\n"
 
-        cpp += f"void {class_name}::{on_func}(const {inp} &msg) {{\n"
-
-        # No authentication check here - it's done in read_message
+        cpp += f"void {class_name}::{on_func}({param}) {{\n"
         body = ""
         if is_void:
-            body += f"this->{func}(msg);\n"
+            body += f"this->{func}({arg});\n"
         else:
-            body += f"if (!this->send_{func}_response(msg)) {{\n"
+            body += f"if (!this->send_{func}_response({arg})) {{\n"
             body += "  this->on_fatal_error();\n"
             body += "}\n"
 

tests/components/epaper_spi/test.esp32-s3-idf.yaml

@@ -25,6 +25,22 @@ display:
     lambda: |-
       it.circle(64, 64, 50, Color::BLACK);
 
+  - platform: epaper_spi
+    spi_id: spi_bus
+    model: waveshare-1.54in-G
+    cs_pin:
+      allow_other_uses: true
+      number: GPIO5
+    dc_pin:
+      allow_other_uses: true
+      number: GPIO17
+    reset_pin:
+      allow_other_uses: true
+      number: GPIO16
+    busy_pin:
+      allow_other_uses: true
+      number: GPIO4
+
   - platform: epaper_spi
     spi_id: spi_bus
     model: waveshare-2.13in-v3

tests/components/lvgl/test.host.yaml

@@ -20,6 +20,8 @@ lvgl:
   - id: lvgl_0
     default_font: space16
     displays: sdl0
+    top_layer:
+
   - id: lvgl_1
     displays: sdl1
     on_idle:

tests/components/template/common-base.yaml

@@ -412,6 +412,7 @@ water_heater:
     name: "Template Water Heater"
     optimistic: true
     current_temperature: !lambda "return 42.0f;"
+    target_temperature: !lambda "return 60.0f;"
     mode: !lambda "return water_heater::WATER_HEATER_MODE_ECO;"
     supported_modes:
       - "OFF"

tests/dashboard/test_web_server.py

@@ -8,6 +8,7 @@ import gzip
 import json
 import os
 from pathlib import Path
+import sys
 from unittest.mock import AsyncMock, MagicMock, Mock, patch
 
 import pytest
@@ -29,7 +30,7 @@ from esphome.dashboard.entries import (
     bool_to_entry_state,
 )
 from esphome.dashboard.models import build_importable_device_dict
-from esphome.dashboard.web_server import DashboardSubscriber
+from esphome.dashboard.web_server import DashboardSubscriber, EsphomeCommandWebSocket
 from esphome.zeroconf import DiscoveredImport
 
 from .common import get_fixture_path
@@ -421,7 +422,7 @@ async def test_download_binary_handler_idedata_fallback(
 
     # Mock idedata response
     mock_image = Mock()
-    mock_image.path = str(bootloader_file)
+    mock_image.path = bootloader_file
     mock_idedata_instance = Mock()
     mock_idedata_instance.extra_flash_images = [mock_image]
     mock_idedata.return_value = mock_idedata_instance
@@ -528,14 +529,22 @@ async def test_download_binary_handler_subdirectory_file_url_encoded(
 @pytest.mark.asyncio
 @pytest.mark.usefixtures("mock_ext_storage_path")
 @pytest.mark.parametrize(
-    "attack_path",
+    ("attack_path", "expected_code"),
     [
-        pytest.param("../../../secrets.yaml", id="basic_traversal"),
-        pytest.param("..%2F..%2F..%2Fsecrets.yaml", id="url_encoded"),
-        pytest.param("zephyr/../../../secrets.yaml", id="traversal_with_prefix"),
-        pytest.param("/etc/passwd", id="absolute_path"),
-        pytest.param("//etc/passwd", id="double_slash_absolute"),
-        pytest.param("....//secrets.yaml", id="multiple_dots"),
+        pytest.param("../../../secrets.yaml", 403, id="basic_traversal"),
+        pytest.param("..%2F..%2F..%2Fsecrets.yaml", 403, id="url_encoded"),
+        pytest.param("zephyr/../../../secrets.yaml", 403, id="traversal_with_prefix"),
+        pytest.param("/etc/passwd", 403, id="absolute_path"),
+        pytest.param("//etc/passwd", 403, id="double_slash_absolute"),
+        pytest.param(
+            "....//secrets.yaml",
+            # On Windows, Path.resolve() treats "..." and "...." as parent
+            # traversal (like ".."), so the path escapes base_dir -> 403.
+            # On Unix, "...." is a literal directory name that stays inside
+            # base_dir but doesn't exist -> 404.
+            403 if sys.platform == "win32" else 404,
+            id="multiple_dots",
+        ),
     ],
 )
 async def test_download_binary_handler_path_traversal_protection(
@@ -543,11 +552,14 @@ async def test_download_binary_handler_path_traversal_protection(
     tmp_path: Path,
     mock_storage_json: MagicMock,
     attack_path: str,
+    expected_code: int,
 ) -> None:
     """Test that DownloadBinaryRequestHandler prevents path traversal attacks.
 
