fix(ssh): reconnecting no longer restarts the remote server

[f4llenz]

Every time the desktop reconnected to an SSH host, it stopped the T3 server it had launched there and started a new one, ending every agent session that server was running. On one host the server restarted on nearly every reconnect, 10 times in one day. It is one of the triggers in #5749.

The launcher reads ~/.t3/userdata/server-runtime.json to find a server that took over the host, such as the background service. Its own server writes to that same file, so on the next connect the launcher took it for another server, stopped it, and then launched a replacement. Now it hands off only when the file names a different process. This does not stop two servers from sharing one home; that is the lock work in #8442 and #9652.

A new test runs the real launch script twice against a stand-in server: the second launch keeps the same server. It also checks that a genuinely different server is still adopted. Without the fix, the test fails because the second launch returns a new process.

Made with Claude Opus 5.5 in Claude Code.

Summary by CodeRabbit

• Bug Fixes
  • Fixed remote SSH launches to correctly reuse an existing server and recognize servers running in the default location.
  • Prevented a running server from being interrupted when its runtime information refers to that same server.

[macroscopeapp]

Approvability

Verdict: Approved at e61a017

Macroscope's review found this PR approvable — This is a small, well-scoped SSH bug fix that prevents a managed server from stopping itself while preserving handoff to a different server. An isolated regression test covers both reuse and external-server scenarios, with no schema, deployment, default, or static-analysis changes.

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• packages/ssh/src/runnerProcess.test.ts
• packages/ssh/src/tunnel.ts

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📝 Walkthrough

Walkthrough

The remote launch script now skips default-runtime handoff when that runtime belongs to the current SSH-managed server. A Unix-only integration test checks repeated launches, adoption of a different default-home server, and cleanup.

Changes

SSH runtime launch

Layer / File(s)	Summary
Runtime reuse and handoff packages/ssh/src/tunnel.ts, packages/ssh/src/runnerProcess.test.ts	The launch script excludes the current SSH-managed PID from the default-runtime handoff condition. The integration test checks managed-server reuse and adoption of another server. It also captures launched processes for cleanup.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to b8f84

The change appears ready to merge after normal checks; no actionable issue is established by the supplied evidence.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: preventing SSH reconnects from restarting the managed remote server.
Description check	✅ Passed	The description explains the problem, the fix, the scope, and the test coverage. It omits the template headings and checklist, but it provides the required substantive information and is focused.

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