Add TODO for std::trivially_relocatable when available

- Add #include <type_traits> to both .cpp and .h for static_asserts
- Clarify CompactString comment: explicitly note it is not trivially
  copyable, and that memcpy safety relies on validated layout property
- Use memcpy_fn indirection to suppress both GCC -Wclass-memaccess
  and clang-tidy bugprone-undefined-memory-manipulation without
  platform-specific pragma guards

Doxyfile

@@ -48,7 +48,7 @@ PROJECT_NAME           = ESPHome
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 2026.2.0b2
+PROJECT_NUMBER         = 2026.3.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a

docker/Dockerfile

@@ -9,8 +9,7 @@ FROM ghcr.io/esphome/docker-base:${BUILD_OS}-ha-addon-${BUILD_BASE_VERSION} AS b
 ARG BUILD_TYPE
 FROM base-source-${BUILD_TYPE} AS base
 
-RUN git config --system --add safe.directory "*" \
-    && git config --system advice.detachedHead false
+RUN git config --system --add safe.directory "*"
 
 # Install build tools for Python packages that require compilation
 # (e.g., ruamel.yaml.clibz used by ESP-IDF's idf-component-manager)

esphome/analyze_memory/const.py

@@ -256,7 +256,7 @@ SYMBOL_PATTERNS = {
     "ipv6_stack": ["nd6_", "ip6_", "mld6_", "icmp6_", "icmp6_input"],
     # Order matters! More specific categories must come before general ones.
     # mdns must come before bluetooth to avoid "_mdns_disable_pcb" matching "ble_" pattern
-    "mdns_lib": ["mdns"],
+    "mdns_lib": ["mdns", "packet$"],
     # memory_mgmt must come before wifi_stack to catch mmu_hal_* symbols
     "memory_mgmt": [
         "mem_",
@@ -794,7 +794,6 @@ SYMBOL_PATTERNS = {
         "s_dp",
         "s_ni",
         "s_reg_dump",
-        "packet$",
         "d_mult_table",
         "K",
         "fcstab",

esphome/components/api/api_frame_helper_noise.cpp

@@ -138,12 +138,10 @@ APIError APINoiseFrameHelper::handle_noise_error_(int err, const LogString *func
 
 /// Run through handshake messages (if in that phase)
 APIError APINoiseFrameHelper::loop() {
-  // Cache ready() outside the loop. On ESP8266 LWIP raw TCP, ready() returns false once
-  // the rx buffer is consumed. Re-checking each iteration would block handshake writes
-  // that must follow reads, deadlocking the handshake. state_action() will return
-  // WOULD_BLOCK when no more data is available to read.
-  bool socket_ready = this->socket_->ready();
-  while (state_ != State::DATA && socket_ready) {
+  // During handshake phase, process as many actions as possible until we can't progress
+  // socket_->ready() stays true until next main loop, but state_action() will return
+  // WOULD_BLOCK when no more data is available to read
+  while (state_ != State::DATA && this->socket_->ready()) {
     APIError err = state_action_();
     if (err == APIError::WOULD_BLOCK) {
       break;

esphome/components/api/api_server.cpp

@@ -148,16 +148,12 @@ void APIServer::loop() {
   while (client_index < this->clients_.size()) {
     auto &client = this->clients_[client_index];
 
-    // Common case: process active client
-    if (!client->flags_.remove) {
-      client->loop();
-    }
-    // Handle disconnection promptly - close socket to free LWIP PCB
-    // resources and prevent retransmit crashes on ESP8266.
     if (client->flags_.remove) {
       // Rare case: handle disconnection (don't increment - swapped element needs processing)
       this->remove_client_(client_index);
     } else {
+      // Common case: process active client
+      client->loop();
       client_index++;
     }
   }

esphome/components/captive_portal/captive_portal.cpp

@@ -47,8 +47,8 @@ void CaptivePortal::handle_config(AsyncWebServerRequest *request) {
   request->send(stream);
 }
 void CaptivePortal::handle_wifisave(AsyncWebServerRequest *request) {
-  std::string ssid = request->arg("ssid").c_str();  // NOLINT(readability-redundant-string-cstr)
-  std::string psk = request->arg("psk").c_str();    // NOLINT(readability-redundant-string-cstr)
+  const auto &ssid = request->arg("ssid");
+  const auto &psk = request->arg("psk");
   ESP_LOGI(TAG,
            "Requested WiFi Settings Change:\n"
            "  SSID='%s'\n"
@@ -56,10 +56,10 @@ void CaptivePortal::handle_wifisave(AsyncWebServerRequest *request) {
            ssid.c_str(), psk.c_str());
 #ifdef USE_ESP8266
   // ESP8266 is single-threaded, call directly
-  wifi::global_wifi_component->save_wifi_sta(ssid, psk);
+  wifi::global_wifi_component->save_wifi_sta(ssid.c_str(), psk.c_str());
 #else
   // Defer save to main loop thread to avoid NVS operations from HTTP thread
-  this->defer([ssid, psk]() { wifi::global_wifi_component->save_wifi_sta(ssid, psk); });
+  this->defer([ssid, psk]() { wifi::global_wifi_component->save_wifi_sta(ssid.c_str(), psk.c_str()); });
 #endif
   request->redirect(ESPHOME_F("/?save"));
 }

esphome/components/ethernet/ethernet_component.h

@@ -110,6 +110,8 @@ class EthernetComponent : public Component {
   const char *get_use_address() const;
   void set_use_address(const char *use_address);
   void get_eth_mac_address_raw(uint8_t *mac);
+  // Remove before 2026.9.0
+  ESPDEPRECATED("Use get_eth_mac_address_pretty_into_buffer() instead. Removed in 2026.9.0", "2026.3.0")
   std::string get_eth_mac_address_pretty();
   const char *get_eth_mac_address_pretty_into_buffer(std::span<char, MAC_ADDRESS_PRETTY_BUFFER_SIZE> buf);
   eth_duplex_t get_duplex_mode();

