TDD Alignment (Step 2)

Core mental model

The TDD is the bridge between what (PRD) and how-to-test (later steps). Misalignment here propagates downstream: an acceptance criterion with no test design becomes an acceptance criterion with no test, becomes a feature shipped without proof.

What it produces

TDD_ALIGNMENT.md with:

• Coverage table: each PRD acceptance criterion → TDD test strategy
• PHI handling table: each L3/L4 field → desensitization step in TDD
• Stage validation table: each PRD stage → TDD's stage-level test plan
• Gaps list (sorted by severity)

Active context bundle

Always load first

1. This SKILL.md
2. Final PRD
3. Submitted TDD
4. COMPLIANCE_TAG.md (PHI field list)

Load on demand

• reference/test-strategy-catalog.md (unit / integration / e2e / chaos / compliance / replay)

Workflow

1. Extract PRD acceptance criteria into a flat list (numbered).
2. For each criterion, find the TDD section that addresses it; record (criterion → tdd-section + test-strategy).
3. Any criterion without a target → gap.
4. For every L3/L4 field in COMPLIANCE_TAG, locate desensitization plan in TDD; missing → gap.
5. For every PRD stage, locate the corresponding TDD stage validation; missing → gap.
6. Emit report; if gaps exist, suggest concrete TDD patches.

Hard gate checklist

• 100% of PRD criteria covered (no gaps)
• Every L3/L4 field has desensitization step named in TDD
• Each PRD stage has corresponding TDD stage validation
• Test strategy named (not just "we'll test it")

Common failure modes

1. "Tests will be written later" handwave: TDD says "comprehensive testing" without naming approach. Mitigation: require strategy name from reference/test-strategy-catalog.md.
2. Forgotten staging tests: PRD has 3 stages, TDD only describes final-state tests. Mitigation: per-stage row in alignment table.
3. PHI assumed handled by infra: developer assumes desensitize happens "somewhere". Mitigation: explicit row per field.

Handoff

After PASS, proceed to Step 3 (OpenSpec change creation).