Drive MCP connection login (RFC 8707 resource) from ucode mcp-proxy - #548
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sunishsheth2009 wants to merge 1 commit into
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Drive MCP connection login (RFC 8707 resource) from ucode mcp-proxy#548sunishsheth2009 wants to merge 1 commit into
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When an AI Gateway MCP service is backed by a per-user connection (e.g. system.ai.github) with no stored credential, the gateway answers a tools call with an RFC 9728 challenge (HTTP 401 + WWW-Authenticate resource_metadata). The proxy currently forwards that to the coding agent as a plain "tools fetch failed" — the connection login never happens. Teach the proxy's httpx auth to detect that challenge and drive an interactive resource-scoped OAuth login: authorization-code + PKCE against /oidc using the published databricks-cli app, with the MCP endpoint URL sent as the RFC 8707 resource indicator so /oidc routes through the connection's /mcp-service-login page. After login the connection credential exists, so the same request is retried and succeeds. - resource_login.py: standalone stdlib OAuth-with-resource flow + loopback callback. - mcp_proxy.py: async_auth_flow detects the challenge, runs the login off the event loop, and retries once. Skipped under DATABRICKS_BEARER (headless/CI). - Tests for authorize-URL/PKCE construction and challenge detection. Co-authored-by: Isaac <no-reply@databricks.com>
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What did you change, and why?
Change: Teach
ucode mcp-proxyto complete an MCP connection login when the AI Gateway asks for one.Why: When an AI Gateway MCP service is backed by a per-user connection (e.g.
system.ai.github) and the user hasn't logged in to that connection yet, the gateway answers a tools call with an RFC 9728 challenge — HTTP 401 +WWW-Authenticate: Bearer resource_metadata="…". A valid Databricks workspace token isn't enough; the connection needs its own login. Today the proxy just forwards that response to the coding agent, which showsconnected · tools fetch failedand the user is stuck with no way to log in.The proxy's
httpxauth now detects that challenge and drives an interactive resource-scoped OAuth login: authorization-code + PKCE against the workspace/oidc, using the publisheddatabricks-cliapp, sending the MCP endpoint URL as the RFC 8707resourceindicator. That indicator makes/oidcroute the browser through the connection's/mcp-service-loginpage → the user signs in to the backing SaaS → the connection credential is stored server-side → the flow returns → the proxy retries the original request, which now succeeds. No coding-agent OAuth (RFC 9728 / dynamic client registration) support required.How do you know it works?
Testing:
uv run pytest tests/test_resource_login.py tests/test_mcp_proxy.py— 35 passing. New tests cover the authorize-URL + PKCE construction and the401/resource_metadatachallenge detection; existing proxy tests still pass.ruff check/formatclean. The interactive browser + token-exchange path is validated end-to-end against staging separately (it requires the gateway-side RFC 9728 challenge to be enabled for the connection).Notes:
DATABRICKS_BEARER(headless/CI) — no browser to drive.resource_login.pyis stdlib-only (no new dependency).This pull request and its description were written by Isaac.