Merge branch 'esp8266-native-build-surgery' into esp8266-native-toolchain-plumbing

esphome/components/api/api_connection.cpp

@@ -1790,10 +1790,12 @@ void APIConnection::complete_authentication_() {
 bool APIConnection::send_hello_response_(const HelloRequest &msg) {
   // Copy client name with truncation if needed (set_client_name handles truncation)
   this->helper_->set_client_name(msg.client_info.c_str(), msg.client_info.size());
-  this->client_api_version_major_ = msg.api_version_major;
+  this->client_api_version_major_ =
-  this->client_api_version_minor_ = msg.api_version_minor;
+      static_cast<uint8_t>(std::min<uint32_t>(msg.api_version_major, std::numeric_limits<uint8_t>::max()));
+  this->client_api_version_minor_ =
+      static_cast<uint8_t>(std::min<uint32_t>(msg.api_version_minor, std::numeric_limits<uint8_t>::max()));
   char peername[socket::SOCKADDR_STR_LEN];
-  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %" PRIu16 ".%" PRIu16, this->helper_->get_client_name(),
+  ESP_LOGV(TAG, "Hello from client: '%s' | %s | API Version %u.%u", this->helper_->get_client_name(),
            this->helper_->get_peername_to(peername), this->client_api_version_major_, this->client_api_version_minor_);
 
   HelloResponse resp;
@@ -2224,7 +2226,7 @@ bool APIConnection::try_to_clear_buffer_slow_(bool log_out_of_space) {
   }
   return false;
 }
-bool APIConnection::send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn,
+bool APIConnection::send_message_(uint32_t payload_size, uint16_t message_type, MessageEncodeFn encode_fn,
                                   const void *msg) {
 #ifdef HAS_PROTO_MESSAGE_DUMP
   // Skip dump for log messages (recursive logging risk) and camera frames (high-frequency noise)
@@ -2253,7 +2255,7 @@ uint16_t APIConnection::encode_to_buffer_slow(uint32_t calculated_size, MessageE
                                               APIConnection *conn, uint32_t remaining_size) {
   return encode_to_buffer(calculated_size, encode_fn, msg, conn, remaining_size);
 }
-bool APIConnection::send_buffer(ProtoWriteBuffer buffer, uint8_t message_type) {
+bool APIConnection::send_buffer(ProtoWriteBuffer buffer, uint16_t message_type) {
   const bool is_log_message = (message_type == SubscribeLogsResponse::MESSAGE_TYPE);
 
   if (!this->try_to_clear_buffer(!is_log_message)) {
@@ -2283,12 +2285,12 @@ void APIConnection::on_fatal_error() {
   this->flags_.remove = true;
 }
 
-bool APIConnection::schedule_message_front_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
+bool APIConnection::schedule_message_front_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size) {
   this->deferred_batch_.add_item_front(entity, message_type, estimated_size);
   return this->schedule_batch_();
 }
 
-bool APIConnection::send_message_smart_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+bool APIConnection::send_message_smart_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                                         uint8_t aux_data_index) {
   if (this->should_send_immediately_(message_type) && this->helper_->can_write_without_blocking()) {
     auto &shared_buf = this->parent_->get_shared_buffer_ref();

esphome/components/api/api_connection.h

@@ -326,8 +326,10 @@ class APIConnection final : public APIServerConnectionBase {
   bool is_marked_for_removal() const { return this->flags_.remove; }
   uint8_t get_log_subscription_level() const { return this->flags_.log_subscription; }
 
