---
phase: 18
slug: auto-timezone-detection-and-ability-to-change-timezone
status: draft
nyquist_compliant: false
wave_0_complete: false
created: 2026-06-14
---

# Phase 18 — Validation Strategy

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

---

## Test Infrastructure

| Property | Value |
|----------|-------|
| **Framework** | vitest |
| **Config file** | apps/api/vitest.config.ts (backend), apps/pwa/vitest.config.ts (frontend) |
| **Quick run command** | `pnpm --filter @familysync/api test -- --run` |
| **Full suite command** | `pnpm -r test -- --run` |
| **Estimated runtime** | ~30 seconds |

---

## Sampling Rate

- **After every task commit:** Run `pnpm --filter @familysync/api test -- --run`
- **After every plan wave:** Run `pnpm -r test -- --run`
- **Before `/gsd-verify-work`:** Full suite must be green
- **Max feedback latency:** 60 seconds

---

## Per-Task Verification Map

| Task ID | Plan | Wave | Requirement | Threat Ref | Secure Behavior | Test Type | Automated Command | File Exists | Status |
|---------|------|------|-------------|------------|-----------------|-----------|-------------------|-------------|--------|
| {N}-01-01 | 01 | 1 | D-05/D-06 | — | tz accessor returns stored value, falls back to process.env.TZ ?? Intl when unset | unit | `pnpm --filter @familysync/api test -- --run` | ❌ W0 | ⬜ pending |

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

> Planner fills this table per task. Key automated coverage targets from RESEARCH.md "Validation Architecture":
> - stored-tz accessor + D-06 fallback chain (unit)
> - IANA validation (try/catch on `Intl.DateTimeFormat`, accepts UTC) (unit)
> - `computeAlertInstantUtc` fed the stored tz vs fallback produces correct 9 AM-local instant (unit)
> - admin change-tz read/write round-trip (integration)
> - all-day reminder fires at 9 AM in the stored zone under a non-UTC value (integration/E2E)

---

## Wave 0 Requirements

- [ ] Backend unit-test stubs for the stored-tz accessor + fallback chain
- [ ] Backend unit-test stubs for IANA validation
- [ ] vitest already present — no framework install needed

*Existing all-day scheduler tests remain green unmodified (mock DB returns no app_config rows → D-06 fallback path).*

---

## Manual-Only Verifications

| Behavior | Requirement | Why Manual | Test Instructions |
|----------|-------------|------------|-------------------|
| Searchable IANA picker UX in /admin Settings | D-04 | Visual/interaction quality | Drive with `playwright-cli`: open /admin Settings, search a zone, save, reload, confirm persisted |

*iOS-Safari standalone behavior is out of scope for this phase.*

---

## 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 < 60s
- [ ] `nyquist_compliant: true` set in frontmatter

**Approval:** pending