Oneshot mode (-z) silent failures and output bugs
Cluster 30623 · hermes cli. Data as of
Nothing open on GitHub. Fix merged in #35384 on 30 May 2026. Check it covers your case.
The short answer
- Known?
- Yes. 4 related items grouped here, 1 issue already closed.
- Fix event
- A fix was merged to main in PR #35384. Check it covers your case. No release data is tracked.
- Tracker
- The maintainers' tracker marks this
resolved, deciding PR #35384. That is separate from the fix event. - Still open
- Nothing open on GitHub.
Multiple reports and fixes around the oneshot CLI mode (-z) silently exiting with empty output, incorrect exit codes, and non-TTY/pipe environment failures. Work spans detection of empty responses, stdout routing, and fail-closed behavior.
Open issues0
Open PRs0
Fixes on record
-
#35384 fix(cli): oneshot (-z) fails closed on empty response or agent crash
files:
hermes_cli/oneshot.py,scripts/release.py,tests/hermes_cli/test_tui_resume_flow.pyShow the diff
-
hermes_cli/oneshot.py@@ -174,28 +174,55 @@ def run_oneshot( # Redirect stderr AND stdout to devnull for the entire call tree. # We'll print the final response to the real stdout at the end. real_stdout = sys.stdout + real_stderr = sys.stderr devnull = open(os.devnull, "w", encoding="utf-8") + response: Optional[str] = None + failure: BaseException | None = None try: with redirect_stdout(devnull), redirect_stderr(devnull): - response = _run_agent( - prompt, - model=model, - provider=provider, - toolsets=explicit_toolsets, - use_config_toolsets=use_config_toolsets, - ) + try: + response = _run_agent( + prompt, + model=model, + provider=provider, + toolsets=explicit_toolsets, + use_config_toolsets=use_config_toolsets, + ) + except BaseException as exc: # noqa: BLE001 + # Capture anything that escapes the agent (including OSError + # from prompt_toolkit/Vt100 when stdout is a non-TTY pipe, + # KeyboardInterrupt, SystemExit, etc.) so we can surface it on + # the real stderr instead of crashing past the redirect with a + # traceback that the caller never sees. A silent exit in a + # cron / SSH / subprocess context is the worst failure mode. + # See #30623. + failure = exc finally: try: devnull.close() except Exception: pass - if response: - real_stdout.write(response) - if not response.endswith("\n"): - real_stdout.write("\n") - real_stdout.flush() + if failure is not None: + # Re-raise control-flow exceptions so the parent handles them as usual + # (Ctrl-C / explicit sys.exit() inside the agent). + if isinstance(failure, (KeyboardInterrupt, SystemExit)): + raise failure + real_stderr.write(f"hermes -z: agent failed: {failure}\n") + real_stderr.flush() + return 1 + + if not (response or "").strip(): + real_stderr.write("hermes -z: no final response was produced; treating the run as failed.\n") + real_stderr.flush() + return 1 + + assert response is not None # narrowed by the empty-response guard above + real_stdout.write(response) + if not response.endswith("\n"): + real_stdout.write("\n") + real_stdout.flush() return 0 -
scripts/release.py@@ -656,6 +656,7 @@ "[redacted:email]": "inchargeautomation-lab", "[redacted:email]": "Bartok9", "[email protected]": "sweetcornna", + "[redacted:email]": "briancl2", "[redacted:email]": "CruxExperts", "[email protected]": "LeonSGP43", "[email protected]": "Kailigithub", -
tests/hermes_cli/test_tui_resume_flow.py@@ -638,6 +638,60 @@ def test_oneshot_rejects_invalid_only_toolsets(monkeypatch, capsys): assert "did not contain any valid toolsets" in err +def test_oneshot_fails_closed_on_empty_final_response(monkeypatch, capsys): + _stub_plugin_discovery(monkeypatch) + import hermes_cli.oneshot as oneshot_mod + + monkeypatch.setattr(oneshot_mod, "_run_agent", lambda *_args, **_kwargs: "") + + assert oneshot_mod.run_oneshot("hello") == 1 + captured = capsys.readouterr() + assert captured.out == "" + assert "no final response" in captured.err + + +def test_oneshot_prints_nonempty_final_response(monkeypatch, capsys): + _stub_plugin_discovery(monkeypatch) + import hermes_cli.oneshot as oneshot_mod + + monkeypatch.setattr(oneshot_mod, "_run_agent", lambda *_args, **_kwargs: "done") + + assert oneshot_mod.run_oneshot("hello") == 0 + captured = capsys.readouterr() + assert captured.out == "done\n" + assert captured.err == "" + + +def test_oneshot_fails_closed_on_agent_exception(monkeypatch, capsys): + _stub_plugin_discovery(monkeypatch) + import hermes_cli.oneshot as oneshot_mod + + def _boom(*_args, **_kwargs): + raise OSError("not a TTY") + + monkeypatch.setattr(oneshot_mod, "_run_agent", _boom) + + assert oneshot_mod.run_oneshot("hello") == 1 + captured = capsys.readouterr() + assert captured.out == "" + assert "agent failed" in captured.err + assert "not a TTY" in captured.err + + +def test_oneshot_reraises_keyboard_interrupt(monkeypatch): + _stub_plugin_discovery(monkeypatch) + import hermes_cli.oneshot as oneshot_mod + import pytest as _pytest + + def _interrupt(*_args, **_kwargs): + raise KeyboardInterrupt + + monkeypatch.setattr(oneshot_mod, "_run_agent", _interrupt) + + with _pytest.raises(KeyboardInterrupt): + oneshot_mod.run_oneshot("hello") + + def test_oneshot_filters_invalid_toolsets_before_redirect(monkeypatch, capsys): _stub_plugin_discovery(monkeypatch) from hermes_cli.oneshot import _validate_explicit_toolsets
-
2 PRs closed without merging
From the close comments: done elsewhere 1 · superseded by another PR 1
Closed issues · 1
- Closed#30623[Bug]: `hermes -z` oneshot exits 0 silently before API call when stdout is non-TTY pipe (SSH/cron/subprocess)
How this cluster was grouped
-
Link evidence (
structural links throughout): every member is connected by structural evidence: shared changed files, or a closing/superseded reference. -
Pairwise link density
0.50: the share of item pairs that carry a link, counting a structural link in full and a relevance-only link at 0.36.1.00means every pair is linked.
Pick up a Lab task
Check whether a fix covers the open issues here, with your own agent. Bring back evidence for maintainers.
Open the LabAt a glance
- Subsystem
- hermes cli
- Merged PRs
- #35384
- Closed issues
- 1
- Attempts
- 2 PRs closed without merging
- Fix link checked
- 30 May 2026