fix(server): allow forks from provider-finished runs

[Yash-Singh1]

What Changed

Allow forks from completed, waiting, failed, interrupted, and cancelled runs. Keep in-progress and rolled-back runs ineligible. Update the Codex replay fixtures and recording script to match current app-server behavior.

Why

A provider-finished run can still have a usable native thread or transcript, even when it ends because of a usage limit or another failure. Restricting forks to completed runs blocked users from continuing that work in a new thread.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

[macroscopeapp]

Approvability

Verdict: Approved at 778fae5

Macroscope's review found this PR approvable — This is a localized server bug fix that permits forks from provider-finished runs while keeping active and rolled-back runs blocked. Native versus portable fork behavior is explicitly bounded and covered by execution tests, with no schema, security, billing, deployment, or default-setting impact.

^{You can add or adjust custom eligibility rules. Learn more.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	4.9 KiB	—	6.8 KiB	✅
Codex	Thread snapshot wire	—	3.7 KiB	—	4.9 KiB	✅
Codex	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Codex	Live turn WebSocket decoded	—	20.4 KiB	—	29.3 KiB	✅
Codex	Live turn messages	—	2	—	8	✅
Claude	Total thread wire	—	4.9 KiB	—	6.8 KiB	✅
Claude	Thread snapshot wire	—	3.7 KiB	—	4.9 KiB	✅
Claude	Live turn WebSocket wire	—	1.2 KiB	—	2.0 KiB	✅
Claude	Live turn WebSocket decoded	—	20.8 KiB	—	29.3 KiB	✅
Claude	Live turn messages	—	2	—	8	✅

Baseline: unavailable · PR result: 778fae5 · Source CI: success

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: 106.1 KiB
• Claude decoded thread snapshot: 106.4 KiB

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