brownfield-drift

---

name: brownfield-drift description: Enforces architecture boundaries defined in PLAN.md. Use when a PR crosses module/service boundaries, when the dev asks "are we following the architecture?", or as a scheduled architecture health check. Not for querying what a module does — use brownfield-chat for that. permissions: allow: - Bash(wednesday-skills drift *) - Bash(git log *)

When to use

• Dev asks "are we following the architecture?" or "is this a valid change?"
• PR touches files near module boundaries or service interfaces
• Weekly architecture health check
• Any cross-service import was just added

When NOT to use

• "What does module X do?" → use brownfield-chat
• "What breaks if I change X?" → use brownfield-chat
• Graph coverage is low on a file → use brownfield-fix (it fills gaps before editing)
• No PLAN.md exists — drift requires machine-readable boundaries in PLAN.md

What to do

1. Run wednesday-skills drift via Bash tool
2. Report violations with:
   • The specific edge that violates the rule
   • The commit that introduced it (when available)
   • The suggested fix per PLAN.md intent
3. For PR reviews: run wednesday-skills drift --since <base-commit> to only report new violations
4. For a single rule: wednesday-skills drift --rule <rule-name>

Adding constraints to PLAN.md

If the project has no constraints block, add one to PLAN.md:

{
  "boundaries": [
    {
      "rule": "frontend-never-imports-db",
      "description": "Frontend components must never import DB layer directly",
      "from": "src/app/**",
      "to": "src/lib/db/**",
      "type": "forbidden"
    },
    {
      "rule": "no-circular-deps",
      "description": "No circular dependencies anywhere",
      "scope": "**",
      "type": "no-cycle"
    }
  ]
}

Violation types

Type	What it catches
forbidden	Import from A → B that should never exist
ownership	Logic pattern appearing outside its designated owner
no-direct-import	Direct import between services that should use API
no-cycle	Circular dependency between modules

Never

• Auto-fix boundary violations — always ask the dev first
• Flag existing violations on a PR that did not introduce them (use --since)
• Run on projects without machine-readable PLAN.md constraints
• Report the same violation twice in one review session

CLI reference

wednesday-skills drift                              # full check
wednesday-skills drift --rule frontend-never-imports-db  # single rule
wednesday-skills drift --since abc1234              # new drift only (for PR review)