[Ryan Waskewich (rwask)]

Summary

The hosted Cloud MCP (mcp.airbyte.com, 1.0.0-rc.42) returns HTTP 500 on every POST /auth/login, so no new user can finish OAuth sign-in. Already-authenticated sessions are unaffected. Datadog shows ~518 failures since 2026-11-06 22:37 UTC:

Exception in ASGI application | ConsentMixin._set_consent_binding_cookie() takes 4 positional arguments but 5 were given

fastmcp 4.1.7 dropped the request parameter from the private _set_consent_binding_cookie. Our fastmcp>=4.0.9,<5.0 range let the prod image resolve 4.1.8, while AirbyteSsoOidcProxy._redirect_upstream still passed request.

Changes:

• _redirect_upstream: self._set_consent_binding_cookie(response, txn.txn_id, consent_token) (no request).
• fastmcp floor raised to >=4.1.7,<5.0; uv.lock resolves 4.1.8.
• check_fastmcp_compatibility() now also checks the positional parameters of _set_consent_binding_cookie, _verify_consent_binding_cookie and _build_upstream_authorize_url, so future signature drift fails at startup instead of on each login.
• Tests: signature-drift coverage, and POST /auth/login (default and SSO) asserts a 302 to the upstream with a transaction-bound consent cookie.

Test plan: pytest tests/unit_tests/test_mcp_sso_auth.py (130 passed), ruff check, pyrefly check. Not yet verified against prod; after release + redeploy, confirm POST /auth/login no longer returns 500 for service:cloud-mcp.

Requested by Ryan Waskewich (Ryan Waskewich (@rwask)).

Link to Devin session: https://app.devin.ai/sessions/aefbc0c0a8764137a0dc2a1a77d252aa
Open in Devin Desktop: https://app.devin.ai/desktop/session/aefbc0c0a8764137a0dc2a1a77d252aa?variant=devin

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring

[github-actions]

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[github-code-quality]

Code coverage overview

Languages: Python

Python / code-coverage/pytest-no-creds

release-candidate/v1 d9f652f	devin/1794496558-fix... b5b2c80	+/-
65%	81%	+16%

View coverage of the 10 most impacted files.

File	release-candidate/v1 d9f652f	devin/1794496558-fix... b5b2c80	+/-
airbyte/_util/api_util.py	36%	66%	+30%
airbyte/mcp/cloud.py	52%	87%	+35%
airbyte/cloud/connectors.py	34%	81%	+47%
airbyte/cloud/connections.py	26%	76%	+50%
airbyte/mcp/_datadog.py	0%	50%	+50%
airbyte/mcp/_telemetry.py	0%	94%	+94%
airbyte/cloud/c...lder/project.py	0%	94%	+94%
airbyte/_direct...ctors/models.py	0%	95%	+95%
airbyte/mcp/_sso_auth.py	0%	96%	+96%
airbyte/cloud/models.py	0%	96%	+96%

Python / code-coverage/pytest

release-candidate/v1 d9f652f	devin/1794496558-fix... b5b2c80	+/-
71%	83%	+12%

View coverage of the 10 most impacted files.

File	release-candidate/v1 d9f652f	devin/1794496558-fix... b5b2c80	+/-
airbyte/cloud/connectors.py	51%	84%	+33%
airbyte/mcp/cloud.py	52%	87%	+35%
airbyte/cloud/connections.py	34%	77%	+43%
airbyte/mcp/_datadog.py	0%	50%	+50%
airbyte/mcp/_telemetry.py	0%	94%	+94%
airbyte/cloud/c...lder/project.py	0%	94%	+94%
airbyte/_direct...ctors/models.py	0%	95%	+95%
airbyte/mcp/_sso_auth.py	0%	96%	+96%
airbyte/cloud/models.py	0%	96%	+96%
airbyte/mcp/int...nc_status_ui.py	0%	97%	+97%

Python / code-coverage/pytest-unit

release-candidate/v1	devin/1794496558-fix... b5b2c80	+/-
—	78%	—

Line coverage data for the release-candidate/v1 branch is not yet available.

View coverage of the 10 most covered files.

File	release-candidate/v1	devin/1794496558-fix... b5b2c80	+/-
airbyte/mcp/_sso_auth.py	—	96%	—
airbyte/cloud/models.py	—	96%	—
airbyte/_direct...ctors/models.py	—	95%	—
airbyte/cloud/client.py	—	91%	—
airbyte/mcp/cloud.py	—	87%	—
airbyte/cloud/connectors.py	—	81%	—
airbyte/progress.py	—	80%	—
airbyte/cloud/connections.py	—	76%	—
airbyte/shared/...ql_processor.py	—	68%	—
airbyte/_util/api_util.py	—	66%	—

ℹ️ Calculations represent line coverage. Results may change as calculations are updated.

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_{Updated November 12, 2026 15:35 UTC}