feat(hooks): scan file-backed messages and harden rm parsing

Two audit gaps in the confirmation hooks, plus the test harness they were missing.

The git-commit and gh-pr-create hooks scanned for AI attribution but only saw inline messages. A commit made with -F/--file or a PR made with --body-file slipped through, since the hook stored a placeholder instead of the file's text, and the publish flow uses -F constantly. A new read_referenced_file helper in _common.py reads the referenced local file (missing, oversized, or non-UTF-8 returns None, which means "couldn't inspect" and never "clean"), so attribution scanning now sees the real committed and posted text. An unreadable file falls through to the existing ask-anyway path.

destructive-bash-confirm.py parsed rm flags by splitting on whitespace, which mangled quoted paths and missed flag variants. detect_rm_rf now tokenizes with shlex, so quoted or spaced paths and combined, separate, or reordered flags all parse. It fails toward asking (a sentinel that still fires the modal) on unbalanced quotes, or when a forced recursive rm sits alongside a pipeline, compound command, substitution, or redirect, since target attribution isn't trustworthy there. The supported and unsupported shell constructs are documented in the docstrings.

These hooks had no tests and weren't in make test. Added a pytest harness under hooks/tests (an importlib-by-path loader, since the hook filenames are hyphenated) with 54 tests across the three hooks and the shared helper, and wired hooks/tests into make test. Full suite green.

1 files changed, 20 insertions, 0 deletions

diff --git a/hooks/_common.py b/hooks/_common.py
index d4bf520..e82f7ed 100644
--- a/hooks/_common.py
+++ b/hooks/_common.py
@@ -16,6 +16,7 @@ the tools themselves.
 """
 
 import json
+import os
 import re
 import sys
 from typing import Optional
@@ -64,6 +65,25 @@ def respond_ask(reason: str, system_message: Optional[str] = None) -> None:
     print(json.dumps(output))
 
 
+def read_referenced_file(path: str, max_bytes: int = 1_000_000) -> Optional[str]:
+    """Read a local file referenced by -F/--file/--body-file so its text can be
+    attribution-scanned. Return the text, or None if it can't be safely read
+    (missing, not a regular file, larger than max_bytes, or not valid UTF-8).
+    None means 'could not inspect', never 'clean'."""
+    if not path:
+        return None
+    try:
+        expanded = os.path.expanduser(path)
+        if not os.path.isfile(expanded):
+            return None
+        if os.path.getsize(expanded) > max_bytes:
+            return None
+        with open(expanded, "r", encoding="utf-8", errors="strict") as fh:
+            return fh.read()
+    except (OSError, UnicodeDecodeError):
+        return None
+
+
 def scan_attribution(text: str) -> list[str]:
     """Return human-readable descriptions of any AI-attribution hits."""
     if not text: