Merge pull request 'Send platform operators to the platform console after sign-in' (#9) from fix/operator-landing into main

Reviewed-on: #9

docs/PILOT_READINESS.md

@@ -98,7 +98,7 @@ seven findings and a retest plan. All of them are addressed on
 | F-04 No way back for deactivated products | Products page lists deactivated products under a toggle, with Reactivate. Deactivating warns about stock still on hand; that stock stays on the Stock page and can be transferred or counted out. |
 | F-05 Eggs shown as litres | Products carry a unit (L, ml, kg, g, pcs, tray, pack), chosen when the product is created and shown everywhere. |
 | F-06 No branch or staff removal | Staff: deactivate/reactivate (previous change). Branches: rename and deactivate/reactivate on the Branches page. A branch can only be deactivated once it has no stock and no active staff; its history stays in reports. |
-| F-07 Purchases shown as cost of goods | Cost of goods sold is now units sold x the product's average buying price. Purchases in the period are shown separately as "Stock purchased", with a "Cash surplus" line. |
+| F-07 Purchases shown as cost of goods | Cost of goods sold covers only units sold (now first-in-first-out per branch; see "Cost of goods sold" below). Purchases in the period are shown separately as "Stock purchased", with a "Cash surplus" line. |
 | STA-04 No invites | Staff and new branch managers can be invited: the owner or manager gets a one-time link (7 days) to send, and the person sets their own password. A new link can be made from Staff. |
 | CAT-12 Zero price, duplicates | Prices must be above zero; product names are unique per business, ignoring case. |
 | OFF-02 Local stock deduction | The till shows each product's stock and deducts every sale immediately, online or offline. |
@@ -157,13 +157,51 @@ platform-wide unique indexes for per-business ones. Until it runs,
 operators cannot open the Platform console and a second business cannot
 reuse an email. It is safe to re-run.
 
+## Tenant isolation is enforced
+
+Every model that holds one business's data carries a guard
+(`src/lib/server/tenantGuard.ts`). A query that does not name exactly one
+business (`businessId: <id>`) throws `TenantScopeError` before it reaches
+the database, so a route that forgets the business filter fails loudly in
+development and in the tests instead of reading or changing another
+business's data.
+
+- Guarded: User, Branch, Product, BranchPricing, Transaction,
+  DailyInventory, Expense, Purchase, StockMovement, StockTransfer. A test
+  fails if a new model with a `businessId` field is added without the guard.
+- Queries that genuinely span businesses must be wrapped in
+  `crossTenant("reason", ...)`: login's email lookup, refresh-session and
+  invite-token lookups, the M-Pesa callback, the platform console, and the
+  maintenance scripts. `git grep crossTenant` lists every one.
+- Related records are loaded with `scopedPopulate`, so a populated branch,
+  product or staff name is also restricted to the business.
+- `tests/isolation.test.ts` sweeps every read route with another business's
+  ids (nothing of theirs comes back) and every write route (all refused,
+  their data unchanged).
+- Not guarded, by design: Business (the tenant itself, always looked up by
+  the session's id), UserSession, MpesaCallbackLog and StockLock.
+
+## Cost of goods sold
+
+The profit report costs sales first-in-first-out, per branch
+(`src/lib/server/costing.ts`). It replays the stock ledger in order. Each
+branch keeps queues of stock at the price it was bought at, and a sale
+takes the oldest first.
+
+- **Transfers carry their cost.** Stock moved between branches arrives at
+  what the sending branch paid.
+- **Opening stock and upward counts** are valued at the product's purchase
+  price at the time (or its first purchase price, if they came first).
+- **A sale recorded before its stock** (e.g. an offline sale before the
+  purchase was entered) is costed by the next stock to arrive at that
+  branch. Until then it counts as "units with no purchase cost on record".
+- **Stock written off** by counts or adjustments is shown as "Stock losses"
+  and deducted in net profit. It is not part of cost of goods sold.
+- Each report replays the business's whole stock history. That is fast at
+  pilot volumes; a business with years of history would want stored cost
+  layers instead.
+
 ## Still open
-- **Isolation by convention.** Tenant filters are still written per route.
-  The tests cover the sales, stock, transfer and access paths, not every
-  route.
-- **Cost of goods is an average.** It uses each product's average buying
-  price across the business, not first-in-first-out per branch. Units sold
-  with no purchase on record are counted and flagged, but have no cost.
 - **M-Pesa, if turned on.** Only one product per payment. A prompt that
   times out still needs a manual check before taking cash.
 - **Not modelled yet:** email verification at signup, sending invites by

scripts/migrate-multitenant.ts

@@ -13,6 +13,7 @@ import { Expense } from "../src/lib/server/models/Expense";
 import { Purchase } from "../src/lib/server/models/Purchase";
 import { Business } from "../src/lib/server/models/Business";
 import { DEFAULT_TIER, TRIAL_DAYS } from "../src/lib/tiers";
+import { crossTenant } from "../src/lib/server/tenantGuard";
 
 async function migrate() {
   await connectDb();
@@ -75,7 +76,7 @@ async function migrate() {
   process.exit(0);
 }
 
-migrate().catch((err) => {
+crossTenant("one-off migration of data from before businesses existed", migrate).catch((err) => {
   console.error("migration failed:", err.message);
   process.exit(1);
 });

scripts/migrate-per-business-identity.ts

@@ -6,6 +6,7 @@ import mongoose from "mongoose";
 import { connectDb } from "../src/lib/server/db";
 import { User } from "../src/lib/server/models/User";
 import { platformAdminEmails } from "../src/lib/server/platform";
+import { crossTenant } from "../src/lib/server/tenantGuard";
 
 /**
  * One-off, safe to re-run. Moves user identity from platform-wide to
@@ -43,7 +44,7 @@ async function main() {
   await mongoose.disconnect();
 }
 
-main().catch((err) => {
+crossTenant("identity migration spans every business", main).catch((err) => {
   console.error("migration failed:", err.message);
   process.exit(1);
 });

scripts/seed.ts

@@ -14,6 +14,7 @@ import { User } from "../src/lib/server/models/User";
 import { Product } from "../src/lib/server/models/Product";
 import { Business } from "../src/lib/server/models/Business";
 import { isPlatformAdminEmail } from "../src/lib/server/platform";
+import { crossTenant } from "../src/lib/server/tenantGuard";
 
 /**
  * Run once against a fresh database: `npm run seed`.
@@ -107,7 +108,7 @@ async function seed() {
   process.exit(0);
 }
 
-seed().catch((err) => {
+crossTenant("seeding may find a legacy admin outside any business", seed).catch((err) => {
   console.error("seed failed:", err.message);
   process.exit(1);
 });

src/app/account/password/page.tsx

@@ -0,0 +1,109 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { useRouter } from "next/navigation";
+import { apiFetch, ApiError } from "@/lib/api";
+import { AuthUser } from "@/lib/types";
+
+const inputClass =
+  "tap-target w-full rounded-xl2 border border-depth-200 bg-white px-4 text-depth-900 shadow-sm transition focus:border-flow-500 focus:outline-none focus:ring-2 focus:ring-flow-500/25";
+
+/** The signed-in user changes their own password. */
+export default function ChangePasswordPage() {
+  const router = useRouter();
+  const [me, setMe] = useState<AuthUser | null>(null);
+  const [current, setCurrent] = useState("");
+  const [next, setNext] = useState("");
+  const [confirm, setConfirm] = useState("");
+  const [error, setError] = useState<string | null>(null);
+  const [done, setDone] = useState(false);
+  const [saving, setSaving] = useState(false);
+
+  useEffect(() => {
+    apiFetch<{ user: AuthUser }>("/api/auth/me")
+      .then((r) => setMe(r.user))
+      .catch(() => router.replace("/login"));
+  }, [router]);
+
+  const home = me?.role === "DELIVERY" ? "/terminal" : "/admin/dashboard";
+
+  async function handleSubmit(e: React.FormEvent) {
+    e.preventDefault();
+    setError(null);
+    if (next.length < 8) return setError("The new password must be at least 8 characters.");
+    if (next !== confirm) return setError("The two new passwords do not match.");
+    setSaving(true);
+    try {
+      await apiFetch("/api/auth/password", {
+        method: "POST",
+        body: JSON.stringify({ currentPassword: current, newPassword: next }),
+      });
+      setDone(true);
+      setCurrent("");
+      setNext("");
+      setConfirm("");
+    } catch (err) {
+      setError(err instanceof ApiError ? err.message : "Could not change your password.");
+    }
+    setSaving(false);
+  }
+
+  return (
+    <main className="flex min-h-screen items-center justify-center bg-sand-50 px-5 py-10">
+      <div className="w-full max-w-md rounded-3xl bg-white p-6 shadow-soft">
+        <h1 className="font-display text-2xl font-bold text-depth-900">Change password</h1>
+        {me && <p className="mt-1 text-sm text-depth-600">{me.email}</p>}
+
+        {done ? (
+          <div className="mt-6">
+            <p className="rounded-lg bg-confirm-500/10 px-3 py-2 text-sm text-confirm-600">
+              Your password is changed. Any other phone or computer signed in to your account has been signed out.
+            </p>
+            <button
+              onClick={() => router.replace(home)}
+              className="tap-target mt-4 w-full rounded-full bg-gradient-to-r from-flow-500 to-flow-700 font-display font-semibold text-white"
+            >
+              Back
+            </button>
+          </div>
+        ) : (
+          <form onSubmit={handleSubmit} className="mt-6 space-y-4">
+            <div>
+              <label htmlFor="current-password" className="mb-1.5 block text-sm font-medium text-depth-700">
+                Current password
+              </label>
+              <input id="current-password" type="password" autoComplete="current-password" value={current} onChange={(e) => setCurrent(e.target.value)} className={inputClass} />
+            </div>
+            <div>
+              <label htmlFor="new-password" className="mb-1.5 block text-sm font-medium text-depth-700">
+                New password
+              </label>
+              <input id="new-password" type="password" autoComplete="new-password" value={next} onChange={(e) => setNext(e.target.value)} className={inputClass} />
+            </div>
+            <div>
+              <label htmlFor="confirm-password" className="mb-1.5 block text-sm font-medium text-depth-700">
+                Confirm new password
+              </label>
+              <input id="confirm-password" type="password" autoComplete="new-password" value={confirm} onChange={(e) => setConfirm(e.target.value)} className={inputClass} />
+            </div>
+            {error && (
+              <p role="alert" className="rounded-lg bg-alert-500/10 px-3 py-2 text-sm text-alert-600">
+                {error}
+              </p>
+            )}
+            <button
+              type="submit"
+              disabled={saving}
+              className="tap-target w-full rounded-full bg-gradient-to-r from-flow-500 to-flow-700 font-display font-semibold text-white disabled:opacity-60"
+            >
+              {saving ? "Saving…" : "Change password"}
+            </button>
+            <button type="button" onClick={() => router.replace(home)} className="w-full text-sm text-depth-500 underline">
+              Cancel
+            </button>
+          </form>
+        )}
+      </div>
+    </main>
+  );
+}

src/app/admin/dashboard/page.tsx

@@ -17,6 +17,7 @@ import BranchRankingList from "@/components/admin/BranchRankingList";
 import ActivityFeedMatrix from "@/components/admin/ActivityFeedMatrix";
 import ReconciliationGrid from "@/components/admin/ReconciliationGrid";
 import StockSummaryCard from "@/components/admin/StockSummaryCard";
+import AccountLinks from "@/components/AccountLinks";
 
 export default function AdminDashboardPage() {
   const router = useRouter();
@@ -112,7 +113,8 @@ export default function AdminDashboardPage() {
   }
 
   const scope: "global" | "branch" = selectedBranchId === "ALL" ? "global" : "branch";
-  const showNoBranchesNudge = me.role === "SUPER_ADMIN" && branchesLoaded && branches.length === 0;
+  // The operator's own business is a placeholder; don't nudge it to set up branches.
+  const showNoBranchesNudge = me.role === "SUPER_ADMIN" && !me.isPlatformAdmin && branchesLoaded && branches.length === 0;
 
   return (
     <main className="min-h-screen bg-sand-50 pb-12">
@@ -129,6 +131,13 @@ export default function AdminDashboardPage() {
                 ? `${me.branchName} Dashboard`
                 : "Branch Dashboard"}
             </h1>
+            <p className="mt-1 text-xs text-sand-200/60">
+              {me.name}
+              {me.isPlatformAdmin && " · Platform operator"}
+            </p>
+            <div className="mt-2">
+              <AccountLinks />
+            </div>
           </div>
           <div className="flex flex-wrap items-center gap-3">
             <GlobalSwitcher
@@ -137,7 +146,7 @@ export default function AdminDashboardPage() {
               onChange={setSelectedBranchId}
               isSuperAdmin={me.role === "SUPER_ADMIN"}
             />
-{me.isPlatformAdmin && (
+            {me.isPlatformAdmin && (
               <Link href="/platform" className="tap-target flex items-center rounded-xl2 bg-gradient-to-r from-flow-500 to-flow-700 px-4 text-sm font-semibold text-depth-950 hover:opacity-90">
                 Platform
               </Link>
@@ -145,6 +154,11 @@ export default function AdminDashboardPage() {
             <Link href="/admin/stock" className="tap-target flex items-center rounded-xl2 bg-white/10 px-4 text-sm font-medium text-white hover:bg-white/15">
               Stock
             </Link>
+            {me.role === "SUPER_ADMIN" && (
+              <Link href="/admin/branches" className="tap-target flex items-center rounded-xl2 bg-white/10 px-4 text-sm font-medium text-white hover:bg-white/15">
+                Branches
+              </Link>
+            )}
             <Link href="/admin/products" className="tap-target flex items-center rounded-xl2 bg-white/10 px-4 text-sm font-medium text-white hover:bg-white/15">
               Products
             </Link>

src/app/admin/reports/page.tsx

@@ -18,6 +18,7 @@ interface ProfitReport {
   unitsSold: number;
   costOfGoodsSold: number;
   unitsWithoutCost: number;
+  stockLosses: number;
   grossProfit: number;
   expenses: number;
   expenseCount: number;
@@ -121,8 +122,9 @@ export default function ReportsPage() {
       ["  M-Pesa", report.mpesaTotal],
       ["Sales count", report.salesCount],
       ["Units sold", report.unitsSold],
-      ["Cost of goods sold (average purchase cost)", report.costOfGoodsSold],
+      ["Cost of goods sold (FIFO per branch)", report.costOfGoodsSold],
       ["Units sold with no purchase cost on record", report.unitsWithoutCost],
+      ["Stock losses (counts and write-offs)", report.stockLosses],
       ["Gross profit", report.grossProfit],
       ["Expenses", report.expenses],
       ["Estimated net profit", report.netProfit],
@@ -248,7 +250,7 @@ export default function ReportsPage() {
                 <p className="text-xs uppercase tracking-wide text-depth-500">Cost of goods sold</p>
                 <p className="mt-1 font-display text-2xl font-bold text-depth-900">{money(report.costOfGoodsSold)}</p>
                 <p className="mt-1 text-xs text-depth-500">
-                  {report.unitsSold} units sold x average buying price
+                  {report.unitsSold} units sold, each at what its branch paid for its oldest stock (first in, first out)
                   {report.unitsWithoutCost > 0 && ` · ${report.unitsWithoutCost} units have no purchase cost on record`}
                 </p>
               </div>
@@ -272,11 +274,11 @@ export default function ReportsPage() {
                 >
                   {money(report.netProfit)}
                 </p>
-                <p className="mt-1 text-xs text-depth-500">Gross profit − expenses</p>
+                <p className="mt-1 text-xs text-depth-500">Gross profit − expenses − stock losses</p>
               </div>
             </div>
 
