docs(phase-5): add validation strategy

.planning/phases/05-waveform-types-and-bank-decoupling/05-VALIDATION.md

@@ -0,0 +1,81 @@
+---
+phase: 5
+slug: waveform-types-and-bank-decoupling
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-03-26
+---
+
+# Phase 5 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | Go testing (`testing` stdlib) |
+| **Config file** | None — standard `go test` |
+| **Quick run command** | `go test ./synth/... ./encode/...` |
+| **Full suite command** | `go test ./...` |
+| **Estimated runtime** | ~5 seconds |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `go test ./synth/... ./encode/...`
+- **After every plan wave:** Run `go 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 |
+|---------|------|------|-------------|-----------|-------------------|-------------|--------|
+| 05-01-01 | 01 | 1 | WAVE-01 | unit | `go test ./synth/... -run TestWaveformCustomPreservesHarmonics` | ❌ W0 | ⬜ pending |
+| 05-01-02 | 01 | 1 | WAVE-01 | unit | `go test ./synth/... -run TestWaveformPresetHarmonics` | ❌ W0 | ⬜ pending |
+| 05-01-03 | 01 | 1 | WAVE-01 | unit | `go test ./synth/... -run TestNewBankAcceptsConfigMap` | ❌ W0 | ⬜ pending |
+| 05-01-04 | 01 | 1 | WAVE-02 | unit | `go test ./synth/... -run TestBandlimitedHarmonicsNoAliasing` | ❌ W0 | ⬜ pending |
+| 05-01-05 | 01 | 1 | WAVE-02 | unit | `go test ./synth/... -run TestSineRegressionVsCustomHarmonics` | ❌ W0 | ⬜ pending |
+| 05-02-01 | 02 | 1 | WAVE-01+02 | unit | `go test ./synth/... -run TestMixerNoClip` | ✅ exists (update) | ⬜ pending |
+| 05-02-02 | 02 | 1 | WAVE-01 | unit/smoke | `go test ./encode/...` | ✅ exists (update) | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+- [ ] `synth/waveform_test.go` — stubs for WAVE-01 (preset harmonics correctness) and WAVE-02 (bandlimit enforcement)
+- [ ] Update `synth/bank_test.go:TestNewBankHas14Layers` to use new two-argument `NewBank` signature
+- [ ] Update `synth/config_test.go:TestNumLayersMatchesAllClasses` to reflect dynamic gain approach
+
+*Existing test infrastructure covers framework and tooling — no new framework install needed.*
+
+---
+
+## Manual-Only Verifications
+
+| Behavior | Requirement | Why Manual | Test Instructions |
+|----------|-------------|------------|-------------------|
+| Audible tonal distinction between waveforms | WAVE-01 | Subjective audio quality | Generate MP3 with each waveform type; listen and confirm distinct timbres |
+| No audible aliasing or buzzing | WAVE-02 | Perceptual audio quality | Play sawtooth/square at low frequencies (65 Hz); confirm clean sound |
+
+---
+
+## 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