diff --git a/esphome/components/esp32/core.cpp b/esphome/components/esp32/core.cpp
index 4886745c06..5249f4a59e 100644
--- a/esphome/components/esp32/core.cpp
+++ b/esphome/components/esp32/core.cpp
@@ -1,17 +1,8 @@
 #ifdef USE_ESP32
 
-#include "esphome/core/defines.h"
-#include "crash_handler.h"
 #include "esphome/core/application.h"
-#include "esphome/core/hal.h"
-#include "esphome/core/helpers.h"
+#include "esphome/core/defines.h"
 #include "preferences.h"
-#include <esp_clk_tree.h>
-#include <esp_cpu.h>
-#include <esp_idf_version.h>
-#include <esp_ota_ops.h>
-#include <esp_task_wdt.h>
-#include <esp_timer.h>
 #include <freertos/FreeRTOS.h>
 #include <freertos/task.h>
 
@@ -22,54 +13,7 @@ extern "C" __attribute__((weak)) void initArduino() {}
 
 namespace esphome {
 
-// yield(), delay(), micros(), millis_64() inlined in hal.h.
-// Use xTaskGetTickCount() when tick rate is 1 kHz (ESPHome's default via sdkconfig),
-// falling back to esp_timer for non-standard rates. IRAM_ATTR is required because
-// Wiegand and ZyAura call millis() from IRAM_ATTR ISR handlers on ESP32.
-// xTaskGetTickCountFromISR() is used in ISR context to satisfy the FreeRTOS API contract.
-uint32_t IRAM_ATTR HOT millis() {
-#if CONFIG_FREERTOS_HZ == 1000
-  if (xPortInIsrContext()) [[unlikely]] {
-    return xTaskGetTickCountFromISR();
-  }
-  return xTaskGetTickCount();
-#else
-  return micros_to_millis(static_cast<uint64_t>(esp_timer_get_time()));
-#endif
-}
-void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
-void arch_restart() {
-  esp_restart();
-  // restart() doesn't always end execution
-  while (true) {  // NOLINT(clang-diagnostic-unreachable-code)
-    yield();
-  }
-}
-
-void arch_init() {
-#ifdef USE_ESP32_CRASH_HANDLER
-  // Read crash data from previous boot before anything else
-  esp32::crash_handler_read_and_clear();
-#endif
-
-  // Enable the task watchdog only on the loop task (from which we're currently running)
-  esp_task_wdt_add(nullptr);
-
-  // Handle OTA rollback: mark partition valid immediately unless USE_OTA_ROLLBACK is enabled,
-  // in which case safe_mode will mark it valid after confirming successful boot.
-#ifndef USE_OTA_ROLLBACK
-  esp_ota_mark_app_valid_cancel_rollback();
-#endif
-}
-void HOT arch_feed_wdt() { esp_task_wdt_reset(); }
-
-uint32_t arch_get_cpu_cycle_count() { return esp_cpu_get_cycle_count(); }
-uint32_t arch_get_cpu_freq_hz() {
-  uint32_t freq = 0;
-  esp_clk_tree_src_get_freq_hz(SOC_MOD_CLK_CPU, ESP_CLK_TREE_SRC_FREQ_PRECISION_CACHED, &freq);
-  return freq;
-}
-
+// HAL functions live in hal.cpp. This file keeps only the loop task setup.
 TaskHandle_t loop_task_handle = nullptr;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 static StaticTask_t loop_task_tcb;        // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 static StackType_t
diff --git a/esphome/components/esp32/hal.cpp b/esphome/components/esp32/hal.cpp
new file mode 100644
index 0000000000..f6199d557f
--- /dev/null
+++ b/esphome/components/esp32/hal.cpp
@@ -0,0 +1,71 @@
+#ifdef USE_ESP32
+
+// defines.h must come before crash_handler.h so USE_ESP32_CRASH_HANDLER is set
+// before crash_handler.h's #ifdef-guarded namespace block is parsed.
+#include "esphome/core/defines.h"
+#include "crash_handler.h"
+#include "esphome/core/hal.h"
+
+#include <esp_clk_tree.h>
+#include <esp_ota_ops.h>
+#include <esp_system.h>
+#include <esp_task_wdt.h>
+#include <esp_timer.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+
+// Empty esp32 namespace block to satisfy ci-custom's lint_namespace check.
+// HAL functions live in namespace esphome (root) — they are not part of the
+// esp32 component's API.
+namespace esphome::esp32 {}  // namespace esphome::esp32
+
+namespace esphome {
+
+// Use xTaskGetTickCount() when tick rate is 1 kHz (ESPHome's default via sdkconfig),
+// falling back to esp_timer for non-standard rates. IRAM_ATTR is required because
+// Wiegand and ZyAura call millis() from IRAM_ATTR ISR handlers on ESP32.
+// xTaskGetTickCountFromISR() is used in ISR context to satisfy the FreeRTOS API contract.
+uint32_t IRAM_ATTR HOT millis() {
+#if CONFIG_FREERTOS_HZ == 1000
+  if (xPortInIsrContext()) [[unlikely]] {
+    return xTaskGetTickCountFromISR();
+  }
+  return xTaskGetTickCount();
+#else
+  return micros_to_millis(static_cast<uint64_t>(esp_timer_get_time()));
+#endif
+}
+
+void arch_restart() {
+  esp_restart();
+  // restart() doesn't always end execution
+  while (true) {  // NOLINT(clang-diagnostic-unreachable-code)
+    yield();
+  }
+}
+
+void arch_init() {
+#ifdef USE_ESP32_CRASH_HANDLER
+  // Read crash data from previous boot before anything else
+  esp32::crash_handler_read_and_clear();
+#endif
+
+  // Enable the task watchdog only on the loop task (from which we're currently running)
+  esp_task_wdt_add(nullptr);
+
+  // Handle OTA rollback: mark partition valid immediately unless USE_OTA_ROLLBACK is enabled,
+  // in which case safe_mode will mark it valid after confirming successful boot.
+#ifndef USE_OTA_ROLLBACK
+  esp_ota_mark_app_valid_cancel_rollback();
+#endif
+}
+
+uint32_t arch_get_cpu_freq_hz() {
+  uint32_t freq = 0;
+  esp_clk_tree_src_get_freq_hz(SOC_MOD_CLK_CPU, ESP_CLK_TREE_SRC_FREQ_PRECISION_CACHED, &freq);
+  return freq;
+}
+
+}  // namespace esphome
+
+#endif  // USE_ESP32
diff --git a/esphome/components/remote_base/remote_base.h b/esphome/components/remote_base/remote_base.h
index d73fff2b0a..e5e923d780 100644
--- a/esphome/components/remote_base/remote_base.h
+++ b/esphome/components/remote_base/remote_base.h
@@ -164,7 +164,7 @@ class RemoteTransmitterBase : public RemoteComponentBase {
     return TransmitCall(this);
   }
   template<typename Protocol>
-  void transmit(const typename Protocol::ProtocolData &data, uint32_t send_times = 1, uint32_t send_wait = 0) {
+  void transmit(const Protocol::ProtocolData &data, uint32_t send_times = 1, uint32_t send_wait = 0) {
     auto call = this->transmit();
     Protocol().encode(call.get_data(), data);
     call.set_send_times(send_times);
@@ -250,10 +250,10 @@ template<typename T> class RemoteReceiverBinarySensor : public RemoteReceiverBin
   }
 