-            <div className="grid grid-cols-1 gap-3 sm:grid-cols-2">
+            <div className="grid grid-cols-1 gap-3 sm:grid-cols-2 lg:grid-cols-3">
               <div className="rounded-xl2 bg-white p-5 shadow-soft">
                 <p className="text-xs uppercase tracking-wide text-depth-500">Stock purchased</p>
                 <p className="mt-1 font-display text-2xl font-bold text-depth-900">{money(report.stockPurchases)}</p>
@@ -290,6 +292,15 @@ export default function ReportsPage() {
                 <p className="mt-1 font-display text-2xl font-bold text-depth-900">{money(report.cashSurplus)}</p>
                 <p className="mt-1 text-xs text-depth-500">Sales − stock purchased − expenses</p>
               </div>
+              <div className="rounded-xl2 bg-white p-5 shadow-soft">
+                <p className="text-xs uppercase tracking-wide text-depth-500">Stock losses</p>
+                <p className={"mt-1 font-display text-2xl font-bold " + (report.stockLosses > 0 ? "text-alert-600" : "text-depth-900")}>
+                  {money(report.stockLosses)}
+                </p>
+                <p className="mt-1 text-xs text-depth-500">
+                  Cost of stock written off by counts, breakage or adjustments. Deducted in net profit.
+                </p>
+              </div>
             </div>
 
             <div className="flex items-center justify-between rounded-xl2 border border-depth-200 bg-sand-100 px-4 py-3">

src/app/admin/staff/page.tsx

@@ -46,7 +46,7 @@ export default function StaffPage() {
   // Inviting is the default: the person sets their own password, so the
   // owner never has to know or pass on anyone's password.
   const [setPasswordNow, setSetPasswordNow] = useState(false);
-  const [inviteLink, setInviteLink] = useState<{ name: string; url: string } | null>(null);
+  const [inviteLink, setInviteLink] = useState<{ name: string; url: string; purpose: "invite" | "reset" } | null>(null);
 
   const isSuperAdmin = me?.role === "SUPER_ADMIN";
 
@@ -99,7 +99,7 @@ export default function StaffPage() {
         }),
       });
       show(name.trim() + " added as " + role.replace("_", " ").toLowerCase(), "success");
-      setInviteLink(result.inviteUrl ? { name: name.trim(), url: result.inviteUrl } : null);
+      setInviteLink(result.inviteUrl ? { name: name.trim(), url: result.inviteUrl, purpose: "invite" } : null);
       setName("");
       setBranchId("");
       setPhoneNumber("");
@@ -121,13 +121,35 @@ export default function StaffPage() {
     return s.role === "DELIVERY" && s.branchId === me.branchId;
   }
 
-  async function newInviteLink(s: StaffMember) {
+  // A new invite link while the person has no password yet; a password
+  // reset link once they have one.
+  async function newPasswordLink(s: StaffMember) {
+    if (!s.invitePending && !window.confirm(`Create a password reset link for ${s.name}? Their current password keeps working until they use it.`)) {
+      return;
+    }
     try {
-      const result = await apiFetch<{ inviteUrl: string }>("/api/users/" + s._id + "/invite", { method: "POST" });
+      const result = await apiFetch<{ inviteUrl: string; purpose: "invite" | "reset" }>("/api/users/" + s._id + "/invite", {
-      setInviteLink({ name: s.name, url: result.inviteUrl });
+        method: "POST",
-      show("New invite link created. The old link no longer works.", "success");
+      });
+      setInviteLink({ name: s.name, url: result.inviteUrl, purpose: result.purpose });
+      show(result.purpose === "reset" ? "Reset link created" : "New invite link created. The old link no longer works.", "success");
     } catch (err) {
-      show(err instanceof ApiError ? err.message : "Could not create an invite link", "error");
+      show(err instanceof ApiError ? err.message : "Could not create a link", "error");
+    }
+  }
+
+  // Owner only: move a manager or cashier to another branch. They are signed
+  // out and sign in again; sales already recorded stay with the old branch.
+  async function moveToBranch(s: StaffMember, branchId: string) {
+    const to = branches.find((b) => b._id === branchId);
+    if (!to || branchId === s.branchId) return;
+    if (!window.confirm(`Move ${s.name} to ${to.branchName}? They will be signed out and must sign in again.`)) return;
+    try {
+      await apiFetch("/api/users/" + s._id, { method: "PATCH", body: JSON.stringify({ branchId }) });
+      show(`${s.name} moved to ${to.branchName}`, "success");
+      await loadStaff();
+    } catch (err) {
+      show(err instanceof ApiError ? err.message : "Could not move this person", "error");
     }
   }
 
@@ -219,8 +241,15 @@ export default function StaffPage() {
 
         {inviteLink && (
           <div className="rounded-xl2 border border-confirm-500/30 bg-confirm-500/10 p-4 text-sm text-depth-800">
-            <p className="font-medium">Send this link to {inviteLink.name} so they can set their password.</p>
+            <p className="font-medium">
-            <p className="mt-1 text-xs text-depth-500">It works once and expires in 7 days. Anyone with the link can claim the account, so send it only to them.</p>
+              {inviteLink.purpose === "reset"
+                ? `Send this password reset link to ${inviteLink.name}.`
+                : `Send this link to ${inviteLink.name} so they can set their password.`}
+            </p>
+            <p className="mt-1 text-xs text-depth-500">
+              It works once and expires in {inviteLink.purpose === "reset" ? "24 hours" : "7 days"}. Anyone with the link can
+              take over the account, so send it only to them.
+            </p>
             <input
               readOnly
               value={inviteLink.url}
@@ -233,7 +262,7 @@ export default function StaffPage() {
                 Copy link
               </button>
               <a
-                href={`https://wa.me/?text=${encodeURIComponent(`Set your Vessel password here: ${inviteLink.url}`)}`}
+                href={`https://wa.me/?text=${encodeURIComponent(`${inviteLink.purpose === "reset" ? "Reset" : "Set"} your Vessel password here: ${inviteLink.url}`)}`}
                 target="_blank"
                 rel="noreferrer"
                 className="rounded-lg border border-depth-200 bg-white px-3 py-1.5 text-xs font-semibold text-depth-700"
@@ -262,7 +291,7 @@ export default function StaffPage() {
               {staff.map((s) => {
                 const branchName = branches.find((b) => b._id === s.branchId)?.branchName;
                 return (
-                  <li key={s._id} className="flex items-center justify-between gap-3 px-4 py-3 animate-fade-up">
+                  <li key={s._id} className="flex flex-wrap items-center justify-between gap-3 px-4 py-3 animate-fade-up">
                     <div className={s.isActive ? "" : "opacity-50"}>
                       <p className="font-medium text-depth-900">
                         {s.name}
@@ -276,16 +305,33 @@ export default function StaffPage() {
                         {branchName ? " · " + branchName : ""}
                       </p>
                     </div>
-                    <div className="flex shrink-0 items-center gap-2">
+                    <div className="flex flex-wrap items-center gap-2">
                       <span className={"rounded-full px-2.5 py-1 text-xs font-medium " + roleBadgeStyles[s.role]}>
                         {s.role.replace("_", " ")}
                       </span>
-                      {canManage(s) && s.isActive && s.invitePending && (
+                      {isSuperAdmin && canManage(s) && s.isActive && s.role !== "SUPER_ADMIN" && branches.length > 1 && (
+                        <select
+                          value=""
+                          onChange={(e) => moveToBranch(s, e.target.value)}
+                          aria-label={`Move ${s.name} to another branch`}
+                          className="rounded-lg border border-depth-200 bg-white px-2 py-1 text-xs text-depth-700"
+                        >
+                          <option value="">Move to…</option>
+                          {branches
+                            .filter((b) => b._id !== s.branchId)
+                            .map((b) => (
+                              <option key={b._id} value={b._id}>
+                                {b.branchName}
+                              </option>
+                            ))}
+                        </select>
+                      )}
+                      {canManage(s) && s.isActive && (
                         <button
-                          onClick={() => newInviteLink(s)}
+                          onClick={() => newPasswordLink(s)}
                           className="rounded-lg border border-depth-200 px-2.5 py-1 text-xs font-medium text-depth-700"
                         >
-                          New link
+                          {s.invitePending ? "New link" : "Reset password"}
                         </button>
                       )}
                       {canManage(s) && (

src/app/api/auth/login/route.ts

@@ -9,6 +9,7 @@ import { signAccessToken, generateRefreshToken, hashRefreshToken, refreshTtlMs }
 import { ACCESS_COOKIE, REFRESH_COOKIE, accessCookieOptions, refreshCookieOptions } from "@/lib/server/auth";
 import { isPlatformAdmin } from "@/lib/server/platform";
 import { objectId } from "@/lib/server/validation";
+import { crossTenant } from "@/lib/server/tenantGuard";
 import { getEnv } from "@/lib/server/env";
 import { tenantAccessError } from "@/lib/server/subscription";
 
@@ -54,7 +55,9 @@ export async function POST(req: NextRequest) {
   // several businesses, each with its own password.
   const filter: Record<string, unknown> = { email: email.toLowerCase(), isActive: true };
   if (businessId) filter.businessId = businessId;
-  const candidates = await User.find(filter).select("+passwordHash");
+  const candidates = await crossTenant("login looks an email up in every business", () =>
+    User.find(filter).select("+passwordHash").exec()
+  );
   if (candidates.length === 0) {
     return NextResponse.json({ error: "Incorrect email or password" }, { status: 401 });
   }
@@ -149,7 +152,7 @@ export async function POST(req: NextRequest) {
     deviceId,
   });
 
-  const branch = user.branchId ? await Branch.findById(user.branchId).lean() : null;
+  const branch = user.branchId ? await Branch.findOne({ _id: user.branchId, businessId: user.businessId }).lean() : null;
   const business = await Business.findById(user.businessId).lean();
 
   const res = NextResponse.json({
@@ -164,7 +167,9 @@ export async function POST(req: NextRequest) {
       phoneNumber: user.phoneNumber,
       email: user.email,
     },
-    redirectTo: user.role === "DELIVERY" ? "/terminal" : "/admin/dashboard",
+    // Platform operators start on the console for every business, not on
+    // their own (placeholder) business's dashboard.
+    redirectTo: isPlatformAdmin(user) ? "/platform" : user.role === "DELIVERY" ? "/terminal" : "/admin/dashboard",
     isPlatformAdmin: isPlatformAdmin(user),
   });
 

src/app/api/auth/me/route.ts

@@ -16,11 +16,11 @@ export async function GET(req: NextRequest) {
   const auth = getAuth(req);
   if (!auth) return NextResponse.json({ error: "Not authenticated" }, { status: 401 });
 
-  const user = await User.findById(auth.sub).lean();
+  const user = await User.findOne({ _id: auth.sub, businessId: auth.businessId }).lean();
   if (!user || !user.isActive) {
     return NextResponse.json({ error: "Not authenticated" }, { status: 401 });
   }
-  const branch = user.branchId ? await Branch.findById(user.branchId).lean() : null;
+  const branch = user.branchId ? await Branch.findOne({ _id: user.branchId, businessId: user.businessId }).lean() : null;
   const business = await Business.findById(user.businessId).lean();
 
   const tier = (business?.tier as TierId) ?? "STARTER";

src/app/api/auth/password/route.ts

@@ -0,0 +1,45 @@
+import { NextRequest, NextResponse } from "next/server";
+import { z } from "zod";
+import bcrypt from "bcryptjs";
+import { connectDb } from "@/lib/server/db";
+import { User } from "@/lib/server/models/User";
+import { UserSession } from "@/lib/server/models/UserSession";
+import { authorize } from "@/lib/server/auth";
+
+export const runtime = "nodejs";
+
+const changeSchema = z.object({
+  currentPassword: z.string().min(1, "Enter your current password"),
+  newPassword: z.string().min(8, "The new password must be at least 8 characters"),
+});
+
+/**
+ * POST /api/auth/password — the signed-in user changes their own password.
+ * Every other device is signed out; this one stays signed in.
+ */
+export async function POST(req: NextRequest) {
+  await connectDb();
+  const gate = authorize(req);
+  if (!gate.ok) return gate.response;
+  const auth = gate.auth;
+
+  const parsed = changeSchema.safeParse(await req.json().catch(() => null));
+  if (!parsed.success) {
+    return NextResponse.json({ error: parsed.error.issues[0]?.message ?? "Invalid request" }, { status: 400 });
+  }
+  const { currentPassword, newPassword } = parsed.data;
+  if (currentPassword === newPassword) {
+    return NextResponse.json({ error: "Choose a password different from the current one" }, { status: 400 });
+  }
+
+  const user = await User.findOne({ _id: auth.sub, businessId: auth.businessId }).select("+passwordHash");
+  if (!user || !user.isActive) return NextResponse.json({ error: "Not authenticated" }, { status: 401 });
+  if (!(await user.comparePassword(currentPassword))) {
+    return NextResponse.json({ error: "Your current password is not correct" }, { status: 400 });
+  }
+
+  user.passwordHash = await bcrypt.hash(newPassword, 12);
+  await user.save();
+  await UserSession.deleteMany({ userId: user._id, deviceId: { $ne: auth.deviceId } });
+  return NextResponse.json({ ok: true });
+}

src/app/api/auth/refresh/route.ts

@@ -4,6 +4,7 @@ import { User } from "@/lib/server/models/User";
 import { UserSession } from "@/lib/server/models/UserSession";
 import { signAccessToken, generateRefreshToken, hashRefreshToken, refreshTtlMs } from "@/lib/server/jwt";
 import { tenantAccessError } from "@/lib/server/subscription";
+import { crossTenant } from "@/lib/server/tenantGuard";
 import { ACCESS_COOKIE, REFRESH_COOKIE, accessCookieOptions, refreshCookieOptions } from "@/lib/server/auth";
 
 export const runtime = "nodejs";
@@ -24,7 +25,9 @@ export async function POST(req: NextRequest) {
     return NextResponse.json({ error: "Session expired. Please log in again." }, { status: 401 });
   }
 