-    Verifies that attempts to use '..' in file paths are sanitized to prevent
-    accessing files outside the build directory. Tests multiple attack vectors.
+    Verifies that attempts to escape the build directory via '..' are rejected
+    using resolve()/relative_to() validation. Tests multiple attack vectors.
+    Real traversals that escape the base directory get 403. Paths like '....'
+    that resolve inside the base directory but don't exist get 404.
     """
     # Create build structure
     build_dir = get_build_path(tmp_path, "test")
@@ -565,14 +577,67 @@ async def test_download_binary_handler_path_traversal_protection(
     mock_storage.firmware_bin_path = firmware_file
     mock_storage_json.load.return_value = mock_storage
 
-    # Attempt path traversal attack - should be blocked
-    with pytest.raises(HTTPClientError) as exc_info:
+    # Mock async_run_system_command so paths that pass validation but don't exist
+    # return 404 deterministically without spawning a real subprocess.
+    with (
+        patch(
+            "esphome.dashboard.web_server.async_run_system_command",
+            new_callable=AsyncMock,
+            return_value=(2, "", ""),
+        ),
+        pytest.raises(HTTPClientError) as exc_info,
+    ):
         await dashboard.fetch(
             f"/download.bin?configuration=test.yaml&file={attack_path}",
             method="GET",
         )
-    # Should get 404 (file not found after sanitization) or 500 (idedata fails)
-    assert exc_info.value.code in (404, 500)
+    assert exc_info.value.code == expected_code
+
+
+@pytest.mark.asyncio
+@pytest.mark.usefixtures("mock_ext_storage_path")
+async def test_download_binary_handler_no_firmware_bin_path(
+    dashboard: DashboardTestHelper,
+    mock_storage_json: MagicMock,
+) -> None:
+    """Test that download returns 404 when firmware_bin_path is None.
+
+    This covers configs created by StorageJSON.from_wizard() where no
+    firmware has been compiled yet.
+    """
+    mock_storage = Mock()
+    mock_storage.name = "test_device"
+    mock_storage.firmware_bin_path = None
+    mock_storage_json.load.return_value = mock_storage
+
+    with pytest.raises(HTTPClientError) as exc_info:
+        await dashboard.fetch(
+            "/download.bin?configuration=test.yaml&file=firmware.bin",
+            method="GET",
+        )
+    assert exc_info.value.code == 404
+
+
+@pytest.mark.asyncio
+@pytest.mark.usefixtures("mock_ext_storage_path")
+@pytest.mark.parametrize("file_value", ["", "%20%20", "%20"])
+async def test_download_binary_handler_empty_file_name(
+    dashboard: DashboardTestHelper,
+    mock_storage_json: MagicMock,
+    file_value: str,
+) -> None:
+    """Test that download returns 400 for empty or whitespace-only file names."""
+    mock_storage = Mock()
+    mock_storage.name = "test_device"
+    mock_storage.firmware_bin_path = Path("/fake/firmware.bin")
+    mock_storage_json.load.return_value = mock_storage
+
+    with pytest.raises(HTTPClientError) as exc_info:
+        await dashboard.fetch(
+            f"/download.bin?configuration=test.yaml&file={file_value}",
+            method="GET",
+        )
+    assert exc_info.value.code == 400
 