-  // Get client API version for feature detection
+  // Get client API version for feature detection.
-  bool client_supports_api_version(uint16_t major, uint16_t minor) const {
+  // Stored versions saturate at 255 (see send_hello_response_), so requesting
+  // a minimum above that can never match.
+  bool client_supports_api_version(uint8_t major, uint8_t minor) const {
     return this->client_api_version_major_ > major ||
            (this->client_api_version_major_ == major && this->client_api_version_minor_ >= minor);
   }
@@ -374,7 +376,7 @@ class APIConnection final : public APIServerConnectionBase {
       return true;
     return this->try_to_clear_buffer_slow_(log_out_of_space);
   }
-  bool send_buffer(ProtoWriteBuffer buffer, uint8_t message_type);
+  bool send_buffer(ProtoWriteBuffer buffer, uint16_t message_type);
 
   const char *get_name() const { return this->helper_->get_client_name(); }
   /// Get peer name (IP address) into caller-provided buffer, returns buf for convenience
@@ -423,7 +425,7 @@ class APIConnection final : public APIServerConnectionBase {
   }
 
   // Non-template buffer management for send_message
-  bool send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn, const void *msg);
+  bool send_message_(uint32_t payload_size, uint16_t message_type, MessageEncodeFn encode_fn, const void *msg);
 
   // Core batch encoding logic. ALWAYS_INLINE so encode_fn devirtualizes at hot call sites.
   // Defined in api_connection_buffer.h (needs APIServer complete).
@@ -664,10 +666,9 @@ class APIConnection final : public APIServerConnectionBase {
 
     struct BatchItem {
       EntityBase *entity;                       // 4 bytes - Entity pointer
-      uint8_t message_type;                     // 1 byte - Message type for protocol and dispatch
+      uint16_t message_type;                    // 2 bytes - Message type for protocol and dispatch
       uint8_t estimated_size;                   // 1 byte - Estimated message size (max 255 bytes)
       uint8_t aux_data_index{AUX_DATA_UNUSED};  // 1 byte - For events: index into entity's event_types
-      // 1 byte padding
     };
 
     std::vector<BatchItem> items;
@@ -677,7 +678,7 @@ class APIConnection final : public APIServerConnectionBase {
     // connections that do, buffers are released after initial sync anyway
 
     // Add item to the batch (with deduplication)
-    void add_item(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+    void add_item(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                   uint8_t aux_data_index = AUX_DATA_UNUSED) {
       // Dedup: O(n) scan but optimized for RAM over performance
       // Skip deduplication for events - they are edge-triggered, every occurrence matters
@@ -693,7 +694,7 @@ class APIConnection final : public APIServerConnectionBase {
       this->items.push_back({entity, message_type, estimated_size, aux_data_index});
     }
     // Add item to the front of the batch (for high priority messages like ping)
-    void add_item_front(EntityBase *entity, uint8_t message_type, uint8_t estimated_size) {
+    void add_item_front(EntityBase *entity, uint16_t message_type, uint8_t estimated_size) {
       // Swap to front avoids expensive vector::insert which shifts all elements
       this->items.push_back({entity, message_type, estimated_size, AUX_DATA_UNUSED});
       if (this->items.size() > 1) {
@@ -758,13 +759,15 @@ class APIConnection final : public APIServerConnectionBase {
 #endif
   } flags_{};  // 2 bytes total
 
-  // 2-byte types immediately after flags_ (no padding between them)
+  // 2-byte type immediately after flags_ (no padding between them)
-  uint16_t client_api_version_major_{0};
+  uint16_t batch_message_type_{0};  // Current message type during batch encoding
-  uint16_t client_api_version_minor_{0};
   // 1-byte types to fill remaining space before next 4-byte boundary
+  // Client API versions are clamped to 255 on receive (see send_hello_response_)
+  uint8_t client_api_version_major_{0};
+  uint8_t client_api_version_minor_{0};
   ActiveIterator active_iterator_{ActiveIterator::NONE};
-  uint8_t batch_message_type_{0};  // Current message type during batch encoding
+  // Total: 2 (flags) + 2 + 1 + 1 + 1 + 1 (batch_header_size_ below) = 8 bytes,
-  // Total: 2 (flags) + 2 + 2 + 1 + 1 = 8 bytes, aligned to 4-byte boundary
+  // aligned to 4-byte boundary
 