-  const user = await User.findById(session.userId);
+  const user = await crossTenant("a refresh session identifies its user before the business is known", () =>
+    User.findById(session.userId).exec()
+  );
   if (!user || !user.isActive) {
     await UserSession.deleteOne({ _id: session._id });
     return NextResponse.json({ error: "Account no longer active" }, { status: 401 });

src/app/api/auth/signup/route.ts

@@ -94,7 +94,7 @@ export async function POST(req: NextRequest) {
     await owner.save();
   } catch (e) {
     await Business.deleteOne({ _id: businessId }).catch(() => {});
-    await User.deleteOne({ _id: ownerId }).catch(() => {});
+    await User.deleteOne({ _id: ownerId, businessId }).catch(() => {});
     const msg = (e as Error).message || "";
     if (msg.includes("duplicate key")) {
       return NextResponse.json({ error: "An account with this email or phone already exists." }, { status: 409 });

src/app/api/branch-prices/route.ts

@@ -106,7 +106,7 @@ export async function PUT(req: NextRequest) {
   }
 
   const row = await BranchPricing.findOneAndUpdate(
-    { branchId, productId },
+    { businessId: auth.businessId, branchId, productId },
     { businessId: auth.businessId, unitPrice, updatedBy: auth.sub },
     { upsert: true, new: true, setDefaultsOnInsert: true }
   ).lean();

src/app/api/branches/route.ts

@@ -106,7 +106,7 @@ export async function POST(req: NextRequest) {
         { status: 201 }
       );
     } catch (err: any) {
-      await Branch.deleteOne({ _id: branch._id }).catch(() => {});
+      await Branch.deleteOne({ _id: branch._id, businessId }).catch(() => {});
       if (err?.code === 11000) {
         return NextResponse.json({ error: "Someone in your business already uses this phone number or email." }, { status: 409 });
       }

src/app/api/expenses/route.ts

@@ -5,6 +5,7 @@ import { Expense, EXPENSE_CATEGORIES } from "@/lib/server/models/Expense";
 import { Branch } from "@/lib/server/models/Branch";
 import { objectId } from "@/lib/server/validation";
 import { authorize, branchParam, MANAGERS } from "@/lib/server/auth";
+import { scopedPopulate } from "@/lib/server/tenantGuard";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
@@ -36,8 +37,8 @@ export async function GET(req: NextRequest) {
   }
 
   const expenses = await Expense.find(filter)
-    .populate("branchId", "branchName")
+    .populate(scopedPopulate("branchId", "branchName", auth.businessId))
-    .populate("recordedBy", "name")
+    .populate(scopedPopulate("recordedBy", "name", auth.businessId))
     .sort({ createdAt: -1 })
     .limit(500)
     .lean();

src/app/api/inventory/dispatch/route.ts

@@ -43,7 +43,7 @@ export async function POST(req: NextRequest) {
 
   const date = parsed.data.date ?? todayNairobi();
   const row = await DailyInventory.findOneAndUpdate(
-    { branchId, productId: parsed.data.productId, date },
+    { businessId: auth.businessId, branchId, productId: parsed.data.productId, date },
     { morningDispatched: parsed.data.morningDispatched, recordedBy: auth.sub, businessId: auth.businessId },
     { upsert: true, new: true, setDefaultsOnInsert: true }
   );

src/app/api/inventory/evening-count/route.ts

@@ -42,7 +42,7 @@ export async function POST(req: NextRequest) {
 
   const date = parsed.data.date ?? todayNairobi();
   const row = await DailyInventory.findOneAndUpdate(
-    { branchId, productId: parsed.data.productId, date },
+    { businessId: auth.businessId, branchId, productId: parsed.data.productId, date },
     { eveningPhysicalCount: parsed.data.eveningPhysicalCount, recordedBy: auth.sub, businessId: auth.businessId },
     { upsert: true, new: true, setDefaultsOnInsert: true }
   );

src/app/api/invites/[token]/route.ts

@@ -4,14 +4,18 @@ import bcrypt from "bcryptjs";
 import { connectDb } from "@/lib/server/db";
 import { User } from "@/lib/server/models/User";
 import { Business } from "@/lib/server/models/Business";
+import { UserSession } from "@/lib/server/models/UserSession";
 import { hashInviteToken } from "@/lib/server/invites";
+import { crossTenant } from "@/lib/server/tenantGuard";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
 
 async function findInvitee(token: string) {
   if (!token || token.length > 100) return null;
-  const user = await User.findOne({ inviteTokenHash: hashInviteToken(token), isActive: true });
+  const user = await crossTenant("an invite token identifies its account before sign-in", () =>
+    User.findOne({ inviteTokenHash: hashInviteToken(token), isActive: true }).exec()
+  );
   if (!user || !user.inviteExpiresAt || user.inviteExpiresAt.getTime() < Date.now()) return null;
   return user;
 }
@@ -24,7 +28,12 @@ export async function GET(_req: NextRequest, { params }: { params: { token: stri
   const user = await findInvitee(params.token);
   if (!user) return NextResponse.json(INVALID, { status: 404 });
   const business = await Business.findById(user.businessId).select("name").lean();
-  return NextResponse.json({ name: user.name, email: user.email, businessName: business?.name ?? null });
+  return NextResponse.json({
+    name: user.name,
+    email: user.email,
+    businessName: business?.name ?? null,
+    purpose: user.invitePurpose === "reset" ? "reset" : "invite",
+  });
 }
 
 const acceptSchema = z.object({ password: z.string().min(8, "Password must be at least 8 characters") });
@@ -42,8 +51,12 @@ export async function POST(req: NextRequest, { params }: { params: { token: stri
   user.passwordHash = await bcrypt.hash(parsed.data.password, 12);
   user.inviteTokenHash = null;
   user.inviteExpiresAt = null;
+  user.invitePurpose = null;
   user.failedLoginAttempts = 0;
   user.lockedUntil = null;
   await user.save();
+  // A new password ends every existing session, so whoever had the old one
+  // (a lost phone, a former colleague) is signed out.
+  await UserSession.deleteMany({ userId: user._id });
   return NextResponse.json({ ok: true, email: user.email });
 }

src/app/api/mpesa/callback/route.ts

@@ -3,6 +3,7 @@ import { connectDb } from "@/lib/server/db";
 import { isMpesaEnabled } from "@/lib/server/env";
 import { Transaction } from "@/lib/server/models/Transaction";
 import { recordSaleMovement } from "@/lib/server/stock";
+import { crossTenant } from "@/lib/server/tenantGuard";
 import { MpesaCallbackLog } from "@/lib/server/models/MpesaCallbackLog";
 
 export const runtime = "nodejs";
@@ -69,7 +70,9 @@ export async function POST(req: NextRequest) {
     mpesaReceiptNumber = receiptItem ? String(receiptItem.Value) : null;
   }
 
-  const txn = await Transaction.findOne({ "mpesaDetails.checkoutRequestId": checkoutRequestId });
+  const txn = await crossTenant("the payment provider's callback is matched by checkout id", () =>
+    Transaction.findOne({ "mpesaDetails.checkoutRequestId": checkoutRequestId }).exec()
+  );
 
   if (!txn) {
     await MpesaCallbackLog.create({

src/app/api/mpesa/status/[transactionId]/route.ts

@@ -26,7 +26,7 @@ export async function GET(req: NextRequest, { params }: { params: { transactionI
       const result = await queryStkStatus(txn.mpesaDetails.checkoutRequestId);
       const code = Number(result.ResultCode);
       if (!Number.isNaN(code) && code !== 1032) {
-        const fresh = await Transaction.findOne({ _id: txn._id, paymentStatus: "PENDING" });
+        const fresh = await Transaction.findOne({ _id: txn._id, businessId: auth.businessId, paymentStatus: "PENDING" });
         if (fresh) {
           fresh.paymentStatus = code === 0 ? "SUCCESS" : "FAILED";
           fresh.mpesaDetails.resultCode = code;

src/app/api/platform/businesses/[id]/owner-reset/route.ts

@@ -0,0 +1,37 @@
+import { NextRequest, NextResponse } from "next/server";
+import { isValidObjectId } from "mongoose";
+import { connectDb } from "@/lib/server/db";
+import { Business } from "@/lib/server/models/Business";
+import { User } from "@/lib/server/models/User";
+import { requirePlatformAdmin } from "@/lib/server/platform";
+import { invitePending, issueInvite } from "@/lib/server/invites";
+
+export const runtime = "nodejs";
+
+/**
+ * POST /api/platform/businesses/:id/owner-reset — operator only. A one-time
+ * password link for a business's owner of record: the way back in for an
+ * owner who has forgotten their password (nobody inside the business can
+ * reset the owner). Send the link to the owner yourself, by a channel you
+ * know is theirs. Their current password keeps working until it is used.
+ */
+export async function POST(req: NextRequest, { params }: { params: { id: string } }) {
+  await connectDb();
+  const admin = await requirePlatformAdmin(req);
+  if (!admin) return NextResponse.json({ error: "Forbidden" }, { status: 403 });
+  if (!isValidObjectId(params.id)) return NextResponse.json({ error: "Business not found" }, { status: 404 });
+
+  const business = await Business.findById(params.id).select("ownerId").lean();
+  if (!business) return NextResponse.json({ error: "Business not found" }, { status: 404 });
+  const owner = await User.findOne({ _id: business.ownerId, businessId: business._id });
+  if (!owner) return NextResponse.json({ error: "This business has no owner account" }, { status: 404 });
+  if (owner._id.toString() === admin.userId) {
+    return NextResponse.json({ error: "Change your own password from Change password instead" }, { status: 409 });
+  }
+  if (!owner.isActive) return NextResponse.json({ error: "The owner's account is deactivated" }, { status: 409 });
+
+  const purpose = invitePending(owner) ? "invite" : "reset";
+  const inviteUrl = issueInvite(owner, req, purpose);
+  await owner.save();
+  return NextResponse.json({ inviteUrl, purpose, email: owner.email, name: owner.name, expiresAt: owner.inviteExpiresAt });
+}

src/app/api/platform/businesses/route.ts

@@ -4,6 +4,7 @@ import { Business } from "@/lib/server/models/Business";
 import { User } from "@/lib/server/models/User";
 import { Branch } from "@/lib/server/models/Branch";
 import { requirePlatformAdmin } from "@/lib/server/platform";
+import { crossTenant } from "@/lib/server/tenantGuard";
 import { TIERS, effectiveMaxBranches, type TierId, type SubscriptionStatus } from "@/lib/tiers";
 
 export const runtime = "nodejs";
@@ -23,23 +24,26 @@ export async function GET(req: NextRequest) {
   const businesses = await Business.find({}).sort({ createdAt: -1 }).lean();
 
   // Usage counts per business in two grouped queries instead of N+1.
-  const [userCounts, branchCounts] = await Promise.all([
+  const [userCounts, branchCounts] = await crossTenant("the platform console counts every business", () =>
-    User.aggregate<{ _id: unknown; count: number }>([
+    Promise.all([
-      { $group: { _id: "$businessId", count: { $sum: 1 } } },
+      User.aggregate<{ _id: unknown; count: number }>([{ $group: { _id: "$businessId", count: { $sum: 1 } } }]).exec(),
-    ]),
       Branch.aggregate<{ _id: unknown; count: number }>([
         { $match: { isActive: { $ne: false } } },
         { $group: { _id: "$businessId", count: { $sum: 1 } } },
-    ]),
+      ]).exec(),
-  ]);
+    ])
+  );
   const userMap = new Map(userCounts.map((u) => [String(u._id), u.count]));
   const branchMap = new Map(branchCounts.map((b) => [String(b._id), b.count]));
 
