Review feedback on #1987: `waitForDeadTransport` polled `/api/mcp/send`,
which answers `transport_error` from two branches — the `isTransportDead()`
short-circuit and the `catch` around a rejected `send()`. Only the first
implies the transport is marked dead, so the stop condition could not tell
them apart from the response alone.
That was safe in practice: `StdioClientTransport.send` rejects only when
`_process` is undefined, and the transport clears `_process` and calls
`onclose` in one synchronous block, so the `catch` branch is not observable
before `markTransportDead()` has run (confirmed empirically — 0/25 probes
returned early). But the safety rested on an SDK-internal ordering this test
neither states nor controls, and if it changed the send test would silently
cover the `catch` branch instead of the short-circuit it names — a regression
with no failing run attached to it.
Poll `/api/mcp/auth-state` instead. For a session connected without an
authState there is no auth provider, so `setAuthState` always throws and
`transport_error` there has exactly one source: the dead-transport
short-circuit. The route never awaits a transport response, so it cannot
hang either. Same cost, exact condition, no dependence on SDK internals.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WLYmVPVLdeYpE6aMTUsCks
b70aed6914