   // Actual header size used by encode_to_buffer for the current message.
   // Read by process_batch_multi_ to pass into MessageInfo.
@@ -813,7 +816,7 @@ class APIConnection final : public APIServerConnectionBase {
   // 2. It's an EventResponse (events are edge-triggered - every occurrence matters)
   // 3. OR: User has opted into immediate sending (should_try_send_immediately = true
   //    AND batch_delay = 0)
-  inline bool should_send_immediately_(uint8_t message_type) const {
+  inline bool should_send_immediately_(uint16_t message_type) const {
     return (
 #ifdef USE_UPDATE
         message_type == UpdateStateResponse::MESSAGE_TYPE ||
@@ -827,11 +830,11 @@ class APIConnection final : public APIServerConnectionBase {
   // Helper method to send a message either immediately or via batching
   // Tries immediate send if should_send_immediately_() returns true and buffer has space
   // Falls back to batching if immediate send fails or isn't applicable
-  bool send_message_smart_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+  bool send_message_smart_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                            uint8_t aux_data_index = DeferredBatch::AUX_DATA_UNUSED);
 
   // Helper function to schedule a deferred message with known message type
-  bool schedule_message_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size,
+  bool schedule_message_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size,
                          uint8_t aux_data_index = DeferredBatch::AUX_DATA_UNUSED) {
     this->deferred_batch_.add_item(entity, message_type, estimated_size, aux_data_index);
     return this->schedule_batch_();
@@ -839,7 +842,7 @@ class APIConnection final : public APIServerConnectionBase {
 
   // Helper function to schedule a high priority message at the front of the batch
   // Out-of-line: callers (on_shutdown, check_keepalive_) are cold paths
-  bool schedule_message_front_(EntityBase *entity, uint8_t message_type, uint8_t estimated_size);
+  bool schedule_message_front_(EntityBase *entity, uint16_t message_type, uint8_t estimated_size);
 
   // Helper function to log client messages with name and peername
   void log_client_(int level, const LogString *message);

esphome/components/api/api_frame_helper.h

@@ -49,16 +49,16 @@ struct ReadPacketBuffer {
 };
 
 // Packed message info structure to minimize memory usage
-// Note: message_type is uint8_t — all current protobuf message types fit in 8 bits.
+// message_type matches the wire formats: noise carries a fixed 16-bit type
-// The noise wire format encodes types as 16-bit, but the high byte is always 0.
+// field, plaintext a type varint. The proto codegen caps message IDs at 16383
-// If message types ever exceed 255, this and encrypt_noise_message_ must be updated.
+// so the plaintext type varint fits the 2 bytes budgeted in HEADER_PADDING.
 struct MessageInfo {
   uint16_t offset;        // Offset in buffer where message starts
   uint16_t payload_size;  // Size of the message payload
-  uint8_t message_type;   // Message type (0-255)
+  uint16_t message_type;  // Message type (0-16383)
   uint8_t header_size;    // Actual header size used (avoids recomputation in write path)
 
-  MessageInfo(uint8_t type, uint16_t off, uint16_t size, uint8_t hdr)
+  MessageInfo(uint16_t type, uint16_t off, uint16_t size, uint8_t hdr)
       : offset(off), payload_size(size), message_type(type), header_size(hdr) {}
 };
 
@@ -173,7 +173,7 @@ class APIFrameHelper {
   }
   // Write a single protobuf message - the hot path (87-100% of all writes).
   // Caller must ensure state is DATA before calling.
-  virtual APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) = 0;
+  virtual APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) = 0;
   // Write multiple protobuf messages in a single batched operation.
   // Caller must ensure state is DATA and messages is not empty.
   // messages contains (message_type, offset, length) for each message in the buffer.
@@ -187,15 +187,15 @@ class APIFrameHelper {
   // Distinguishes protocols via frame_footer_size_ (noise always has a non-zero MAC
   // footer, plaintext has footer=0). If a protocol with a plaintext footer is ever
   // added, this should become a virtual method.
-  uint8_t frame_header_size(uint16_t payload_size, uint8_t message_type) const {
+  uint8_t frame_header_size(uint16_t payload_size, uint16_t message_type) const {
 #if defined(USE_API_NOISE) && defined(USE_API_PLAINTEXT)
     return this->frame_footer_size_
                ? this->frame_header_padding_
-               : static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint8(message_type));
+               : static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint16(message_type));
 #elif defined(USE_API_NOISE)
     return this->frame_header_padding_;
 #else  // USE_API_PLAINTEXT only
-    return static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint8(message_type));
+    return static_cast<uint8_t>(1 + ProtoSize::varint16(payload_size) + ProtoSize::varint16(message_type));
 #endif
   }
   // Get the frame footer size required by this protocol

