GitHub Actions: IDD validation workflow

[slusset]

Intent

CI/CD pipeline that validates project integrity on every PR:

Phase 1 (now — plan + Python)

• Plan validation: tools/validate-plan.py checks roadmap schema and invariants
• Python checks: type checking, import verification
• Test runner: pytest for unit tests

Phase 2 (when IDD specs exist)

• IDD validation via upstream idd-check GitHub Action
• BDD feature files have matching step implementations
• Traceability from narrative → spec → code → test
• PR review checks IDD coverage

Phase 3 (when agents are operational)

• Contract validation: AsyncAPI/JSON-RPC schemas are valid
• Spec-before-code enforcement: implementation changes require spec changes

Artifacts

• .github/workflows/ci.yml (Phase 1)
• .github/workflows/idd-validate.yml (Phase 2)

Roadmap

• Phase 1 maps to m1-foundation (plan-layer capability)
• Phase 2 maps to IDD spec work (across milestones)
• Phase 3 maps to m2-invocation and beyond