Fix async/await bugs found by headless E2E test

- Make get_client() sync (was async but did no async work). Callers
  that omitted await silently got a coroutine object instead of the
  SerialClient, causing "'coroutine' object has no attribute 'connect'"
  errors on every tool call.

- Fix esp32_connect: use get_client_or_none() for init check and
  client.event_queue.wait_for() for boot event (wait_event() didn't
  exist on SerialClient).

- Normalise Response.data to dict at parse time — firmware returns
  bare strings on some error paths, which broke .get() calls in tool
  error handlers.

- Remove stale await from ble.py (9 calls) and classic.py (4 calls).

Tested with dual-MCP headless claude session: 26/27 PASS.

src/mcbluetooth_esp32/protocol.py

@@ -138,11 +138,15 @@ class Response:
     def from_json(cls, line: str) -> Response:
         """Parse a JSON line known to be a response."""
         obj = json.loads(line)
+        raw_data = obj.get("data", {})
+        # Firmware may return a bare string on some error paths — normalise to dict
+        if isinstance(raw_data, str):
+            raw_data = {"error": raw_data}
         return cls(
             type=MsgType(obj["type"]),
             id=obj["id"],
             status=Status(obj["status"]),
-            data=obj.get("data", {}),
+            data=raw_data if isinstance(raw_data, dict) else {},
         )
 
 

src/mcbluetooth_esp32/serial_client.py

@@ -263,7 +263,7 @@ class SerialClient:
 _client: SerialClient | None = None
 
 
-async def get_client() -> SerialClient:
+def get_client() -> SerialClient:
     """Get the singleton serial client.
 
     Raises:

src/mcbluetooth_esp32/tools/ble.py

@@ -35,7 +35,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             response = await client.send_command(CMD_BLE_ENABLE)
             return response.data
         except Exception as exc:
@@ -52,7 +52,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             response = await client.send_command(CMD_BLE_DISABLE)
             return response.data
         except Exception as exc:
@@ -76,7 +76,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {
                 "enable": enable,
                 "interval_ms": interval_ms,
@@ -108,7 +108,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {}
             if name is not None:
                 params["name"] = name
@@ -141,7 +141,7 @@ def register_tools(mcp: FastMCP) -> None:
             Dict containing the assigned service handle.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {
                 "uuid": uuid,
                 "primary": primary,
@@ -175,7 +175,7 @@ def register_tools(mcp: FastMCP) -> None:
             Dict containing the assigned characteristic handle.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {
                 "service_handle": service_handle,
                 "uuid": uuid,
@@ -207,7 +207,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {
                 "char_handle": char_handle,
                 "value": value,
@@ -231,7 +231,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {"char_handle": char_handle}
             response = await client.send_command(CMD_GATT_NOTIFY, params)
             return response.data
@@ -250,7 +250,7 @@ def register_tools(mcp: FastMCP) -> None:
             Status dict from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             response = await client.send_command(CMD_GATT_CLEAR)
             return response.data
         except Exception as exc:

src/mcbluetooth_esp32/tools/classic.py

@@ -30,7 +30,7 @@ def register_tools(mcp: FastMCP) -> None:
             Response data from the ESP32 including current BT state.
         """
         try:
-            client = await get_client()
+            client = get_client()
             response = await client.send_command(CMD_CLASSIC_ENABLE)
             if response.status == Status.OK:
                 return {"status": "ok", **response.data}
@@ -49,7 +49,7 @@ def register_tools(mcp: FastMCP) -> None:
             Response data from the ESP32 confirming BT is disabled.
         """
         try:
-            client = await get_client()
+            client = get_client()
             response = await client.send_command(CMD_CLASSIC_DISABLE)
             if response.status == Status.OK:
                 return {"status": "ok", **response.data}
@@ -75,7 +75,7 @@ def register_tools(mcp: FastMCP) -> None:
             Response data confirming the new discoverable state.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params = {"discoverable": discoverable, "timeout": timeout}
             response = await client.send_command(CMD_CLASSIC_SET_DISCOVERABLE, params)
             if response.status == Status.OK:
@@ -110,7 +110,7 @@ def register_tools(mcp: FastMCP) -> None:
             Response data with the pairing result from the ESP32.
         """
         try:
-            client = await get_client()
+            client = get_client()
             params: dict[str, Any] = {"address": address, "accept": accept}
             if passkey is not None:
                 params["passkey"] = passkey

src/mcbluetooth_esp32/tools/connection.py

@@ -32,9 +32,10 @@ def register_tools(mcp: FastMCP) -> None:
             Connection status including port, baudrate, and whether the
             device responded with a boot event.
         """
-        try:
+        from ..serial_client import get_client_or_none
-            client = get_client()
+
-        except NotConnected:
+        client = get_client_or_none()
+        if client is None:
             client = init_client(port=port, baudrate=baudrate)
 
         try:
@@ -45,7 +46,7 @@ def register_tools(mcp: FastMCP) -> None:
         # Give the ESP32 a moment to send its boot event
         boot_received = False
         try:
-            event = await asyncio.wait_for(client.wait_event("boot"), timeout=2.0)
+            event = await client.event_queue.wait_for(event_name="boot", timeout=2.0)
             boot_received = event is not None
         except TimeoutError:
             pass