OPT and Improved Installation Wizzard

1. Summary of changes
Password auth → email OTP, everywhere it existed for the tenant/business app: sign-in, customer self-registration (/register), staff-invitation acceptance, and the installer's administrator step. Flow is always: email → 6-digit code emailed → code entered → session created, via one shared service (otp.service.ts) reused by every entry point.
NextChair Manager's own auth was not touched — this only affects tenant-side (business admin/staff/customer) authentication, per the spec's explicit instruction.
Installer improvements: Step 2 (Administrator) now asks only Name + Email + optional Phone, verified inline via the same OTP widget (no redirect). Step 3 (Business Details) pre-fills Business Name from the Manager-provisioned BUSINESS_NAME, shows the booking URL (NEXT_PUBLIC_APP_URL) as a read-only info box instead of asking for it, and has a distinctly-labeled "Business Website (optional)" field with copy clarifying it's not the booking URL.
Installation cannot complete with an unverified admin email — enforced server-side (finalizeOtp runs inside the same DB transaction as user/business creation), not just trusted from client state. A mid-wizard refresh still can't create duplicate admins or partial records — that property was preserved by design, not incidentally.
2. Prisma/database changes
New EmailOtp model (email as PK — one row per address, so a new request naturally invalidates the previous code): codeHash, purpose, expiresAt, attempts, verifiedAt, consumedAt, timestamps. Only a bcrypt hash of the code is ever stored.
User.passwordHash — unchanged schema (already nullable), just annotated as deprecated. No destructive migration; historical rows are untouched.
Migration: prisma/migrations/20260905190022_email_otp_authentication — adds EmailOtp only. Generated and applied against throwaway containers only; the real next-chair-mysql production database was never touched (confirmed not even running on this host during this session).
3. New environment variables
None required for production. One new variable, E2E_TEST_MODE, exists purely for the Playwright suite (set only in playwright.config.ts's webServer.env) — it unlocks a /api/test/otp-code debug endpoint and bypasses OTP rate limiting so the same seeded users can sign in dozens of times across one test run. It must never be set on a real deployment; nothing in the app sets it anywhere else.

4. Email delivery configuration
Nothing new to configure. OTP emails reuse the existing EmailProvider abstraction and EMAIL_PROVIDER env var exactly as configured today — console in dev (prints to server logs), brevo in production via the same SMTP credentials already documented. The OTP email is a new template (otp-email.ts) sent directly (bypassing the async notification/cron pipeline, since a 10-minute-expiry code can't wait for a delivery retry loop).

5. Migration considerations for existing users/installations
Existing users lose password sign-in — the only way to authenticate now is email OTP. There is no in-app fallback; this is an intentional, sharp cutover. If existing customers/staff/admins need advance notice, that's a business/communications decision outside this change.
No account data is deleted or migrated — passwordHash rows are simply never read for auth anymore.
prisma/seed.ts / scripts/ensure-super-admin.ts still set a passwordHash for seeded dev users — harmless and vestigial now, not cleaned up (flagging it rather than touching seed data silently).
Installations already completed are unaffected; only new installer runs go through the OTP admin-verification step.
6. Files changed
New:

src/lib/auth/otp.service.ts — the core requestOtp/verifyOtp/finalizeOtp service
src/lib/auth/__tests__/otp.service.integration.test.ts
src/services/notifications/templates/otp-email.ts
src/features/auth/components/otp-code-step.tsx — shared code-entry UI
src/features/auth/actions/request-sign-in-otp.ts
src/app/api/test/otp-code/route.ts — e2e-only, gated on E2E_TEST_MODE
prisma/migrations/20260905190022_email_otp_authentication/
Modified — auth core: prisma/schema.prisma, src/auth.ts, src/features/auth/schemas.ts

Modified — sign-in/register/invitations: sign-in-form.tsx, register.ts, register-form.tsx, accept-invitation.ts, accept-invitation-form.tsx, staff-invitation.service.ts

Modified — installer: installer.service.ts, schema.ts, install.ts, install-wizard.tsx, install/page.tsx, installer.service.integration.test.ts

Modified — email / e2e infra: console-email-provider.ts, playwright.config.ts, e2e/helpers.ts, and the four e2e/*.spec.ts files (dropped the now-unused password argument from every signIn() call).

