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[v2] ClientSession runs on JSONRPCDispatcher; BaseSession removed (#2838)

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Max 2026-06-15 14:46:34 +01:00 • committed by GitHub
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23
tests/interaction/README.md
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@ -193,11 +193,13 @@ many requirements at once; if the assertions would be separate, write separate t
### Notifications and concurrency
The client's receive loop dispatches each incoming message to completion before reading the next,
and the in-memory transport delivers everything on one ordered stream. Together these guarantee
that every notification a server handler emits before its response reaches the client callback
before the originating request returns — so tests collect notifications into a plain list and
assert after the call, with no synchronisation. The exceptions:
The client's dispatcher starts a task per incoming notification in arrival order but does not
await it before reading the next message, so completion order is not structural. What still
holds: the in-memory transport delivers everything on one ordered stream, and a callback that
records synchronously (no `await` before the append) finishes its scheduling slice before the
awaited request's waiter — woken strictly later — resumes. So tests whose callbacks are plain
appends may still collect into a list and assert after the call. A callback that awaits before
recording loses that ordering and must synchronise. The other exceptions:
- a notification not triggered by a request the test is awaiting needs an `anyio.Event` set in
the receiving handler and awaited under `anyio.fail_after(5)`;
@ -220,9 +222,8 @@ but still inside an outer `async with`, and no restructure can avoid it.
A handful of `# pragma: lax no cover` markers in `src/` cover teardown exception handlers whose
execution is timing-dependent under the in-process HTTP bridge — the POST-stream and
stateless-session `except Exception` handlers in `server/streamable_http*.py`, the `_terminated`
check in `message_router`, and the response-stream double-close guard in
`BaseSession._receive_loop`. `strict-no-cover` does not check `lax` lines; do not promote them to
strict `no cover` without first making the teardown ordering deterministic. The suite also relies
on a one-line `src/mcp/server/sse.py` fix (`sse_stream_reader.aclose()`) that closes a stream the
SSE leg would otherwise leak.
stateless-session `except Exception` handlers in `server/streamable_http*.py` and the
`_terminated` check in `message_router`. `strict-no-cover` does not check `lax` lines; do not
promote them to strict `no cover` without first making the teardown ordering deterministic. The
suite also relies on a one-line `src/mcp/server/sse.py` fix (`sse_stream_reader.aclose()`) that
closes a stream the SSE leg would otherwise leak.