   // Owner contact lookup.
   const ownerIds = businesses.map((b) => b.ownerId);
-  const owners = await User.find({ _id: { $in: ownerIds } })
+  const owners = await crossTenant("the platform console lists every business's owner", () =>
+    User.find({ _id: { $in: ownerIds } })
       .select("name email phoneNumber")
-    .lean();
+      .lean()
+      .exec()
+  );
   const ownerMap = new Map(owners.map((o) => [String(o._id), o]));
 
   const rows = businesses.map((b) => {

src/app/api/purchases/route.ts

@@ -7,6 +7,7 @@ import { ACTIVE_BRANCH, Branch } from "@/lib/server/models/Branch";
 import { objectId } from "@/lib/server/validation";
 import { recordMovement } from "@/lib/server/stock";
 import { authorize, branchParam, MANAGERS } from "@/lib/server/auth";
+import { scopedPopulate } from "@/lib/server/tenantGuard";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
@@ -36,8 +37,8 @@ export async function GET(req: NextRequest) {
   }
 
   const purchases = await Purchase.find(filter)
-    .populate("branchId", "branchName")
+    .populate(scopedPopulate("branchId", "branchName", auth.businessId))
-    .populate("recordedBy", "name")
+    .populate(scopedPopulate("recordedBy", "name", auth.businessId))
     .sort({ createdAt: -1 })
     .limit(500)
     .lean();

src/app/api/reports/profit/route.ts

@@ -6,6 +6,7 @@ import { Purchase } from "@/lib/server/models/Purchase";
 import { Expense } from "@/lib/server/models/Expense";
 import { authorize, badRequest, branchParam, MANAGERS } from "@/lib/server/auth";
 import { dayRangeNairobi, isBusinessDate, startOfMonthNairobi } from "@/lib/server/businessDay";
+import { costOfGoodsSold as fifoCost } from "@/lib/server/costing";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
@@ -15,11 +16,13 @@ export const dynamic = "force-dynamic";
  *
  * Management overview, NOT accounting (full accounting is out of the PRD's scope).
  *   Revenue            SUCCESS sales in the period
- *   Cost of goods sold units sold x that product's average purchase cost
+ *   Cost of goods sold first-in-first-out per branch: each unit sold costs
- *                      (all purchases up to the end of the period)
+ *                      what that branch paid for its oldest stock on hand
+ *                      (see src/lib/server/costing.ts)
  *   Gross profit       revenue - cost of goods sold
  *   Expenses           operating expenses in the period
- *   Net profit         gross profit - expenses
+ *   Stock losses       cost of stock written off by counts and adjustments
+ *   Net profit         gross profit - expenses - stock losses
  * Shown separately, because buying stock is not the same as using it:
  *   Stock purchased    cash spent on stock in the period
  *   Cash surplus       revenue - stock purchased - expenses
@@ -47,7 +50,7 @@ export async function GET(req: NextRequest) {
   const branchObjId = branchId ? new mongoose.Types.ObjectId(branchId) : null;
   const inPeriod = { businessId: businessObjId, createdAt: { $gte: from, $lt: to }, ...(branchObjId ? { branchId: branchObjId } : {}) };
 
-  const [salesByProduct, avgCosts, purchaseAgg, expenseAgg] = await Promise.all([
+  const [salesByProduct, cost, purchaseAgg, expenseAgg] = await Promise.all([
     Transaction.aggregate<{
       _id: Types.ObjectId;
       revenue: number;
@@ -68,12 +71,7 @@ export async function GET(req: NextRequest) {
         },
       },
     ]),
-    // Average buying price per product across the business (suppliers
+    fifoCost(auth.businessId, { from, to, branchId }),
-    // charge every branch alike), using everything bought up to period end.
-    Purchase.aggregate<{ _id: Types.ObjectId; cost: number; qty: number }>([
-      { $match: { businessId: businessObjId, productId: { $ne: null }, createdAt: { $lt: to } } },
-      { $group: { _id: "$productId", cost: { $sum: "$totalCost" }, qty: { $sum: "$quantity" } } },
-    ]),
     Purchase.aggregate<{ total: number; count: number }>([
       { $match: inPeriod },
       { $group: { _id: null, total: { $sum: "$totalCost" }, count: { $sum: 1 } } },
@@ -84,19 +82,18 @@ export async function GET(req: NextRequest) {
     ]),
   ]);
 
-  const avgCost = new Map(avgCosts.filter((c) => c.qty > 0).map((c) => [c._id.toString(), c.cost / c.qty]));
+  let revenue = 0, cashTotal = 0, mpesaTotal = 0, salesCount = 0, unitsSold = 0;
-  let revenue = 0, cashTotal = 0, mpesaTotal = 0, salesCount = 0, unitsSold = 0, unitsWithoutCost = 0, costOfGoodsSold = 0;
   for (const s of salesByProduct) {
     revenue += s.revenue;
     cashTotal += s.cashTotal;
     mpesaTotal += s.mpesaTotal;
     salesCount += s.lines;
     unitsSold += s.units;
-    const unitCost = avgCost.get(s._id.toString());
-    if (unitCost === undefined) unitsWithoutCost += s.units;
-    else costOfGoodsSold += s.units * unitCost;
   }
-  costOfGoodsSold = Math.round(costOfGoodsSold * 100) / 100;
+  const costOfGoodsSold = cost.costOfGoodsSold;
+  // Sales recorded before the stock ledger existed have no stock movement,
+  // so FIFO cannot cost them: count them as uncosted too.
+  const unitsWithoutCost = Math.max(cost.unitsWithoutCost, unitsSold - cost.unitsCosted);
 
   const stockPurchases = purchaseAgg[0]?.total ?? 0;
   const expenses = expenseAgg[0]?.total ?? 0;
@@ -111,13 +108,15 @@ export async function GET(req: NextRequest) {
     salesCount,
     unitsSold,
     costOfGoodsSold,
-    // Units sold of products never bought through Purchases: their cost
+    costMethod: "FIFO per branch",
-    // is unknown, so gross profit overstates by their cost.
+    // Units sold whose cost is unknown (no purchase price for that stock on
+    // record): gross profit overstates by their cost.
     unitsWithoutCost,
+    stockLosses: cost.stockLosses,
     grossProfit,
     expenses,
     expenseCount: expenseAgg[0]?.count ?? 0,
-    netProfit: Math.round((grossProfit - expenses) * 100) / 100,
+    netProfit: Math.round((grossProfit - expenses - cost.stockLosses) * 100) / 100,
     stockPurchases,
     purchaseCount: purchaseAgg[0]?.count ?? 0,
     cashSurplus: Math.round((revenue - stockPurchases - expenses) * 100) / 100,

src/app/api/stock/adjustments/route.ts

@@ -64,7 +64,7 @@ export async function POST(req: NextRequest) {
   const lockedBranch = branchId;
   try {
     const quantity = await withStockLock(auth.businessId, lockedBranch, data.productId, async () => {
-      const already = await StockMovement.exists({ type: "ADJUSTMENT", refId });
+      const already = await StockMovement.exists({ type: "ADJUSTMENT", refId, businessId: auth.businessId });
       if (!already) {
         const before = await stockOf(auth.businessId, lockedBranch, data.productId);
         const delta = data.mode === "COUNT" ? data.quantity - before : data.quantity;

src/app/api/stock/movements/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from "next/server";
 import { connectDb } from "@/lib/server/db";
 import { StockMovement } from "@/lib/server/models/StockMovement";
 import { authorize, branchParam, MANAGERS } from "@/lib/server/auth";
+import { scopedPopulate } from "@/lib/server/tenantGuard";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
@@ -23,9 +24,9 @@ export async function GET(req: NextRequest) {
   const movements = await StockMovement.find(filter)
     .sort({ createdAt: -1 })
     .limit(limit)
-    .populate("branchId", "branchName")
+    .populate(scopedPopulate("branchId", "branchName", auth.businessId))
-    .populate("productId", "label unit")
+    .populate(scopedPopulate("productId", "label unit", auth.businessId))
-    .populate("recordedBy", "name")
+    .populate(scopedPopulate("recordedBy", "name", auth.businessId))
     .lean();
   return NextResponse.json({ movements });
 }

src/app/api/stock/transfers/route.ts

@@ -5,6 +5,7 @@ import { ACTIVE_BRANCH, Branch } from "@/lib/server/models/Branch";
 import { Product } from "@/lib/server/models/Product";
 import { StockTransfer, IStockTransfer } from "@/lib/server/models/StockTransfer";
 import { authorize, branchParam, MANAGERS } from "@/lib/server/auth";
+import { scopedPopulate } from "@/lib/server/tenantGuard";
 import { objectId } from "@/lib/server/validation";
 import { recordMovement, stockOf, StockBusyError, withStockLock } from "@/lib/server/stock";
 
@@ -27,10 +28,10 @@ export async function GET(req: NextRequest) {
   const transfers = await StockTransfer.find(filter)
     .sort({ createdAt: -1 })
     .limit(100)
-    .populate("fromBranchId", "branchName")
+    .populate(scopedPopulate("fromBranchId", "branchName", auth.businessId))
-    .populate("toBranchId", "branchName")
+    .populate(scopedPopulate("toBranchId", "branchName", auth.businessId))
-    .populate("productId", "label unit")
+    .populate(scopedPopulate("productId", "label unit", auth.businessId))
-    .populate("recordedBy", "name")
+    .populate(scopedPopulate("recordedBy", "name", auth.businessId))
     .lean();
   return NextResponse.json({ transfers });
 }

src/app/api/transactions/cash/route.ts

@@ -167,10 +167,8 @@ export async function POST(req: NextRequest) {
       } catch (err: unknown) {
         if ((err as { code?: number })?.code !== 11000) throw err;
         // Already recorded by an earlier attempt: reuse it.
-        const existing = await Transaction.findOne({ clientUuid: `${sale.clientUuid}:${index}` });
+        const existing = await Transaction.findOne({ clientUuid: `${sale.clientUuid}:${index}`, businessId: auth.businessId });
-        if (!existing || existing.businessId.toString() !== auth.businessId) {
+        if (!existing) return reject("This sale id is already in use.");
-          return reject("This sale id is already in use.");
-        }
         txn = existing;
       }
       // Idempotent, and also repairs a line whose stock movement was not

src/app/api/transactions/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from "next/server";
 import { connectDb } from "@/lib/server/db";
 import { Transaction } from "@/lib/server/models/Transaction";
 import { authorize, branchParam } from "@/lib/server/auth";
+import { scopedPopulate } from "@/lib/server/tenantGuard";
 import { startOfTodayNairobi } from "@/lib/server/businessDay";
 
 export const runtime = "nodejs";
@@ -26,7 +27,7 @@ export async function GET(req: NextRequest) {
   const transactions = await Transaction.find(filter)
     .sort({ createdAt: -1 })
     .limit(limit)
-    .populate("branchId", "branchName")
+    .populate(scopedPopulate("branchId", "branchName", auth.businessId))
     .lean();
 
   return NextResponse.json({ transactions });

src/app/api/users/[id]/invite/route.ts

@@ -3,14 +3,17 @@ import { isValidObjectId } from "mongoose";
 import { connectDb } from "@/lib/server/db";
 import { User } from "@/lib/server/models/User";
 import { authorize, MANAGERS } from "@/lib/server/auth";
-import { issueInvite } from "@/lib/server/invites";
+import { invitePending, issueInvite } from "@/lib/server/invites";
 
 export const runtime = "nodejs";
 
 /**
- * POST /api/users/:id/invite — a new invite link for someone who has not
+ * POST /api/users/:id/invite — a one-time password link for a staff member:
- * accepted theirs yet (lost or expired). The previous link stops working.
+ *   - an INVITE link while they have not set a password yet (lost or expired invite);
- * Owners: anyone in the business. Managers: their own branch's cashiers.
+ *   - a RESET link once they have (forgotten password). Their current password
+ *     keeps working until the link is used; using it signs them out everywhere.
+ * The previous link stops working either way.
+ * Owners: anyone in the business but themselves. Managers: their own branch's cashiers.
  */
 export async function POST(req: NextRequest, { params }: { params: { id: string } }) {
   await connectDb();
@@ -23,13 +26,17 @@ export async function POST(req: NextRequest, { params }: { params: { id: string
   if (!user) return NextResponse.json({ error: "User not found" }, { status: 404 });
 
   if (auth.role === "BRANCH_MANAGER" && !(user.role === "DELIVERY" && user.branchId?.toString() === auth.branchId)) {
-    return NextResponse.json({ error: "Branch managers may only invite delivery staff in their own branch" }, { status: 403 });
+    return NextResponse.json({ error: "Branch managers may only do this for delivery staff in their own branch" }, { status: 403 });
   }
-  if (!user.inviteExpiresAt) {
+  if (user._id.toString() === auth.sub) {
-    return NextResponse.json({ error: "This person has already set their password" }, { status: 409 });
+    return NextResponse.json({ error: "Change your own password from Change password instead" }, { status: 409 });
+  }
+  if (!user.isActive) {
+    return NextResponse.json({ error: "Reactivate this account first" }, { status: 409 });
   }
 
-  const inviteUrl = issueInvite(user, req);
+  const purpose = invitePending(user) ? "invite" : "reset";
+  const inviteUrl = issueInvite(user, req, purpose);
   await user.save();
-  return NextResponse.json({ inviteUrl, expiresAt: user.inviteExpiresAt });
+  return NextResponse.json({ inviteUrl, purpose, expiresAt: user.inviteExpiresAt });
 }

src/app/api/users/[id]/route.ts

@@ -69,7 +69,14 @@ export async function PATCH(req: NextRequest, { params }: { params: { id: string
     }
     const branch = await Branch.findOne({ _id: branchId, businessId: auth.businessId, ...ACTIVE_BRANCH }).lean();
     if (!branch) return NextResponse.json({ error: "Branch not found in your business" }, { status: 404 });
+    const fromBranch = target.branchId;
     target.branchId = branch._id;
+    // A moved manager stops being the old branch's manager, and becomes the
+    // new branch's manager if it has none.
+    if (target.role === "BRANCH_MANAGER" && fromBranch?.toString() !== branch._id.toString()) {
+      await Branch.updateOne({ _id: fromBranch, businessId: auth.businessId, managerId: target._id }, { managerId: null });
+      await Branch.updateOne({ _id: branch._id, businessId: auth.businessId, managerId: null }, { managerId: target._id });
+    }
   }
   if (isActive !== undefined) target.isActive = isActive;
   await target.save();

src/app/api/users/route.ts

@@ -8,7 +8,7 @@ import { authorize, branchParam, MANAGERS } from "@/lib/server/auth";
 import { objectId } from "@/lib/server/validation";
 import { normalizeKenyanPhone } from "@/lib/server/phone";
 import { userLimitError, loadTier } from "@/lib/server/subscription";
-import { issueInvite, unusablePasswordHash } from "@/lib/server/invites";
+import { invitePending, issueInvite, unusablePasswordHash } from "@/lib/server/invites";
 
 export const runtime = "nodejs";
 export const dynamic = "force-dynamic";
@@ -26,7 +26,7 @@ export async function GET(req: NextRequest) {
   const users = await User.find(filter).select("-passwordHash -inviteTokenHash").sort({ name: 1 }).lean();
   // invitePending: the person has not set their password yet.
   return NextResponse.json({
-    users: users.map((u) => ({ ...u, invitePending: !!u.inviteExpiresAt })),
+    users: users.map((u) => ({ ...u, invitePending: invitePending(u) })),
   });
 }
 

src/app/invite/[token]/page.tsx

@@ -8,6 +8,7 @@ interface Invite {
   name: string;
   email: string;
   businessName: string | null;
+  purpose: "invite" | "reset";
 }
 
 const inputClass =
@@ -60,9 +61,12 @@ export default function InvitePage() {
         ) : (
           <>
             <p className="text-xs uppercase tracking-wide text-flow-600">{invite.businessName ?? "Vessel"}</p>
-            <h1 className="mt-1 font-display text-2xl font-bold text-depth-900">Welcome, {invite.name}</h1>
+            <h1 className="mt-1 font-display text-2xl font-bold text-depth-900">
+              {invite.purpose === "reset" ? `Reset your password, ${invite.name}` : `Welcome, ${invite.name}`}
+            </h1>
             <p className="mt-2 text-sm text-depth-600">
-              Choose a password. You will sign in with <strong>{invite.email}</strong> and this password.
+              {invite.purpose === "reset" ? "Choose a new password. Every device signed in to your account will be signed out." : "Choose a password."}{" "}
+              You will sign in with <strong>{invite.email}</strong> and this password.
             </p>
             <form onSubmit={handleSubmit} className="mt-6 space-y-4">
               <div>

src/app/login/page.tsx

@@ -36,6 +36,7 @@ export default function LoginPage() {
   // Set when this email and password open accounts in more than one business.
   const [choices, setChoices] = useState<BusinessChoice[] | null>(null);
   const [invited, setInvited] = useState(false);
+  const [showForgot, setShowForgot] = useState(false);
 
   useEffect(() => {
     setInvited(new URLSearchParams(window.location.search).get("invited") === "1");
@@ -226,9 +227,17 @@ export default function LoginPage() {
                   />
                   Remember me
                 </label>
-                <span className="font-medium text-flow-600">Forgot password?</span>
+                <button type="button" onClick={() => setShowForgot((v) => !v)} className="font-medium text-flow-600">
+                  Forgot password?
+                </button>
               </div>
 
