feat(oauth): make proactive token refresh window configurable (--oauth-refresh-leeway)#57
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The 60 s leeway in ensure_token() was hard-coded; tune via the new --oauth-refresh-leeway SECONDS flag (or MCP_OAUTH_REFRESH_LEEWAY env var). Default 60 s preserves existing behaviour. Negative values are rejected at parse time. Use cases (cf. mcp-remote#252): - ASes whose refresh token lifetime is barely longer than the access token's — the default 60 s margin can race expiry; raise leeway for clock-skew tolerance. - Deployments with extremely short access tokens — drop leeway towards 0 to keep cache hits useful. Cross-linked in WORKAROUNDS.md alongside typescript-sdk#1954, which documents the upstream side of the bug (no leeway check at all). Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
- Replace ineffective patch.dict('os.environ', {}, clear=False) with
monkeypatch.delenv for proper teardown
- Pass env var value as string to argparse so invalid values surface as
argparse errors instead of a raw Python ValueError on startup
- Add test for invalid env var value (covers the new error path)
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
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Fixes #56
Summary
--oauth-refresh-leeway SECONDS(default60, env varMCP_OAUTH_REFRESH_LEEWAY)ensure_token()cache-validity checkWhy
mcp-stdio already does proactive token refresh —
ensure_token()treats acached access token as expired when its real expiry is within 60 s. This is
fine for most ASes, but a real-world deployment (mcp-remote#252)
issues refresh tokens that outlive the access token by only ~1 s. Under those
conditions, even mcp-stdio's 60 s window is too generous: the refresh races
the AS revocation. Make the window tunable.
A related upstream bug is typescript-sdk#1954
—
adaptOAuthProvider.token()returns expired tokens with no leeway check atall. mcp-stdio is structurally immune to that side; this PR is purely about
exposing configurability of the leeway we already have.
Scope
src/mcp_stdio/oauth.py—ensure_token()gainsrefresh_leeway: float = 60.0src/mcp_stdio/cli.py— new flag + env var +_non_negative_floatargparse typerelay.py(the 401-reactive refresh path) — untouched, leeway is proactive onlyTest plan
pytest tests/ -v— 367 tests pass (+7 new)TestEnsureToken: leeway=0 / leeway=300 / default leeway=60TestMain: default / flag / env var / negative-rejectionmcp-stdio --helpshows the new flagmcp-stdio --oauth-refresh-leeway -1 ...exits with argparse error🤖 Generated with Claude Code