docs(phase-6): add validation strategy

.planning/phases/06-background-worker/06-VALIDATION.md

@@ -0,0 +1,80 @@
+---
+phase: 6
+slug: background-worker
+status: draft
+nyquist_compliant: false
+wave_0_complete: false
+created: 2026-05-15
+---
+
+# Phase 6 — Validation Strategy
+
+> Per-phase validation contract for feedback sampling during execution.
+
+---
+
+## Test Infrastructure
+
+| Property | Value |
+|----------|-------|
+| **Framework** | go test |
+| **Config file** | backend/go.mod |
+| **Quick run command** | `cd backend && go build ./cmd/worker/...` |
+| **Full suite command** | `cd backend && go test ./... && go build ./...` |
+| **Estimated runtime** | ~10 seconds |
+
+---
+
+## Sampling Rate
+
+- **After every task commit:** Run `cd backend && go build ./cmd/worker/...`
+- **After every plan wave:** Run `cd backend && go test ./... && go build ./...`
+- **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 |
+|---------|------|------|-------------|------------|-----------------|-----------|-------------------|-------------|--------|
+| 06-01-01 | 01 | 1 | WORK-01 | — | N/A | build | `cd backend && go build ./cmd/worker/...` | ✅ | ⬜ pending |
+| 06-01-02 | 01 | 1 | WORK-01 | — | N/A | unit | `cd backend && go test ./internal/worker/...` | ❌ W0 | ⬜ pending |
+| 06-02-01 | 02 | 1 | WORK-02 | — | N/A | unit | `cd backend && go test ./internal/jobs/...` | ❌ W0 | ⬜ pending |
+| 06-03-01 | 03 | 2 | WORK-03 | — | N/A | manual | Worker logs show retry backoff entries | — | ⬜ pending |
+| 06-04-01 | 04 | 2 | WORK-04 | — | N/A | build | `cd backend && go build ./...` | ✅ | ⬜ pending |
+
+*Status: ⬜ pending · ✅ green · ❌ red · ⚠️ flaky*
+
+---
+
+## Wave 0 Requirements
+
+- [ ] `backend/internal/worker/worker_test.go` — stubs for WORK-01 worker startup
+- [ ] `backend/internal/jobs/jobs_test.go` — stubs for WORK-02 periodic job registration
+
+*If none: "Existing infrastructure covers all phase requirements."*
+
+---
+
+## Manual-Only Verifications
+
+| Behavior | Requirement | Why Manual | Test Instructions |
+|----------|-------------|------------|-------------------|
+| Heartbeat logs "worker heartbeat" every ~1 min | WORK-02 | Requires running binary with real Postgres | `just worker` and observe logs for 2 min |
+| Orphan cleanup runs on schedule and logs results | WORK-02 | Requires real DB + S3 state | Insert orphan row, start worker, wait for cleanup run |
+| Failed job retried with backoff visible in logs | WORK-03 | Requires real river runtime | Register a job that fails, observe retry log entries |
+| Web binary enqueues job, worker picks up within seconds | WORK-04 | Integration between two running binaries | `just dev` + enqueue trigger, observe worker logs |
+
+---
+
+## 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