diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 43b721c2d5..5efd839673 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -2425,7 +2425,7 @@ message ZWaveProxyFrame {
   option (ifdef) = "USE_ZWAVE_PROXY";
   option (no_delay) = true;
 
-  bytes data = 1 [(pointer_to_buffer) = true];
+  bytes data = 1;
 }
 
 enum ZWaveProxyRequestType {
@@ -2439,5 +2439,5 @@ message ZWaveProxyRequest {
   option (ifdef) = "USE_ZWAVE_PROXY";
 
   ZWaveProxyRequestType type = 1;
-  bytes data = 2 [(pointer_to_buffer) = true];
+  bytes data = 2;
 }
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 6275b4c211..e08cf65bb9 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1046,7 +1046,7 @@ class SubscribeLogsRequest final : public ProtoDecodableMessage {
 class SubscribeLogsResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 29;
-  static constexpr uint8_t ESTIMATED_SIZE = 11;
+  static constexpr uint8_t ESTIMATED_SIZE = 21;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "subscribe_logs_response"; }
 #endif
@@ -1069,7 +1069,7 @@ class SubscribeLogsResponse final : public ProtoMessage {
 class NoiseEncryptionSetKeyRequest final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 124;
-  static constexpr uint8_t ESTIMATED_SIZE = 9;
+  static constexpr uint8_t ESTIMATED_SIZE = 19;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "noise_encryption_set_key_request"; }
 #endif
@@ -1161,7 +1161,7 @@ class HomeassistantActionRequest final : public ProtoMessage {
 class HomeassistantActionResponse final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 130;
-  static constexpr uint8_t ESTIMATED_SIZE = 24;
+  static constexpr uint8_t ESTIMATED_SIZE = 34;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "homeassistant_action_response"; }
 #endif
@@ -1388,7 +1388,7 @@ class ListEntitiesCameraResponse final : public InfoResponseProtoMessage {
 class CameraImageResponse final : public StateResponseProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 44;
-  static constexpr uint8_t ESTIMATED_SIZE = 20;
+  static constexpr uint8_t ESTIMATED_SIZE = 30;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "camera_image_response"; }
 #endif
@@ -2123,7 +2123,7 @@ class BluetoothGATTReadRequest final : public ProtoDecodableMessage {
 class BluetoothGATTReadResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 74;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 27;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_read_response"; }
 #endif
@@ -2146,7 +2146,7 @@ class BluetoothGATTReadResponse final : public ProtoMessage {
 class BluetoothGATTWriteRequest final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 75;
-  static constexpr uint8_t ESTIMATED_SIZE = 19;
+  static constexpr uint8_t ESTIMATED_SIZE = 29;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_write_request"; }
 #endif
@@ -2182,7 +2182,7 @@ class BluetoothGATTReadDescriptorRequest final : public ProtoDecodableMessage {
 class BluetoothGATTWriteDescriptorRequest final : public ProtoDecodableMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 77;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 27;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_write_descriptor_request"; }
 #endif
@@ -2218,7 +2218,7 @@ class BluetoothGATTNotifyRequest final : public ProtoDecodableMessage {
 class BluetoothGATTNotifyDataResponse final : public ProtoMessage {
  public:
   static constexpr uint8_t MESSAGE_TYPE = 79;
-  static constexpr uint8_t ESTIMATED_SIZE = 17;
+  static constexpr uint8_t ESTIMATED_SIZE = 27;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const char *message_name() const override { return "bluetooth_gatt_notify_data_response"; }
 #endif
diff --git a/esphome/components/esp32_improv/__init__.py b/esphome/components/esp32_improv/__init__.py
index 2e69d400ca..ad2f057163 100644
--- a/esphome/components/esp32_improv/__init__.py
+++ b/esphome/components/esp32_improv/__init__.py
@@ -3,7 +3,7 @@ import esphome.codegen as cg
 from esphome.components import binary_sensor, esp32_ble, improv_base, output
 from esphome.components.esp32_ble import BTLoggers
 import esphome.config_validation as cv
-from esphome.const import CONF_ID, CONF_ON_STATE, CONF_TRIGGER_ID
+from esphome.const import CONF_ID, CONF_ON_START, CONF_ON_STATE, CONF_TRIGGER_ID
 
