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.

src/lib/business/get-primary-business.ts

@@ -0,0 +1,21 @@
+import { cache } from "react";
+import { prisma } from "@/lib/db/prisma";
+
+/**
+ * v1 is single-business (see docs/implementation-plan.md §11) — every
+ * page that needs "the business" fetches it through here rather than
+ * hardcoding a slug or re-querying independently. Wrapped in React's
+ * `cache()` so multiple Server Components in the same request (a layout
+ * and its page, for instance) share one query instead of issuing it
+ * once each.
+ */
+export const getPrimaryBusiness = cache(async () => {
+  return prisma.business.findFirstOrThrow({
+    include: {
+      locations: true,
+      hours: true,
+      settings: true,
+      bookingRule: true,
+    },
+  });
+});

src/lib/business/opening-status.ts

@@ -0,0 +1,45 @@
+import { minutesFromMidnight, todayIn, weekdayOf } from "@/lib/time/business-time";
+import { Weekday } from "@/generated/prisma/enums";
+
+export interface OpeningStatus {
+  isOpen: boolean;
+  label: string;
+}
+
+interface DayHoursRow {
+  dayOfWeek: Weekday;
+  isClosed: boolean;
+  opensAtMinutes: number | null;
+  closesAtMinutes: number | null;
+}
+
+function formatMinutes(minutes: number): string {
+  const h = Math.floor(minutes / 60);
+  const m = minutes % 60;
+  return `${String(h).padStart(2, "0")}:${String(m).padStart(2, "0")}`;
+}
+
+/**
+ * Purely presentational (read-only "open now?" label for the home page)
+ * — not part of the booking engine's own open/closed check, which
+ * AvailabilityService already performs independently as a real booking
+ * rule. This is display-only, so it lives here rather than in
+ * services/scheduling.
+ */
+export function computeOpeningStatus(hours: DayHoursRow[], timezone: string): OpeningStatus {
+  const today = todayIn(timezone);
+  const weekday = weekdayOf(today);
+  const todayHours = hours.find((h) => h.dayOfWeek === weekday);
+
+  if (!todayHours || todayHours.isClosed || todayHours.opensAtMinutes === null || todayHours.closesAtMinutes === null) {
+    return { isOpen: false, label: "Closed today" };
+  }
+
+  const nowMinutes = minutesFromMidnight(new Date(), timezone);
+  const isOpen = nowMinutes >= todayHours.opensAtMinutes && nowMinutes < todayHours.closesAtMinutes;
+
+  return {
+    isOpen,
+    label: isOpen ? `Open until ${formatMinutes(todayHours.closesAtMinutes)}` : `Closed · Opens ${formatMinutes(todayHours.opensAtMinutes)}`,
+  };
+}