diff --git a/veilid-python/tests/test_routing_context.py b/veilid-python/tests/test_routing_context.py
index eb730b80..8003ad56 100644
--- a/veilid-python/tests/test_routing_context.py
+++ b/veilid-python/tests/test_routing_context.py
@@ -4,6 +4,7 @@ import asyncio
 
 import pytest
 import veilid
+from veilid.types import OperationId
 
 from .conftest import server_info
 
@@ -20,7 +21,8 @@ async def test_routing_contexts(api_connection):
 
 @pytest.mark.asyncio
 async def test_routing_context_app_message_loopback():
-    app_message_queue = asyncio.Queue()
+    # Seriously, mypy?
+    app_message_queue: asyncio.Queue = asyncio.Queue()
 
     async def app_message_queue_update_callback(update: veilid.VeilidUpdate):
         if update.kind == veilid.VeilidUpdateKind.APP_MESSAGE:
@@ -51,13 +53,14 @@ async def test_routing_context_app_message_loopback():
         update: veilid.VeilidUpdate = await asyncio.wait_for(
             app_message_queue.get(), timeout=10
         )
-        appmsg: veilid.VeilidAppMessage = update.detail
-        assert appmsg.message == message
+
+        assert isinstance(update.detail, veilid.VeilidAppMessage)
+        assert update.detail.message == message
 
 
 @pytest.mark.asyncio
 async def test_routing_context_app_call_loopback():
-    app_call_queue = asyncio.Queue()
+    app_call_queue: asyncio.Queue = asyncio.Queue()
 
     async def app_call_queue_update_callback(update: veilid.VeilidUpdate):
         if update.kind == veilid.VeilidUpdateKind.APP_CALL:
@@ -88,12 +91,19 @@ async def test_routing_context_app_call_loopback():
         update: veilid.VeilidUpdate = await asyncio.wait_for(
             app_call_queue.get(), timeout=10
         )
-        appcall: veilid.VeilidAppCall = update.detail
+        appcall = update.detail
+
+        assert isinstance(appcall, veilid.VeilidAppCall)
         assert appcall.message == request
 
         # now we reply to the request
         reply = b"qwer5678"
-        await api.app_call_reply(appcall.call_id, reply)
+        # TK: OperationId use to be a subclass of `int`. When I wrapped `appcall.call_id` in int(),
+        # this failed JSON schema validation, which defines `call_id` as a string. Maybe that was a
+        # typo, and OperationId is really *supposed* to be a str? Alternatively, perhaps the
+        # signature of `app_call_reply` is wrong and it's supposed to take a type other than
+        # OperationId?
+        await api.app_call_reply(OperationId(appcall.call_id), reply)
 
         # now we should get the reply from the call
         result = await app_call_task
diff --git a/veilid-python/veilid/json_api.py b/veilid-python/veilid/json_api.py
index b7858f88..02007243 100644
--- a/veilid-python/veilid/json_api.py
+++ b/veilid-python/veilid/json_api.py
@@ -49,8 +49,8 @@ _VALIDATOR_RECV_MESSAGE = _get_schema_validator(
 
 
 class _JsonVeilidAPI(VeilidAPI):
-    reader: asyncio.StreamReader
-    writer: asyncio.StreamWriter
+    reader: Optional[asyncio.StreamReader]
+    writer: Optional[asyncio.StreamWriter]
     update_callback: Callable[[VeilidUpdate], Awaitable]
     handle_recv_messages_task: Optional[asyncio.Task]
     validate_schemas: bool
@@ -85,6 +85,7 @@ class _JsonVeilidAPI(VeilidAPI):
         await self.lock.acquire()
         try:
             self.reader = None
+            assert self.writer is not None
             self.writer.close()
             await self.writer.wait_closed()
             self.writer = None
@@ -138,6 +139,7 @@ class _JsonVeilidAPI(VeilidAPI):
     async def handle_recv_messages(self):
         # Read lines until we're done
         try:
+            assert self.reader is not None
             while True:
                 linebytes = await self.reader.readline()
                 if not linebytes.endswith(b"\n"):
@@ -225,6 +227,7 @@ class _JsonVeilidAPI(VeilidAPI):
 
         # Send to socket
         try:
+            assert writer is not None
             writer.write(reqbytes)
             await writer.drain()
         except Exception:
diff --git a/veilid-python/veilid/types.py b/veilid-python/veilid/types.py
index fa85057f..d1766fab 100644
--- a/veilid-python/veilid/types.py
+++ b/veilid-python/veilid/types.py
@@ -82,7 +82,7 @@ class ByteCount(int):
     pass
 
 
-class OperationId(int):
+class OperationId(str):
     pass