---
phase: 2
slug: audio-synthesis-engine
status: draft
nyquist_compliant: true
wave_0_complete: true
tdd_model: co-creation
created: 2026-03-26
---

# Phase 2 — Validation Strategy

> Per-phase validation contract for feedback sampling during execution.

---

## Test Infrastructure

| Property | Value |
|----------|-------|
| **Framework** | go test (stdlib) |
| **Config file** | none — existing Go test infrastructure |
| **Quick run command** | `go test ./synth/... ./encode/...` |
| **Full suite command** | `go test ./...` |
| **Estimated runtime** | ~5 seconds |

---

## TDD Model

This phase uses **co-creation TDD**: tests are written within the same task as the implementation, following RED-GREEN-REFACTOR within each task. All TDD tasks are marked with `tdd="true"` in their plan XML. Test files are created as part of the task, not as a separate Wave 0 plan.

This is explicitly chosen over pre-existing stub TDD because:
1. Each task's `<behavior>` block defines expected test cases before implementation begins
2. The executor writes tests FIRST (RED), then implementation (GREEN) within the same task
3. No test file exists before the task starts — the task creates both test and implementation

Wave 0 requirements are limited to environment/tooling setup (gcc, ffprobe, go-lame dependency), handled by Plan 01 Task 1.

---

## 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 | TDD | Status |
|---------|------|------|-------------|-----------|-------------------|-----|--------|
| 02-01-01 | 01 | 1 | SYNTH-01 | setup | `go version && gcc --version && ffprobe -version && grep "go-lame" go.mod && CGO_ENABLED=1 go build ./...` | n/a | ⬜ pending |
| 02-01-02 | 01 | 1 | SYNTH-01, SYNTH-02 | unit | `cd /home/dev/workspace/yoloyolo && go test ./synth/... -v -count=1` | co-creation | ⬜ pending |
| 02-02-01 | 02 | 2 | SYNTH-03 | unit | `cd /home/dev/workspace/yoloyolo && go test ./synth/... -run "TestPan\|TestStereo\|TestClamp" -v -count=1` | co-creation | ⬜ pending |
| 02-02-02 | 02 | 2 | SYNTH-03 | unit | `cd /home/dev/workspace/yoloyolo && go test ./synth/... -run "TestNewBank\|TestRenderWindow\|TestMixerNoClip\|TestStereoPan\|TestMultipleWindows" -v -count=1` | co-creation | ⬜ pending |
| 02-03-01 | 03 | 3 | OUT-02, OUT-03 | integration | `cd /home/dev/workspace/yoloyolo && CGO_ENABLED=1 go test ./encode/... -v -count=1` | co-creation | ⬜ pending |
| 02-03-02 | 03 | 3 | OUT-01 | build | `cd /home/dev/workspace/yoloyolo && go build -o /dev/null ./cmd/netsynth/ && go run ./cmd/netsynth/ --help 2>&1 \| grep -q "\-o.*output" && echo "OK"` | n/a | ⬜ pending |

*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*

---

## Wave 0 Requirements

- [x] `gcc` — C compiler required for go-lame CGo compilation (Plan 01, Task 1)
- [x] `ffprobe` — MP3 validation in acceptance tests (Plan 01, Task 1)
- [x] `go get github.com/sjzar/go-lame@v0.0.9` — MP3 encoding dependency (Plan 01, Task 1)
- [x] `go-audio/wav` — **Skipped.** Per CONTEXT.md Claude's Discretion grant; write PCM bytes directly to LameWriter (CLAUDE.md updated).

*Test stubs are co-created with implementation in each TDD task (see TDD Model section above).*

---

## Manual-Only Verifications

| Behavior | Requirement | Why Manual | Test Instructions |
|----------|-------------|------------|-------------------|
| Perceptually distinct drone tones per traffic class | SYNTH-01 | Subjective audio quality | Play output MP3, verify each class sounds distinct |
| Amplitude rises/falls audibly with traffic volume | SYNTH-02 | Subjective perception | Listen for volume changes across windows with varying traffic |
| Stereo panning creates spatial separation | SYNTH-03 | Subjective audio quality | Listen with headphones, verify bass center and highs spread |

---

## Validation Sign-Off

- [x] All tasks have `<automated>` verify commands matching plan blocks
- [x] Sampling continuity: no 3 consecutive tasks without automated verify (all tasks have automated verify)
- [x] Wave 0 covers environment/tooling setup (Plan 01, Task 1)
- [x] Co-creation TDD model documented; test expectations defined in `<behavior>` blocks
- [x] No watch-mode flags
- [x] Feedback latency < 5s
- [x] `nyquist_compliant: true` set in frontmatter

**Approval:** ready