docs(phase-5): add validation strategy

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/phases/05-design-system-token-rework/05-VALIDATION.md

@@ -0,0 +1,74 @@
+---
+phase: 5
+slug: design-system-token-rework
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-04-20
+---
+
+# Phase 5 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | vitest (existing) |
+| **Config file** | `vite.config.ts` |
+| **Quick run command** | `bun run build` |
+| **Full suite command** | `bun run build && bun run lint` |
+| **Estimated runtime** | ~15 seconds |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `bun run build`
+- **After every plan wave:** Run `bun run build && bun run lint`
+- **Before `/gsd-verify-work`:** Full suite must be green
+- **Max feedback latency:** 15 seconds
+
+---
+
+## Per-Task Verification Map
+
+| Task ID | Plan | Wave | Requirement | Threat Ref | Secure Behavior | Test Type | Automated Command | File Exists | Status |
+|---------|------|------|-------------|------------|-----------------|-----------|-------------------|-------------|--------|
+| 5-01-01 | 01 | 1 | DS-01 | — | N/A | build | `bun run build` | ✅ | ⬜ pending |
+| 5-01-02 | 01 | 1 | DS-02 | — | N/A | build | `bun run build` | ✅ | ⬜ pending |
+| 5-01-03 | 01 | 1 | DS-03 | — | N/A | build | `bun run build` | ✅ | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+*Existing infrastructure covers all phase requirements.*
+
+---
+
+## Manual-Only Verifications
+
+| Behavior | Requirement | Why Manual | Test Instructions |
+|----------|-------------|------------|-------------------|
+| Sharp corners visible on all 9 pages | DS-01 | Visual verification — no programmatic way to confirm rendered border radius from tests | Open each page, inspect all cards/buttons/inputs for 0px radius |
+| Category colors visibly colorful against white | DS-02 | Perception-based — WCAG contrast can be calculated but "visibly colorful" is subjective | Open categories page, compare swatches against white background |
+| Layout uncluttered with consistent whitespace | DS-03 | Visual rhythm/spacing is a design judgment | Compare before/after screenshots of all 9 pages |
+
+---
+
+## 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 < 15s
+- [ ] `nyquist_compliant: true` set in frontmatter
+
+**Approval:** pending