[esphome.ota] Move OTA wake pointer out of Application into ota_esphome.cpp

Following the zephyr_mcumgr precedent, keep the single-instance pointer
as a file-scope static inside ota_esphome.cpp instead of plumbing an
ota_wake_component_ slot and setter through Application. The extern "C"
wake trampoline also lives in the same TU now, so nothing in core/
touches OTA-specific state.

Guard the C and C++ call sites on USE_OTA_PLATFORM_ESPHOME (added as a
-D flag from components/esphome/ota/__init__.py) instead of the broader
ESPHOME_USE_OTA that base ota/ used to emit — the trampoline symbol only
exists when the esphome OTA platform is actually compiled in.

Also drop the dead host yield_with_select_ wake hook (host has no OTA
platform today).

esphome/components/esphome/ota/__init__.py

@@ -155,6 +155,10 @@ async def to_code(config: ConfigType) -> None:
         cg.add(var.set_auth_password(config[CONF_PASSWORD]))
         cg.add_define("USE_OTA_PASSWORD")
     cg.add_define("USE_OTA_VERSION", config[CONF_VERSION])
+    # Build flag (not a define in defines.h) so lwip_fast_select.c — a .c file that
+    # can't include defines.h — can still gate its wake hook on the esphome OTA
+    # platform being compiled in.
+    cg.add_build_flag("-DUSE_OTA_PLATFORM_ESPHOME")
 
     await cg.register_component(var, config)
     await ota_to_code(var, config)

esphome/components/esphome/ota/ota_esphome.cpp

@@ -31,6 +31,22 @@ static constexpr size_t OTA_BUFFER_SIZE = 1024;                  // buffer size
 static constexpr uint32_t OTA_SOCKET_TIMEOUT_HANDSHAKE = 20000;  // milliseconds for initial handshake
 static constexpr uint32_t OTA_SOCKET_TIMEOUT_DATA = 90000;       // milliseconds for data transfer
 
+// File-scope pointer to the single ESPHomeOTAComponent instance. The final_validate in
+// __init__.py rejects multi-port configs, so only one exists. Set in setup() and used
+// by the extern "C" wake trampoline below, which is called from socket wake paths
+// (lwip_fast_select listener filter, raw-TCP accept_fn_).
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+static ESPHomeOTAComponent *global_esphome_ota_component = nullptr;
+
+// Trampoline called from C and C++ socket wake paths. Must be safe from any context
+// (LwIP TCP/IP task, user-level IRQ on RP2040). enable_loop_soon_any_context() uses
+// volatile flags only — no locks, no allocations.
+extern "C" void esphome_wake_ota_component_any_context() {
+  if (global_esphome_ota_component != nullptr) {
+    global_esphome_ota_component->enable_loop_soon_any_context();
+  }
+}
+
 void ESPHomeOTAComponent::setup() {
   this->server_ = socket::socket_ip_loop_monitored(SOCK_STREAM, 0).release();  // monitored for incoming connections
   if (this->server_ == nullptr) {
@@ -70,7 +86,7 @@ void ESPHomeOTAComponent::setup() {
   }
 
   // loop() self-disables on its first idle tick; no explicit disable_loop() needed here.
-  App.set_ota_wake_component(this);
+  global_esphome_ota_component = this;
 #ifdef USE_LWIP_FAST_SELECT
   // Filter fast-select wakes to this listener only. If the sock lookup returns nullptr,
   // no wakes fire and loop() falls back to the self-disable safety net.

esphome/components/ota/__init__.py

@@ -103,9 +103,6 @@ BASE_OTA_SCHEMA = cv.Schema(
 @coroutine_with_priority(CoroPriority.OTA_UPDATES)
 async def to_code(config):
     cg.add_define("USE_OTA")
-    # Separate -D flag so .c files can see it — .c can't include defines.h (macros.h
-    # pulls in Arduino.h). Different name avoids USE_OTA redefinition warnings.
-    cg.add_build_flag("-DESPHOME_USE_OTA")
     CORE.add_job(final_step)
 
     if CORE.is_rp2040 and CORE.using_arduino:

esphome/components/socket/lwip_raw_tcp_impl.cpp

@@ -10,8 +10,11 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/wake.h"
 #include "esphome/core/log.h"
-#ifdef USE_OTA
-#include "esphome/core/application.h"
+
+#ifdef USE_OTA_PLATFORM_ESPHOME
+// Defined in components/esphome/ota/ota_esphome.cpp. Marks the ESPHome OTA component
+// pending-enable from the raw-TCP accept callback (per-pcb, implicitly filtered).
+extern "C" void esphome_wake_ota_component_any_context();
 #endif
 
