Files
PaperClipAI/doc
DottaandClaude 1402e92d1f fix(native): take back an executor lease that lapsed only because the host slept (#20474)
## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work
> - A native run holds an execution lease on its
`native_run_finalizations` row. The lease lasts 20 minutes, and the
owner renews it every 5 minutes.
> - When a laptop sleeps for longer than the lease, the wall clock and
the database clock move past `lease_expires_at`. The server's monotonic
timers barely move.
> - After the wake, the next renewal finds its own lease expired. It
interrupts a healthy turn with `native_session_lease_lost`, and the user
must click Retry. Nobody else took the lease.
> - Several background consumers act on an expired lease without
changing its owner. So expiry alone cannot simply be ignored for the
owner.
> - This pull request makes takeover explicit. The same owner can take
back its own lapsed lease only when no other actor has recorded anything
on the row or the run.
> - The benefit is that a run interrupted only by host sleep continues
with no Retry. A real takeover still fences the late owner out.

## Linked Issues or Issue Description

**What happened?**
The restart-chaos time fault TM2 stops the server and runner tree and
ages every database time by one hour, as a stand-in for a laptop that
slept. After the thaw, the next 5-minute renewal of the native execution
lease found the lease expired. It interrupted the turn
(`turn.interrupted` at 300 s, `native_session_lease_lost`). The failure
settlement was then refused with the same code, and the UI showed
"Couldn't finish this attempt" with Retry. The owner, attempt, boot and
pid were unchanged. Evidence: wave `w-20261110T051535-s304` t01 (TM2, 1
h) failed R3. t02 in the same wave (TM1, a 113 s server-only freeze with
no clock jump) passed, so the failure follows the clock jump and not the
pause.

**Is this a harness artifact?**
No. TM2 ages the stored rows, and a real sleep moves the clock forward.
Both produce the same comparison: a stored `lease_expires_at` is earlier
than `clock_timestamp()` after the wake. The server's renewal timer and
local deadline use the monotonic clock. On macOS and Linux that clock
does not count suspended time, so they do not notice the sleep in either
case. The first database check after the wake is the renewal predicate
`lease_expires_at > clock_timestamp()`, and it fails in both cases.

**Expected behavior**
A run whose lease lapsed only because time jumped, and that no other
actor claimed, keeps running and finishes without Retry.

**Steps to reproduce**
`node cli/node_modules/tsx/dist/cli.mjs tests/restart-chaos/main.ts
--env local --adapters codex --workloads B5 --faults TM2
--time-age-hours 1 --concurrency 1 --tasks 2 --seed 304` with the
harness from #20458.

Refs #20458, #20500

## What Changed

- `native-execution-lease.ts`: add `nativeExecutionLeaseHeldCondition`
and `lockNativeExecutionLeaseForReacquire`. A lease is held when it is
live. For a local run, it is also held when it lapsed and is untouched.
"Untouched" means all of these are true:
  - the claimed generation matches;
  - the phase is `observed` and no result is accepted;
- `recovery_state`, `recovery_request_id`, `failure_code` and
`next_attempt_at` are null;
  - `controller_host_hash` is not the board's attested-stopped stamp;
- the run is still `running`, without the ownership-unverified error
code and without a `nativeStartupCleanup` marker.
- The caller's WHERE already matches the owner token, attempt and
controller boot/pid/start.
- The lock helper locks the coordinator row. If the lease lapsed, it
also takes a share lock on the run row. The predicate then reads the
latest committed run, and an in-flight run write cannot slip past it.
- Renewal (`startNativeSessionExecutionLeaseRenewal` /
`renewNativeSessionExecutionLease`) takes back a lapsed lease when the
executor passes its claimed generation. Remote targets never do. A
deadlock (40P01) on that rare path retries at the next tick, as a
statement timeout already does.
- `native-session-executor.ts`: the executor passes its generation to
renewal. Failure settlement and the final release use the same lock and
condition. After a result is accepted, a lapsed lease can only be
relinquished (set to null), never renewed, because workspace
finalization may act on it.
- New `native-execution-lease-reacquire.test.ts` (embedded Postgres, 24
cases).
- `doc/plans/2026-11-09-explicit-native-lease-claim-tokens.md`: step 2,
which adds explicit claim tokens for the consumers this PR does not yet
move.

