Catch the PR #28452 failure mode (orphan merge-conflict markers in
hermes_cli/config.py) on the user side: after git pull succeeds, compile
the files every 'hermes' invocation imports at startup. If any has a
syntax error, git reset --hard back to the pre-pull SHA so the install
stays bootable. User can retry once a fix lands upstream.
- New _capture_head_sha() + _validate_critical_files_syntax() helpers
- Wires both into _cmd_update_impl after the pull/reset succeeds
- Tests cover the helpers, the rollback flow, and a production-tree
invariant (CI fails if main itself has a syntax error in a critical
file — catches future broken commits before users hit them)
Teknium
aedb8ac83b