 AUTO_LOAD = ["esp32_ble_server", "improv_base"]
 CODEOWNERS = ["@jesserockz"]
@@ -15,7 +15,6 @@ CONF_BLE_SERVER_ID = "ble_server_id"
 CONF_IDENTIFY_DURATION = "identify_duration"
 CONF_ON_PROVISIONED = "on_provisioned"
 CONF_ON_PROVISIONING = "on_provisioning"
-CONF_ON_START = "on_start"
 CONF_ON_STOP = "on_stop"
 CONF_STATUS_INDICATOR = "status_indicator"
 CONF_WIFI_TIMEOUT = "wifi_timeout"
diff --git a/esphome/components/esp8266/__init__.py b/esphome/components/esp8266/__init__.py
index c4969a79b2..77ccaf52c1 100644
--- a/esphome/components/esp8266/__init__.py
+++ b/esphome/components/esp8266/__init__.py
@@ -28,6 +28,7 @@ from .const import (
     KEY_ESP8266,
     KEY_FLASH_SIZE,
     KEY_PIN_INITIAL_STATES,
+    KEY_WAVEFORM_REQUIRED,
     esp8266_ns,
 )
 from .gpio import PinInitialState, add_pin_initial_states_array
@@ -192,7 +193,12 @@ async def to_code(config):
 
     cg.add_platformio_option(
         "extra_scripts",
-        ["pre:testing_mode.py", "pre:exclude_updater.py", "post:post_build.py"],
+        [
+            "pre:testing_mode.py",
+            "pre:exclude_updater.py",
+            "pre:exclude_waveform.py",
+            "post:post_build.py",
+        ],
     )
 
     conf = config[CONF_FRAMEWORK]
@@ -264,10 +270,24 @@ async def to_code(config):
             cg.add_platformio_option("board_build.ldscript", ld_script)
 
     CORE.add_job(add_pin_initial_states_array)
+    CORE.add_job(finalize_waveform_config)
+
+
+@coroutine_with_priority(CoroPriority.WORKAROUNDS)
+async def finalize_waveform_config() -> None:
+    """Add waveform stubs define if waveform is not required.
+
+    This runs at WORKAROUNDS priority (-999) to ensure all components
+    have had a chance to call require_waveform() first.
+    """
+    if not CORE.data.get(KEY_ESP8266, {}).get(KEY_WAVEFORM_REQUIRED, False):
+        # No component needs waveform - enable stubs and exclude Arduino waveform code
+        # Use build flag (visible to both C++ code and PlatformIO script)
+        cg.add_build_flag("-DUSE_ESP8266_WAVEFORM_STUBS")
 
 
 # Called by writer.py
-def copy_files():
+def copy_files() -> None:
     dir = Path(__file__).parent
     post_build_file = dir / "post_build.py.script"
     copy_file_if_changed(
@@ -284,3 +304,8 @@ def copy_files():
         exclude_updater_file,
         CORE.relative_build_path("exclude_updater.py"),
     )
+    exclude_waveform_file = dir / "exclude_waveform.py.script"
+    copy_file_if_changed(
+        exclude_waveform_file,
+        CORE.relative_build_path("exclude_waveform.py"),
+    )
diff --git a/esphome/components/esp8266/const.py b/esphome/components/esp8266/const.py
index b718306b01..14425cde68 100644
--- a/esphome/components/esp8266/const.py
+++ b/esphome/components/esp8266/const.py
@@ -1,4 +1,5 @@
 import esphome.codegen as cg
+from esphome.core import CORE
 
 KEY_ESP8266 = "esp8266"
 KEY_BOARD = "board"
@@ -6,6 +7,25 @@ KEY_PIN_INITIAL_STATES = "pin_initial_states"
 CONF_RESTORE_FROM_FLASH = "restore_from_flash"
 CONF_EARLY_PIN_INIT = "early_pin_init"
 KEY_FLASH_SIZE = "flash_size"
+KEY_WAVEFORM_REQUIRED = "waveform_required"
 