Consumer inventory (readers of
`native_run_finalizations.lease_expires_at` that can act on a lapsed
lease):
- Restart recovery and takeover (`claimNativeRestartRecoveries`): claims
first. It writes `recovery_state`, `lease_owner` or `controller_*` under
the coordinator lock.
- Finalizer and cleanup claims: claim first (`lease_owner`).
- Failed-run owner release, environment settlement, observed-workspace
preservation, retained-session cleanup: require a terminal run status,
`committed`, or a recovery state. The rule refuses all of these.
- Finalization reconciler, live recovery: require `retryable_failure`, a
field the rule checks.
- Board controller-stopped confirmation: writes `controller_host_hash`,
which the rule checks.
- Startup cleanup promotion: writes the run's `nativeStartupCleanup`
marker, which the rule checks. It also applies only to runner-task
leases.
- Another server's orphan sweep: writes the run's ownership-unverified
code. The rule checks it when the marker lands first. The reverse order
is deferred (see Risks).
- Workspace finalization copyback: acts on a lapsed post-result lease
without a coordinator write. Post-result leases are therefore never
renewed (deferred to step 2).
- Accepted-result and token lease settlement, checkpoints, cancellation
delivery, admission and the other readers: act on live leases only, or
are read-only.

## Verification

- `cd server && npx vitest run
src/services/native-runtime/native-execution-lease-reacquire.test.ts`
passes (24/24) on this branch. With the source files from
`origin/master`, 5 fail, including "lets the same owner take back a
lease that lapsed untouched" and "renews from the shared timer after the
sleep instead of interrupting the turn".
- (a) The owner takes back its lapsed lease when no other actor claimed
it. Also covered: the shared 5-minute timer, rows saved by the previous
release, and the post-result relinquish.
- (b) 14 cases where a consumer claimed first fence the owner out and
leave the row unchanged. A release over a recorded recovery claim is
refused. A different boot (a deploy mid-run), a different generation, a
missing generation and a remote target are refused.
- (c) Races have exactly one winner: a claimant and the owner lock the
coordinator in each order, an in-flight run status write races the
owner, and 8 simultaneous starts each have one winner.
- Existing suites pass: `native-execution-lease.test.ts`,
`native-session-executor.test.ts`, `native-runner-restart-recovery`,
`native-runner-restart-lease-renewal`,
`native-runner-restart-preparation` and
`native-runner-restart-checkpoint-cost` integration tests.
- Live proof: `B5 × TM2 --time-age-hours 1 --tasks 2 --seed 304` with
`--server-from` this branch. Wave `w-20261110T083444-s304` passed 2/2,
with no Retry and no `native_session_lease_lost`.
- Both runs ran past the 300 s renewal after the one-hour aging, at the
exact point where `origin/master` fails. t01 ran 310 s and t02 ran 319
s. Each was a single run that succeeded.
- The harness used the aging exclusion from #20500 (merged): process
start identity is not aged. Without that exclusion, TM2 also moves
`controller_process_started_at`. The live owner then fails its identity
check, which a real sleep never causes. An earlier wave on the unpatched
harness, `w-20261110T072106-s304`, failed 0/2 for that reason only.

## Risks

- Previous release: no persisted shape changes and no migration. Rows
saved by the previous release have the same columns, and a null
`controller_host_hash` is accepted. A deploy that lands mid-run cannot
take back the old server's lease, because the boot and pid differ.
- On the normal path, a live lease takes the same single coordinator
lock as before. The run share lock is taken only after a lapse, and
nothing is added before `turn.start`.
- Deferred to step 2 (see the plan):
- The orphan sweep of another server process can read the row before the
owner takes the lease back and write after. That run would carry an
ownership-unverified error while it is live.
- Shared-workspace holder detection reads a silent run with lapsed
leases as gone.
  - Post-result leases are not renewed.
  - Remote leases are unchanged.

## Model Used

- Claude Opus 5.5 (`claude-opus-5-5`), Anthropic, used in Claude Code
with tool use (shell, file editing, sub-agent code audit).

## 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
- [ ] All Paperclip CI gates are green
- [ ] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [ ] I will address all Greptile and reviewer comments before
requesting merge

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

---------

Co-authored-by: Claude <noreply@anthropic.com>
2026-11-10 02:47:53 -06:00
..
…
…
…
…
…