feat(worktrees): track setup progress and recover cancelled drafts

[rynfar]

New worktrees previously exposed little setup progress, and a cancelled or interrupted setup could strand its prompt or leave a starting session behind. This adopts the complete upstream setup series across server, web/desktop, and mobile: staged checkout/script progress, cancellation with cleanup, durable prompts and history, optional blocking setup scripts, and a fresh composer for background sends.

Pylon adaptations preserve admission receipts, source epochs, compaction, provider ownership, remote authorization and existing message context. Additional fixes retain retry drafts through early prompt persistence, keep failed background sends separate from newer drafts, settle interrupted preparing receipts even when rollback fails, scope retention timers, and stop motion when hidden, unfocused or reduced-motion is enabled. Canonical sandbox paths are excluded from session discovery on macOS.

Closes #605. Continues #598 and the existing-port reconciliation in #604. The review cursor stays unchanged. This group accounts for 10 of the 164 remaining sources in the frozen range, leaving 154 after merge. No release or physical-device update is included.

Verification

• 1,389 focused tests passed across 27 files, including the new draft-retention regression and the 64-test timeline rendering suite.
• Scoped typechecks passed for server, web, mobile, contracts, client-runtime and desktop; final web and mobile checks passed after recovery and native sheet changes. Scoped lint reports no errors.
• Mutation check: the preparing-receipt regression fails with the old implementation and passes with the fix.
• Isolated web and iOS: live stages and script output; leaving/reopening; cancellation removes the worktree without starting a provider; foreground cancellation restores the original prompt; iOS cancellation of a background send preserves both the original prompt and a separately edited new draft.
• Before/after clients use baseline 2ed2480add and the task implementation against the same disposable setup. Before/after screenshots and web videos and final iOS cancellation evidence are uploaded. iOS is the representative native platform; Android-specific sheet execution was not exercised. Blocking scripts and live cancellation require an updated server; older servers retain their existing behavior.
• Final native check: Details → Cancel setup → Edit task restores both the original prompt and an additional note entered during setup. The iOS modal uses the existing React Native layout to keep its buttons responsive.
• Rebased cleanly onto ad3325050d (including fix(prime): restore follow-up input after stopping subagents #606), whose Prime-only changes do not overlap this series. CI must pass on the PR head before merge.

Upstream attribution

Original author commits are preserved with cherry-pick provenance. Thanks to the upstream contributors for the complete setup series; Pylon-specific follow-up fixes are in a separate commit.

• dd6ba84dc96f83000388e14b90f6533d5f63315d — fix(server): fall back when new worktrees are unavailable (#6208)
• 73b206f4bf99e7e98ae144a9d9edbf7cb2700fc1 — feat(web): show each worktree setup step and let users cancel it (#11372)
• 5ea6439816470288d3f2b6b43635fea41fbbb101 — feat(web): inline worktree setup rows and async setup scripts (#11832)
• 5623089aea68ca62811f51321686c259fa4c810f — fix(server): disable color probes in worktree setup (#11843)
• 0310cbf9f46ca94e9df0231a3440bca08ac44709 — fix: keep worktree setup visible after leaving and reopening the thread (#11836)
• 2c19283afed1e3b69a9af33360980527aeb37494 — feat(server): persist the worktree setup send and progress on the thread (#11852)
• ae53072af0560c0606202b87b5fdb7e52d48ac5c — fix(web): keep the composer ready during background worktree setup (#11883)
• 0f5a1513e09fb41e0d0f86157aff64cc3657975d — fix(web): stop the worktree setup card from flashing and shifting (#12015)
• 3bee4c286e586c2eb7f8d196a65b4b5ea6a95241 — fix(server): settle cancelled worktree setup before rollback (#12176)
• 4abb07eac3d47543b5804e8039633ac8ad7f67d2 — feat(mobile): port worktree setup progress and agent handoff (#12177)

Implemented with GPT-6 in Codex.

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Project	Deployment	Actions	Updated
pylon-marketing	Ready	Preview	Sep 17, 2026 7:34pm UTC

[rynfar]

Verified against disposable Pylon state. Baseline 2ed2480add and updated clients show the same running setup.

Web before	Web after

iOS before	iOS after	iOS details

Cancellation restored the original prompt to its draft:

Live progress and details:

web-setup-progress.mp4

Cancellation and prompt recovery:

web-cancel-recovery.mp4

Also verified: cancelling a background setup from iOS removes its worktree, restores "Original background task prompt." in its original draft, and leaves "New draft must stay untouched." in the separate fresh web draft. No provider turn started. The setup used an intentionally waiting script to exercise cancellation.

[rynfar]

@codex review

[rynfar]

Completed the combined-diff review, including upstream PR context and Pylon entry points. Findings fixed before landing:

• Preparing-session receipt interruption now records failure if thread rollback also fails; the regression fails without the fix.
• Early prompt persistence no longer finalizes the web retry draft before an agent owns it. Live cancellation returns the original prompt.
• Background failure recovery only updates its own draft; a separate newly edited draft remains intact (verified by cancellation from iOS).
• Retention timers belong to the service scope. Native/web motion stops when unfocused or backgrounded and respects reduced motion.
• Live setup subscriptions are capability-gated for older servers. Existing auth scopes, admission state, compaction/source epochs, inline context, and provider-specific code are preserved.
• macOS canonical worktree paths remain excluded from imported-session scanning; the previous test failure also reproduced at baseline.

CI's unused-export finding was fixed in b60c5a4a53291edac60cdfea57e59baca9af24f3. Final-head CI remains the merge gate. The automated review request has not returned a review; this is the implementation agent's review, not an independent approval.

[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	13.9 KiB	14.0 KiB	+41 B (+0.3%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.2 KiB	7.2 KiB	0 B (0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.7 KiB	6.8 KiB	+41 B (+0.6%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	58.0 KiB	58.0 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	14.0 KiB	14.0 KiB	−11 B (−0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.2 KiB	7.2 KiB	−14 B (−0.2%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.8 KiB	6.8 KiB	+3 B (+0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	58.9 KiB	58.9 KiB	+44 B (+0.1%)	66.4 KiB	✅
Claude	Live turn messages	9	10	+1 (+11.1%)	21	✅

Baseline: ad33250 · PR result: 01c1f50 · 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: 115.6 KiB
• Claude decoded thread snapshot: 116.3 KiB

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

[rynfar]

Final iOS verification: replaced the nested navigation stack inside the setup modal because its React actions did not receive taps. The existing React Native modal layout responds immediately. A fresh mobile send was cancelled from Details; Edit task recovered both the original prompt and the note entered during setup. Cancellation also worked after reopening the app. The server removed both unfinished threads without starting a provider turn.

Updated sheet, recovered draft, and native cancellation video:

mobile-cancel-recovery.mp4