  public:
-  void set_data(typename T::ProtocolData data) { data_ = data; }
+  void set_data(T::ProtocolData data) { data_ = data; }
 
  protected:
-  typename T::ProtocolData data_;
+  T::ProtocolData data_;
 };
 
 template<typename T>
@@ -278,7 +278,7 @@ class RemoteTransmittable {
 
  protected:
   template<typename Protocol>
-  void transmit_(const typename Protocol::ProtocolData &data, uint32_t send_times = 1, uint32_t send_wait = 0) {
+  void transmit_(const Protocol::ProtocolData &data, uint32_t send_times = 1, uint32_t send_wait = 0) {
     this->transmitter_->transmit<Protocol>(data, send_times, send_wait);
   }
   RemoteTransmitterBase *transmitter_;
diff --git a/esphome/core/finite_set_mask.h b/esphome/core/finite_set_mask.h
index 616c69353d..272337ff76 100644
--- a/esphome/core/finite_set_mask.h
+++ b/esphome/core/finite_set_mask.h
@@ -55,7 +55,7 @@ template<typename ValueType, int MaxBits> struct DefaultBitPolicy {
 ///
 template<typename ValueType, typename BitPolicy = DefaultBitPolicy<ValueType, 16>> class FiniteSetMask {
  public:
-  using bitmask_t = typename BitPolicy::mask_t;
+  using bitmask_t = BitPolicy::mask_t;
 
   constexpr FiniteSetMask() = default;
 
diff --git a/esphome/core/hal.h b/esphome/core/hal.h
index e20797cf95..312effa7b0 100644
--- a/esphome/core/hal.h
+++ b/esphome/core/hal.h
@@ -30,15 +30,11 @@
 
 namespace esphome {
 
-// ESP8266 inlines delayMicroseconds() and arch_feed_wdt() in hal/hal_esp8266.h;
-// every other platform keeps them out-of-line in components/<platform>/core.cpp.
-#ifndef USE_ESP8266
-void delayMicroseconds(uint32_t us);  // NOLINT(readability-identifier-naming)
-void arch_feed_wdt();
-#endif
+// Cross-platform declarations. delayMicroseconds(), arch_feed_wdt(),
+// arch_get_cpu_cycle_count() vary per platform (some inline, some
+// out-of-line) so they live in hal/hal_<platform>.h.
 void __attribute__((noreturn)) arch_restart();
 void arch_init();
-uint32_t arch_get_cpu_cycle_count();
 uint32_t arch_get_cpu_freq_hz();
 
 #ifndef USE_ESP8266
diff --git a/esphome/core/hal/hal_esp32.h b/esphome/core/hal/hal_esp32.h
index e755337540..2bff424441 100644
--- a/esphome/core/hal/hal_esp32.h
+++ b/esphome/core/hal/hal_esp32.h
@@ -4,6 +4,8 @@
 
