## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work
> - Agent adapters use execution targets to exchange input and output
with sandbox processes
> - The sandbox input path can expose partial files, and the poller can
delete or stop on invalid input
> - These timing windows can lose agent input without a clear error
> - This pull request makes host writes atomic and makes the poller
retry invalid files before it drops them
> - The benefit is reliable sandbox input delivery with visible failure
after bounded retries
## Linked Issues or Issue Description
Closes#10874
## What Changed
- Decode host input into a temporary file, then rename it onto the final
JSON path.
- Apply the same atomic write pattern to the filesystem client.
- Parse each input file before deletion.
- Retry parse failures and drop a file after the bounded retry limit
with an error event.
- Add regression tests for empty, partial, and permanently malformed
input files.
## Verification
- `pnpm exec vitest run
packages/adapter-utils/src/execution-target-stdin-race.test.ts` passes
5/5 tests.
- Related sandbox callback, execution target, and sandbox execution
suites pass 71/71 tests.
- TypeScript checks pass for the changed files.
- The regression suite fails on the old code and passes on this change.
## Risks
- Low risk. The change affects sandbox input file handling and adds
bounded retry behavior.
- A permanently malformed file now creates an error event after the
retry limit.
> This bug fix does not add a core feature, so a roadmap change is not
needed.
## Model Used
Codex, OpenAI GPT-5, current agent runtime, large context window, tool
use and code review support.
## 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>
8f478242f1