+              {showForgot && (
+                <p className="rounded-lg bg-sand-100 px-3 py-2 text-sm text-depth-700">
+                  Ask your branch manager or business owner for a password reset link (Staff page, Reset password). If
+                  you are the owner, contact Digital Chances support for one.
+                </p>
+              )}
               {invited && !error && (
                 <p className="rounded-lg bg-confirm-500/10 px-3 py-2 text-sm text-confirm-600">
                   Your password is set. Sign in with your email and new password.

src/app/page.tsx

@@ -12,7 +12,9 @@ export default function RootPage() {
     (async () => {
       try {
         const result = await apiFetch<{ user: AuthUser }>("/api/auth/me");
-        if (result.user.role === "DELIVERY") {
+        if (result.user.isPlatformAdmin) {
+          router.replace("/platform");
+        } else if (result.user.role === "DELIVERY") {
           router.replace("/terminal");
         } else {
           router.replace("/admin/dashboard");

src/app/platform/page.tsx

@@ -6,6 +6,7 @@ import { apiFetch, ApiError } from "@/lib/api";
 import { AuthUser } from "@/lib/types";
 import { useToast } from "@/components/ui/Toast";
 import { SkeletonList } from "@/components/ui/Skeleton";
+import AccountLinks from "@/components/AccountLinks";
 
 type TierId = "STARTER" | "GROWTH" | "ENTERPRISE";
 type SubStatus = "TRIALING" | "ACTIVE" | "PAST_DUE" | "SUSPENDED";
@@ -63,6 +64,7 @@ export default function PlatformPage() {
   const [stats, setStats] = useState<Stats | null>(null);
   const [loading, setLoading] = useState(true);
   const [savingId, setSavingId] = useState<string | null>(null);
+  const [ownerLink, setOwnerLink] = useState<{ business: string; name: string; email: string; url: string } | null>(null);
 
   useEffect(() => {
     (async () => {
@@ -107,6 +109,23 @@ export default function PlatformPage() {
     setSavingId(null);
   }
 
+  // A one-time password link for a business's owner (an owner who forgot
+  // their password has nobody inside the business who can reset it).
+  async function ownerReset(b: BizRow) {
+    if (!window.confirm(`Create a password link for the owner of ${b.name}? Send it only to the owner, by a channel you know is theirs.`)) {
+      return;
+    }
+    try {
+      const r = await apiFetch<{ inviteUrl: string; email: string; name: string }>(
+        "/api/platform/businesses/" + b.id + "/owner-reset",
+        { method: "POST" }
+      );
+      setOwnerLink({ business: b.name, name: r.name, email: r.email, url: r.inviteUrl });
+    } catch (err) {
+      show(err instanceof ApiError ? err.message : "Could not create the link", "error");
+    }
+  }
+
   if (!ready) {
     return (
       <main className="min-h-screen bg-depth-950 pb-12">
@@ -130,6 +149,12 @@ export default function PlatformPage() {
             Every business on your platform, across all tenants. Change plans, extend billing periods,
             and suspend accounts here.
           </p>
+          <div className="mt-3 flex items-center gap-4">
+            <a href="/admin/dashboard" className="text-sm text-sand-200/70 underline underline-offset-2 hover:text-white">
+              Your business dashboard
+            </a>
+            <AccountLinks />
+          </div>
         </div>
       </header>
 
@@ -144,6 +169,28 @@ export default function PlatformPage() {
           </div>
         )}
 
+        {ownerLink && (
+          <div className="rounded-xl2 border border-confirm-500/30 bg-confirm-500/10 p-4 text-sm">
+            <p className="font-medium text-white">
+              Password link for {ownerLink.name} ({ownerLink.email}), owner of {ownerLink.business}
+            </p>
+            <p className="mt-1 text-xs text-white/60">
+              It works once and expires within 24 hours (7 days if they never set a password). Whoever opens it can take
+              over the account: send it only to the owner, by a channel you know is theirs.
+            </p>
+            <input
+              readOnly
+              value={ownerLink.url}
+              onFocus={(e) => e.target.select()}
+              aria-label="Owner password link"
+              className="mt-3 w-full rounded-lg border border-white/20 bg-depth-900 px-3 py-2 font-mono text-xs text-white"
+            />
+            <button onClick={() => setOwnerLink(null)} className="mt-2 text-xs text-white/60 underline">
+              Done
+            </button>
+          </div>
+        )}
+
         {loading ? (
           <SkeletonList rows={4} />
         ) : rows.length === 0 ? (
@@ -158,6 +205,7 @@ export default function PlatformPage() {
                 b={b}
                 saving={savingId === b.id}
                 onPatch={patch}
+                onOwnerReset={ownerReset}
               />
             ))}
           </div>
@@ -180,10 +228,12 @@ function BusinessCard({
   b,
   saving,
   onPatch,
+  onOwnerReset,
 }: {
   b: BizRow;
   saving: boolean;
   onPatch: (id: string, update: Record<string, unknown>, label: string) => void;
+  onOwnerReset: (b: BizRow) => void;
 }) {
   const overBranches = b.maxBranches !== null && b.branchCount > b.maxBranches;
   const overUsers = b.maxUsers !== null && b.userCount > b.maxUsers;
@@ -287,6 +337,15 @@ function BusinessCard({
             Reactivate
           </button>
         )}
+        {b.owner && (
+          <button
+            type="button"
+            onClick={() => onOwnerReset(b)}
+            className="tap-target rounded-xl2 border border-white/20 px-4 text-sm font-medium text-white/80"
+          >
+            Owner password link
+          </button>
+        )}
       </div>
     </div>
   );

src/app/terminal/page.tsx

@@ -17,7 +17,8 @@ import {
   type QueuedSale,
   type QueueOwner,
 } from "@/lib/offlineQueue";
-import { clearSession, loadSession, saveSession, type StockSnapshot } from "@/lib/sessionCache";
+import { loadSession, saveSession, type StockSnapshot } from "@/lib/sessionCache";
+import { signOut } from "@/lib/signOut";
 import { MAX_LINES_PER_SALE } from "@/lib/syncProtocol";
 import { useToast } from "@/components/ui/Toast";
 import ProductGrid from "@/components/terminal/ProductGrid";
@@ -392,12 +393,7 @@ export default function TerminalPage() {
       );
       if (!ok) return;
     }
-    try {
+    await signOut();
-      await apiFetch("/api/auth/logout", { method: "POST" });
-    } catch {
-      // Offline: the cookies expire on their own; still clear this device.
-    }
-    clearSession();
     router.replace("/login");
   }
 
@@ -451,11 +447,16 @@ export default function TerminalPage() {
             >
               {connected ? "● Online" : "● Offline"}
             </span>
+            <div className="flex gap-3">
+              <button onClick={() => router.push("/account/password")} className="text-xs text-sand-200/60 underline underline-offset-2">
+                Password
+              </button>
               <button onClick={handleSignOut} className="text-xs text-sand-200/60 underline underline-offset-2">
                 Sign out
               </button>
             </div>
           </div>
+        </div>
       </header>
 
       <div className="mx-auto -mt-3 max-w-md space-y-4 px-5">

src/components/AccountLinks.tsx

@@ -0,0 +1,26 @@
+"use client";
+
+import Link from "next/link";
+import { useRouter } from "next/navigation";
+import { signOut } from "@/lib/signOut";
+
+/** Change password + Sign out, for the dark page headers. */
+export default function AccountLinks() {
+  const router = useRouter();
+  return (
+    <div className="flex items-center gap-3 whitespace-nowrap text-sm">
+      <Link href="/account/password" className="text-sand-200/70 underline underline-offset-2 hover:text-white">
+        Change password
+      </Link>
+      <button
+        onClick={async () => {
+          await signOut();
+          router.replace("/login");
+        }}
+        className="text-sand-200/70 underline underline-offset-2 hover:text-white"
+      >
+        Sign out
+      </button>
+    </div>
+  );
+}

src/lib/server/costing.ts

@@ -0,0 +1,194 @@
+import mongoose, { Types } from "mongoose";
+import { StockMovement, type MovementType } from "@/lib/server/models/StockMovement";
+import { Purchase } from "@/lib/server/models/Purchase";
+
+/**
+ * Cost of goods sold, first-in-first-out, per branch.
+ *
+ * The stock ledger is replayed in order. Each branch keeps, per product, a
+ * queue of cost layers (quantity at a unit cost). Stock coming in adds a
+ * layer; stock going out takes from the oldest layers first:
+ *
+ *   PURCHASE      in, at the purchase's unit cost
+ *   TRANSFER_IN   in, at the cost of the layers the sending branch gave up
+ *   ADJUSTMENT +  in (opening stock, a count that found more), at an
+ *                 estimated cost: the latest purchase price for the product
+ *                 at that time, or the first one after it if none yet
+ *   SALE          out: its cost is cost of goods sold
+ *   TRANSFER_OUT  out: its cost travels with the stock to the other branch
+ *   ADJUSTMENT -  out (breakage, a count that found less): its cost is a
+ *                 stock loss, reported separately from cost of goods
+ *
+ * Stock can go negative (an offline sale recorded before the stock it came
+ * from). The units sold short wait as a deficit and are costed by the next
+ * stock that arrives at that branch, which is where they must have come
+ * from. Units still uncosted at the end are reported as unitsWithoutCost.
+ *
+ * The replay reads the whole history, in order, so a sale is costed against
+ * what was actually on hand when it happened, whatever period is being
+ * reported; only events inside the period (and branch) are added up. A sale
+ * made short in the period is costed by stock that arrived later, even
+ * after the period ended.
+ */
+
+type Id = Types.ObjectId | string;
+
+interface Layer {
+  qty: number;
+  unitCost: number | null; // null: cost unknown
+}
+
+interface Deficit {
+  qty: number;
+  kind: "sale" | "loss" | "transfer";
+  counts: boolean; // inside the reported period and branch
+}
+
+interface Position {
+  layers: Layer[];
+  deficits: Deficit[];
+}
+
+export interface CostOfGoods {
+  costOfGoodsSold: number;
+  unitsCosted: number; // units sold in the period that have a cost
+  unitsWithoutCost: number; // units sold in the period whose cost is unknown
+  stockLosses: number; // cost of stock written off by counts or adjustments in the period
+}
+
+// Process transfers' outgoing side before the incoming side, so the cost is known.
+const TYPE_ORDER: Record<MovementType, number> = {
+  PURCHASE: 0,
+  ADJUSTMENT: 1,
+  TRANSFER_OUT: 2,
+  TRANSFER_IN: 3,
+  SALE: 4,
+};
+
+const round2 = (n: number) => Math.round(n * 100) / 100;
+
+/** Take `qty` units from the front of `layers`; returns what was taken and the shortfall. */
+function take(layers: Layer[], qty: number): { taken: Layer[]; short: number } {
+  const taken: Layer[] = [];
+  let need = qty;
+  while (need > 0 && layers.length > 0) {
+    const head = layers[0];
+    const n = Math.min(head.qty, need);
+    taken.push({ qty: n, unitCost: head.unitCost });
+    head.qty -= n;
+    need -= n;
+    if (head.qty === 0) layers.shift();
+  }
+  return { taken, short: need };
+}
+
+export async function costOfGoodsSold(
+  businessId: Id,
+  period: { from: Date; to: Date; branchId?: Id | null }
+): Promise<CostOfGoods> {
+  const biz = new mongoose.Types.ObjectId(businessId.toString());
+  const branchFilter = period.branchId ? period.branchId.toString() : null;
+
+  const [movements, purchases] = await Promise.all([
+    StockMovement.find({ businessId: biz })
+      .select("branchId productId type quantity refId createdAt")
+      .sort({ createdAt: 1, _id: 1 })
+      .lean(),
+    Purchase.find({ businessId: biz, productId: { $ne: null } })
+      .select("productId unitCost createdAt")
+      .sort({ createdAt: 1 })
+      .lean(),
+  ]);
+  movements.sort(
+    (a, b) => a.createdAt.getTime() - b.createdAt.getTime() || TYPE_ORDER[a.type] - TYPE_ORDER[b.type]
+  );
+
+  const purchaseCost = new Map(purchases.map((p) => [p._id.toString(), p.unitCost]));
+  const priceHistory = new Map<string, { at: number; unitCost: number }[]>();
+  for (const p of purchases) {
+    const key = p.productId!.toString();
+    if (!priceHistory.has(key)) priceHistory.set(key, []);
+    priceHistory.get(key)!.push({ at: p.createdAt.getTime(), unitCost: p.unitCost });
+  }
+  const estimateCost = (productId: string, at: number): number | null => {
+    const history = priceHistory.get(productId);
+    if (!history || history.length === 0) return null;
+    let latest: number | null = null;
+    for (const h of history) {
+      if (h.at <= at) latest = h.unitCost;
+      else break;
+    }
+    return latest ?? history[0].unitCost;
+  };
+
+  const positions = new Map<string, Position>();
+  const position = (branch: string, product: string) => {
+    const key = `${branch}:${product}`;
+    if (!positions.has(key)) positions.set(key, { layers: [], deficits: [] });
+    return positions.get(key)!;
+  };
+  const inTransit = new Map<string, Layer[]>(); // transfer refId -> layers given up by the sender
+
+  const result = { costOfGoodsSold: 0, unitsCosted: 0, unitsWithoutCost: 0, stockLosses: 0 };
+  const charge = (kind: Deficit["kind"], layers: Layer[]) => {
+    for (const l of layers) {
+      if (kind === "sale") {
+        if (l.unitCost === null) result.unitsWithoutCost += l.qty;
+        else {
+          result.costOfGoodsSold += l.qty * l.unitCost;
+          result.unitsCosted += l.qty;
+        }
+      } else if (kind === "loss" && l.unitCost !== null) {
+        result.stockLosses += l.qty * l.unitCost;
+      }
+    }
+  };
+
+  for (const m of movements) {
+    const branch = m.branchId.toString();
+    const product = m.productId.toString();
+    const pos = position(branch, product);
+    const at = m.createdAt.getTime();
+    const counts =
+      at >= period.from.getTime() && at < period.to.getTime() && (!branchFilter || branch === branchFilter);
+
+    if (m.quantity > 0) {
+      let incoming: Layer[];
+      if (m.type === "PURCHASE") incoming = [{ qty: m.quantity, unitCost: purchaseCost.get(m.refId) ?? null }];
+      else if (m.type === "TRANSFER_IN") incoming = (inTransit.get(m.refId) ?? [{ qty: m.quantity, unitCost: null }]).map((l) => ({ ...l }));
+      else incoming = [{ qty: m.quantity, unitCost: estimateCost(product, at) }];
+
+      // Stock that was already sold short is covered first, at this stock's cost.
+      while (pos.deficits.length > 0 && incoming.length > 0) {
+        const d = pos.deficits[0];
+        const { taken, short } = take(incoming, d.qty);
+        if (d.counts) charge(d.kind, taken);
+        d.qty = short;
+        if (d.qty === 0) pos.deficits.shift();
+      }
+      pos.layers.push(...incoming);
+    } else if (m.quantity < 0) {
+      const kind: Deficit["kind"] = m.type === "SALE" ? "sale" : m.type === "TRANSFER_OUT" ? "transfer" : "loss";
+      const { taken, short } = take(pos.layers, -m.quantity);
+      if (kind === "transfer") {
+        // The receiving branch inherits this cost; any shortfall arrives with no known cost.
+        inTransit.set(m.refId, short > 0 ? [...taken, { qty: short, unitCost: null }] : taken);
+      } else if (counts) {
+        charge(kind, taken);
+      }
+      if (short > 0) pos.deficits.push({ qty: short, kind, counts: counts && kind !== "transfer" });
+    }
+  }
+
+  // Short sales in the period that no later stock has covered yet.
+  for (const pos of positions.values()) {
+    for (const d of pos.deficits) if (d.counts && d.kind === "sale") result.unitsWithoutCost += d.qty;
+  }
+
+  return {
+    costOfGoodsSold: round2(result.costOfGoodsSold),
+    unitsCosted: result.unitsCosted,
+    unitsWithoutCost: result.unitsWithoutCost,
+    stockLosses: round2(result.stockLosses),
+  };
+}