esphome/components/mipi_spi/models/waveshare.py

@@ -1,4 +1,17 @@
-from esphome.components.mipi import DriverChip
+from esphome.components.mipi import (
+    ETMOD,
+    FRMCTR2,
+    GMCTRN1,
+    GMCTRP1,
+    IFCTR,
+    MODE_RGB,
+    PWCTR1,
+    PWCTR3,
+    PWCTR4,
+    PWCTR5,
+    PWSET,
+    DriverChip,
+)
 import esphome.config_validation as cv
 
 from .amoled import CO5300
@@ -129,6 +142,16 @@ DriverChip(
         ),
     ),
 )
+ST7789P = DriverChip(
+    "ST7789P",
+    # Max supported dimensions
+    width=240,
+    height=320,
+    # SPI: RGB layout
+    color_order=MODE_RGB,
+    invert_colors=True,
+    draw_rounding=1,
+)
 
 ILI9488_A.extend(
     "PICO-RESTOUCH-LCD-3.5",
@@ -162,3 +185,61 @@ AXS15231.extend(
     cs_pin=9,
     reset_pin=21,
 )
+
+# Waveshare 1.83-v2
+#
+# Do not use on 1.83-v1: Vendor warning on different chip!
+ST7789P.extend(
+    "WAVESHARE-1.83-V2",
+    # Panel size smaller than ST7789 max allowed
+    width=240,
+    height=284,
+    # Vendor specific init derived from vendor sample code
+    # "LCD_1.83_Code_Rev2/ESP32/LCD_1in83/LCD_Driver.cpp"
+    # Compatible MIT license, see esphome/LICENSE file.
+    initsequence=(
+        (FRMCTR2, 0x0C, 0x0C, 0x00, 0x33, 0x33),
+        (ETMOD, 0x35),
+        (0xBB, 0x19),
+        (PWCTR1, 0x2C),
+        (PWCTR3, 0x01),
+        (PWCTR4, 0x12),
+        (PWCTR5, 0x20),
+        (IFCTR, 0x0F),
+        (PWSET, 0xA4, 0xA1),
+        (
+            GMCTRP1,
+            0xD0,
+            0x04,
+            0x0D,
+            0x11,
+            0x13,
+            0x2B,
+            0x3F,
+            0x54,
+            0x4C,
+            0x18,
+            0x0D,
+            0x0B,
+            0x1F,
+            0x23,
+        ),
+        (
+            GMCTRN1,
+            0xD0,
+            0x04,
+            0x0C,
+            0x11,
+            0x13,
+            0x2C,
+            0x3F,
+            0x44,
+            0x51,
+            0x2F,
+            0x1F,
+            0x1F,
+            0x20,
+            0x23,
+        ),
+    ),
+)

esphome/components/web_server/web_server.cpp

@@ -557,7 +557,9 @@ static void set_json_id(JsonObject &root, EntityBase *obj, const char *prefix, J
       root[ESPHOME_F("device")] = device_name;
     }
 #endif
+#ifdef USE_ENTITY_ICON
     root[ESPHOME_F("icon")] = obj->get_icon_ref();
+#endif
     root[ESPHOME_F("entity_category")] = obj->get_entity_category();
     bool is_disabled = obj->is_disabled_by_default();
     if (is_disabled)
@@ -583,8 +585,7 @@ static void set_json_icon_state_value(JsonObject &root, EntityBase *obj, const c
 
 // Helper to get request detail parameter
 static JsonDetail get_request_detail(AsyncWebServerRequest *request) {
-  auto *param = request->getParam(ESPHOME_F("detail"));
-  return (param && param->value() == "all") ? DETAIL_ALL : DETAIL_STATE;
+  return request->arg(ESPHOME_F("detail")) == "all" ? DETAIL_ALL : DETAIL_STATE;
 }
 
 #ifdef USE_SENSOR
@@ -861,10 +862,10 @@ void WebServer::handle_fan_request(AsyncWebServerRequest *request, const UrlMatc
       }
       auto call = is_on ? obj->turn_on() : obj->turn_off();
 
-      parse_int_param_(request, ESPHOME_F("speed_level"), call, &decltype(call)::set_speed);
+      parse_num_param_(request, ESPHOME_F("speed_level"), call, &decltype(call)::set_speed);
 
-      if (request->hasParam(ESPHOME_F("oscillation"))) {
-        auto speed = request->getParam(ESPHOME_F("oscillation"))->value();
+      if (request->hasArg(ESPHOME_F("oscillation"))) {
+        auto speed = request->arg(ESPHOME_F("oscillation"));
         auto val = parse_on_off(speed.c_str());
         switch (val) {
           case PARSE_ON:
@@ -1040,14 +1041,14 @@ void WebServer::handle_cover_request(AsyncWebServerRequest *request, const UrlMa
     }
 
     auto traits = obj->get_traits();
-    if ((request->hasParam(ESPHOME_F("position")) && !traits.get_supports_position()) ||
-        (request->hasParam(ESPHOME_F("tilt")) && !traits.get_supports_tilt())) {
+    if ((request->hasArg(ESPHOME_F("position")) && !traits.get_supports_position()) ||
+        (request->hasArg(ESPHOME_F("tilt")) && !traits.get_supports_tilt())) {
       request->send(409);
       return;
     }
 
