Phase 4

Seed data extended with a second barber (different hours/services), a beard-trim service + category, breaks, time off, a guest customer, and appointments in all three key states — verified against a live throwaway Postgres.
14 new integration tests (38 total with Phase 3's) covering guest/authenticated booking, any-barber assignment, slot-conflict handling, ownership enforcement, guest-data isolation, and book-again repricing.
Playwright E2E suite for the 6 required customer journeys, with its own global-setup.ts that migrates and seeds a database automatically.
Full verification pass, which caught and fixed three real bugs along the way (not just test-workarounds):
A date off-by-one bug in the calendar picker that made real weekdays show as closed for anyone in a UTC+ timezone (including the business's own).
A dialog that could vanish mid-confirmation on cancellation, before the customer could read the late-cancellation notice.
A silent test-cleanup leak in the Phase 3 fixtures that had been leaking stray businesses since Phase 3.
Plus a baseline desktop-responsive fix (centered max-w-2xl columns) across Home/Appointments/Settings/booking flow, since desktop had been effectively unstyled.
Final state: 90 unit tests, 38 integration tests, and all 6 E2E journeys passing together on a fresh database; clean tsc, eslint, and next build. Full writeup with routes, security model, guest-matching rules, known limitations, and what to check before Phase 5 is in docs/phase-4-summary.md.

package.json

@@ -16,7 +16,8 @@
     "prisma:seed": "tsx prisma/seed.ts",
     "test": "vitest run",
     "test:watch": "vitest",
-    "test:integration": "vitest run --config vitest.integration.config.mts"
+    "test:integration": "vitest run --config vitest.integration.config.mts",
+    "test:e2e": "playwright test"
   },
   "repository": {
     "type": "git",
@@ -44,10 +45,12 @@
     "react": "^19.2.8",
     "react-dom": "^19.2.8",
     "react-hook-form": "^7.84.0",
+    "server-only": "^0.0.1",
     "tailwind-merge": "^3.6.0",
     "zod": "^4.4.3"
   },
   "devDependencies": {
+    "@playwright/test": "^1.62.1",
     "@tailwindcss/postcss": "^4.3.3",
     "@types/bcryptjs": "^2.4.6",
     "@types/luxon": "^3.7.3",