src/lib/server/invites.ts

@@ -4,6 +4,10 @@ import type { NextRequest } from "next/server";
 import type { IUser } from "@/lib/server/models/User";
 
 export const INVITE_TTL_MS = 7 * 24 * 60 * 60 * 1000;
+/** Reset links are shorter-lived: they can take over an account that is already in use. */
+export const RESET_TTL_MS = 24 * 60 * 60 * 1000;
+
+export type LinkPurpose = "invite" | "reset";
 
 export function hashInviteToken(token: string): string {
   return crypto.createHash("sha256").update(token).digest("hex");
@@ -14,14 +18,20 @@ export async function unusablePasswordHash(): Promise<string> {
   return bcrypt.hash(crypto.randomBytes(32).toString("hex"), 12);
 }
 
+/** Whether the account is waiting for its first password (not a reset). */
+export function invitePending(user: Pick<IUser, "inviteExpiresAt" | "invitePurpose">): boolean {
+  return !!user.inviteExpiresAt && user.invitePurpose !== "reset";
+}
+
 /**
- * Give the user a fresh invite (any earlier link stops working) and return
+ * Give the user a fresh one-time password link (any earlier link stops
- * the link to send them. The caller saves the user.
+ * working) and return it to send them. The caller saves the user.
  */
-export function issueInvite(user: IUser, req: NextRequest): string {
+export function issueInvite(user: IUser, req: NextRequest, purpose: LinkPurpose = "invite"): string {
   const token = crypto.randomBytes(32).toString("base64url");
   user.inviteTokenHash = hashInviteToken(token);
-  user.inviteExpiresAt = new Date(Date.now() + INVITE_TTL_MS);
+  user.inviteExpiresAt = new Date(Date.now() + (purpose === "reset" ? RESET_TTL_MS : INVITE_TTL_MS));
+  user.invitePurpose = purpose;
   const origin = process.env.APP_URL?.replace(/\/$/, "") || req.nextUrl.origin;
   return `${origin}/invite/${token}`;
 }

src/lib/server/models/Branch.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 export interface IBranch extends Document {
@@ -30,5 +31,7 @@ const branchSchema = new Schema<IBranch>(
 /** Filter for branches that are in use. */
 export const ACTIVE_BRANCH = { isActive: { $ne: false } } as const;
 
+branchSchema.plugin(tenantGuard);
+
 export const Branch =
   (models.Branch as Model<IBranch>) || model<IBranch>("Branch", branchSchema);

src/lib/server/models/DailyInventory.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 export interface IDailyInventory extends Document {
@@ -40,6 +41,8 @@ dailyInventorySchema.index({ branchId: 1, date: 1 });
 // One ledger row per branch+product+day.
 dailyInventorySchema.index({ branchId: 1, productId: 1, date: 1 }, { unique: true });
 
+dailyInventorySchema.plugin(tenantGuard);
+
 export const DailyInventory =
   (models.DailyInventory as Model<IDailyInventory>) ||
   model<IDailyInventory>("DailyInventory", dailyInventorySchema);

src/lib/server/models/Expense.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 // Business expense categories. Kept as a constrained string set so the UI
@@ -46,5 +47,7 @@ expenseSchema.index({ category: 1 });
 
 // `models.Expense` guard avoids OverwriteModelError on serverless warm
 // re-invocations where the module is evaluated more than once.
+expenseSchema.plugin(tenantGuard);
+
 export const Expense =
   (models.Expense as Model<IExpense>) || model<IExpense>("Expense", expenseSchema);

src/lib/server/models/Product.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 export interface IProduct extends Document {
@@ -32,6 +33,8 @@ const productSchema = new Schema<IProduct>(
   { timestamps: true }
 );
 
+productSchema.plugin(tenantGuard);
+
 export const Product =
   (models.Product as Model<IProduct>) || model<IProduct>("Product", productSchema);
 
@@ -57,6 +60,8 @@ const branchPricingSchema = new Schema<IBranchPricing>(
 );
 branchPricingSchema.index({ branchId: 1, productId: 1 }, { unique: true });
 
+branchPricingSchema.plugin(tenantGuard);
+
 export const BranchPricing =
   (models.BranchPricing as Model<IBranchPricing>) ||
   model<IBranchPricing>("BranchPricing", branchPricingSchema);

src/lib/server/models/Purchase.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 // A recorded stock purchase from a supplier. Completing a purchase is what
@@ -40,5 +41,7 @@ const purchaseSchema = new Schema<IPurchase>(
 purchaseSchema.index({ branchId: 1, createdAt: -1 });
 purchaseSchema.index({ productId: 1 });
 
+purchaseSchema.plugin(tenantGuard);
+
 export const Purchase =
   (models.Purchase as Model<IPurchase>) || model<IPurchase>("Purchase", purchaseSchema);

src/lib/server/models/StockMovement.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 export const MOVEMENT_TYPES = ["SALE", "PURCHASE", "TRANSFER_OUT", "TRANSFER_IN", "ADJUSTMENT"] as const;
@@ -46,6 +47,8 @@ stockMovementSchema.index({ type: 1, refId: 1 }, { unique: true });
 stockMovementSchema.index({ businessId: 1, branchId: 1, productId: 1 });
 stockMovementSchema.index({ businessId: 1, branchId: 1, createdAt: -1 });
 
+stockMovementSchema.plugin(tenantGuard);
+
 export const StockMovement =
   (models.StockMovement as Model<IStockMovement>) ||
   model<IStockMovement>("StockMovement", stockMovementSchema);

src/lib/server/models/StockTransfer.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 export interface IStockTransfer extends Document {
@@ -35,6 +36,8 @@ const stockTransferSchema = new Schema<IStockTransfer>(
 stockTransferSchema.index({ businessId: 1, clientUuid: 1 }, { unique: true });
 stockTransferSchema.index({ businessId: 1, createdAt: -1 });
 
+stockTransferSchema.plugin(tenantGuard);
+
 export const StockTransfer =
   (models.StockTransfer as Model<IStockTransfer>) ||
   model<IStockTransfer>("StockTransfer", stockTransferSchema);

src/lib/server/models/Transaction.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 
 export type PaymentMethod = "CASH" | "MPESA";
@@ -105,6 +106,8 @@ transactionSchema.index({ businessId: 1, createdAt: -1 });
 transactionSchema.index({ paymentStatus: 1 });
 transactionSchema.index({ businessId: 1, saleId: 1 });
 
+transactionSchema.plugin(tenantGuard);
+
 export const Transaction =
   (models.Transaction as Model<ITransaction>) ||
   model<ITransaction>("Transaction", transactionSchema);

src/lib/server/models/User.ts

@@ -1,3 +1,4 @@
+import { tenantGuard } from "@/lib/server/tenantGuard";
 import { Schema, model, models, Model, Types, Document } from "mongoose";
 import bcrypt from "bcryptjs";
 
@@ -24,11 +25,15 @@ export interface IUser extends Document {
   isActive: boolean;
   failedLoginAttempts: number;
   lockedUntil: Date | null;
-  // Pending invite: the person sets their own password through a one-time
+  // A one-time link through which the person sets their own password.
-  // link. Only the SHA-256 of the token is stored. Until they accept, the
+  // Only the SHA-256 of the token is stored.
-  // account has a random unknown password, so it cannot be signed into.
+  //   invite: a new account; until accepted it has a random unknown password.
+  //   reset:  a forgotten password; the old password keeps working until the
+  //           link is used, and using it signs the account out everywhere.
+  // Rows from before invitePurpose existed have null, which means invite.
   inviteTokenHash: string | null;
   inviteExpiresAt: Date | null;
+  invitePurpose: "invite" | "reset" | null;
   createdAt: Date;
   updatedAt: Date;
 
@@ -50,6 +55,7 @@ const userSchema = new Schema<IUser>(
     lockedUntil: { type: Date, default: null },
     inviteTokenHash: { type: String, default: null, index: { sparse: true } },
     inviteExpiresAt: { type: Date, default: null },
+    invitePurpose: { type: String, enum: ["invite", "reset", null], default: null },
   },
   { timestamps: true }
 );
@@ -80,5 +86,7 @@ userSchema.methods.comparePassword = async function (password: string): Promise<
   return bcrypt.compare(password, this.passwordHash);
 };
 
+userSchema.plugin(tenantGuard);
+
 export const User =
   (models.User as Model<IUser>) || model<IUser>("User", userSchema);

src/lib/server/platform.ts

@@ -48,7 +48,9 @@ export async function requirePlatformAdmin(
 ): Promise<{ userId: string; email: string } | null> {
   const auth = getAuth(req);
   if (!auth) return null;
-  const user = await User.findById(auth.sub).select("email isActive platformAdmin").lean();
+  const user = await User.findOne({ _id: auth.sub, businessId: auth.businessId })
+    .select("email isActive platformAdmin")
+    .lean();
   if (!user || !user.isActive) return null;
   if (!isPlatformAdmin(user)) return null;
   return { userId: auth.sub, email: user.email };

src/lib/server/stock.ts

@@ -4,6 +4,7 @@ import { ACTIVE_BRANCH, Branch } from "@/lib/server/models/Branch";
 import { Product } from "@/lib/server/models/Product";
 import { Purchase } from "@/lib/server/models/Purchase";
 import { StockLock } from "@/lib/server/models/StockLock";
+import { crossTenant } from "@/lib/server/tenantGuard";
 import type { ITransaction } from "@/lib/server/models/Transaction";
 
 type Id = Types.ObjectId | string;
@@ -26,7 +27,7 @@ export interface MovementInput {
  */
 export async function recordMovement(m: MovementInput): Promise<void> {
   await StockMovement.updateOne(
-    { type: m.type, refId: m.refId },
+    { type: m.type, refId: m.refId, businessId: m.businessId },
     {
       $setOnInsert: {
         businessId: m.businessId,
@@ -155,11 +156,14 @@ export async function getStockLevels(businessId: Id, branchId?: Id | null): Prom
 export async function backfillPurchaseMovements(businessId?: Id): Promise<number> {
   const filter: Record<string, unknown> = { productId: { $ne: null } };
   if (businessId) filter.businessId = new mongoose.Types.ObjectId(businessId.toString());
+  const purchases = businessId
+    ? await Purchase.find(filter).lean()
+    : await crossTenant("the backfill runs over every business", () => Purchase.find(filter).lean().exec());
 