 #ifdef USE_ESP8266
@@ -857,10 +860,11 @@ err_t LWIPRawListenImpl::accept_fn_(struct tcp_pcb *newpcb, err_t err) {
   tcp_err(newpcb, LWIPRawListenImpl::s_queued_err_fn);
   tcp_recv(newpcb, LWIPRawListenImpl::s_queued_recv_fn);
   LWIP_LOG("Accepted connection, queue size: %d", this->accepted_socket_count_);
-#ifdef USE_OTA
+#ifdef USE_OTA_PLATFORM_ESPHOME
   // Mark OTA pending-enable before the wake below — flags must be visible before the
-  // main task runs. accept_fn_ is per-pcb, so filtering is implicit here.
-  esphome::App.wake_ota_component_any_context();
+  // main task runs. accept_fn_ is per-pcb, so filtering is implicit here (only fires
+  // for completed handshakes to whichever listener owns newpcb).
+  esphome_wake_ota_component_any_context();
 #endif
   // Wake the main loop immediately so it can accept the new connection.
   esphome::wake_loop_any_context();

esphome/core/application.cpp

@@ -449,11 +449,6 @@ void Application::enable_pending_loops_() {
   }
 }
 
-#if defined(USE_OTA) && defined(USE_LWIP_FAST_SELECT)
-// C trampoline called from lwip_fast_select.c when the listener filter matches.
-extern "C" void esphome_wake_ota_component_any_context() { App.wake_ota_component_any_context(); }
-#endif
-
 #ifdef USE_LWIP_FAST_SELECT
 bool Application::register_socket(struct lwip_sock *sock) {
   // It modifies monitored_sockets_ without locking — must only be called from the main loop.
@@ -559,12 +554,6 @@ void Application::yield_with_select_(uint32_t delay_ms) {
     // ret > 0: socket(s) have data ready - normal and expected
     // ret == 0: timeout occurred - normal and expected
     if (ret >= 0) [[likely]] {
-#ifdef USE_OTA
-      // No-op today — host has no esphome OTA platform, so ota_wake_component_ is null.
-      if (ret > 0) {
-        this->wake_ota_component_any_context();
-      }
-#endif
       // Yield if zero timeout since select(0) only polls without yielding
       if (delay_ms == 0) [[unlikely]] {
         yield();

esphome/core/application.h

@@ -559,18 +559,6 @@ class Application {
   /// Wake from any context (ISR, thread, callback).
   static void IRAM_ATTR wake_loop_any_context() { esphome::wake_loop_any_context(); }
 
-#ifdef USE_OTA
-  void set_ota_wake_component(Component *component) { this->ota_wake_component_ = component; }
-  // Marks OTA pending-enable from socket wake paths. Does NOT wake the main task —
-  // every caller already does. Callable from LwIP TCP/IP task and user-IRQ context.
-  void wake_ota_component_any_context() {
-    if (this->ota_wake_component_ != nullptr) {
-      this->ota_wake_component_->pending_enable_loop_ = true;
-      this->has_pending_enable_loop_requests_ = true;
-    }
-  }
-#endif
-
  protected:
   friend Component;
 #ifdef USE_HOST
@@ -646,9 +634,6 @@ class Application {
 
   // Pointer-sized members first
   Component *current_component_{nullptr};
-#ifdef USE_OTA
-  Component *ota_wake_component_{nullptr};
-#endif
 
   // std::vector (3 pointers each: begin, end, capacity)
   // Partitioned vector design for looping components

esphome/core/lwip_fast_select.c

@@ -157,11 +157,12 @@ _Static_assert(offsetof(struct lwip_sock, rcvevent) == ESPHOME_LWIP_SOCK_RCVEVEN
 // Saved original event_callback pointer — written once in first hook_socket(), read from TCP/IP task.
 static netconn_callback s_original_callback = NULL;
 
-#ifdef ESPHOME_USE_OTA
-// ESPHOME_USE_OTA (not USE_OTA): this .c file can't include defines.h — macros.h →
-// Arduino.h would break the C compile. ota/__init__.py emits -DESPHOME_USE_OTA.
+#ifdef USE_OTA_PLATFORM_ESPHOME
+// This .c file can't include defines.h — macros.h → Arduino.h would break the C
+// compile. esphome/ota/__init__.py emits -DUSE_OTA_PLATFORM_ESPHOME via
+// cg.add_build_flag so both this TU and C++ call sites can see the same name.
 static struct netconn *s_ota_listener_conn = NULL;
-extern void esphome_wake_ota_component_any_context(void);  // trampoline in application.cpp
+extern void esphome_wake_ota_component_any_context(void);  // defined in ota_esphome.cpp
 
 void esphome_fast_select_set_ota_listener_sock(struct lwip_sock *sock) {
   s_ota_listener_conn = (sock != NULL) ? sock->conn : NULL;
@@ -184,7 +185,7 @@ static void esphome_socket_event_callback(struct netconn *conn, enum netconn_evt
   // (rcvevent++ with a NULL pbuf or error in recvmbox), so error conditions
   // already wake the main loop through the RCVPLUS path.
   if (evt == NETCONN_EVT_RCVPLUS) {
-#ifdef ESPHOME_USE_OTA
+#ifdef USE_OTA_PLATFORM_ESPHOME
     // Mark OTA pending-enable only for events on its listen socket. MUST happen
     // before xTaskNotifyGive so the flags are visible when the main task wakes.
     if (conn == s_ota_listener_conn) {