fix(t3-thread): restart the managed watcher after CLI deployment

[jimprince]

CLI snapshot deployment could leave a watcher using a runtime that pruning deletes. Restart the managed Linux user watcher after verified promotion, prove its service PID owns the live lease in that runtime, and protect every predecessor used by any live leased watcher before deletion. The same pruning guard covers unmanaged watchers and --prune-only.

The new namespace imports pass affected lint. All eight existing production cases plus six pruning cases pass; both unmanaged deletion regressions failed first and fail when the guard is removed. The gated Vite adapter passes through heavy-check, serially with lint. Separate real nested-cwd fixtures prove predecessor preservation in both paths.

Bounds: Linux boot/start/cwd verification; unknown/live legacy leases fail closed, stale identities and retained-current leases permit pruning. Non-Linux hosts with a lease fail closed and are untested. Read-only preflight/rechecks are point-in-time observations, not a lock against concurrent launch. No lease deletion or owner signalling.

Integration: exact refreshed fork-t3-thread-prebuilt stack source483520e9ea0c78fd3b26d4c0c49c165d3182c105, metadata f90f52e. Candidate CI attempt1 passed and the repository exact-source evidence validator accepted it: https://github.com/jimprince/t3code/actions/runs/37411637644/attempts/1. This PR is an exact-tree review snapshot; its ordinary merge preview cannot satisfy canonical StGit metadata policy. Do not merge it directly or relax the gate. Parent holds canonical stack integration; original publication leases pass read-only check. Installed CLI/live services and frozen PR81 remain untouched.

Tracking: https://git.bradleyprince.com/brad/t3code-fork/issues/150; bounded watcher repair record154. Infrastructure docs: https://git.bradleyprince.com/brad/local-controller/pulls/161.

Model: GPT-6.1-Sol. Harness: Codex in T3 Code.

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	−31 B (−0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	+4 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.4 KiB	−35 B (−0.5%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.3 KiB	56.2 KiB	−88 B (−0.2%)	66.4 KiB	✅
Codex	Live turn messages	10	8	−2 (−20.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	−4 B (−0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	−1 B (−0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	−3 B (−0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: 58ac47e · PR result: 39e1cae · Source CI: failure

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.0 KiB
• Claude decoded thread snapshot: 114.7 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.