   let added = 0;
-  for await (const p of Purchase.find(filter).lean().cursor()) {
+  for (const p of purchases) {
     const refId = p._id.toString();
-    if (await StockMovement.exists({ type: "PURCHASE", refId })) continue;
+    if (await StockMovement.exists({ type: "PURCHASE", refId, businessId: p.businessId })) continue;
     await recordMovement({
       businessId: p.businessId,
       branchId: p.branchId,

src/lib/server/tenantGuard.ts

@@ -0,0 +1,114 @@
+import { AsyncLocalStorage } from "async_hooks";
+import { Types, type MongooseQueryMiddleware, type Schema } from "mongoose";
+
+/**
+ * Tenant isolation, enforced instead of remembered.
+ *
+ * Every model that holds one business's data is guarded: a query against
+ * it that does not name exactly one business (`businessId: <id>`) throws
+ * TenantScopeError before it reaches the database. A route that forgets
+ * the business filter therefore fails loudly in development and in the
+ * test suite, instead of quietly reading or changing another business's
+ * data in production.
+ *
+ * The few queries that legitimately span businesses (login looking an
+ * email up everywhere, an invite token, the payment provider's callback,
+ * the platform console, maintenance scripts) must say so explicitly:
+ *
+ *   await crossTenant("login looks the email up in every business", () => User.find(...));
+ *
+ * Guarded: find, findOne (and findById / exists), findOneAndUpdate /
+ * Delete / Replace, updateOne / updateMany, replaceOne, deleteOne /
+ * deleteMany, countDocuments, distinct, and aggregate (its first stage
+ * must be a $match naming the business). populate() runs a find on the
+ * referenced model, so populate through `scopedPopulate` below.
+ *
+ * Not guarded, by design: Business (the tenant itself, always looked up by
+ * the id from the session), UserSession (keyed by the signed-in user),
+ * MpesaCallbackLog (provider audit log), StockLock (key already contains
+ * the business). Document saves and inserts are covered by `businessId`
+ * being a required field.
+ */
+
+export class TenantScopeError extends Error {
+  constructor(model: string, op: string) {
+    super(
+      `Tenant isolation: ${model}.${op} must filter by a single businessId ` +
+        `(or run inside crossTenant("why", ...) if it really spans businesses).`
+    );
+    this.name = "TenantScopeError";
+  }
+}
+
+const crossTenantReason = new AsyncLocalStorage<string>();
+
+/**
+ * Run `fn`, whose queries deliberately span businesses. `reason` documents
+ * why. The result is awaited inside the scope, so a lazy Mongoose query
+ * returned by `fn` executes while the exemption applies.
+ */
+export function crossTenant<T>(reason: string, fn: () => PromiseLike<T>): Promise<T> {
+  if (!reason.trim()) throw new Error("crossTenant needs a reason");
+  return crossTenantReason.run(reason, async () => await fn());
+}
+
+/** True when the filter pins exactly one business. */
+export function namesOneBusiness(filter: unknown): boolean {
+  if (!filter || typeof filter !== "object") return false;
+  const f = filter as Record<string, unknown>;
+  const v = f.businessId;
+  if (typeof v === "string" || v instanceof Types.ObjectId) return true;
+  if (v && typeof v === "object" && "$eq" in (v as object)) {
+    const eq = (v as { $eq: unknown }).$eq;
+    return typeof eq === "string" || eq instanceof Types.ObjectId;
+  }
+  return Array.isArray(f.$and) && f.$and.some(namesOneBusiness);
+}
+
+const QUERY_OPS: MongooseQueryMiddleware[] = [
+  "find",
+  "findOne",
+  "findOneAndUpdate",
+  "findOneAndDelete",
+  "findOneAndReplace",
+  "updateOne",
+  "updateMany",
+  "replaceOne",
+  "deleteOne",
+  "deleteMany",
+  "countDocuments",
+  "distinct",
+];
+
+const guardedSchemas = new WeakSet<Schema>();
+
+/** Whether a schema has the guard (the test suite checks every business-scoped model does). */
+export function isTenantGuarded(schema: Schema): boolean {
+  return guardedSchemas.has(schema);
+}
+
+/** Mongoose plugin: apply to every schema with a `businessId` path. */
+export function tenantGuard(schema: Schema): void {
+  guardedSchemas.add(schema);
+
+  schema.pre(QUERY_OPS, function (this: any) {
+    if (crossTenantReason.getStore()) return;
+    if (!namesOneBusiness(this.getFilter())) throw new TenantScopeError(this.model.modelName, this.op);
+  });
+
+  schema.pre("aggregate", function (this: any) {
+    if (crossTenantReason.getStore()) return;
+    const first = this.pipeline()[0];
+    if (!first || !namesOneBusiness(first.$match)) {
+      throw new TenantScopeError(this._model?.modelName ?? "Model", "aggregate");
+    }
+  });
+}
+
+/**
+ * populate() options that keep the referenced documents inside the
+ * business too (populate queries the referenced model, which is guarded).
+ */
+export function scopedPopulate(path: string, select: string, businessId: string | Types.ObjectId) {
+  return { path, select, match: { businessId } };
+}

src/lib/signOut.ts

@@ -0,0 +1,16 @@
+import { apiFetch } from "@/lib/api";
+import { clearSession } from "@/lib/sessionCache";
+
+/**
+ * End this device's session and forget the cached terminal session. Works
+ * offline too: the server session then expires on its own, and this device
+ * keeps nothing that would sign it back in.
+ */
+export async function signOut(): Promise<void> {
+  try {
+    await apiFetch("/api/auth/logout", { method: "POST" });
+  } catch {
+    // Offline or already signed out.
+  }
+  clearSession();
+}

tests/access.test.ts

@@ -15,7 +15,7 @@ import * as login from "@/app/api/auth/login/route";
 import * as signup from "@/app/api/auth/signup/route";
 import * as stkpush from "@/app/api/mpesa/stkpush/route";
 import * as callback from "@/app/api/mpesa/callback/route";
-import { json, makeTenant, params, req, uuid } from "./helpers";
+import { json, makeTenant, params, req, uuid, db } from "./helpers";
 
 describe("role-based access on the backend", () => {
   it("blocks cashiers from owner-level money endpoints with 403", async () => {
@@ -78,7 +78,7 @@ describe("user deactivation", () => {
       params({ id: t.cashierA.id })
     );
     expect(res.status).toBe(200);
-    expect((await User.findById(t.cashierA.id))!.isActive).toBe(false);
+    expect((await db(() => User.findById(t.cashierA.id)))!.isActive).toBe(false);
     expect(await UserSession.countDocuments({ userId: t.cashierA.id })).toBe(0);
   });
 
@@ -105,7 +105,7 @@ describe("tenant status", () => {
   it("refuses login for a suspended business", async () => {
     const t = await makeTenant();
     const passwordHash = await bcrypt.hash("correct-horse", 4);
-    await User.updateOne({ _id: t.cashierA.id }, { passwordHash });
+    await db(() => User.updateOne({ _id: t.cashierA.id }, { passwordHash }));
     await Business.updateOne({ _id: t.businessId }, { subscriptionStatus: "SUSPENDED" });
 
     const res = await login.POST(
@@ -119,7 +119,7 @@ describe("tenant status", () => {
   it("still allows login for an active business", async () => {
     const t = await makeTenant();
     const passwordHash = await bcrypt.hash("correct-horse", 4);
-    await User.updateOne({ _id: t.managerA.id }, { passwordHash });
+    await db(() => User.updateOne({ _id: t.managerA.id }, { passwordHash }));
     const res = await login.POST(
       req("POST", "/api/auth/login", {
         body: { email: t.managerA.email, password: "correct-horse", deviceId: uuid() },

tests/account.test.ts

@@ -0,0 +1,147 @@
+import { describe, expect, it } from "vitest";
+import bcrypt from "bcryptjs";
+import { User } from "@/lib/server/models/User";
+import { Branch } from "@/lib/server/models/Branch";
+import { UserSession } from "@/lib/server/models/UserSession";
+import * as invite from "@/app/api/users/[id]/invite/route";
+import * as invites from "@/app/api/invites/[token]/route";
+import * as users from "@/app/api/users/route";
+import * as userById from "@/app/api/users/[id]/route";
+import * as password from "@/app/api/auth/password/route";
+import * as login from "@/app/api/auth/login/route";
+import * as ownerReset from "@/app/api/platform/businesses/[id]/owner-reset/route";
+import { db, json, makeTenant, params, req, uuid, type Actor } from "./helpers";
+
+const DEVICE = "00000000-0000-4000-8000-000000000001"; // the device tokenFor() signs in on
+
+async function setPassword(a: Actor, pw: string) {
+  await db(() => User.updateOne({ _id: a.id }, { passwordHash: bcrypt.hashSync(pw, 4) }));
+}
+const signIn = (a: Actor, pw: string) =>
+  login.POST(req("POST", "/x", { body: { email: a.email, password: pw, deviceId: uuid() } }));
+const tokenOf = (url: string) => url.split("/invite/")[1];
+const sessions = (a: Actor) => db(() => UserSession.countDocuments({ userId: a.id }));
+
+describe("password reset links", () => {
+  it("lets a manager reset their cashier's forgotten password; the old one works until the link is used", async () => {
+    const t = await makeTenant();
+    await setPassword(t.cashierA, "old-password");
+    await signIn(t.cashierA, "old-password"); // a session on some phone
+
+    const r = await json(await invite.POST(req("POST", "/x", { as: t.managerA }), params({ id: t.cashierA.id })));
+    expect(r.status).toBe(200);
+    expect(r.body.purpose).toBe("reset");
+    expect((await signIn(t.cashierA, "old-password")).status).toBe(200);
+
+    const page = await json(await invites.GET(req("GET", "/x"), params({ token: tokenOf(r.body.inviteUrl) })));
+    expect(page.body.purpose).toBe("reset");
+
+    const accept = await invites.POST(req("POST", "/x", { body: { password: "new-password" } }), params({ token: tokenOf(r.body.inviteUrl) }));
+    expect(accept.status).toBe(200);
+    expect(await sessions(t.cashierA)).toBe(0); // every device signed out
+    expect((await signIn(t.cashierA, "old-password")).status).toBe(401);
+    expect((await signIn(t.cashierA, "new-password")).status).toBe(200);
+  });
+
+  it("does not show a reset as a pending invite", async () => {
+    const t = await makeTenant();
+    await invite.POST(req("POST", "/x", { as: t.owner }), params({ id: t.cashierA.id }));
+    const list = await json(await users.GET(req("GET", "/api/users", { as: t.owner })));
+    expect(list.body.users.find((u: any) => u._id === t.cashierA.id).invitePending).toBe(false);
+  });
+
+  it("expires a reset link after 24 hours", async () => {
+    const t = await makeTenant();
+    const r = await json(await invite.POST(req("POST", "/x", { as: t.owner }), params({ id: t.cashierA.id })));
+    const user = await db(() => User.findById(t.cashierA.id).lean());
+    const hours = (user!.inviteExpiresAt!.getTime() - Date.now()) / 3_600_000;
+    expect(hours).toBeGreaterThan(23.9);
+    expect(hours).toBeLessThanOrEqual(24);
+    await db(() => User.updateOne({ _id: t.cashierA.id }, { inviteExpiresAt: new Date(Date.now() - 1000) }));
+    expect((await invites.GET(req("GET", "/x"), params({ token: tokenOf(r.body.inviteUrl) }))).status).toBe(404);
+  });
+
+  it("keeps managers to their own cashiers, and nobody resets themselves", async () => {
+    const t = await makeTenant();
+    const post = (as: Actor, id: string) => invite.POST(req("POST", "/x", { as }), params({ id }));
+    expect((await post(t.managerA, t.cashierB.id)).status).toBe(403);
+    expect((await post(t.managerA, t.owner.id)).status).toBe(403);
+    expect((await post(t.owner, t.owner.id)).status).toBe(409);
+    expect((await post(t.cashierA, t.cashierB.id)).status).toBe(403);
+  });
+
+  it("lets the platform operator give a business owner a reset link, and nobody else", async () => {
+    const t = await makeTenant("Customer Co");
+    const home = await makeTenant("Operator Co");
+    await db(() => User.updateOne({ _id: home.owner.id }, { email: "operator@aquaflow.test", platformAdmin: true }));
+    const operator = { ...home.owner, email: "operator@aquaflow.test" };
+
+    const ok = await json(await ownerReset.POST(req("POST", "/x", { as: operator }), params({ id: t.businessId })));
+    expect(ok.status).toBe(200);
+    expect(ok.body).toMatchObject({ purpose: "reset", email: t.owner.email.toLowerCase() });
+
+    expect((await ownerReset.POST(req("POST", "/x", { as: t.owner }), params({ id: t.businessId }))).status).toBe(403);
+  });
+});
+
+describe("changing your own password", () => {
+  it("needs the current password, then signs out every other device but this one", async () => {
+    const t = await makeTenant();
+    await setPassword(t.managerA, "current-pass");
+    await signIn(t.managerA, "current-pass"); // another device
+    await db(() => UserSession.create({ userId: t.managerA.id, deviceId: DEVICE, refreshTokenHash: "x", expiresAt: new Date(Date.now() + 86_400_000) }));
+    expect(await sessions(t.managerA)).toBe(2);
+
+    const change = (currentPassword: string, newPassword: string) =>
+      password.POST(req("POST", "/x", { as: t.managerA, body: { currentPassword, newPassword } }));
+    expect((await change("wrong-pass", "brand-new-pass")).status).toBe(400);
+    expect((await change("current-pass", "short")).status).toBe(400);
+    expect((await change("current-pass", "brand-new-pass")).status).toBe(200);
+
+    expect(await sessions(t.managerA)).toBe(1);
+    expect(await db(() => UserSession.exists({ userId: t.managerA.id, deviceId: DEVICE }))).toBeTruthy();
+    expect((await signIn(t.managerA, "brand-new-pass")).status).toBe(200);
+  });
+});
+
+describe("moving staff between branches", () => {
+  it("moves a manager, updates both branches' manager, and signs them out", async () => {
+    const t = await makeTenant();
+    await db(() => Branch.updateOne({ _id: t.branchA }, { managerId: t.managerA.id }));
+    await db(() => UserSession.create({ userId: t.managerA.id, deviceId: uuid(), refreshTokenHash: "x", expiresAt: new Date(Date.now() + 86_400_000) }));
+
+    const res = await userById.PATCH(req("PATCH", "/x", { as: t.owner, body: { branchId: t.branchB } }), params({ id: t.managerA.id }));
+    expect(res.status).toBe(200);
+    const [a, b, mgr] = await Promise.all([
+      db(() => Branch.findById(t.branchA).lean()),
+      db(() => Branch.findById(t.branchB).lean()),
+      db(() => User.findById(t.managerA.id).lean()),
+    ]);
+    expect(a!.managerId).toBeNull();
+    expect(b!.managerId!.toString()).toBe(t.managerA.id);
+    expect(mgr!.branchId!.toString()).toBe(t.branchB);
+    expect(await sessions(t.managerA)).toBe(0);
+  });
+
+  it("only lets the owner move people, and only to an active branch", async () => {
+    const t = await makeTenant();
+    const move = (as: Actor, branchId: string) =>
+      userById.PATCH(req("PATCH", "/x", { as, body: { branchId } }), params({ id: t.cashierA.id }));
+    expect((await move(t.managerA, t.branchB)).status).toBe(403);
+    await db(() => Branch.updateOne({ _id: t.branchB }, { isActive: false }));
+    expect((await move(t.owner, t.branchB)).status).toBe(404);
+  });
+});
+
+describe("where sign-in lands", () => {
+  it("sends the platform operator to the platform console, owners to the dashboard, cashiers to the till", async () => {
+    const t = await makeTenant();
+    await Promise.all([setPassword(t.owner, "owner-pass"), setPassword(t.cashierA, "cashier-pass")]);
+    expect((await json(await signIn(t.owner, "owner-pass"))).body.redirectTo).toBe("/admin/dashboard");
+    expect((await json(await signIn(t.cashierA, "cashier-pass"))).body.redirectTo).toBe("/terminal");
+
+    await db(() => User.updateOne({ _id: t.owner.id }, { email: "operator@aquaflow.test", platformAdmin: true }));
+    const operator = { ...t.owner, email: "operator@aquaflow.test" };
+    expect((await json(await signIn(operator, "owner-pass"))).body.redirectTo).toBe("/platform");
+  });
+});