esphome/components/api/api_frame_helper_noise.cpp

@@ -442,7 +442,7 @@ APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
 }
 // Encrypt a single noise message in place and return the encrypted frame length.
 // Returns APIError::OK on success.
-APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
+APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint16_t message_type,
                                                      uint16_t &encrypted_len_out) {
   // The noise frame header is written after encryption, when the size is known
 
@@ -472,7 +472,7 @@ APIError APINoiseFrameHelper::encrypt_noise_message_(uint8_t *buf_start, uint16_
   return APIError::OK;
 }
 
-APIError APINoiseFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
+APIError APINoiseFrameHelper::write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) {
 #ifdef ESPHOME_DEBUG_API
   assert(this->state_ == State::DATA);
 #endif

esphome/components/api/api_frame_helper_noise.h

@@ -31,7 +31,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
 #endif
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
+  APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 
  protected:
@@ -44,7 +44,7 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   APIError state_action_handshake_write_();
   APIError try_read_frame_();
   APIError write_frame_(const uint8_t *data, uint16_t len);
-  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint8_t message_type,
+  APIError encrypt_noise_message_(uint8_t *buf_start, uint16_t payload_size, uint16_t message_type,
                                   uint16_t &encrypted_len_out);
   APIError init_handshake_();
   APIError check_handshake_finished_();

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -5,6 +5,7 @@
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include "api_pb2.h"
 #include "proto.h"
 #include <cstring>
 #include <cinttypes>
@@ -252,24 +253,21 @@ ESPHOME_ALWAYS_INLINE static inline void encode_varint_16(uint16_t value, uint8_
   *p = static_cast<uint8_t>(value);
 }
 
-// Encode an 8-bit varint (1-2 bytes) using pre-computed length.
+// The generator rejects message IDs above MAX_MESSAGE_TYPE, so the type varint
-ESPHOME_ALWAYS_INLINE static inline void encode_varint_8(uint8_t value, uint8_t varint_len, uint8_t *p) {
+// can never outgrow the 2 bytes HEADER_PADDING budgets for it. Without this
-  if (varint_len == 2) {
+// bound, write_plaintext_header's header_offset would underflow for the first
-    *p++ = static_cast<uint8_t>(value | 0x80);
+// message in a batch and the header write would land outside the buffer.
-    *p = static_cast<uint8_t>(value >> 7);
+static_assert(1 + 3 + ProtoSize::varint16(MAX_MESSAGE_TYPE) <= APIPlaintextFrameHelper::HEADER_PADDING,
-  } else {
+              "HEADER_PADDING cannot fit the type varint of the largest message ID");
-    *p = value;
-  }
-}
 
 // Write plaintext header into pre-allocated padding before payload.
 // padding_size: bytes reserved before payload (HEADER_PADDING for first/single msg,
 //               actual header size for contiguous batch messages).
 // Returns the total header length (indicator + varints).
 ESPHOME_ALWAYS_INLINE static inline uint8_t write_plaintext_header(uint8_t *buf_start, uint16_t payload_size,
-                                                                   uint8_t message_type, uint8_t padding_size) {
+                                                                   uint16_t message_type, uint8_t padding_size) {
   uint8_t size_varint_len = ProtoSize::varint16(payload_size);
-  uint8_t type_varint_len = ProtoSize::varint8(message_type);
+  uint8_t type_varint_len = ProtoSize::varint16(message_type);
   uint8_t total_header_len = 1 + size_varint_len + type_varint_len;
 