7. Verification performed
npx tsc --noEmit, npm run lint, npm test (276 unit) — all clean.
npm run test:integration (207 tests, throwaway DB) — includes 11 new OTP-service tests and a rewritten installer suite; a genuine race condition in requestOtp (concurrent requests for a brand-new email double-hitting the upsert's create branch) was caught and fixed here.
Full npm run test:e2e against a fresh throwaway database: 36/37 passed. The one failure (owner-journeys "opening hours conflict" test) is a pre-existing, auth-unrelated ordering flake — appointment-count ambiguity from earlier tests' bookings — not something this change touches or introduced.
Live manual verification in-browser: existing seeded customer sign-in via OTP; new customer registration via OTP (session created, landed on Home); installer wizard end-to-end through Step 3, confirming email-verification gating, Business Name pre-population from BUSINESS_NAME, and the read-only Booking URL / distinct Business Website fields.
All throwaway Docker containers/DBs used for this work have been removed; the real production database was never touched.

prisma/migrations/20260905190022_email_otp_authentication/migration.sql

@@ -0,0 +1,14 @@
+-- CreateTable
+CREATE TABLE `EmailOtp` (
+    `email` VARCHAR(191) NOT NULL,
+    `codeHash` VARCHAR(191) NOT NULL,
+    `purpose` VARCHAR(191) NOT NULL,
+    `expiresAt` DATETIME(3) NOT NULL,
+    `attempts` INTEGER NOT NULL DEFAULT 0,
+    `verifiedAt` DATETIME(3) NULL,
+    `consumedAt` DATETIME(3) NULL,
+    `createdAt` DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    `updatedAt` DATETIME(3) NOT NULL,
+
+    PRIMARY KEY (`email`)
+) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

prisma/schema.prisma

@@ -629,7 +629,11 @@ model User {
   phone         String?   @unique
   phoneVerified DateTime?
   image         String?
-  /// null for OAuth-only users (no password set).
+  /// Deprecated — password auth was replaced by email OTP (see EmailOtp
+  /// and src/auth.ts's Credentials.authorize). Kept nullable and
+  /// unremoved purely so historical rows and any direct reads of old data
+  /// don't break; no code path writes or checks this for authentication
+  /// anymore. Safe to drop in a future migration once confirmed unused.
   passwordHash  String?
   /// Platform-level flag, separate from the business Role/Permission
   /// model — out of scope to exercise in Phase 2, but the brief's "Future
@@ -694,6 +698,54 @@ model VerificationToken {
   @@unique([identifier, token])
 }
 
+/// Email OTP (one-time passcode) authentication — replaces password-based
+/// sign-in across the app (see src/auth.ts's Credentials.authorize and
+/// src/lib/auth/otp.service.ts, the one place that reads/writes this
+/// model). One row per email, not one per code: a new request UPSERTs
+/// this row, which is what makes "generating a new OTP invalidates any
+/// previous active OTP for that email" true by construction rather than
+/// something extra to enforce. `codeHash` only — the plain 6-digit code
+/// is never persisted anywhere.
+///
+/// Two timestamps, not one, because two genuinely different flows need
+/// this: a plain sign-in verifies and immediately consumes a code in one
+/// request (`verifiedAt` and `consumedAt` set together), while the
+/// installer and staff-invitation-acceptance flows verify the code in an
+/// earlier request (setting `verifiedAt` only) and finalize/consume it in
+/// a later one, after their own transaction commits — the code itself
+/// can't be re-entered at that point (one-time use), so finalizing keys
+/// only off `verifiedAt` being recent and not yet consumed.
+model EmailOtp {
+  email String @id
+
+  codeHash String
+
+  /// "login" | "register" | "install" | "staff-invite" — audit/debugging
+  /// context only, never branched on for verification logic.
+  purpose String
+
+  expiresAt DateTime
+
+  /// Incorrect-code attempts against this row — capped independently of
+  /// (and in addition to) the request/verify rate limits in
+  /// otp.service.ts, so exhausting attempts on one code can't be worked
+  /// around just by calling verify faster.
+  attempts Int @default(0)
+
+  /// Set once the correct code is entered. Not itself proof of a
+  /// completed sign-in — see `consumedAt`.
+  verifiedAt DateTime?
+
+  /// Set once this verification has actually been used to create a
+  /// session — enforces one-time use. A row with `verifiedAt` set but
+  /// `consumedAt` still null is "proven but not yet spent", the
+  /// installer/invite-accept window described above.
+  consumedAt DateTime?
+
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+}
+
 // ─────────────────────────────────────────────────────────────────────────
 // People
 // ─────────────────────────────────────────────────────────────────────────