write_file/patch targeting AGENTS.md, CLAUDE.md, SOUL.md, .cursorrules, or a
project-local .hermes config dir now ALWAYS prompt the human for approval —
even under --yolo/auto-approve — and fail closed when no human channel
exists. These files steer future agent behavior, so an injected write to
them is a prompt-injection persistence vector.
Design:
- New _check_protected_instruction_write() in tools/file_tools.py, a
sibling of _check_sensitive_path that returns approval-required rather
than a hard error. It realpaths before matching (symlink lesson from
#41351), matches basenames case-insensitively in ANY directory, rejects
'./x/../AGENTS.md' traversal via normpath, and gates files whose
immediate parent dir is `.hermes` (project-local config) while exempting
the authoritative ~/.hermes home (governed by its own guards).
- Approval is ONE-OPERATION only: no session/permanent persistence, no
yolo bypass — intentionally does not route through _run_approval_gate.
Gateway sessions get the button round-trip with allow_permanent and
allow_session both False; CLI uses the per-thread approval callback;
no channel at all = BLOCKED (fail closed).
- Multi-file V4A patches: ONE protected file gates the ENTIRE patch (a
single prompt lists all protected targets; deny applies nothing).
- Config: security.protected_instruction_files (default true) and
security.protected_instruction_extra_patterns (fnmatch on basename).
Config read failure keeps the gate ON.
Tests: 22 new cases in tests/tools/test_file_write_safety.py covering the
adversarial checklist — deny/approve/yolo-bypass attempt, symlink at a
protected target, case variants, relative traversal, arbitrary-directory
basenames, project-local .hermes, checkout-nested-under-~/.hermes
non-gating, patch replace + V4A multi-file atomicity, gateway round-trip,
fail-closed with no human, config off/extra patterns.
Ported from: RooCodeInc/Roo-Code RooProtectedController (Apache-2.0);
companion: #58631 (terminal vector), symlink lesson from #41351.
Teknium
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