# NousResearch/hermes-agent · Fix pipe I/O failures when fd exceeds FD_SETSIZE

## Open now

- Nothing open on GitHub.

These items address a bug where terminal and tool output is lost when pipe file descriptors reach or exceed FD_SETSIZE. The fix replaces select()-based draining with poll() or selector APIs that handle high-numbered file descriptors correctly.

## TL;DR

- 8 member(s): 0 open issue(s), 1 closed issue(s), 0 open PR(s), 1 merged PR(s), 6 PR(s) closed without merging.
- A fix was merged to main in PR #142299. Verify it addresses your case.
- **Recommended:** read PR #142299 (and any competing PRs below) before filing. Confirm the merged change covers your symptom.

## Maintainer resolution verdict

- Internal-tracker verdict over this cluster's issue members: `resolved` · deciding PR(s): `pr-142299`. This is distinct from the fix status above. Weigh it yourself.

## How this cluster was grouped

- Link evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.
- Pairwise link density `0.29`: the share of member pairs that carry a link, counting a structural link in full and a relevance-only link at 0.36. `1.00` means every pair is linked.

## Closed / duplicate issues

- #94928: \[Bug\]: Desktop: terminal/read_file return empty output when pipe fds exceed FD_SETSIZE

## Prior & competing PRs

- **#142299: fix(terminal): command output no longer vanishes above 1024 open fds (#94928, salvage #142125)**. merged to main · fix tier `verified`
  - maintainer direction: category `merged`; implication `superseded`
  - files: `contributors/emails/[redacted:email]`, `hermes_cli/pty_bridge.py`, `tests/hermes_cli/test_pty_bridge.py`, `tests/tools/test_drain_high_fd.py`, `tools/environments/base_output.py`, `tools/environments/fd_wait.py`, `tools/process_registry.py`
- **#94934: fix(tools): drain high-fd pipes with selectors instead of select**. closed without merge
  - maintainer direction: category `silent_close`; implication `active`
- **#94937: fix(tools): drain high-fd pipes with selectors instead of select**. closed without merge
  - maintainer direction: category `duplicate_of`; implication `duplicate`; refs `#94939`, `#94928`
- **#94939: fix(terminal): drain stdout with poll() so output survives pipe fds >= FD_SETSIZE (#94928)**. closed without merge
  - maintainer direction: category `superseded_by_pr`; implication `superseded`; refs `#94937`, `#94928`, `#94928`, `#8340`
- **#95177: fix(tools): drain high-fd pipes with selectors instead of select**. closed without merge
  - maintainer direction: category `volume_quota`; implication `active`
- **#135141: fix(terminal): retain subprocess output above FD_SETSIZE**. closed without merge
  - maintainer direction: category `superseded_by_pr`; implication `superseded`; refs `0b8dee00faf`, `355910814ab`, `#142299`
- **#142125: fix(terminal): drain stdout with selectors to survive fd >= FD_SETSIZE**. closed without merge
  - maintainer direction: category `implemented_elsewhere`; implication `superseded`; refs `0b8dee00faf`, `9b6b243762f`, `0910e488d4e`, `#142299`

## Fix status

- Merged to main in PR #142299 (cited above). No release data is tracked. Verify downstream.
- Fix last verified (merged) `2026-10-21`.
- Subsystem: `environments`