Pin the carve alignment, name the node-abort contract, fix strays

The static_assert enforces what the carve comment claims; the node header
now states that aborting inside on_connected() can leave on_disconnect
unpaired; the passive-proxy test comment names the current gate; the
pending-regs comment lands on the right member (lost to an aborted batch).

esphome/components/ble_client/ble_client.h

@@ -81,10 +81,11 @@ class BLEClient final : public BLEClientBase {
 
   std::vector<BLEClientNode *> nodes_;
 #ifdef USE_BLE_CLIENT_GATT_NODES
-  // Nodes on the neutral surface; fed the translated callbacks and
-  // auto-established after the on_connected fan-out.
+  // Raise if a migrated node needs more concurrent registrations.
   static constexpr uint8_t MAX_PENDING_NOTIFY_REGS = 4;
 
+  // Nodes on the neutral surface; fed the translated callbacks and
+  // auto-established after the on_connected fan-out.
   StaticVector<BLEClientNode *, ESPHOME_BLE_CLIENT_MAX_NODES> gatt_nodes_;
   // Reconnect backoff after materializer failures.
   ConnectBackoff gatt_backoff_;

esphome/components/ble_client/ble_client_node.h

@@ -28,6 +28,8 @@ class BLEClientNode {
   // Neutral surface, delivered by both engines. The table is borrowed: copy
   // handles during on_connected(). All nodes see all completions; filter by
   // handle.
+  // A node that disconnects from inside on_connected() aborts the fan-out;
+  // the user's on_disconnect may then fire without a preceding on_connect.
   virtual void on_connected(const ble_device_base::GattServiceTable &table) {}
   virtual void on_disconnected() {}
   virtual void on_notify(uint16_t handle, const uint8_t *data, uint16_t len) {}

esphome/components/bluetooth_connection/gatt_service_table_bluedroid.cpp

@@ -117,6 +117,8 @@ bool BluedroidServiceTable::build(esp_gatt_if_t gattc_if, uint16_t conn_id, uint
 
   // The arrays share one block; carving stays aligned because each struct's
   // strictest member is the UUID and array sizes are multiples of it.
+  static_assert(alignof(ble_device_base::GattService) == alignof(ble_device_base::GattCharacteristic) &&
+                alignof(ble_device_base::GattCharacteristic) >= alignof(ble_device_base::GattDescriptor));
   size_t svc_bytes = this->service_total_ * sizeof(ble_device_base::GattService);
   size_t char_bytes = char_total * sizeof(ble_device_base::GattCharacteristic);
   size_t total_bytes = svc_bytes + char_bytes + desc_total * sizeof(ble_device_base::GattDescriptor);

tests/components/bluetooth_proxy/test-passive.esp32-c6-idf.yaml

@@ -1,5 +1,5 @@
 # Advertisement-only proxy on esp32 by explicit choice: no GATT backend is
-# compiled (USE_BLE_GATT_CLIENT unset), which pins the SERVES_PROXY gating and the
+# compiled (USE_BLE_GATT_CLIENT unset), which pins the USE_BLUETOOTH_PROXY_CONNECTIONS gating and the
 # address-scoped maintenance path that a connections build never exercises.
 # Under batch grouping the active default build is what runs; the standalone
 # compile of this fixture is what exercises the passive gating.