The dispatch wrapper was rewriting scope['path'] from '/mcp' to '/'
before handing off to FastMCP. But FastMCP's streamable_http_app
mounts the JSON-RPC handler at '/mcp' (its default), so the rewritten
'/' had no matching route and FastMCP returned 404. Auth middleware
was correctly firing first (a no-auth request still gets 401), the
bug was only on the post-auth path.
Symptom: `claude mcp add ...` succeeds, registration shows in
`claude mcp list`, but connection fails because the initialize
handshake returns 404 instead of an MCP capabilities response.
Fix: pass the scope through unmodified. FastMCP's own routing matches
the '/mcp' path.
Also tightened the integration test that should have caught this —
it was asserting `status != 401`, which a 404 trivially passes. Now
asserts `== 200`, the actual expected response for initialize.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
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