 
 @pytest.mark.asyncio
@@ -1654,3 +1719,25 @@ async def test_websocket_check_origin_multiple_trusted_domains(
             assert data["event"] == "initial_state"
         finally:
             ws.close()
+
+
+def test_proc_on_exit_calls_close() -> None:
+    """Test _proc_on_exit sends exit event and closes the WebSocket."""
+    handler = Mock(spec=EsphomeCommandWebSocket)
+    handler._is_closed = False
+
+    EsphomeCommandWebSocket._proc_on_exit(handler, 0)
+
+    handler.write_message.assert_called_once_with({"event": "exit", "code": 0})
+    handler.close.assert_called_once()
+
+
+def test_proc_on_exit_skips_when_already_closed() -> None:
+    """Test _proc_on_exit does nothing when WebSocket is already closed."""
+    handler = Mock(spec=EsphomeCommandWebSocket)
+    handler._is_closed = True
+
+    EsphomeCommandWebSocket._proc_on_exit(handler, 0)
+
+    handler.write_message.assert_not_called()
+    handler.close.assert_not_called()

tests/integration/fixtures/water_heater_template.yaml

@@ -10,6 +10,7 @@ water_heater:
     name: Test Boiler
     optimistic: true
     current_temperature: !lambda "return 45.0f;"
+    target_temperature: !lambda "return 60.0f;"
     # Note: No mode lambda - we want optimistic mode changes to stick
     # A mode lambda would override mode changes in loop()
     supported_modes:

tests/integration/test_udp.py

@@ -93,23 +93,34 @@ async def udp_listener(port: int = 0) -> AsyncGenerator[tuple[int, UDPReceiver]]
         sock.close()
 
 
+def _get_free_udp_port() -> int:
+    """Get a free UDP port by binding to port 0 and releasing."""
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.bind(("127.0.0.1", 0))
+    port = sock.getsockname()[1]
+    sock.close()
+    return port
+
+
 @pytest.mark.asyncio
 async def test_udp_send_receive(
     yaml_config: str,
     run_compiled: RunCompiledFunction,
     api_client_connected: APIClientConnectedFactory,
 ) -> None:
-    """Test UDP component can send messages with multiple addresses configured."""
-    # Track log lines to verify dump_config output
+    """Test UDP component can send and receive messages."""
     log_lines: list[str] = []
+    receive_event = asyncio.Event()
 
     def on_log_line(line: str) -> None:
         log_lines.append(line)
+        if "Received UDP:" in line:
+            receive_event.set()
 
-    async with udp_listener() as (udp_port, receiver):
-        # Replace placeholders in the config
-        config = yaml_config.replace("UDP_LISTEN_PORT_PLACEHOLDER", str(udp_port + 1))
-        config = config.replace("UDP_BROADCAST_PORT_PLACEHOLDER", str(udp_port))
+    async with udp_listener() as (broadcast_port, receiver):
+        listen_port = _get_free_udp_port()
+        config = yaml_config.replace("UDP_LISTEN_PORT_PLACEHOLDER", str(listen_port))
+        config = config.replace("UDP_BROADCAST_PORT_PLACEHOLDER", str(broadcast_port))
 
         async with (
             run_compiled(config, line_callback=on_log_line),
@@ -169,3 +180,19 @@ async def test_udp_send_receive(
             assert "Address: 127.0.0.2" in log_text, (
                 f"Address 127.0.0.2 not found in dump_config. Log: {log_text[-2000:]}"
             )
+
+            # Test receiving a UDP packet (exercises on_receive with std::span)
+            test_payload = b"TEST_RECEIVE_UDP"
+            send_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+            try:
+                send_sock.sendto(test_payload, ("127.0.0.1", listen_port))
+            finally:
+                send_sock.close()
+
+            try:
+                await asyncio.wait_for(receive_event.wait(), timeout=5.0)
+            except TimeoutError:
+                pytest.fail(
+                    f"on_receive did not fire. Expected 'Received UDP:' in logs. "
+                    f"Last log lines: {log_lines[-20:]}"
+                )

tests/integration/test_water_heater_template.py

@@ -85,6 +85,9 @@ async def test_water_heater_template(
         assert initial_state.current_temperature == 45.0, (
             f"Expected current temp 45.0, got {initial_state.current_temperature}"
         )
+        assert initial_state.target_temperature == 60.0, (
+            f"Expected target temp 60.0, got {initial_state.target_temperature}"
+        )
 
