# NousResearch/hermes-agent · MCP stdio liveness check inversion bug

## Open now

- Nothing open on GitHub.

An inverted boolean condition in the MCP stdio subprocess liveness check caused all stdio tool calls to unconditionally fast-fail with a 'subprocess has exited' error. These members identify the bug and apply a fix.

## TL;DR

- 3 member(s): 0 open issue(s), 1 closed issue(s), 0 open PR(s), 1 merged PR(s), 1 PR(s) closed without merging.
- A fix was merged to main in PR #94339. Verify it addresses your case.
- **Recommended:** read PR #94339 (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: `unresolved`. 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evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.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 `0.67`: 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

- #94637: MCP stdio tool calls always fast-fail with 'subprocess has exited' after #85125 3b

## Prior & competing PRs

- **#94339: fix(mcp): un-invert the stdio children liveness check**. merged to main · fix tier `verified`
  - maintainer direction: category `merged`
  - files: `tests/tools/test_mcp_stdio_children_dead.py`, `tools/mcp_tool.py`
- **#94661: fix(mcp): un-invert stdio children liveness check — stop unconditional stdio fast-fail (Closes #94637)**. closed without merge
  - maintainer direction: category `superseded_by_pr`; implication `superseded`; refs `#94339`

## Fix status

- Merged to main in PR #94339 (cited above). No release data is tracked. Verify downstream.
- Fix last verified (merged) `2026-08-27`.