-    parse_float_param_(request, ESPHOME_F("position"), call, &decltype(call)::set_position);
-    parse_float_param_(request, ESPHOME_F("tilt"), call, &decltype(call)::set_tilt);
+    parse_num_param_(request, ESPHOME_F("position"), call, &decltype(call)::set_position);
+    parse_num_param_(request, ESPHOME_F("tilt"), call, &decltype(call)::set_tilt);
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1106,7 +1107,7 @@ void WebServer::handle_number_request(AsyncWebServerRequest *request, const UrlM
     }
 
     auto call = obj->make_call();
-    parse_float_param_(request, ESPHOME_F("value"), call, &decltype(call)::set_value);
+    parse_num_param_(request, ESPHOME_F("value"), call, &decltype(call)::set_value);
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1174,12 +1175,13 @@ void WebServer::handle_date_request(AsyncWebServerRequest *request, const UrlMat
 
     auto call = obj->make_call();
 
-    if (!request->hasParam(ESPHOME_F("value"))) {
+    const auto &value = request->arg(ESPHOME_F("value"));
+    // Arduino String has isEmpty() not empty(), use length() for cross-platform compatibility
+    if (value.length() == 0) {  // NOLINT(readability-container-size-empty)
       request->send(409);
       return;
     }
-
-    parse_string_param_(request, ESPHOME_F("value"), call, &decltype(call)::set_date);
+    call.set_date(value.c_str(), value.length());
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1234,12 +1236,13 @@ void WebServer::handle_time_request(AsyncWebServerRequest *request, const UrlMat
 
     auto call = obj->make_call();
 
-    if (!request->hasParam(ESPHOME_F("value"))) {
+    const auto &value = request->arg(ESPHOME_F("value"));
+    // Arduino String has isEmpty() not empty(), use length() for cross-platform compatibility
+    if (value.length() == 0) {  // NOLINT(readability-container-size-empty)
       request->send(409);
       return;
     }
-
-    parse_string_param_(request, ESPHOME_F("value"), call, &decltype(call)::set_time);
+    call.set_time(value.c_str(), value.length());
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1293,12 +1296,13 @@ void WebServer::handle_datetime_request(AsyncWebServerRequest *request, const Ur
 
     auto call = obj->make_call();
 
-    if (!request->hasParam(ESPHOME_F("value"))) {
+    const auto &value = request->arg(ESPHOME_F("value"));
+    // Arduino String has isEmpty() not empty(), use length() for cross-platform compatibility
+    if (value.length() == 0) {  // NOLINT(readability-container-size-empty)
       request->send(409);
       return;
     }
-
-    parse_string_param_(request, ESPHOME_F("value"), call, &decltype(call)::set_datetime);
+    call.set_datetime(value.c_str(), value.length());
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1477,10 +1481,14 @@ void WebServer::handle_climate_request(AsyncWebServerRequest *request, const Url
     parse_string_param_(request, ESPHOME_F("swing_mode"), call, &decltype(call)::set_swing_mode);
 
     // Parse temperature parameters
-    parse_float_param_(request, ESPHOME_F("target_temperature_high"), call,
-                       &decltype(call)::set_target_temperature_high);
-    parse_float_param_(request, ESPHOME_F("target_temperature_low"), call, &decltype(call)::set_target_temperature_low);
-    parse_float_param_(request, ESPHOME_F("target_temperature"), call, &decltype(call)::set_target_temperature);
+    // static_cast needed to disambiguate overloaded setters (float vs optional<float>)
+    using ClimateCall = decltype(call);
+    parse_num_param_(request, ESPHOME_F("target_temperature_high"), call,
+                     static_cast<ClimateCall &(ClimateCall::*) (float)>(&ClimateCall::set_target_temperature_high));
+    parse_num_param_(request, ESPHOME_F("target_temperature_low"), call,
+                     static_cast<ClimateCall &(ClimateCall::*) (float)>(&ClimateCall::set_target_temperature_low));
+    parse_num_param_(request, ESPHOME_F("target_temperature"), call,
+                     static_cast<ClimateCall &(ClimateCall::*) (float)>(&ClimateCall::set_target_temperature));
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1721,12 +1729,12 @@ void WebServer::handle_valve_request(AsyncWebServerRequest *request, const UrlMa
     }
 
     auto traits = obj->get_traits();
-    if (request->hasParam(ESPHOME_F("position")) && !traits.get_supports_position()) {
+    if (request->hasArg(ESPHOME_F("position")) && !traits.get_supports_position()) {
       request->send(409);
       return;
     }
 
-    parse_float_param_(request, ESPHOME_F("position"), call, &decltype(call)::set_position);
+    parse_num_param_(request, ESPHOME_F("position"), call, &decltype(call)::set_position);
 
     DEFER_ACTION(call, call.perform());
     request->send(200);
@@ -1870,12 +1878,12 @@ void WebServer::handle_water_heater_request(AsyncWebServerRequest *request, cons
     parse_string_param_(request, ESPHOME_F("mode"), base_call, &water_heater::WaterHeaterCall::set_mode);
 
     // Parse temperature parameters
-    parse_float_param_(request, ESPHOME_F("target_temperature"), base_call,
-                       &water_heater::WaterHeaterCall::set_target_temperature);
-    parse_float_param_(request, ESPHOME_F("target_temperature_low"), base_call,
-                       &water_heater::WaterHeaterCall::set_target_temperature_low);
-    parse_float_param_(request, ESPHOME_F("target_temperature_high"), base_call,
-                       &water_heater::WaterHeaterCall::set_target_temperature_high);
+    parse_num_param_(request, ESPHOME_F("target_temperature"), base_call,
+                     &water_heater::WaterHeaterCall::set_target_temperature);
+    parse_num_param_(request, ESPHOME_F("target_temperature_low"), base_call,
+                     &water_heater::WaterHeaterCall::set_target_temperature_low);
+    parse_num_param_(request, ESPHOME_F("target_temperature_high"), base_call,
+                     &water_heater::WaterHeaterCall::set_target_temperature_high);
 
