## Thinking Path
> - Paperclip manages AI agents and their work.
> - The runner starts ACPX sessions and controls their resources.
> - An aborted admission can leave sandbox preparation active after the
opening promise rejects.
> - Test teardown can then remove the sandbox directory before that work
ends.
> - This pull request retains and observes each unfinished admission
stage.
> - The change gives runtime resources and temporary directories one
deterministic cleanup owner.
## Linked Issues or Issue Description
**What happened?**
Under full test load, an aborted admission test can end before sandbox
preparation settles. Test teardown then removes the temporary session
directory. The active preparation can report an unhandled `ENOENT`
error.
**Expected behavior**
An aborted admission must observe and retain all active preparation
work. Test teardown must wait until that work settles.
**Steps to reproduce**
1. Run the complete `@paperclipai/paperclip-runner` test suite under CI
load.
2. Abort runtime admission during credential or sandbox preparation.
3. Observe an intermittent test timeout or an unhandled
missing-directory error.
**Paperclip version or commit**
The failure occurred on a branch based on commit `b1f4910ee`. This fix
is based on current `master` commit `4d30efa8e`.
**Deployment mode**
The failure occurred in GitHub Actions on a source build.
## What Changed
- Retain each unfinished abortable admission stage in the global
runtime-host cleanup set.
- Notify the embedding lifecycle when an aborted stage needs deferred
cleanup.
- Make test teardown abort and await all active opening and cleanup
promises before directory removal.
- Replace time-based stage detection with exact deferred stage signals.
- Add a deterministic regression test for an abort during sandbox
preparation.
## Verification
- Ran the focused runtime-host file in 20 separate processes. All 20
runs passed without an unhandled error.
- Ran `pnpm --filter @paperclipai/paperclip-runner exec vitest run
src/drivers/acpx/runtime-host.test.ts` after the rebase. All 27 tests
passed.
- Ran `pnpm --filter @paperclipai/paperclip-runner check:all` after the
rebase. The full command passed.
- The final TypeScript test stage passed 127 files and 1,490 tests. All
Rust checks, tests, and parity checks passed.
- Greptile reviewed two heads. The final review is 5/5 with no open
comments.
- All latest-head CI and security checks passed. One unrelated workspace
test passed on its permitted rerun.
## Risks
- Risk is low. An aborted stage now delays final runtime-host cleanup
until its active operation settles.
- A stage that never settles can delay embedding shutdown. The existing
stage operations have bounded or controlled owners.
- The regression test holds sandbox preparation and confirms the new
cleanup order.
> 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
OpenAI Codex with GPT-5 assisted this change. The environment did not
provide the exact deployment ID or context size. The model used
reasoning, shell tools, code editing, and test execution.
## 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
---------
Co-authored-by: Paperclip <noreply@paperclip.ing>
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