fix(agent): Reconnect signed-commit MCP server after session refresh

[charlesvien]

Problem

In cloud runs, a session refresh disconnected the signed-commit MCP server (posthog-code-tools), so the agent could no longer commit and a turn's work appeared lost while raw git stays blocked.

Changes

1. Rebuild a fresh in-process server on refresh instead of reusing the dead instance (the SDK rejects re-connecting it with "Already connected to a transport")
2. Self-heal: reconnect the server before each prompt and when the guard hook blocks a raw git commit
3. Bound the status check with a timeout so a wedged control channel can't stall the turn
4. Clear stale MCP tool metadata cache on refresh and reconnect
5. Honest guard-hook message when signing is briefly unavailable (changes are safe in the working tree)
6. Tests for refresh rebuild, self-heal paths, status timeout, and guard wiring

How did you test this?

Manually

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

[charlesvien]

• fix(agent): Reconnect signed-commit MCP server after session refresh #2724 👈 (View in Graphite)
• main

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[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 9c3362c.}

[stamphog]

The PR exceeds the auto-review size limit and has zero reviews. The behavioral changes — in-flight mutation of session MCP state, pre-prompt self-healing before every cloud turn, and cache clearing on reconnect — are non-trivial and warrant a domain expert sign-off before auto-approval.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "simplify signed-commit heal and dedup te..." | Re-trigger Greptile}

[stamphog]

The PR exceeds the auto-review size limit (589 lines across 9 files), and the bot review flagged substantive behavioral concerns: in-flight mutation of session MCP state, pre-prompt self-healing before every cloud turn, and cache clearing on reconnect. These are non-trivial agent session management changes that need a domain expert sign-off.

[joshsny]

Should we allow attempts for non-signed commits? We've had quite a few issues with the signed commit tool and it's not required on all repos, on the other hand it's nice to have this available as an MCP tool that we can track and later restrict the permissions for, will leave it for you to decide