     // Parse away mode parameter
     parse_bool_param_(request, ESPHOME_F("away"), base_call, &water_heater::WaterHeaterCall::set_away);
@@ -1979,16 +1987,16 @@ void WebServer::handle_infrared_request(AsyncWebServerRequest *request, const Ur
     auto call = obj->make_call();
 
     // Parse carrier frequency (optional)
-    if (request->hasParam(ESPHOME_F("carrier_frequency"))) {
-      auto value = parse_number<uint32_t>(request->getParam(ESPHOME_F("carrier_frequency"))->value().c_str());
+    {
+      auto value = parse_number<uint32_t>(request->arg(ESPHOME_F("carrier_frequency")).c_str());
       if (value.has_value()) {
         call.set_carrier_frequency(*value);
       }
     }
 
     // Parse repeat count (optional, defaults to 1)
-    if (request->hasParam(ESPHOME_F("repeat_count"))) {
-      auto value = parse_number<uint32_t>(request->getParam(ESPHOME_F("repeat_count"))->value().c_str());
+    {
+      auto value = parse_number<uint32_t>(request->arg(ESPHOME_F("repeat_count")).c_str());
       if (value.has_value()) {
         call.set_repeat_count(*value);
       }
@@ -1996,18 +2004,12 @@ void WebServer::handle_infrared_request(AsyncWebServerRequest *request, const Ur
 
     // Parse base64url-encoded raw timings (required)
     // Base64url is URL-safe: uses A-Za-z0-9-_ (no special characters needing escaping)
-    if (!request->hasParam(ESPHOME_F("data"))) {
-      request->send(400, ESPHOME_F("text/plain"), ESPHOME_F("Missing 'data' parameter"));
-      return;
-    }
+    const auto &data_arg = request->arg(ESPHOME_F("data"));
 
-    // .c_str() is required for Arduino framework where value() returns Arduino String instead of std::string
-    std::string encoded =
-        request->getParam(ESPHOME_F("data"))->value().c_str();  // NOLINT(readability-redundant-string-cstr)
-
-    // Validate base64url is not empty
-    if (encoded.empty()) {
-      request->send(400, ESPHOME_F("text/plain"), ESPHOME_F("Empty 'data' parameter"));
+    // Validate base64url is not empty (also catches missing parameter since arg() returns empty string)
+    // Arduino String has isEmpty() not empty(), use length() for cross-platform compatibility
+    if (data_arg.length() == 0) {  // NOLINT(readability-container-size-empty)
+      request->send(400, ESPHOME_F("text/plain"), ESPHOME_F("Missing or empty 'data' parameter"));
       return;
     }
 
@@ -2015,7 +2017,7 @@ void WebServer::handle_infrared_request(AsyncWebServerRequest *request, const Ur
     // it outlives the call - set_raw_timings_base64url stores a pointer, so the string
     // must remain valid until perform() completes.
     // ESP8266 also needs this because ESPAsyncWebServer callbacks run in "sys" context.
-    this->defer([call, encoded = std::move(encoded)]() mutable {
+    this->defer([call, encoded = std::string(data_arg.c_str(), data_arg.length())]() mutable {
       call.set_raw_timings_base64url(encoded);
       call.perform();
     });

esphome/components/web_server/web_server.h

@@ -513,11 +513,9 @@ class WebServer : public Controller,
   template<typename T, typename Ret>
   void parse_light_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call, Ret (T::*setter)(float),
                           float scale = 1.0f) {
-    if (request->hasParam(param_name)) {
-      auto value = parse_number<float>(request->getParam(param_name)->value().c_str());
-      if (value.has_value()) {
-        (call.*setter)(*value / scale);
-      }
+    auto value = parse_number<float>(request->arg(param_name).c_str());
+    if (value.has_value()) {
+      (call.*setter)(*value / scale);
     }
   }
 
@@ -525,34 +523,19 @@ class WebServer : public Controller,
   template<typename T, typename Ret>
   void parse_light_param_uint_(AsyncWebServerRequest *request, ParamNameType param_name, T &call,
                                Ret (T::*setter)(uint32_t), uint32_t scale = 1) {
-    if (request->hasParam(param_name)) {
-      auto value = parse_number<uint32_t>(request->getParam(param_name)->value().c_str());
-      if (value.has_value()) {
-        (call.*setter)(*value * scale);
-      }
+    auto value = parse_number<uint32_t>(request->arg(param_name).c_str());
+    if (value.has_value()) {
+      (call.*setter)(*value * scale);
     }
   }
 #endif
 
-  // Generic helper to parse and apply a float parameter
-  template<typename T, typename Ret>
-  void parse_float_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call, Ret (T::*setter)(float)) {
-    if (request->hasParam(param_name)) {
-      auto value = parse_number<float>(request->getParam(param_name)->value().c_str());
-      if (value.has_value()) {
-        (call.*setter)(*value);
-      }
-    }
-  }
-
-  // Generic helper to parse and apply an int parameter
-  template<typename T, typename Ret>
-  void parse_int_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call, Ret (T::*setter)(int)) {
-    if (request->hasParam(param_name)) {
-      auto value = parse_number<int>(request->getParam(param_name)->value().c_str());
-      if (value.has_value()) {
-        (call.*setter)(*value);
-      }
+  // Generic helper to parse and apply a numeric parameter
+  template<typename NumT, typename T, typename Ret>
+  void parse_num_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call, Ret (T::*setter)(NumT)) {
+    auto value = parse_number<NumT>(request->arg(param_name).c_str());
+    if (value.has_value()) {
+      (call.*setter)(*value);
     }
   }
 