   // The header is right-justified within the padding so it sits immediately before payload.
@@ -292,12 +290,12 @@ ESPHOME_ALWAYS_INLINE static inline uint8_t write_plaintext_header(uint8_t *buf_
 
   // Encode varints directly into buffer using pre-computed lengths
   encode_varint_16(payload_size, size_varint_len, buf_start + header_offset + 1);
-  encode_varint_8(message_type, type_varint_len, buf_start + header_offset + 1 + size_varint_len);
+  encode_varint_16(message_type, type_varint_len, buf_start + header_offset + 1 + size_varint_len);
 
   return total_header_len;
 }
 
-APIError APIPlaintextFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
+APIError APIPlaintextFrameHelper::write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) {
 #ifdef ESPHOME_DEBUG_API
   assert(this->state_ == State::DATA);
 #endif

esphome/components/api/api_frame_helper_plaintext.h

@@ -10,7 +10,8 @@ class APIPlaintextFrameHelper final : public APIFrameHelper {
   // Plaintext header structure (worst case):
   // Pos 0: indicator (0x00)
   // Pos 1-3: payload size varint (up to 3 bytes)
-  // Pos 4-5: message type varint (up to 2 bytes)
+  // Pos 4-5: message type varint (up to 2 bytes; covers message IDs up to
+  //          16383, enforced by the proto codegen)
   // Pos 6+: actual payload data
   static constexpr uint8_t HEADER_PADDING = 1 + 3 + 2;  // indicator + size varint + type varint
 
@@ -21,7 +22,7 @@ class APIPlaintextFrameHelper final : public APIFrameHelper {
   APIError init() override;
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
+  APIError write_protobuf_packet(uint16_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 #ifdef USE_API_NOISE
   // After try_read_frame_ returned PROTOCOL_SWITCH_TO_NOISE: copy out the

esphome/components/api/proto.h

@@ -684,11 +684,6 @@ class ProtoSize {
     return value < VARINT_THRESHOLD_1_BYTE ? 1 : (value < VARINT_THRESHOLD_2_BYTE ? 2 : 3);
   }
 
-  // Varint encoded length for an 8-bit value (1 or 2 bytes).
-  static constexpr inline uint8_t ESPHOME_ALWAYS_INLINE varint8(uint8_t value) {
-    return value < VARINT_THRESHOLD_1_BYTE ? 1 : 2;
-  }
-
   /**
    * @brief Calculates the size in bytes needed to encode a uint32_t value as a varint
    *

esphome/components/esp32_ble_tracker/__init__.py

@@ -143,6 +143,13 @@ def validate_max_connections_deprecated(config: ConfigType) -> ConfigType:
 # BLE uses the airtime wifi does not claim.
 IDF_SCAN_WINDOW_FIX_VERSION = cv.Version(5, 5, 5)
 
+# Above this the scanner holds the shared radio long enough that wifi drops
+# packets and connections on some access points (others cope fine, which is
+# why this is a warning and not an error); old proxy configs with 1100 ms
+# windows are a recurring cause of instability (esphome/esphome#18655). Only
+# wifi shares the radio; long windows are fine on ethernet builds.
+MAX_RECOMMENDED_WIFI_SCAN_WINDOW = TimePeriod(milliseconds=600)
+
 
 @dataclass
 class TrackerData:
@@ -209,6 +216,45 @@ def _raise_defaulted_scan_window(config: ConfigType) -> ConfigType:
     return config
 
