# NousResearch/hermes-agent · ACP step callback falsey tool result handling

## Open now

- Nothing open on GitHub.

These issues and PRs concern a bug where falsey values (such as empty strings) returned as tool results are incorrectly overwritten with None in the ACP step callback. The proposed fix changes a truthiness check to a key-presence check to preserve such values.

## 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 #109109. Verify it addresses your case.
- **Recommended:** read PR #109109 (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-109109`. 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evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.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

- #10845: ACP step callback rewrites empty-string tool results to None

## Prior & competing PRs

- **#10868: fix(acp): preserve falsey tool results in step callback**. closed without merge · fix tier `suggested`
  - maintainer direction: category `merged_via`; implication `superseded`; refs `#109109`, `#10844`
  - _suggested-tier fix detail withheld; re-request with `?tier=all` to include it._
- **#109109: fix(acp): empty-string tool results and messages=\[\] reach ACP clients unchanged (#10845, #10844, salvage #10868)**. merged to main · fix tier `verified`
  - maintainer direction: category `merged`
  - files: `acp_adapter/events.py`, `acp_adapter/server.py`, `tests/acp/test_events.py`, `tests/acp/test_server.py`

## Fix status

- Merged to main in PR #109109 (cited above). No release data is tracked. Verify downstream.
- Fix last verified (merged) `2026-09-12`.
- Subsystem: `acp`