Files
PaperClipAI/doc
DottaandClaude Opus 5.5 fd6e71a7ff fix(native): restore a warm backup when its source sandbox is idle (#20627)
## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - Native runs on remote sandboxes keep a warm sandbox and a verified
harness backup so the next run continues the same provider session
> - A run that starts while the previous run's workspace export is still
saving gets a new (created) sandbox lease, because reuse skips an
exporting sandbox
> - When that run prepares the harness, it finds a backup but no
recorded reusable lease, and it fails closed with
`runner_harness_state_mismatch: backup_without_reusable_lease`
> - #20278 accepted a destroyed source and a settled restore hold as
retired backup sources, but not an idle warm source that is still
`retained` for reuse
> - This pull request accepts an idle warm source under the same proofs,
claims it so it is never resumed again, and covers the resumed lease
that the failed run leaves behind
> - The benefit is that these recoveries continue the same session
automatically instead of blocking the task

## Linked Issues or Issue Description

Refs #20278

**What happened?**
A monitor wake started about 90 seconds after the previous run on the
same task finished. The previous run's warm sandbox lease was `retained`
with policy `reuse_by_environment`, but its workspace export was still
saving. Reuse skipped it and created a new sandbox. Workspace
realization waited for the export (about 136 s) and restored the saved
files. Then harness preparation found the previous run's backup (its
lease stamp names this exact manifest, and no provider work followed
it). The source lease was not destroyed and was not a restore hold, so
the run failed with `native_session_recovery_failed: Error:
runner_harness_state_mismatch: backup_without_reusable_lease` and the
task was blocked.

**What did you expect?**
The run continues the same provider session. The idle source sandbox
holds exactly the backed-up state, so restoring the backup into the new
sandbox is safe.

**Steps to reproduce**
1. Finish a warm native run on a remote sandbox. Its workspace export is
still saving.
2. Start the next run on the same task before the export settles.
3. Reuse skips the exporting sandbox and creates a new lease. Harness
preparation fails with `backup_without_reusable_lease`.
4. A retry resumes that new lease, which has no harness state, and fails
with `resumed_unavailable`.

## What Changed

- `native-retired-backup-source.ts`: an idle warm source is a third
retired backup source. It must be `released` or `retained` with policy
`reuse_by_environment`, its own run must be terminal and not the current
run, and it must have no cleanup in flight, no restore hold or pending
shutdown settlement, and no pending native workspace export. The backup
stamp, single-owner chain, and later-provider-work checks still apply.
- Before the restore, the idle source is claimed with a compare-and-swap
on the checked row. The claim moves its `reusableSandboxLease` scope
into a `reusableSandboxLeaseSuperseded` receipt. Reuse never resumes
that older state again, and the next acquisition treats it as obsolete
and destroys it. If a run resumed or changed the source first, the claim
matches no row and the backup is not restored.
- `environments.ts`: a cross-run reuse handoff now requires that the
source row has no superseded receipt. The supersede claim and the
handoff compete on the same row, so an acquisition that selected the
source before the claim cannot resume it afterward.
- The proof now rejects a backup whose source is the target allocation
itself (`targetProviderLeaseId`).
- `native-session-executor.ts`: a resumed lease whose sandbox has no
harness state at all (`unavailable`) restores the backup under the same
proof. This recovers the lease that the failed run left behind, so rows
saved by older releases recover after deploy without a migration.
- `doc/execution-semantics.md`: documents the idle-source rule, the
supersede claim, and the resumed stateless lease.

## Verification

- Red before the fix, green after:
- `native-session-executor.test.ts` "restores a warm backup into a
created lease only when an idle warm source finished its run and its
export" failed with `backup_without_reusable_lease`.
- "... a resumed lease never held the session and the warm source is
idle" failed with `resumed_unavailable`.
- `native-retired-backup-source.integration.test.ts` (real Postgres)
"authorizes an idle retained/released warm source and claims it as
superseded" failed (returned false).
- Integration test "refuses a reuse handoff of a source superseded while
its provider resume was pending" fails without the handoff guard and
passes with it.
- Safety rows stay refused: source run still running, workspace export
pending, cleanup in flight, restore into its own allocation, stamp names
another checkpoint, provider work after the backup, two host leases for
one allocation, claim lost to another run, and a resumed lease that lost
its own state. Existing destroyed-source and restore-hold rows are
unchanged.
- `cd server && npx vitest run
src/services/native-runtime/native-session-executor.test.ts
src/services/native-runtime/native-retired-backup-source.integration.test.ts
src/services/native-runtime/remote-warm-session-recovery.test.ts` passes
(1408 tests).
- `npx tsc --noEmit -p server/tsconfig.json` passes.
- `pnpm verify` exits 2 because a global CI input
(`doc/execution-semantics.md`) changed. Required CI supplies the broad
coverage.

## Risks

- Previous-release story: no persisted shape changes. Lease rows saved
by earlier releases carry forward. The new
`reusableSandboxLeaseSuperseded` metadata key is additive.
- The idle source is destroyed at the next acquisition for its
workspace. Its state is the verified backup, which the restored lease
now holds, so no work is lost.
- Not covered: when the source cannot be proven retired or idle (for
example a live owner or later provider work), the run still fails closed
with the same named code. An automatic fresh-session fallback for that
case is not in this PR.
- The root trigger (reuse skips a sandbox while its export saves, then
waits for that export) is unchanged. This PR does not change the reuse
lookup.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- Claude Opus 5.5 (Anthropic), model ID `claude-opus-5-5`, with tool use
and code execution in Claude Code.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with `Fixes: #` / `Closes
#` / `Refs #` OR (b) described the issue in-PR following the relevant
issue template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub `#NNN` / `github.com/paperclipai/paperclip`
URLs)
- [x] My branch name describes the change (e.g. `docs/...`, `fix/...`)
and contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
2026-11-10 14:11:10 -06:00
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