[BUG] Cowork — GitHub connector unusable: OAuth DCR unsupported, UI shows misleading state, Disconnect button dead

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Cowork's GitHub connector (plugin:engineering:github) is fully non-functional and cannot be reset. Five compounding issues:

1. OAuth fails immediately. When Claude invokes the connector's authenticate tool, it returns:

SDK auth failed: Incompatible auth server: does not support dynamic client registration. Ask the user to run /mcp and authenticate manually.

Root cause: GitHub's MCP server (https://api.githubcopilot.com/mcp/) does not support OAuth Dynamic Client Registration (RFC 7591), which is what Cowork's auto-auth uses.

1. The suggested fallback (/mcp) does not exist in Cowork. That slash command is a Claude Code feature. There is no documented manual-auth path inside Cowork mode.

1. UI shows misleading state. Customize → Connectors shows a Disconnect button next to GitHub, implying it's connected. In reality no tools loaded and no auth ever completed.

1. Disconnect button is unresponsive. Clicking it produces no state change, no error, no feedback. The connector cannot be reset from the UI.

1. App restart does not clear state. Quitting and relaunching the Claude desktop app does not reset the connector — the stale "Disconnect" UI persists.

Net result: no path to use GitHub from inside Cowork. Other engineering plugin connectors that support DCR (Linear, Slack, Notion, Atlassian) authenticate normally — this is GitHub-specific.

What Should Happen?

• The GitHub connector should either authenticate successfully or surface a usable manual-auth fallback inside Cowork (accept a personal access token, or a client ID/secret pair).
• The Customize → Connectors UI should reflect actual connection state — show Connect (not Disconnect) when auth has never completed.
• The Disconnect button should work and reset the connector to a clean state.
• The error message should reference a path that exists in Cowork, not /mcp (which is Claude Code only).

Error Messages/Logs

SDK auth failed: Incompatible auth server: does not support dynamic client registration. Ask the user to run /mcp and authenticate manually.

Steps to Reproduce

1. Open the Claude desktop app and switch to Cowork mode.
2. Open Customize → Connectors. Locate the Engineering plugin's GitHub connector.
3. In chat, ask Claude to do anything requiring GitHub (e.g., "show me recent commits on my repo").
4. Observe the OAuth handshake fail with: SDK auth failed: Incompatible auth server: does not support dynamic client registration. Ask the user to run /mcp and authenticate manually.
5. Return to Customize → Connectors. Note that GitHub shows a Disconnect button (implying connected), even though no tools loaded.
6. Click Disconnect. Nothing happens — no state change, no error, no feedback.
7. Quit and relaunch the Claude desktop app. The stale "Disconnect" state persists.

Note: /mcp (suggested by the error) is a Claude Code feature, not available in Cowork.

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

N/A — Claude desktop app (Cowork mode), not Claude Code CLI. Nathan to fill in actual app version.

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

Note on repo choice: This is a Cowork bug, not a Claude Code CLI bug. Filing here because existing Cowork bug reports (e.g. #29848, #50360, #49276) have been filed in this repo and triaged. Several required form fields (Claude Code Version, Terminal/Shell) don't really apply to Cowork — answered as best as possible.

Other engineering plugin connectors that authenticate fine (and use DCR): Linear, Slack, Notion, Atlassian — confirming the issue is GitHub-MCP-specific, not a Cowork-wide auth problem.

Suggested fixes (ordered by impact):

1. Add a manual OAuth path in Cowork for MCP servers that don't support Dynamic Client Registration — accept a personal access token, or a client ID/secret pair, via the connector UI.
2. Fix the Disconnect button in Customize → Connectors so the connector can be reset to a clean state.
3. Show Connect (not Disconnect) for connectors that have never completed auth, so the UI reflects actual state.
4. Update the SDK error message — the /mcp hint is not valid in Cowork (it's a Claude Code-only command). Point Cowork users to a Cowork-specific path.