 # esp8266 namespace is already defined by arduino, manually prefix esphome
 esp8266_ns = cg.global_ns.namespace("esphome").namespace("esp8266")
+
+
+def require_waveform() -> None:
+    """Mark that Arduino waveform/PWM support is required.
+
+    Call this from components that need the Arduino waveform generator
+    (startWaveform, stopWaveform, analogWrite, Tone, Servo).
+
+    If no component calls this, the waveform code is excluded from the build
+    to save ~596 bytes of RAM and 464 bytes of flash.
+
+    Example:
+        from esphome.components.esp8266.const import require_waveform
+
+        async def to_code(config):
+            require_waveform()
+    """
+    CORE.data.setdefault(KEY_ESP8266, {})[KEY_WAVEFORM_REQUIRED] = True
diff --git a/esphome/components/esp8266/exclude_waveform.py.script b/esphome/components/esp8266/exclude_waveform.py.script
new file mode 100644
index 0000000000..35d6bc31f6
--- /dev/null
+++ b/esphome/components/esp8266/exclude_waveform.py.script
@@ -0,0 +1,50 @@
+# pylint: disable=E0602
+Import("env")  # noqa
+
+import os
+
+# Filter out waveform/PWM code from the Arduino core build
+# This saves ~596 bytes of RAM and 464 bytes of flash by not
+# instantiating the waveform generator state structures (wvfState + pwmState).
+#
+# The waveform code is used by: analogWrite, Tone, Servo, and direct
+# startWaveform/stopWaveform calls. ESPHome's esp8266_pwm component
+# calls require_waveform() to keep this code when needed.
+#
+# When excluded, we provide stub implementations of stopWaveform() and
+# _stopPWM() since digitalWrite() calls these unconditionally.
+
+
+def has_define_flag(env, name):
+    """Check if a define exists in the build flags."""
+    define_flag = f"-D{name}"
+    # Check BUILD_FLAGS (where ESPHome puts its defines)
+    for flag in env.get("BUILD_FLAGS", []):
+        if flag == define_flag or flag.startswith(f"{define_flag}="):
+            return True
+    # Also check CPPDEFINES list (parsed defines)
+    for define in env.get("CPPDEFINES", []):
+        if isinstance(define, tuple):
+            if define[0] == name:
+                return True
+        elif define == name:
+            return True
+    return False
+
+# USE_ESP8266_WAVEFORM_STUBS is defined when no component needs waveform
+if has_define_flag(env, "USE_ESP8266_WAVEFORM_STUBS"):
+
+    def filter_waveform_from_core(env, node):
+        """Filter callback to exclude waveform files from framework build."""
+        path = node.get_path()
+        filename = os.path.basename(path)
+        if filename in (
+            "core_esp8266_waveform_pwm.cpp",
+            "core_esp8266_waveform_phase.cpp",
+        ):
+            print(f"ESPHome: Excluding {filename} from build (waveform not required)")
+            return None
+        return node
+
+    # Apply the filter to framework sources
+    env.AddBuildMiddleware(filter_waveform_from_core, "**/cores/esp8266/*.cpp")
diff --git a/esphome/components/esp8266/waveform_stubs.cpp b/esphome/components/esp8266/waveform_stubs.cpp
new file mode 100644
index 0000000000..686e03c6a9
--- /dev/null
+++ b/esphome/components/esp8266/waveform_stubs.cpp
@@ -0,0 +1,34 @@
+#ifdef USE_ESP8266_WAVEFORM_STUBS
+
+// Stub implementations for Arduino waveform/PWM functions.
+//
+// When the waveform generator is not needed (no esp8266_pwm component),
+// we exclude core_esp8266_waveform_pwm.cpp from the build to save ~596 bytes
+// of RAM and 464 bytes of flash.
+//
+// These stubs satisfy calls from the Arduino GPIO code when the real
+// waveform implementation is excluded. They must be in the global namespace
+// with C linkage to match the Arduino core function declarations.
+
+#include <cstdint>
+
+// Empty namespace to satisfy linter - actual stubs must be at global scope
+namespace esphome::esp8266 {}  // namespace esphome::esp8266
+
+extern "C" {
+
+// Called by Arduino GPIO code to stop any waveform on a pin
+int stopWaveform(uint8_t pin) {
+  (void) pin;
+  return 1;  // Success (no waveform to stop)
+}
+
+// Called by Arduino GPIO code to stop any PWM on a pin
+bool _stopPWM(uint8_t pin) {
+  (void) pin;
+  return false;  // No PWM was running
+}
+
+}  // extern "C"
+
+#endif  // USE_ESP8266_WAVEFORM_STUBS
diff --git a/esphome/components/esp8266_pwm/output.py b/esphome/components/esp8266_pwm/output.py
index 2ddf4b9014..a78831c516 100644
--- a/esphome/components/esp8266_pwm/output.py
+++ b/esphome/components/esp8266_pwm/output.py
@@ -1,6 +1,7 @@
 from esphome import automation, pins
 import esphome.codegen as cg
 from esphome.components import output
+from esphome.components.esp8266.const import require_waveform
 import esphome.config_validation as cv
 from esphome.const import CONF_FREQUENCY, CONF_ID, CONF_NUMBER, CONF_PIN
 