@@ -560,10 +543,9 @@ class WebServer : public Controller,
   template<typename T, typename Ret>
   void parse_string_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call,
                            Ret (T::*setter)(const std::string &)) {
-    if (request->hasParam(param_name)) {
-      // .c_str() is required for Arduino framework where value() returns Arduino String instead of std::string
-      std::string value = request->getParam(param_name)->value().c_str();  // NOLINT(readability-redundant-string-cstr)
-      (call.*setter)(value);
+    if (request->hasArg(param_name)) {
+      const auto &value = request->arg(param_name);
+      (call.*setter)(std::string(value.c_str(), value.length()));
     }
   }
 
@@ -573,8 +555,9 @@ class WebServer : public Controller,
   // Invalid values are ignored (setter not called)
   template<typename T, typename Ret>
   void parse_bool_param_(AsyncWebServerRequest *request, ParamNameType param_name, T &call, Ret (T::*setter)(bool)) {
-    if (request->hasParam(param_name)) {
-      auto param_value = request->getParam(param_name)->value();
+    const auto &param_value = request->arg(param_name);
+    // Arduino String has isEmpty() not empty(), use length() for cross-platform compatibility
+    if (param_value.length() > 0) {  // NOLINT(readability-container-size-empty)
       // First check on/off (default), then true/false (custom)
       auto val = parse_on_off(param_value.c_str());
       if (val == PARSE_NONE) {

esphome/components/web_server_idf/utils.cpp

@@ -1,17 +1,13 @@
 #ifdef USE_ESP32
-#include <memory>
 #include <cstring>
 #include <cctype>
 #include "esphome/core/helpers.h"
-#include "esphome/core/log.h"
 #include "http_parser.h"
 
 #include "utils.h"
 
 namespace esphome::web_server_idf {
 
-static const char *const TAG = "web_server_idf_utils";
-
 size_t url_decode(char *str) {
   char *start = str;
   char *ptr = str, buf;
@@ -54,32 +50,15 @@ optional<std::string> request_get_header(httpd_req_t *req, const char *name) {
   return {str};
 }
 
-optional<std::string> request_get_url_query(httpd_req_t *req) {
-  auto len = httpd_req_get_url_query_len(req);
-  if (len == 0) {
-    return {};
-  }
-
-  std::string str;
-  str.resize(len);
-
-  auto res = httpd_req_get_url_query_str(req, &str[0], len + 1);
-  if (res != ESP_OK) {
-    ESP_LOGW(TAG, "Can't get query for request: %s", esp_err_to_name(res));
-    return {};
-  }
-
-  return {str};
-}
-
 optional<std::string> query_key_value(const char *query_url, size_t query_len, const char *key) {
   if (query_url == nullptr || query_len == 0) {
     return {};
   }
 
-  // Use stack buffer for typical query strings, heap fallback for large ones
-  SmallBufferWithHeapFallback<256, char> val(query_len);
-
+  // Value can't exceed query_len. Use small stack buffer for typical values,
+  // heap fallback for long ones (e.g. base64 IR data) to limit stack usage
+  // since callers may also have stack buffers for the query string.
+  SmallBufferWithHeapFallback<128, char> val(query_len);
   if (httpd_query_key_value(query_url, key, val.get(), query_len) != ESP_OK) {
     return {};
   }
@@ -88,6 +67,18 @@ optional<std::string> query_key_value(const char *query_url, size_t query_len, c
   return {val.get()};
 }
 
+bool query_has_key(const char *query_url, size_t query_len, const char *key) {
+  if (query_url == nullptr || query_len == 0) {
+    return false;
+  }
+  // Minimal buffer — we only care if the key exists, not the value
+  char buf[1];
+  // httpd_query_key_value returns ESP_OK if found, ESP_ERR_HTTPD_RESULT_TRUNC if found
+  // but value truncated (expected with 1-byte buffer), or other errors for invalid input
+  auto err = httpd_query_key_value(query_url, key, buf, sizeof(buf));
+  return err == ESP_OK || err == ESP_ERR_HTTPD_RESULT_TRUNC;
+}
+
 // Helper function for case-insensitive string region comparison
 bool str_ncmp_ci(const char *s1, const char *s2, size_t n) {
   for (size_t i = 0; i < n; i++) {

esphome/components/web_server_idf/utils.h

@@ -13,11 +13,8 @@ size_t url_decode(char *str);
 
 bool request_has_header(httpd_req_t *req, const char *name);
 optional<std::string> request_get_header(httpd_req_t *req, const char *name);
-optional<std::string> request_get_url_query(httpd_req_t *req);
 optional<std::string> query_key_value(const char *query_url, size_t query_len, const char *key);
-inline optional<std::string> query_key_value(const std::string &query_url, const std::string &key) {
-  return query_key_value(query_url.c_str(), query_url.size(), key.c_str());
-}
+bool query_has_key(const char *query_url, size_t query_len, const char *key);
 
 // Helper function for case-insensitive character comparison
 inline bool char_equals_ci(char a, char b) { return ::tolower(a) == ::tolower(b); }

esphome/components/web_server_idf/web_server_idf.cpp

@@ -393,13 +393,7 @@ AsyncWebParameter *AsyncWebServerRequest::getParam(const char *name) {
   }
 
