exemptMcpEndpoint compared origin + pathname, which misses legacy SSE
entirely: SSEClientTransport opens the configured URL and is handed a
SEPARATE message endpoint by the server, then POSTs every JSON-RPC
message to that second pathname. Those were bounded and body-buffered
as OAuth traffic, so a slow tool call over SSE would be severed at 30s
and reported as an OAuthRequestTimeoutError.
It compares origin alone now. That is exact rather than approximate:
the SDK enforces that the SSE message endpoint shares the stream URL's
origin and rejects one that does not, so every MCP request this chain
carries is same-origin with the configured URL by construction.
The cost, stated in the docblock and pinned by a test: an OAuth
endpoint on the MCP server's own origin is exempt here and so unbounded
on this chain. The OAuth chain still bounds the Inspector's own
requests to it, so only the SDK's transport-internal OAuth against a
same-origin server falls back to where it was before #2319.
Caller cancellation was also still swallowed in two later places in the
compat probe loop — `probe.text()` has its own catch, and `fetch`
resolves on headers, so an abort mid-body landed there and was answered
with the preceding 404; and an abort during releaseBody's await would
have carried on probing. Both recheck the signal now, and all three
sites throw the caller's own `reason` rather than whatever shape the
layer beneath rejected with.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YFnM6RqB4nXqNysgUYmjmq
Signed-off-by: cliffhall <cliff@futurescale.com>
5a1c157a79