@@ -34,7 +35,9 @@ CONFIG_SCHEMA = cv.All(
 )
 
 
-async def to_code(config):
+async def to_code(config) -> None:
+    require_waveform()
+
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     await output.register_output(var, config)
diff --git a/esphome/components/voice_assistant/__init__.py b/esphome/components/voice_assistant/__init__.py
index 59c7ec8383..d28c786dd8 100644
--- a/esphome/components/voice_assistant/__init__.py
+++ b/esphome/components/voice_assistant/__init__.py
@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_ON_CLIENT_DISCONNECTED,
     CONF_ON_ERROR,
     CONF_ON_IDLE,
+    CONF_ON_START,
     CONF_SPEAKER,
 )
 
@@ -24,7 +25,6 @@ CONF_ON_INTENT_END = "on_intent_end"
 CONF_ON_INTENT_PROGRESS = "on_intent_progress"
 CONF_ON_INTENT_START = "on_intent_start"
 CONF_ON_LISTENING = "on_listening"
-CONF_ON_START = "on_start"
 CONF_ON_STT_END = "on_stt_end"
 CONF_ON_STT_VAD_END = "on_stt_vad_end"
 CONF_ON_STT_VAD_START = "on_stt_vad_start"
diff --git a/esphome/const.py b/esphome/const.py
index 1d46e81f9d..518247aa60 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -710,6 +710,7 @@ CONF_ON_RELEASE = "on_release"
 CONF_ON_RESPONSE = "on_response"
 CONF_ON_SHUTDOWN = "on_shutdown"
 CONF_ON_SPEED_SET = "on_speed_set"
+CONF_ON_START = "on_start"
 CONF_ON_STATE = "on_state"
 CONF_ON_SUCCESS = "on_success"
 CONF_ON_TAG = "on_tag"
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 5b68c6a3d2..7293f2abbc 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -362,12 +362,12 @@ def create_field_type_info(
             # Traditional fixed array approach with copy (takes priority)
             return FixedArrayBytesType(field, fixed_size)
 
-        # For SOURCE_CLIENT only messages (decode but no encode), use pointer
+        # For messages that decode (SOURCE_CLIENT or SOURCE_BOTH), use pointer
         # for zero-copy access to the receive buffer
-        if needs_decode and not needs_encode:
+        if needs_decode:
             return PointerToBytesBufferType(field, None)
 
-        # For SOURCE_BOTH/SOURCE_SERVER, explicit annotation is still needed
+        # For SOURCE_SERVER (encode only), explicit annotation is still needed
         if get_field_opt(field, pb.pointer_to_buffer, False):
             return PointerToBytesBufferType(field, None)
 
diff --git a/script/ci-custom.py b/script/ci-custom.py
index 609d89403f..f0676d594b 100755
--- a/script/ci-custom.py
+++ b/script/ci-custom.py
@@ -552,6 +552,8 @@ def convert_path_to_relative(abspath, current):
     exclude=[
         "esphome/components/libretiny/generate_components.py",
         "esphome/components/web_server/__init__.py",
+        # const.py has absolute import in docstring example for external components
+        "esphome/components/esp8266/const.py",
     ],
 )
 def lint_relative_py_import(fname: Path, line, col, content):