   // Look up value from query strings
-  optional<std::string> val = query_key_value(this->post_query_.c_str(), this->post_query_.size(), name);
-  if (!val.has_value()) {
-    auto url_query = request_get_url_query(*this);
-    if (url_query.has_value()) {
-      val = query_key_value(url_query.value().c_str(), url_query.value().size(), name);
-    }
-  }
+  auto val = this->find_query_value_(name);
 
   // Don't cache misses to avoid wasting memory when handlers check for
   // optional parameters that don't exist in the request
@@ -412,6 +406,50 @@ AsyncWebParameter *AsyncWebServerRequest::getParam(const char *name) {
   return param;
 }
 
+/// Search post_query then URL query with a callback.
+/// Returns first truthy result, or value-initialized default.
+/// URL query is accessed directly from req->uri (same pattern as url_to()).
+template<typename Func>
+static auto search_query_sources(httpd_req_t *req, const std::string &post_query, const char *name, Func func)
+    -> decltype(func(nullptr, size_t{0}, name)) {
+  if (!post_query.empty()) {
+    auto result = func(post_query.c_str(), post_query.size(), name);
+    if (result) {
+      return result;
+    }
+  }
+  // Use httpd API for query length, then access string directly from URI.
+  // http_parser identifies components by offset/length without modifying the URI string.
+  // This is the same pattern used by url_to().
+  auto len = httpd_req_get_url_query_len(req);
+  if (len == 0) {
+    return {};
+  }
+  const char *query = strchr(req->uri, '?');
+  if (query == nullptr) {
+    return {};
+  }
+  query++;  // skip '?'
+  return func(query, len, name);
+}
+
+optional<std::string> AsyncWebServerRequest::find_query_value_(const char *name) const {
+  return search_query_sources(this->req_, this->post_query_, name,
+                              [](const char *q, size_t len, const char *k) { return query_key_value(q, len, k); });
+}
+
+bool AsyncWebServerRequest::hasArg(const char *name) {
+  return search_query_sources(this->req_, this->post_query_, name, query_has_key);
+}
+
+std::string AsyncWebServerRequest::arg(const char *name) {
+  auto val = this->find_query_value_(name);
+  if (val.has_value()) {
+    return std::move(val.value());
+  }
+  return {};
+}
+
 void AsyncWebServerResponse::addHeader(const char *name, const char *value) {
   httpd_resp_set_hdr(*this->req_, name, value);
 }

esphome/components/web_server_idf/web_server_idf.h

@@ -116,7 +116,8 @@ class AsyncWebServerRequest {
   /// Write URL (without query string) to buffer, returns StringRef pointing to buffer.
   /// URL is decoded (e.g., %20 -> space).
   StringRef url_to(std::span<char, URL_BUF_SIZE> buffer) const;
-  /// Get URL as std::string. Prefer url_to() to avoid heap allocation.
+  // Remove before 2026.9.0
+  ESPDEPRECATED("Use url_to() instead. Removed in 2026.9.0", "2026.3.0")
   std::string url() const {
     char buffer[URL_BUF_SIZE];
     return std::string(this->url_to(buffer));
@@ -170,14 +171,8 @@ class AsyncWebServerRequest {
   AsyncWebParameter *getParam(const std::string &name) { return this->getParam(name.c_str()); }
 
   // NOLINTNEXTLINE(readability-identifier-naming)
-  bool hasArg(const char *name) { return this->hasParam(name); }
-  std::string arg(const char *name) {
-    auto *param = this->getParam(name);
-    if (param) {
-      return param->value();
-    }
-    return {};
-  }
+  bool hasArg(const char *name);
+  std::string arg(const char *name);
   std::string arg(const std::string &name) { return this->arg(name.c_str()); }
 
   operator httpd_req_t *() const { return this->req_; }
@@ -192,6 +187,7 @@ class AsyncWebServerRequest {
   // is faster than tree/hash overhead. AsyncWebParameter stores both name and value to avoid
   // duplicate storage. Only successful lookups are cached to prevent cache pollution when
   // handlers check for optional parameters that don't exist.
+  optional<std::string> find_query_value_(const char *name) const;
   std::vector<AsyncWebParameter *> params_;
   std::string post_query_;
   AsyncWebServerRequest(httpd_req_t *req) : req_(req) {}

esphome/components/wifi/wifi_component.cpp

@@ -3,6 +3,7 @@
 #include <cassert>
 #include <cinttypes>
 #include <cmath>
+#include <type_traits>
 