         # Test changing to GAS mode
         client.water_heater_command(test_water_heater.key, mode=WaterHeaterMode.GAS)

tests/unit_tests/test_cpp_generator.py

@@ -248,6 +248,12 @@ class TestLiterals:
             (cg.FloatLiteral(4.2), "4.2f"),
             (cg.FloatLiteral(1.23456789), "1.23456789f"),
             (cg.FloatLiteral(math.nan), "NAN"),
+            (cg.FlashStringLiteral("hello"), 'ESPHOME_F("hello")'),
+            (cg.FlashStringLiteral(""), 'ESPHOME_F("")'),
+            (
+                cg.FlashStringLiteral('quote"here'),
+                'ESPHOME_F("quote\\042here")',
+            ),
         ),
     )
     def test_str__simple(self, target: cg.Literal, expected: str):
@@ -624,3 +630,75 @@ class TestProcessLambda:
         # Test invalid tuple format (single element)
         with pytest.raises(AssertionError):
             await cg.process_lambda(lambda_obj, [(int,)])
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_std_string_returns_flash_literal() -> None:
+    """Static string with std::string output_type returns FlashStringLiteral."""
+    result = await cg.templatable("hello", [], ct.std_string)
+
+    assert isinstance(result, cg.FlashStringLiteral)
+    assert str(result) == 'ESPHOME_F("hello")'
+
+
+@pytest.mark.asyncio
+async def test_templatable__empty_string_with_std_string() -> None:
+    """Empty static string with std::string output_type returns FlashStringLiteral."""
+    result = await cg.templatable("", [], ct.std_string)
+
+    assert isinstance(result, cg.FlashStringLiteral)
+    assert str(result) == 'ESPHOME_F("")'
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_none_output_type() -> None:
+    """Static string with output_type=None returns raw string (no wrapping)."""
+    result = await cg.templatable("hello", [], None)
+
+    assert isinstance(result, str)
+    assert result == "hello"
+
+
+@pytest.mark.asyncio
+async def test_templatable__int_with_std_string() -> None:
+    """Non-string value with std::string output_type returns raw value."""
+    result = await cg.templatable(42, [], ct.std_string)
+
+    assert result == 42
+
+
+@pytest.mark.asyncio
+async def test_templatable__string_with_non_string_output_type() -> None:
+    """Static string with non-std::string output_type returns raw string."""
+    result = await cg.templatable("hello", [], ct.bool_)
+
+    assert isinstance(result, str)
+    assert result == "hello"
+
+
+@pytest.mark.asyncio
+async def test_templatable__with_to_exp_callable() -> None:
+    """When to_exp is provided, it is applied to non-template values."""
+    result = await cg.templatable(42, [], None, to_exp=lambda x: x * 2)
+
+    assert result == 84
+
+
+@pytest.mark.asyncio
+async def test_templatable__with_to_exp_dict() -> None:
+    """When to_exp is a dict, value is looked up."""
+    mapping: dict[str, int] = {"on": 1, "off": 0}
+    result = await cg.templatable("on", [], None, to_exp=mapping)
+
+    assert result == 1
+
+
+@pytest.mark.asyncio
+async def test_templatable__lambda_with_std_string() -> None:
+    """Lambda value returns LambdaExpression, not FlashStringLiteral."""
+    from esphome.core import Lambda
+
+    lambda_obj = Lambda('return "hello";')
+    result = await cg.templatable(lambda_obj, [], ct.std_string)
+
+    assert isinstance(result, cg.LambdaExpression)

tests/unit_tests/test_wizard.py

@@ -2,7 +2,7 @@
 
 from pathlib import Path
 from typing import Any
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
 import pytest
 from pytest import MonkeyPatch
@@ -632,3 +632,14 @@ def test_wizard_accepts_rpipico_board(tmp_path: Path, monkeypatch: MonkeyPatch):
     # rpipico doesn't support WiFi, so no api_encryption_key or ota_password
     assert "api_encryption_key" not in call_kwargs
     assert "ota_password" not in call_kwargs
+
+
+def test_fallback_psk_uses_secrets_choice(
+    default_config: dict[str, Any],
+) -> None:
+    """Test that fallback PSK is generated using secrets.choice."""
+    with patch("esphome.wizard.secrets.choice", return_value="X") as mock_choice:
+        config = wz.wizard_file(**default_config)
+
+    assert 'password: "XXXXXXXXXXXX"' in config
+    assert mock_choice.call_count == 12