`_normalize_command_for_detection` strips backslash-escapes before matching
DANGEROUS_PATTERNS and HARDLINE_PATTERNS, but the strip rule was
`re.sub(r'\\([^\n])', r'\1', ...)` — its `[^\n]` class deliberately skips
newlines. A backslash immediately followed by a newline is a POSIX line
continuation: the shell removes BOTH characters and joins the tokens, so
`rm -rf \<newline>/` executes as `rm -rf /`. With the dangling backslash left
in place, the structured rm/dd/mkfs patterns no longer match because a literal
`\` sits wedged between the tokens they expect to be adjacent.
The worst consequence is on the HARDLINE floor. The dangerous-command layer
still fired here only by accident (the generic `\brm\s+-[^\s]*r` "recursive
delete" rule needs no path), and that layer is bypassed by `--yolo` /
`approvals.mode=off`. The hardline blocklist — the unconditional floor reserved
for catastrophic, unrecoverable commands and meant to hold even under yolo —
anchors the root path directly after the flags, so `rm -rf \<newline>/`,
`rm -r\<newline>f /`, and `rm -rf \<newline>~` all slipped past it entirely.
A yolo session could therefore wipe the root filesystem.
The fix collapses line continuations (`\` + `\n` or `\r\n`) to nothing,
mirroring the shell, before the existing escape strip runs. This was the gap
left by 621bf3a87, which added the escape strip but only for non-newline chars.
## What does this PR do?
Closes a shell line-continuation bypass in the dangerous-command detector.
Before: `rm -rf \<newline>/` normalized to `rm -rf \<newline>/`, so the
hardline root-delete patterns did not match and the command could run under
`--yolo`. After: line continuations are collapsed first, the command
normalizes to `rm -rf /`, and the hardline floor blocks it unconditionally.
## Related Issue
N/A
## Type of Change
- [x] 🔒 Security fix
## Changes Made
- `tools/approval.py`: in `_normalize_command_for_detection`, add
`command = re.sub(r'\\\r?\n', '', command)` ahead of the existing
backslash-escape strip so shell line continuations (`\`+newline, LF or CRLF)
are removed exactly as the shell would, instead of leaving a stray backslash
that breaks the structured patterns.
- `tests/tools/test_hardline_blocklist.py`: add a parametrized
`test_hardline_blocks_line_continuation` covering the root, in-flag, home,
CRLF, and mkfs continuation forms, plus
`test_line_continuation_root_wipe_cannot_bypass_hardline` asserting the
continuation root wipe stays blocked even with `HERMES_YOLO_MODE=1`.
## How to Test
1. Reproduce: stash the `tools/approval.py` change and run
`scripts/run_tests.sh tests/tools/test_hardline_blocklist.py` — the new
line-continuation cases fail (`rm -rf \<newline>/` is not flagged hardline,
and leaks past the floor under yolo).
2. Restore the change and rerun the file — all 106 tests pass.
3. Regression: `scripts/run_tests.sh tests/tools/test_approval.py` (the
existing fullwidth/ANSI/null-byte normalization and multiline cases still
pass).
## Checklist
### Code
- [x] I've read the Contributing Guide
- [x] My commit messages follow Conventional Commits (`fix(scope):`, `feat(scope):`, etc.)
- [x] I searched for existing PRs to make sure this isn't a duplicate
- [x] My PR contains **only** changes related to this fix/feature (no unrelated commits)
- [x] I've run `pytest tests/ -q` and all tests pass
- [x] I've added tests for my changes (required for bug fixes, strongly encouraged for features)
- [x] I've tested on my platform: macOS 15 (Darwin 25.5.0)
### Documentation & Housekeeping
- [x] I've updated relevant documentation (README, `docs/`, docstrings) — or N/A
- [x] I've updated `cli-config.yaml.example` if I added/changed config keys — or N/A
- [x] I've updated `CONTRIBUTING.md` or `AGENTS.md` if I changed architecture or workflows — or N/A
- [x] I've considered cross-platform impact (Windows, macOS) — handles both LF and CRLF line endings
- [x] I've updated tool descriptions/schemas if I changed tool behavior — or N/A
# Conflicts:
# tools/approval.py
17f07aebdc