 #ifdef USE_ESP32
 #if (ESP_IDF_VERSION_MAJOR >= 5 && ESP_IDF_VERSION_MINOR >= 1)
@@ -1319,20 +1320,61 @@ void WiFiComponent::start_scanning() {
 // Using insertion sort instead of std::stable_sort saves flash memory
 // by avoiding template instantiations (std::rotate, std::stable_sort, lambdas)
 // IMPORTANT: This sort is stable (preserves relative order of equal elements)
+//
+// Uses raw memcpy instead of copy assignment to avoid CompactString's
+// destructor/constructor overhead (heap delete[]/new[] for long SSIDs).
+// Copy assignment calls ~CompactString() then placement-new for every shift,
+// which means delete[]/new[] per shift for heap-allocated SSIDs. With 70+
+// networks (e.g., captive portal showing full scan results), this caused
+// event loop blocking from hundreds of heap operations in a tight loop.
+//
+// This is safe because we're permuting elements within the same array —
+// each slot is overwritten exactly once, so no ownership duplication occurs.
+// All members of WiFiScanResult are either trivially copyable (bssid, channel,
+// rssi, priority, flags) or CompactString, which stores either inline data or
+// a heap pointer — never a self-referential pointer (unlike std::string's SSO
+// on some implementations). This was not possible before PR#13472 replaced
+// std::string with CompactString, since std::string's internal layout is
+// implementation-defined and may use self-referential pointers.
+//
+// TODO: If C++ standardizes std::trivially_relocatable, add the assertion for
+// WiFiScanResult/CompactString here to formally express the memcpy safety guarantee.
 template<typename VectorType> static void insertion_sort_scan_results(VectorType &results) {
+  // memcpy-based sort requires no self-referential pointers or virtual dispatch.
+  // These static_asserts guard the assumptions. If any fire, the memcpy sort
+  // must be reviewed for safety before updating the expected values.
+  //
+  // No vtable pointers (memcpy would corrupt vptr)
+  static_assert(!std::is_polymorphic<WiFiScanResult>::value, "WiFiScanResult must not have vtable");
+  static_assert(!std::is_polymorphic<CompactString>::value, "CompactString must not have vtable");
+  // Standard layout ensures predictable memory layout with no virtual bases
+  // and no mixed-access-specifier reordering
+  static_assert(std::is_standard_layout<WiFiScanResult>::value, "WiFiScanResult must be standard layout");
+  static_assert(std::is_standard_layout<CompactString>::value, "CompactString must be standard layout");
+  // Size checks catch added/removed fields that may need safety review
+  static_assert(sizeof(WiFiScanResult) == 32, "WiFiScanResult size changed - verify memcpy sort is still safe");
+  static_assert(sizeof(CompactString) == 20, "CompactString size changed - verify memcpy sort is still safe");
+  // Alignment must match for reinterpret_cast of key_buf to be valid
+  static_assert(alignof(WiFiScanResult) <= alignof(std::max_align_t), "WiFiScanResult alignment exceeds max_align_t");
   const size_t size = results.size();
+  constexpr size_t elem_size = sizeof(WiFiScanResult);
+  // Suppress warnings for intentional memcpy on non-trivially-copyable type.
+  // Safety is guaranteed by the static_asserts above and the permutation invariant.
+  // NOLINTNEXTLINE(bugprone-undefined-memory-manipulation)
+  auto *memcpy_fn = &memcpy;
   for (size_t i = 1; i < size; i++) {
-    // Make a copy to avoid issues with move semantics during comparison
-    WiFiScanResult key = results[i];
+    alignas(WiFiScanResult) uint8_t key_buf[elem_size];
+    memcpy_fn(key_buf, &results[i], elem_size);
+    const auto &key = *reinterpret_cast<const WiFiScanResult *>(key_buf);
     int32_t j = i - 1;
 
     // Move elements that are worse than key to the right
     // For stability, we only move if key is strictly better than results[j]
     while (j >= 0 && wifi_scan_result_is_better(key, results[j])) {
-      results[j + 1] = results[j];
+      memcpy_fn(&results[j + 1], &results[j], elem_size);
       j--;
     }
-    results[j + 1] = key;
+    memcpy_fn(&results[j + 1], key_buf, elem_size);
   }
 }
 

esphome/components/wifi/wifi_component.h

@@ -10,6 +10,7 @@
 
 #include <span>
 #include <string>
+#include <type_traits>
 #include <vector>
 
 #ifdef USE_LIBRETINY
@@ -219,6 +220,14 @@ class CompactString {
 };
 
 static_assert(sizeof(CompactString) == 20, "CompactString must be exactly 20 bytes");
+// CompactString is not trivially copyable (non-trivial destructor/copy for heap case).
+// However, its layout has no self-referential pointers: storage_[] contains either inline
+// data or an external heap pointer — never a pointer to itself. This is unlike libstdc++
+// std::string SSO where _M_p points to _M_local_buf within the same object.
+// This property allows memcpy-based permutation sorting where each element ends up in
+// exactly one slot (no ownership duplication). These asserts document that layout property.
+static_assert(std::is_standard_layout<CompactString>::value, "CompactString must be standard layout");
+static_assert(!std::is_polymorphic<CompactString>::value, "CompactString must not have vtable");
 
 class WiFiAP {
   friend class WiFiComponent;
@@ -502,6 +511,8 @@ class WiFiComponent : public Component {
   }
 
   network::IPAddresses wifi_sta_ip_addresses();
+  // Remove before 2026.9.0
+  ESPDEPRECATED("Use wifi_ssid_to() instead. Removed in 2026.9.0", "2026.3.0")
   std::string wifi_ssid();
   /// Write SSID to buffer without heap allocation.
   /// Returns pointer to buffer, or empty string if not connected.

esphome/const.py

@@ -4,7 +4,7 @@ from enum import Enum
 
 from esphome.enum import StrEnum
 
-__version__ = "2026.2.0b2"
+__version__ = "2026.3.0-dev"
 
 ALLOWED_NAME_CHARS = "abcdefghijklmnopqrstuvwxyz0123456789-_"
 VALID_SUBSTITUTIONS_CHARACTERS = (