 #include <cstdint>
 #include <esp_attr.h>
+#include <esp_cpu.h>
+#include <esp_task_wdt.h>
 #include <freertos/FreeRTOS.h>
 #include <freertos/task.h>
 
@@ -15,6 +17,11 @@
 
 namespace esphome {
 
+// Forward decl from helpers.h (esphome/core/helpers.h) — kept here so this
+// header does not need to pull the rest of helpers.h.
+// NOLINTNEXTLINE(readability-redundant-declaration)
+void delay_microseconds_safe(uint32_t us);
+
 /// Returns true when executing inside an interrupt handler.
 __attribute__((always_inline)) inline bool in_isr_context() { return xPortInIsrContext() != 0; }
 
@@ -30,6 +37,11 @@ __attribute__((always_inline)) inline uint64_t millis_64() {
   return micros_to_millis<uint64_t>(static_cast<uint64_t>(esp_timer_get_time()));
 }
 
+// NOLINTNEXTLINE(readability-identifier-naming)
+__attribute__((always_inline)) inline void delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
+__attribute__((always_inline)) inline void arch_feed_wdt() { esp_task_wdt_reset(); }
+__attribute__((always_inline)) inline uint32_t arch_get_cpu_cycle_count() { return esp_cpu_get_cycle_count(); }
+
 }  // namespace esphome
 
 #endif  // USE_ESP32
diff --git a/esphome/core/hal/hal_esp8266.h b/esphome/core/hal/hal_esp8266.h
index 04326a3579..484118f1f5 100644
--- a/esphome/core/hal/hal_esp8266.h
+++ b/esphome/core/hal/hal_esp8266.h
@@ -60,6 +60,8 @@ __attribute__((always_inline)) inline uint16_t progmem_read_uint16(const uint16_
 __attribute__((always_inline)) inline void delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
 __attribute__((always_inline)) inline void arch_feed_wdt() { system_soft_wdt_feed(); }
 
+uint32_t arch_get_cpu_cycle_count();
+
 }  // namespace esphome
 
 #endif  // USE_ESP8266
diff --git a/esphome/core/hal/hal_host.h b/esphome/core/hal/hal_host.h
index 145fe4ea9c..682a1a422b 100644
--- a/esphome/core/hal/hal_host.h
+++ b/esphome/core/hal/hal_host.h
@@ -19,6 +19,10 @@ uint32_t micros();
 uint32_t millis();
 uint64_t millis_64();
 
+void delayMicroseconds(uint32_t us);  // NOLINT(readability-identifier-naming)
+void arch_feed_wdt();
+uint32_t arch_get_cpu_cycle_count();
+
 }  // namespace esphome
 
 #endif  // USE_HOST
diff --git a/esphome/core/hal/hal_libretiny.h b/esphome/core/hal/hal_libretiny.h
index e0d92735bb..e9d33b7753 100644
--- a/esphome/core/hal/hal_libretiny.h
+++ b/esphome/core/hal/hal_libretiny.h
@@ -88,6 +88,10 @@ __attribute__((always_inline)) inline uint32_t millis() { return static_cast<uin
 #endif
 __attribute__((always_inline)) inline uint64_t millis_64() { return Millis64Impl::compute(millis()); }
 
+void delayMicroseconds(uint32_t us);  // NOLINT(readability-identifier-naming)
+void arch_feed_wdt();
+uint32_t arch_get_cpu_cycle_count();
+
 }  // namespace esphome
 
 #endif  // USE_LIBRETINY
diff --git a/esphome/core/hal/hal_rp2040.h b/esphome/core/hal/hal_rp2040.h
index 156ff33b86..2a1d67b4a3 100644
--- a/esphome/core/hal/hal_rp2040.h
+++ b/esphome/core/hal/hal_rp2040.h
@@ -35,6 +35,10 @@ __attribute__((always_inline)) inline uint32_t micros() { return static_cast<uin
 __attribute__((always_inline)) inline uint32_t millis() { return micros_to_millis(::time_us_64()); }
 __attribute__((always_inline)) inline uint64_t millis_64() { return micros_to_millis<uint64_t>(::time_us_64()); }
 
+void delayMicroseconds(uint32_t us);  // NOLINT(readability-identifier-naming)
+void arch_feed_wdt();
+uint32_t arch_get_cpu_cycle_count();
+
 }  // namespace esphome
 
 #endif  // USE_RP2040
diff --git a/esphome/core/hal/hal_zephyr.h b/esphome/core/hal/hal_zephyr.h
index e28be5c775..6707c85b2c 100644
--- a/esphome/core/hal/hal_zephyr.h
+++ b/esphome/core/hal/hal_zephyr.h
@@ -19,6 +19,10 @@ uint32_t micros();
 uint32_t millis();
 uint64_t millis_64();
 
+void delayMicroseconds(uint32_t us);  // NOLINT(readability-identifier-naming)
+void arch_feed_wdt();
+uint32_t arch_get_cpu_cycle_count();
+
 }  // namespace esphome
 
 #endif  // USE_ZEPHYR