## Thinking Path
> - Paperclip is the open source app people use to manage AI agents for
work
> - The server exposes live event updates to board and agent clients
over WebSocket upgrade requests
> - WebSocket upgrade authorization can be asynchronous, leaving the raw
HTTP upgrade socket in server-owned code before `ws` takes over
> - If the client disconnects during that authorization window, the
server can still try to reject or upgrade a closed socket
> - A raw socket write after peer disconnect can emit `EPIPE` /
`ECONNRESET`, and without a listener that can become process-fatal
> - This pull request hardens the pre-`ws` upgrade socket path and adds
regression coverage for disconnect/error races
> - The benefit is that live event reconnect churn degrades gracefully
instead of risking a server crash
## Linked Issues or Issue Description
External public context: Refs
https://github.com/aronprins/paperclip-desktop/issues/14
No matching open upstream issue or PR was found when searching
`paperclipai/paperclip` for `EPIPE`, `rejectUpgrade`, `live-events-ws`,
`websocket upgrade`, and related socket-write terms.
### Bug report
**What happened?**
The live events WebSocket upgrade handler could write a rejection
response to the raw upgrade socket after the peer had already
disconnected during async authorization. A transport-level `EPIPE` or
similar socket error on that raw socket can terminate the server process
if it is emitted without an error listener.
**Expected behavior**
The server should not write to destroyed/non-writable upgrade sockets,
should tolerate raw socket errors while authorization is pending, and
should not call `handleUpgrade()` after the socket is no longer
writable.
**Steps to reproduce**
1. Start a Paperclip server with live events enabled.
2. Open a raw WebSocket upgrade request to
`/api/companies/:companyId/events/ws`.
3. Disconnect the client before async authorization resolves.
4. Let the server take the reject or upgrade path.
5. Observe that the pre-fix path can still write to or upgrade a closed
socket.
**Paperclip version or commit**
Reproduced by static inspection on `master` before this PR at
`950484d20`.
**Deployment mode**
Any mode using live event WebSocket upgrades. The report was originally
observed from local Desktop embedding, but the vulnerable code is in the
server package.
## What Changed
- Added a writable-state guard for raw upgrade sockets before rejecting
or completing an upgrade.
- Changed rejection responses from raw `write()` + `destroy()` to
guarded `end()` with warning logging if rejection fails synchronously.
- Attached a temporary raw socket error listener during the async
upgrade authorization window and cleaned it up on socket close or
successful `ws.handleUpgrade()`.
- Added regression tests for rejecting after an early socket close and
for handling raw socket `error` events while authorization is pending.
## Verification
- `pnpm exec vitest run server/src/__tests__/live-events-ws.test.ts`
- `pnpm --filter @paperclipai/server typecheck`
- `git diff --check`
## Risks
- Low risk: the change is scoped to the live-events WebSocket upgrade
path before `ws` takes ownership of the socket.
- Rejected upgrade responses now use graceful `socket.end(...)`; clients
should still receive the same HTTP status text when the socket is
writable.
- The temporary error listener is removed before successful
`handleUpgrade()` so normal WebSocket client error handling remains
owned by the existing `connection` path.
> 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 coding agent with repository-aware tool use, shell
command execution, GitHub connector access, and local code editing.
## 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] If this change affects the UI, I have included before/after
screenshots
- [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
- [x] I will address all Greptile and reviewer comments before
requesting merge
---------
Co-authored-by: Paperclip <noreply@paperclip.ing>
Aron Prins
e93d78b46c