## Thinking Path
> - Paperclip is the open source control plane people use to manage AI
agents for work
> - Local process adapters can enforce network allowlists through a
Unix-socket proxy inside the Linux sandbox
> - The proxy socket was created under `os.tmpdir()`, which can be a
deeply nested run-specific directory
> - Linux Unix-domain socket paths are limited to 107 usable bytes, so
deep temporary paths can be silently truncated during bind
> - A truncated proxy socket resets every confined outbound connection,
including the model provider API, before the agent can do work
> - This pull request creates proxy sockets under the short `/tmp` path
when possible and validates the path length before bind
> - The benefit is reliable sandboxed egress under deep `TMPDIR` values
and an explicit error instead of an opaque connection-reset storm
## Linked Issues or Issue Description
### Pre-submission checklist
- [x] I searched existing open and closed issues and this is not a
duplicate.
- [x] I can reproduce this on upstream `master`.
- [x] I confirmed the error originates in Paperclip's local-process
sandbox proxy.
### What happened?
Sandboxed local-process agents using `networkScope: "allowlist"` could
lose all proxied egress when `TMPDIR` was deeply nested because
`proxy.sock` exceeded Linux's Unix socket path limit. The truncated bind
surfaced as repeated connection resets, including for provider API
traffic.
### Expected behavior
Proxy creation should use a Linux-safe short path and fail explicitly if
no safe socket path can be created.
### Steps to reproduce
1. Set `TMPDIR` to a path long enough that
`<TMPDIR>/paperclip-network-sandbox-XXXXXX/proxy.sock` exceeds 107
bytes.
2. Build or run a local-process sandbox with `networkScope:
"allowlist"`.
3. Make an HTTP or HTTPS request through the generated sandbox proxy.
4. Observe connection resets from the overlong Unix socket path on
affected code.
### Paperclip version or commit
Upstream `master` before this change.
### Deployment mode
Other — Linux local-process adapters using Bubblewrap network
allowlisting.
### Installation method
Built from source.
### Agent adapter(s) involved
Codex and any other local-process adapter using the shared sandbox
utility.
### Operating system
Linux.
### Additional context
GitHub search found no duplicate public issue or pull request for this
defect.
## What Changed
- Add a Linux Unix-socket byte-length guard that reports the unsafe path
before binding.
- Create network proxy temporary directories under `/tmp` first, with
`os.tmpdir()` as a validated fallback.
- Use the safe temporary-directory helper at both allowlist proxy
creation sites while preserving trusted URL handling.
- Add regression coverage that sets a deliberately deep `TMPDIR` and
verifies the working socket remains within 107 bytes under `/tmp`.
## Verification
- `node
/srv/paperclip/home/paperclipai/paperclip/node_modules/vitest/vitest.mjs
run packages/adapter-utils/src/local-process-sandbox.test.ts` — 8
passed, 4 environment-gated tests skipped.
- `git diff --check origin/master...HEAD` — passed.
- Greptile Review — passed after reviewing 2 files with 0 comments and
no unresolved threads; this repository integration did not emit a
separate numeric confidence score.
- Full GitHub CI matrix — passed after one rerun of an unrelated ACPX
`ENOTEMPTY` cleanup flake.
- Package typecheck was attempted, but the existing shared install
cannot resolve `acpx/runtime`; the failure is outside the changed files
and is expected to be covered by CI's clean dependency install.
## Risks
- Low risk: the change is limited to Linux sandbox proxy
temporary-directory selection and validation.
- Systems without a writable `/tmp` fall back to `os.tmpdir()` only when
the resulting socket path is safe; otherwise startup now fails loudly
instead of producing connection resets.
- No schema, API, UI, migration, or documentation behavior changes.
> 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, `gpt-5.3-codex`, tool-enabled coding agent with managed
reasoning and code execution; context-window size is not exposed by the
runtime.
## 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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