Upstream integration cycle: reliability and client recovery

[rynfar]

Continue the frozen upstream review bbedad0278bbf753503184c00e0c09a0eab6679c..6d1d549441be84f19696ab59ed7e2fbf305280d4 against Pylon after notification integration #583 (00b2ffc23f0a945bbf658de40acae281ae2fd69d). User approved proceeding with the recommended catch-up sequence. No new upstream inventory is needed.

Implement and verify these bounded groups in separate PRs:

• Antigravity health and runtime temp ownership: 8c18b5bb21a5349fbadba8c77456ea34c41b7339 (#12008). Preserve concurrent process ownership; no blanket deletion of shared temp roots.
• Checkpoint correctness: 8130a9f13a1ef506f4393423ded21d71f3c9b5e4 (#10944), d42a3bd2ae3e698141b26f6426aa28d8886e1754 (#8432).
• Git/turn responsiveness: 901db896691da5ab7b7428ef8a5da52883f831dd (#11970), 5b377e2a047569ff928ccc6b07a900f698332496 (#11405).
• Desktop startup/paste and cached history: b20d29dc438bcabb2c25e85976dc108169bb4c6d (#11857), 96bddf81258090690bfcf4e6a6414aa0dcf1910a (#11958), a5da32750125c3bedb959bf331e5e49e95b95e5d (#8309).

Keep the global review cursor unchanged. The rest of the saved 209-source inventory remains outside this bounded implementation sequence; 25 sources have merged Pylon-history matches requiring no blind re-port. No release or installation is authorized. Merge each PR only with green final-head checks and developer approval.

Verification: focused regressions and scoped server/client/desktop typechecks and lint. CI owns repository-wide checks. UI changes require isolated browser evidence. Preserve Prime, exact rollback, cancellation, provider ownership, and remote/multi-environment contracts.

[rynfar]

Implementation checkpoint against Pylon 00b2ffc23f0a945bbf658de40acae281ae2fd69d; frozen upstream head unchanged.

• fix(antigravity): avoid spawning runtimes for health checks #586 Antigravity health/temp ownership: head 7f57442be7; 61 focused tests, server typecheck/lint pass. CI green at this checkpoint. Excludes unsafe blanket startup sweep; abrupt termination may leave runtime temp directories.
• fix(checkpoints): publish durable refs and preserve captured state #588 checkpoint durability/projection: head 2087600460; 57 focused tests including real capture/restore, server typecheck/lint pass. Preserve Pylon capture path; no unrelated sparse-index optimization.
• fix(clients): prevent duplicate startup and preserve cached history #589 desktop startup/cached history: head 8f71409ba9; 37 focused tests, desktop/client-runtime/web typechecks and lint pass. #11958 covered by absent custom paste dispatch, not imported.
• fix(server): keep Git waits off provider lifecycle ingestion #590 Git/turn responsiveness: head 41a964aee7; 175 focused tests, server typecheck/lint pass. Confirmed diffs re-enter Pylon runtime/Stop/incarnation fences; regression covers retirement while detection is pending. The upstream new-turn-after-failure test now makes a user admission, matching Pylon's lifecycle rules.

CI is being checked on the remaining heads. These four PRs are not merged; the approval to merge #583 has already been fulfilled and is not treated as blanket approval for these new PRs. No release/installation performed. Each PR carries source attribution and a compact ledger entry. The global review cursor remains unchanged.

Remaining review groups after this bounded sequence: durable worktree setup/follow-ups, provider/chat features, source-control improvements, broader UI/mobile work, and the coordinated distribution series described in the initial inventory. No new upstream fetch expands the frozen range.

[rynfar]

All four implementation PRs now have green active CI checks on their current heads, with no submitted review findings:

PR	Final checked head	Focused tests
#586 Antigravity health/temp ownership	7f57442be7bc7f9975dbaa25f457e3436d6c98a2	61
#588 Checkpoint durability/projection	2087600460e2fa99a466ee20fc02341ce61cbe87	57
#589 Desktop startup/cached history	8f71409ba90cebab039609233cab0e3aae3f0700	37
#590 Git/turn responsiveness	41a964aee7174f60462b11d4c4b2ce476ed6cf94	175

330 focused tests pass in total, plus the scoped typechecks/lint and CI. Seven sources are implemented and one paste-fix source is covered by Pylon's absent custom dispatch path. The PRs await developer merge approval. Merge through PRs, resolve any ledger-only conflicts while preserving all records, and require checks on any updated head. No release or installation performed; review cursor unchanged.

The isolated notification verification servers and browser from #583 have been stopped; reproduction state and uploaded evidence are preserved. Implementation worktrees are clean and remain available. No new backend is running for these four batches.

[rynfar]

Completed with developer merge approval and green final-head checks:

• fix(antigravity): avoid spawning runtimes for health checks #586 Antigravity installation-only health probes and owned runtime temporary directories. Merge 5dad0b0cba0752f0e90dbe0eb7745d2f793f1c5e.
• fix(checkpoints): publish durable refs and preserve captured state #588 Durable checkpoint objects/refs and monotonic checkpoint projection. Merge ad808bf7920647d3df0ebcb1674f94d006d24c26.
• fix(clients): prevent duplicate startup and preserve cached history #589 Single desktop startup and cached history/pagination recovery. Merge eb61689f842dead7c036056c51297cea1199c7ef.
• fix(server): keep Git waits off provider lifecycle ingestion #590 Bounded short Git command concurrency and diff detection outside lifecycle ingestion, retaining Pylon admission/Stop/runtime fences. Merge 1eedd6713c0ebeffb25490fb842e4c95cf5109be.

330 focused regressions passed during implementation, with scoped types and lint. After #586 landed, the remaining branches were rebased in dependency order; only the upstream review log conflicted, and all entries were retained. Range comparisons confirmed unchanged implementation patches. All refreshed CI checks passed, including Linux/Windows packaged desktop smoke. The final merged product tree exactly matches the tested #590 head 65586a2dd5fbcdaad9fc8cee65e436e8550e9835.

Original source authorship and cherry-pick source references are preserved through merge commits. Seven bounded upstream sources were adopted; the paste source is covered by Pylon's absence of the duplicate custom dispatch. All eight sources in this issue have a disposition. Task branches were removed; isolated worktrees retained detached and clean.

The broader frozen review remains incomplete and its global cursor is unchanged. This closes only the approved reliability/client-recovery batch. No release or installation was performed.