Follow-up on the #42278 salvage (#98222): `a && b & &>/dev/null c` is valid
bash but rewrote to `a && { b & } &>/dev/null c`, which binds the redirect to
the brace group and orphans `c`. Treat a suffix starting with `&>` as command
text and insert the `;` separator. Adds bash -n coverage for that shape, for
the `;;` case-arm terminator (must NOT gain a separator), a multi-line mixed
form, and separator idempotence.
`_rewrite_compound_background` rewrites `A && B &` into `A && { B & }` to
avoid the subshell-wait process leak. When another statement follows the
backgrounded compound on the same line (`A && B & C`), the trailing `&`
was the only separator between the compound and `C`. The rewrite consumed
that `&` into the brace group and produced `A && { B & } C`. A brace group
must be terminated by `;`, `&`, `|`, a newline, or `)`/`}` before the next
command, so the result is a bash syntax error and the entire command fails
to run — neither `A`, `B`, nor `C` execute. The rewrite is applied by
default to every foreground command, so a valid command is silently
mangled into one that errors out.
This restores a `;` separator after the closing `}` when the suffix
resumes with command text. Only spaces and tabs are stripped before the
check; a newline already terminates the group, and an existing separator
(`;`, `&`, `|`, `)`, `}`) is left untouched, so previously-correct rewrites
are unchanged.
## What does this PR do?
Fixes a rewrite in `_rewrite_compound_background` that turned a valid
foreground command of the form `A && B & C` into the bash syntax error
`A && { B & } C`, causing the whole command to fail. A `;` is now inserted
after the brace group whenever a further statement follows on the same
line, while leaving commands that already end in a separator/newline
untouched.
## Related Issue
N/A
## Type of Change
- [x] 🐛 Bug fix (non-breaking change that fixes an issue)
- [ ] ✨ New feature (non-breaking change that adds functionality)
- [ ] 🔒 Security fix
- [ ] 📝 Documentation update
- [ ] ✅ Tests (adding or improving test coverage)
- [ ] ♻️ Refactor (no behavior change)
- [ ] 🎯 New skill (bundled or hub)
## Changes Made
- `tools/terminal_tool.py`: in `_rewrite_compound_background`, insert a `;`
after the rewritten `{ ... & }` brace group when the trailing suffix
begins with command text rather than a separator/terminator.
- `tests/tools/test_terminal_compound_background.py`: add
`TestTrailingStatementSeparator` for the string-level rewrites and
`TestRewriteIsValidBash`, which runs the rewriter output through
`bash -n` for parse validity plus one end-to-end execution check.
## How to Test
1. Run `pytest tests/tools/test_terminal_compound_background.py -q`.
2. Before the fix, `_rewrite_compound_background("echo hi && sleep 5 & echo done")`
returns `echo hi && { sleep 5 & } echo done`; `bash -n -c` on that string
exits 2 with `syntax error near unexpected token 'echo'`.
3. After the fix it returns `echo hi && { sleep 5 & } ; echo done`, which
parses and runs, and the trailing statement executes.
## Checklist
### Code
- [x] I've read the Contributing Guide
- [x] My commit messages follow Conventional Commits
- [x] I searched for existing PRs to make sure this isn't a duplicate
- [x] My PR contains only changes related to this fix
- [x] I've run `pytest tests/tools/test_terminal_compound_background.py -q` (50 passed)
- [x] I've added tests for my changes
- [x] I've tested on my platform: macOS 15.5
### Documentation & Housekeeping
- [x] I've updated relevant documentation — N/A
- [x] I've updated `cli-config.yaml.example` if I added/changed config keys — N/A
- [x] I've updated `CONTRIBUTING.md` or `AGENTS.md` — N/A
- [x] I've considered cross-platform impact: the rewrite is
platform-independent; the `bash -n` test is skipped when bash is absent
- [x] I've updated tool descriptions/schemas — N/A
Second, deeper pass over tools/gateway/hermes_cli plus first pass over
the trees wave 1 missed (acp, acp_adapter, skills, computer_use, docker,
dashboard, conformance, monitoring, secret_sources, hermes_state,
providers). Same rubric as wave 1 (AGENTS.md test policy); security,
alternation/caching invariants, issue-number regressions, and E2E kept.
Real test-quality fixes found and rooted out along the way:
- tests/tools/test_command_guards.py made real auxiliary-LLM HTTPS calls
(DEFAULT_CONFIG smart-approval leaked in) — pinned approval
mode=manual via autouse fixture: 17.4s → 0.4s.
- test_model_switch_custom_providers.py / test_user_providers_model_switch.py
silently probed live provider catalogs (~2s/test) — stubbed
cached_provider_model_ids/provider_model_ids/fetch_api_models.