 
+def _warn_long_scan_window_with_wifi(config: ConfigType) -> ConfigType:
+    """Warn when the scan window is long enough to starve wifi.
+
+    Runs after _raise_defaulted_scan_window so it sees the final window.
+    software_coexistence is only present when wifi is configured, so ethernet
+    builds never warn: BLE has the radio to itself there. Presence is what
+    matters, not the value; with the arbiter disabled a long window starves
+    wifi outright.
+    """
+    params = config[CONF_SCAN_PARAMETERS]
+    window = params[CONF_WINDOW]
+    if CONF_SOFTWARE_COEXISTENCE not in config:
+        return config
+    if window <= MAX_RECOMMENDED_WIFI_SCAN_WINDOW:
+        return config
+    if _get_data().scan_window_defaulted:
+        # The window was raised to match the interval, so point at the key the
+        # user actually set.
+        _LOGGER.warning(
+            "BLE scan interval of %s sets the scan window to the same value, "
+            "which starves wifi on the same radio and can cause wifi disconnects "
+            "depending on the access point; keep the interval at or below %s "
+            "(for example interval: 320ms). Long windows are only a problem with "
+            "wifi, they are fine on ethernet",
+            params[CONF_INTERVAL],
+            MAX_RECOMMENDED_WIFI_SCAN_WINDOW,
+        )
+        return config
+    _LOGGER.warning(
+        "BLE scan window of %s with wifi on the same radio starves wifi and "
+        "can cause wifi disconnects depending on the access point; keep the "
+        "window at or below %s (for example interval: 320ms, window: 300ms). "
+        "Long windows are only a problem with wifi, they are fine on ethernet",
+        window,
+        MAX_RECOMMENDED_WIFI_SCAN_WINDOW,
+    )
+    return config
+
+
 # 320 ms is the ESP-IDF reference scan interval; the shared schema also
 # tightens validation to the controller's 2.5 ms .. 10240 ms range and rejects
 # window/interval pairs that collapse to the same 0.625 ms unit count.
@@ -271,6 +317,7 @@ CONFIG_SCHEMA = cv.All(
     ).extend(cv.COMPONENT_SCHEMA),
     validate_max_connections_deprecated,
     _raise_defaulted_scan_window,
+    _warn_long_scan_window_with_wifi,
 )
 
 

script/api_protobuf/api_protobuf.py

@@ -475,6 +475,19 @@ TYPE_INFO: dict[int, TypeInfo] = {}
 # TYPE_DOUBLE = 1, TYPE_FIXED64 = 6, TYPE_SFIXED64 = 16, TYPE_SINT64 = 18
 UNSUPPORTED_TYPES = {1: "double", 6: "fixed64", 16: "sfixed64", 18: "sint64"}
 
+# The plaintext frame header budgets 2 varint bytes for the message type
+# (APIPlaintextFrameHelper::HEADER_PADDING), which caps message IDs at 16383.
+MAX_MESSAGE_ID = 16383
+
+
+def validate_message_id(message_id: int, message_name: str) -> None:
+    """Reject message IDs whose plaintext type varint would not fit in 2 bytes."""
+    if message_id > MAX_MESSAGE_ID:
+        raise ValueError(
+            f"Message ID {message_id} for {message_name} exceeds the plaintext "
+            f"2-byte type varint maximum ({MAX_MESSAGE_ID})"
+        )
+
 
 def validate_field_type(field_type: int, field_name: str = "") -> None:
     """Validate that the field type is supported by ESPHome API.
@@ -2549,14 +2562,10 @@ def build_message_type(
 
     # Add MESSAGE_TYPE method if this is a service message
     if message_id is not None:
-        # Validate that message_id fits in uint8_t
+        validate_message_id(message_id, desc.name)
-        if message_id > 255:
-            raise ValueError(
-                f"Message ID {message_id} for {desc.name} exceeds uint8_t maximum (255)"
-            )
 
         # Add static constexpr for message type
-        public_content.append(f"static constexpr uint8_t MESSAGE_TYPE = {message_id};")
+        public_content.append(f"static constexpr uint16_t MESSAGE_TYPE = {message_id};")
 
         # Add estimated size constant
         estimated_size = calculate_message_estimated_size(desc)
@@ -3212,8 +3221,12 @@ def main() -> None:
 #include "api_pb2_includes.h"
 """
 
-    content += """
+    content += f"""
-namespace esphome::api {
+namespace esphome::api {{
+
+// Upper bound on message IDs, enforced by the code generator: the plaintext
+// frame header budgets 2 varint bytes for the type (HEADER_PADDING).
+static constexpr uint16_t MAX_MESSAGE_TYPE = {MAX_MESSAGE_ID};
 
