Both watcher.py (ConfigWatcher) and skill_loader/watcher.py
(SkillsWatcher) used hashlib.md5() for file-integrity change detection.
MD5 is collision-prone: a crafted config file could produce the same
hash as a benign one, silently suppressing the hot-reload callback and
preventing agents from picking up legitimate config changes.
Replace hashlib.md5 → hashlib.sha256 in both _hash_file() methods.
Update docstrings, comments, and the type-annotation comment
(rel_path → md5 hex → sha256 hex).
Test update: test_skills_watcher.py — rename helper _md5 → _sha256,
update the hash-length assertion from 32 (MD5) to 64 (SHA-256), and
rename the test from test_hash_file_returns_md5_for_existing_file to
test_hash_file_returns_sha256_for_existing_file. All 25 watcher tests
pass.
Note: H2 (a2a_client.py timeout=None) was already fixed in Cycle 5
(timeout=httpx.Timeout(connect=30.0, read=300.0, ...)) — confirmed by
code review before opening this PR.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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