- test_telegram_noise_filter.py: 15-platform copy-paste matrix over
shared gateway.run logic → 3 representative platforms (55s → 3.9s).
- test_gateway_shutdown.py: stop()'s 5s interrupt-deadline loop spun on
MagicMock agents — interrupt.side_effect now clears _running_agents
(22s → 1.0s).
- test_gateway_inactivity_timeout.py poll-harness timings shrunk 3-5x
(24s → 1.1s); test_mcp_stability.py backoff/SIGTERM-grace sleeps
patched (15.4s → 2.5s); test_async_delegation.py negative-drain wait
5s → 0.5s.
- test_telegram_init_deadline.py: loop-block margin restored to 1.0s
with rationale comment — the watchdog-dump assertion needs the loop
blocked well past deadline+grace under parallel load (flaked once in
the 40-worker verification run at a 0.2s margin).
Verification: full hermetic suite via scripts/run_tests.sh —
2,438 files, 21,718 tests passed, 0 failed, 293.9s wall.
Suite totals vs original baseline: 46,820 → 19,757 test functions
(−57.8%), wall 583.5s → 293.9s (−50%), subprocess CPU 13,564s → 11,623s.
Remove unused imports (F401) and duplicate/shadowed import
redefinitions (F811) across the codebase using ruff's safe
autofixes. No behavioral changes -- imports only.
- ~1400 safe autofixes applied across 644 files (net -1072 lines)
- __init__.py re-exports preserved (excluded from F401 removal so
public re-export surfaces stay intact)
- Re-exports that are imported or monkeypatched by tests but look
unused in their defining module are kept with explicit # noqa:
F401 (gateway/run.py load_dotenv; run_agent re-exports from
agent.message_sanitization, agent.context_compressor,
agent.retry_utils, agent.prompt_builder, agent.process_bootstrap,
agent.codex_responses_adapter)
- Unsafe F841 (unused-variable) fixes deliberately skipped -- those
can change behavior when the RHS has side effects
- ruff lints remain disabled in pyproject.toml (only PLW1514 is
selected); this is a one-time cleanup, not a config change
Verification:
- python -m compileall: clean
- pytest --collect-only: all 27161 tests collect (zero import errors)
- core entry points import clean (run_agent, model_tools, cli,
toolsets, hermes_state, batch_runner, gateway)
- static scan: every name any test imports directly from an edited
module still resolves
bash parses `A && B &` with `&&` tighter than `&`, so it forks a subshell
for the compound and backgrounds the subshell. Inside the subshell, B
runs foreground, so the subshell waits for B. When B is a process that
doesn't naturally exit (`python3 -m http.server`, `yes > /dev/null`, a
long-running daemon), the subshell is stuck in `wait4` forever and leaks
as an orphan reparented to init.
Observed in production: agents running `cd X && python3 -m http.server
8000 &>/dev/null & sleep 1 && curl ...` as a "start a local server, then
verify it" one-liner. Outer bash exits cleanly; the subshell never does.
Across ~3 days of use, 8 unique stuck-terminal events and 7 leaked
bash+server pairs accumulated on the fleet, with some sessions appearing
hung from the user's perspective because the subshell's open stdout pipe
kept the terminal tool's drain thread blocked.
This is distinct from the `set +m` fix in 933fbd8f (which addressed
interactive-shell job-control waiting at exit). `set +m` doesn't help
here because `bash -c` is non-interactive and job control is already
off; the problem is the subshell's own internal wait for its foreground
B, not the outer shell's job-tracking.
The fix: walk the command shell-aware (respecting quotes, parens, brace
groups, `&>`/`>&` redirects), find `A && B &` / `A || B &` at depth 0
and rewrite the tail to `A && { B & }`. Brace groups don't fork a
subshell — they run in the current shell. `B &` inside the group is a
simple background (no subshell wait). The outer `&` is absorbed into
the group, so the compound no longer needs an explicit subshell.
`&&` error-propagation is preserved exactly: if A fails, `&&`
short-circuits and B never runs.
- Skips quoted strings, comment lines, and `(…)` subshells
- Handles `&>/dev/null`, `2>&1`, `>&2` without mistaking them for `&`
- Resets chain state at `;`, `|`, and newlines
- Tracks brace depth so already-rewritten output is idempotent
- Walks using the existing `_read_shell_token` tokenizer, matching the
pattern of `_rewrite_real_sudo_invocations`
Called once from `BaseEnvironment.execute` right after
`_prepare_command`, so it runs for every backend (local, ssh, docker,
modal, etc.) with no per-backend plumbing.
34 new tests covering rewrite cases, preservation cases, redirect
edge-cases, quoting/parens/backticks, idempotency, and empty/edge
inputs. End-to-end verified on a test VM: the exact vela-incident
command now returns in ~1.3s with no leaked bash, only the intentional
backgrounded server.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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