docs(phase-12): add validation strategy

.planning/phases/12-comparison-view/12-VALIDATION.md

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+---
+phase: 12
+slug: comparison-view
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-03-17
+---
+
+# Phase 12 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | Bun test (built-in) |
+| **Config file** | None — uses `bun test` directly |
+| **Quick run command** | `bun test` |
+| **Full suite command** | `bun test` |
+| **Estimated runtime** | ~5 seconds |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `bun test`
+- **After every plan wave:** Run `bun test`
+- **Before `/gsd:verify-work`:** Full suite must be green
+- **Max feedback latency:** 5 seconds
+
+---
+
+## Per-Task Verification Map
+
+| Task ID | Plan | Wave | Requirement | Test Type | Automated Command | File Exists | Status |
+|---------|------|------|-------------|-----------|-------------------|-------------|--------|
+| 12-01-01 | 01 | 1 | COMP-01 | manual-only (UI/browser) | — | N/A | ⬜ pending |
+| 12-01-02 | 01 | 1 | COMP-02 | unit (if delta util extracted) | `bun test tests/lib/comparison-deltas.test.ts` | ❌ W0 | ⬜ pending |
+| 12-01-03 | 01 | 1 | COMP-03 | manual-only (CSS/browser) | — | N/A | ⬜ pending |
+| 12-01-04 | 01 | 1 | COMP-04 | manual-only (UI state) | — | N/A | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+- [ ] `tests/lib/comparison-deltas.test.ts` — stubs for COMP-02 delta computation (optional; skip if deltas stay inlined in React component via useMemo)
+
+*Existing `bun test` infrastructure covers all backend services. This phase is pure frontend — no backend tests are broken.*
+
+---
+
+## Manual-Only Verifications
+
+| Behavior | Requirement | Why Manual | Test Instructions |
+|----------|-------------|------------|-------------------|
+| Candidates display all fields in tabular columns | COMP-01 | UI rendering — no backend logic | Open thread with 2+ candidates, toggle compare view, verify all fields visible |
+| Table scrolls horizontally with sticky label column | COMP-03 | CSS behavior — requires browser | Narrow viewport to <768px, verify horizontal scroll, verify label column stays fixed |
+| Resolved thread shows read-only view with winner marked | COMP-04 | UI state — requires resolved thread | Open resolved thread, toggle compare view, verify winner column highlighted, no interactive elements |
+| Missing weight/price shows dash, not zero | COMP-04 | UI rendering for null data | Add candidate with no weight, toggle compare, verify "—" not "0g" |
+
+---
+
+## Validation Sign-Off
+
+- [ ] All tasks have `<automated>` verify or Wave 0 dependencies
+- [ ] Sampling continuity: no 3 consecutive tasks without automated verify
+- [ ] Wave 0 covers all MISSING references
+- [ ] No watch-mode flags
+- [ ] Feedback latency < 5s
+- [ ] `nyquist_compliant: true` set in frontmatter
+
+**Approval:** pending