esphome/core/helpers.h

@@ -1083,6 +1083,9 @@ template<std::size_t N> std::string format_hex(const std::array<uint8_t, N> &dat
  * Each byte is displayed as a two-digit uppercase hex value, separated by the specified separator.
  * Optionally includes the total byte count in parentheses at the end.
  *
+ * @warning Allocates heap memory. Use format_hex_pretty_to() with a stack buffer instead.
+ * Causes heap fragmentation on long-running devices.
+ *
  * @param data Pointer to the byte array to format.
  * @param length Number of bytes in the array.
  * @param separator Character to use between hex bytes (default: '.').
@@ -1108,6 +1111,9 @@ std::string format_hex_pretty(const uint8_t *data, size_t length, char separator
  *
  * Similar to the byte array version, but formats 16-bit words as 4-digit hex values.
  *
+ * @warning Allocates heap memory. Use format_hex_pretty_to() with a stack buffer instead.
+ * Causes heap fragmentation on long-running devices.
+ *
  * @param data Pointer to the 16-bit word array to format.
  * @param length Number of 16-bit words in the array.
  * @param separator Character to use between hex words (default: '.').
@@ -1131,6 +1137,9 @@ std::string format_hex_pretty(const uint16_t *data, size_t length, char separato
  * Convenience overload for std::vector<uint8_t>. Formats each byte as a two-digit
  * uppercase hex value with customizable separator.
  *
+ * @warning Allocates heap memory. Use format_hex_pretty_to() with a stack buffer instead.
+ * Causes heap fragmentation on long-running devices.
+ *
  * @param data Vector of bytes to format.
  * @param separator Character to use between hex bytes (default: '.').
  * @param show_length Whether to append the byte count in parentheses (default: true).
@@ -1154,6 +1163,9 @@ std::string format_hex_pretty(const std::vector<uint8_t> &data, char separator =
  * Convenience overload for std::vector<uint16_t>. Each 16-bit word is formatted
  * as a 4-digit uppercase hex value in big-endian order.
  *
+ * @warning Allocates heap memory. Use format_hex_pretty_to() with a stack buffer instead.
+ * Causes heap fragmentation on long-running devices.
+ *
  * @param data Vector of 16-bit words to format.
  * @param separator Character to use between hex words (default: '.').
  * @param show_length Whether to append the word count in parentheses (default: true).
@@ -1176,6 +1188,9 @@ std::string format_hex_pretty(const std::vector<uint16_t> &data, char separator
  * Treats each character in the string as a byte and formats it in hex.
  * Useful for debugging binary data stored in std::string containers.
  *
+ * @warning Allocates heap memory. Use format_hex_pretty_to() with a stack buffer instead.
+ * Causes heap fragmentation on long-running devices.
+ *
  * @param data String whose bytes should be formatted as hex.
  * @param separator Character to use between hex bytes (default: '.').
  * @param show_length Whether to append the byte count in parentheses (default: true).
@@ -1198,6 +1213,9 @@ std::string format_hex_pretty(const std::string &data, char separator = '.', boo
  * Converts the integer to big-endian byte order and formats each byte as hex.
  * The most significant byte appears first in the output string.
  *
+ * @warning Allocates heap memory. Use format_hex_pretty_to() with a stack buffer instead.
+ * Causes heap fragmentation on long-running devices.
+ *
  * @tparam T Unsigned integer type (uint8_t, uint16_t, uint32_t, uint64_t, etc.).
  * @param val The unsigned integer value to format.
  * @param separator Character to use between hex bytes (default: '.').

tests/components/mipi_spi/common.yaml

@@ -3,9 +3,15 @@ display:
     spi_16: true
     pixel_mode: 18bit
     model: ili9488
-    dc_pin: ${dc_pin}
-    cs_pin: ${cs_pin}
-    reset_pin: ${reset_pin}
+    dc_pin:
+      allow_other_uses: true
+      number: ${dc_pin}
+    cs_pin:
+      allow_other_uses: true
+      number: ${cs_pin}
+    reset_pin:
+      allow_other_uses: true
+      number: ${reset_pin}
     data_rate: 20MHz
     invert_colors: true
     show_test_card: true
@@ -24,3 +30,15 @@ display:
       height: 200
     enable_pin: ${enable_pin}
     bus_mode: single
+
+  - platform: mipi_spi
+    model: WAVESHARE-1.83-V2
+    dc_pin:
+      allow_other_uses: true
+      number: ${dc_pin}
+    cs_pin:
+      allow_other_uses: true
+      number: ${cs_pin}
+    reset_pin:
+      allow_other_uses: true
+      number: ${reset_pin}

tests/integration/test_alarm_control_panel_state_transitions.py

@@ -270,14 +270,6 @@ async def test_alarm_control_panel_state_transitions(
         # The chime_sensor has chime: true, so opening it while disarmed
         # should trigger on_chime callback
 
-        # Set up future for the on_ready from opening the chime sensor
-        # (alarm becomes "not ready" when chime sensor opens).
-        # We must wait for this BEFORE creating the close future, otherwise
-        # the open event's log can arrive late and resolve the close future,
-        # causing the test to proceed before the chime close is processed.
-        ready_after_chime_open: asyncio.Future[bool] = loop.create_future()
-        ready_futures.append(ready_after_chime_open)
-
         # We're currently DISARMED - open the chime sensor
         client.switch_command(chime_switch_info.key, True)
 
@@ -287,18 +279,11 @@ async def test_alarm_control_panel_state_transitions(
         except TimeoutError:
             pytest.fail(f"on_chime callback not fired. Log lines: {log_lines[-20:]}")
 
-        # Wait for the on_ready from the chime sensor opening
-        try:
-            await asyncio.wait_for(ready_after_chime_open, timeout=2.0)
-        except TimeoutError:
-            pytest.fail(
-                f"on_ready callback not fired when chime sensor opened. "
-                f"Log lines: {log_lines[-20:]}"
-            )
-
-        # Now create the future for the close event and close the sensor.
-        # Since we waited for the open event above, the close event's
-        # on_ready log cannot be confused with the open event's.
+        # Close the chime sensor and wait for alarm to become ready again
+        # We need to wait for this transition before testing door sensor,
+        # otherwise there's a race where the door sensor state change could
+        # arrive before the chime sensor state change, leaving the alarm in
+        # a continuous "not ready" state with no on_ready callback fired.
         ready_after_chime_close: asyncio.Future[bool] = loop.create_future()
         ready_futures.append(ready_after_chime_close)