Automatically adds trailers to commits when running in Gas Town agent context:
- Executed-By: agent identity (e.g., beads/crew/dave)
- Rig: the rig name
- Role: crew, polecat, witness, etc.
- Molecule: pinned molecule ID (if any)
Detection sources:
1. GT_ROLE environment variable (set by Gas Town sessions)
2. cwd path patterns (crew/, polecats/, witness/, refinery/)
Trailers are skipped for:
- Human commits (no agent context detected)
- Merge commits (have their own format)
- Commits that already have Executed-By trailer (avoid duplicates)
Executed-By: beads/crew/dave
Rig: beads
Role: crew