 """
 

tests/component_tests/esp32_ble_tracker/test_scan_window_default.py

@@ -12,6 +12,7 @@ arbiter a full-duty scan would starve wifi, so the 30 ms default is kept.
 from __future__ import annotations
 
 from collections.abc import Callable
+import logging
 from pathlib import Path
 
 import pytest
@@ -221,3 +222,54 @@ def test_connection_scan_window_codegen(
     assert window_call in main_cpp
     assert ("set_connection_scan_window(48)" in main_cpp) == connection_call
     assert ("'connection_scan_window' has no effect" in caplog.text) == warns
+
+
+@pytest.mark.parametrize(
+    ("wifi", "params", "expect_warning"),
+    [
+        (True, {"interval": "1100ms", "window": "1100ms"}, True),
+        (True, {"interval": "1100ms", "window": "601ms"}, True),
+        (True, {"interval": "1100ms", "window": "600ms"}, False),
+        (False, {"interval": "1100ms", "window": "1100ms"}, False),
+    ],
+)
+def test_long_window_with_wifi_warns(
+    stage_esp32: Callable[..., None],
+    caplog: pytest.LogCaptureFixture,
+    wifi: bool,
+    params: ConfigType,
+    expect_warning: bool,
+) -> None:
+    """A scan window above 600 ms warns only when wifi shares the radio."""
+    stage_esp32("5.5.5", wifi=wifi)
+    with caplog.at_level(logging.WARNING):
+        _scan_params({"scan_parameters": params})
+    assert ("starves wifi" in caplog.text) is expect_warning
+
+
+def test_long_window_warns_with_coexistence_disabled(
+    stage_esp32: Callable[..., None],
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """Disabling the arbiter is the worst case for a long window, so it still warns."""
+    stage_esp32("5.5.5", wifi=True)
+    with caplog.at_level(logging.WARNING):
+        _scan_params(
+            {
+                CONF_SOFTWARE_COEXISTENCE: False,
+                "scan_parameters": {"interval": "1100ms", "window": "1100ms"},
+            }
+        )
+    assert "BLE scan window of 1100ms" in caplog.text
+
+
+def test_raised_window_warning_points_at_interval(
+    stage_esp32: Callable[..., None],
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    """When the window was raised to a long interval, the warning names the interval."""
+    stage_esp32("5.5.5", wifi=True)
+    with caplog.at_level(logging.WARNING):
+        _scan_params({"scan_parameters": {"interval": "1s"}})
+    assert "BLE scan interval of 1s" in caplog.text
+    assert "BLE scan window of" not in caplog.text

tests/unit_tests/components/api/test_api_protobuf_generator.py

@@ -15,7 +15,12 @@ import pytest
 
 sys.path.insert(0, str(Path(__file__).parents[4] / "script" / "api_protobuf"))
 
-from api_protobuf import _make_ifdef_line, get_varint64_ifdef  # noqa: E402
+from api_protobuf import (  # noqa: E402
+    MAX_MESSAGE_ID,
+    _make_ifdef_line,
+    get_varint64_ifdef,
+    validate_message_id,
+)
 from google.protobuf import descriptor_pb2  # noqa: E402
 
 
@@ -91,3 +96,14 @@ def test_make_ifdef_line_conjunction_and_negation() -> None:
     assert (
         _make_ifdef_line("USE_X && !USE_Y") == "#if defined(USE_X) && !defined(USE_Y)"
     )
+
+
+def test_message_id_at_maximum_is_accepted() -> None:
+    # 16383 is the largest ID whose plaintext type varint fits the 2 bytes
+    # budgeted in HEADER_PADDING.
+    validate_message_id(MAX_MESSAGE_ID, "MaxMessage")
+
+
+def test_message_id_above_maximum_is_rejected() -> None:
+    with pytest.raises(ValueError, match="exceeds the plaintext"):
+        validate_message_id(MAX_MESSAGE_ID + 1, "TooBigMessage")