tests/branchPrices.test.ts

@@ -4,7 +4,7 @@ import { BranchPricing } from "@/lib/server/models/Product";
 import * as prices from "@/app/api/branch-prices/route";
 import * as products from "@/app/api/products/route";
 import * as cash from "@/app/api/transactions/cash/route";
-import { json, makeTenant, req, uuid, type Actor, type Tenant } from "./helpers";
+import { json, makeTenant, req, uuid, type Actor, type Tenant, db } from "./helpers";
 
 const setPrice = (as: Actor, branchId: string, productId: string, unitPrice: number) =>
   prices.PUT(req("PUT", "/api/branch-prices", { as, body: { branchId, productId, unitPrice } }));
@@ -44,7 +44,7 @@ describe("branch prices", () => {
     const t = await makeTenant();
     await setPrice(t.owner, t.branchA, t.water20, 180);
     await setPrice(t.owner, t.branchA, t.water20, 200);
-    expect(await BranchPricing.countDocuments({})).toBe(0);
+    expect(await db(() => BranchPricing.countDocuments({}))).toBe(0);
 
     await setPrice(t.owner, t.branchA, t.water5, 55);
     const reset = await prices.DELETE(
@@ -85,6 +85,6 @@ describe("branch prices", () => {
     expect((await setPrice(t.owner, other.branchA, t.water20, 150)).status).toBe(404);
     expect((await setPrice(t.owner, t.branchA, other.water20, 150)).status).toBe(404);
     expect((await prices.GET(req("GET", "/api/branch-prices?branchId=" + other.branchA, { as: t.owner }))).status).toBe(404);
-    expect(await BranchPricing.countDocuments({})).toBe(0);
+    expect(await db(() => BranchPricing.countDocuments({}))).toBe(0);
   });
 });

tests/concurrency.test.ts

@@ -4,7 +4,7 @@ import { StockTransfer } from "@/lib/server/models/StockTransfer";
 import { StockLock } from "@/lib/server/models/StockLock";
 import * as adjustments from "@/app/api/stock/adjustments/route";
 import * as transfers from "@/app/api/stock/transfers/route";
-import { makeTenant, req, uuid, type Tenant } from "./helpers";
+import { makeTenant, req, uuid, type Tenant, db } from "./helpers";
 
 async function openingStock(t: Tenant, quantity: number) {
   await adjustments.POST(
@@ -35,7 +35,7 @@ describe("concurrent stock changes", () => {
     expect(statuses.filter((s) => s === 409)).toHaveLength(3);
     expect(await stockOf(t.businessId, t.branchA, t.water20)).toBe(2);
     expect(await stockOf(t.businessId, t.branchB, t.water20)).toBe(8);
-    expect(await StockTransfer.countDocuments({})).toBe(2);
+    expect(await db(() => StockTransfer.countDocuments({}))).toBe(2);
   });
 
   it("holds across repeated races, not just once", async () => {

tests/costing.test.ts

@@ -0,0 +1,110 @@
+import { describe, expect, it } from "vitest";
+import mongoose from "mongoose";
+import { costOfGoodsSold } from "@/lib/server/costing";
+import { StockMovement } from "@/lib/server/models/StockMovement";
+import { Transaction } from "@/lib/server/models/Transaction";
+import { Purchase } from "@/lib/server/models/Purchase";
+import { startOfMonthNairobi } from "@/lib/server/businessDay";
+import * as cash from "@/app/api/transactions/cash/route";
+import * as purchases from "@/app/api/purchases/route";
+import * as adjustments from "@/app/api/stock/adjustments/route";
+import * as transfers from "@/app/api/stock/transfers/route";
+import * as profit from "@/app/api/reports/profit/route";
+import { json, makeTenant, req, uuid, type Actor, type Tenant } from "./helpers";
+
+const ALL_TIME = { from: new Date(0), to: new Date(Date.now() + 86_400_000) };
+
+const buy = (t: Tenant, branchId: string, quantity: number, unitCost: number, productId = t.water20) =>
+  purchases.POST(req("POST", "/x", { as: t.owner, body: { branchId, supplierName: "Supplier", productId, quantity, unitCost } }));
+
+const sell = (cashier: Actor, quantity: number, productId: string) =>
+  cash.POST(req("POST", "/x", { as: cashier, body: { sales: [{ clientUuid: uuid(), lines: [{ productId, quantity }] }] } }));
+
+const adjust = (t: Tenant, mode: "COUNT" | "DELTA", quantity: number) =>
+  adjustments.POST(
+    req("POST", "/x", { as: t.owner, body: { clientUuid: uuid(), branchId: t.branchA, productId: t.water20, mode, quantity } })
+  );
+
+/** Move everything recorded so far to `when` (tests need history in an earlier period). */
+async function backdate(t: Tenant, when: Date) {
+  // The raw collection: Mongoose treats createdAt as immutable.
+  const filter = { businessId: new mongoose.Types.ObjectId(t.businessId) };
+  await StockMovement.collection.updateMany(filter, { $set: { createdAt: when } });
+  await Transaction.collection.updateMany(filter, { $set: { createdAt: when } });
+  await Purchase.collection.updateMany(filter, { $set: { createdAt: when } });
+}
+
+describe("cost of goods sold: FIFO per branch", () => {
+  it("costs the oldest stock first, not an average", async () => {
+    const t = await makeTenant();
+    await buy(t, t.branchA, 10, 10);
+    await buy(t, t.branchA, 10, 20);
+    await sell(t.cashierA, 15, t.water20);
+    const c = await costOfGoodsSold(t.businessId, ALL_TIME);
+    expect(c).toMatchObject({ costOfGoodsSold: 200, unitsCosted: 15, unitsWithoutCost: 0 }); // 10x10 + 5x20 (the average would say 225)
+  });
+
+  it("costs each branch at what that branch paid", async () => {
+    const t = await makeTenant();
+    await buy(t, t.branchA, 10, 10);
+    await buy(t, t.branchB, 10, 30);
+    await sell(t.cashierB, 2, t.water20);
+    await sell(t.cashierA, 1, t.water20);
+    expect((await costOfGoodsSold(t.businessId, ALL_TIME)).costOfGoodsSold).toBe(70);
+    expect((await costOfGoodsSold(t.businessId, { ...ALL_TIME, branchId: t.branchA })).costOfGoodsSold).toBe(10);
+    expect((await costOfGoodsSold(t.businessId, { ...ALL_TIME, branchId: t.branchB })).costOfGoodsSold).toBe(60);
+  });
+
+  it("carries the sending branch's cost with a transfer", async () => {
+    const t = await makeTenant();
+    await buy(t, t.branchA, 10, 10);
+    await transfers.POST(
+      req("POST", "/x", {
+        as: t.owner,
+        body: { clientUuid: uuid(), fromBranchId: t.branchA, toBranchId: t.branchB, productId: t.water20, quantity: 5 },
+      })
+    );
+    await buy(t, t.branchB, 5, 30);
+    await sell(t.cashierB, 6, t.water20);
+    // B's oldest stock is the 5 transferred at 10, then 1 of its own at 30.
+    expect((await costOfGoodsSold(t.businessId, { ...ALL_TIME, branchId: t.branchB })).costOfGoodsSold).toBe(80);
+  });
+
+  it("costs a sale made before its stock was recorded by the stock that arrives next", async () => {
+    const t = await makeTenant();
+    await sell(t.cashierA, 3, t.water20); // offline sale, nothing on the books yet
+    expect(await costOfGoodsSold(t.businessId, ALL_TIME)).toMatchObject({ costOfGoodsSold: 0, unitsWithoutCost: 3 });
+    await buy(t, t.branchA, 10, 12);
+    expect(await costOfGoodsSold(t.businessId, ALL_TIME)).toMatchObject({ costOfGoodsSold: 36, unitsWithoutCost: 0 });
+  });
+
+  it("reports written-off stock as a loss, not as cost of goods sold, and deducts it in net profit", async () => {
+    const t = await makeTenant();
+    await buy(t, t.branchA, 10, 10);
+    await adjust(t, "COUNT", 8);
+    expect(await costOfGoodsSold(t.businessId, ALL_TIME)).toMatchObject({ costOfGoodsSold: 0, stockLosses: 20 });
+    const { body } = await json(await profit.GET(req("GET", "/api/reports/profit", { as: t.owner })));
+    expect(body).toMatchObject({ stockLosses: 20, grossProfit: 0, netProfit: -20 });
+  });
+
+  it("values opening stock at the product's purchase price", async () => {
+    const t = await makeTenant();
+    await adjust(t, "DELTA", 10); // opening stock, before any purchase was recorded
+    await buy(t, t.branchA, 10, 15);
+    await sell(t.cashierA, 12, t.water20);
+    expect((await costOfGoodsSold(t.businessId, ALL_TIME)).costOfGoodsSold).toBe(180);
+  });
+
+  it("counts only the period's sales, costed against what was left from earlier periods", async () => {
+    const t = await makeTenant();
+    await buy(t, t.branchA, 10, 10);
+    await sell(t.cashierA, 6, t.water20);
+    const lastMonth = new Date(startOfMonthNairobi().getTime() - 5 * 86_400_000);
+    await backdate(t, lastMonth);
+    await buy(t, t.branchA, 10, 20);
+    await sell(t.cashierA, 6, t.water20); // 4 left from last month at 10, then 2 at 20
+
+    const { body } = await json(await profit.GET(req("GET", "/api/reports/profit", { as: t.owner })));
+    expect(body).toMatchObject({ costMethod: "FIFO per branch", unitsSold: 6, costOfGoodsSold: 80, unitsWithoutCost: 0 });
+  });
+});

tests/followups.test.ts

@@ -19,7 +19,7 @@ import * as profit from "@/app/api/reports/profit/route";
 import * as cash from "@/app/api/transactions/cash/route";
 import * as adjustments from "@/app/api/stock/adjustments/route";
 import * as transfers from "@/app/api/stock/transfers/route";
-import { json, makeTenant, params, req, uuid, type Tenant } from "./helpers";
+import { json, makeTenant, params, req, uuid, type Tenant, db } from "./helpers";
 
 async function setPlan(t: Tenant, tier: string, subscriptionStatus: string) {
   await Business.updateOne({ _id: t.businessId }, { tier, subscriptionStatus });
@@ -39,7 +39,7 @@ describe("F-01 trial branch allowance", () => {
   it("counts only active branches, and a paid Starter plan allows one", async () => {
     const t = await makeTenant();
     await setPlan(t, "STARTER", "TRIALING");
-    await Branch.updateOne({ _id: t.branchB }, { isActive: false });
+    await db(() => Branch.updateOne({ _id: t.branchB }, { isActive: false }));
     expect((await branches.POST(req("POST", "/x", { as: t.owner, body: newBranch("C") }))).status).toBe(201);
 
     await setPlan(t, "STARTER", "ACTIVE");
@@ -70,7 +70,7 @@ describe("F-06 branch deactivation", () => {
     expect(withStaff.status).toBe(409);
     expect((await withStaff.json()).error).toMatch(/active staff/);
 
-    await User.updateOne({ _id: t.cashierB.id }, { isActive: false });
+    await db(() => User.updateOne({ _id: t.cashierB.id }, { isActive: false }));
     expect((await deactivate()).status).toBe(200);
 
     // Hidden from pickers, kept on the Branches page.
@@ -82,7 +82,7 @@ describe("F-06 branch deactivation", () => {
 
   it("will not reactivate a branch past the plan's limit", async () => {
     const t = await makeTenant();
-    await Branch.updateOne({ _id: t.branchB }, { isActive: false });
+    await db(() => Branch.updateOne({ _id: t.branchB }, { isActive: false }));
     await setPlan(t, "STARTER", "ACTIVE");
     const res = await branchById.PATCH(req("PATCH", "/x", { as: t.owner, body: { isActive: true } }), params({ id: t.branchB }));
     expect(res.status).toBe(403);
@@ -100,12 +100,12 @@ describe("F-03 report period validation", () => {
 });
 
 describe("F-07 cost of goods sold", () => {
-  it("costs only the units sold, at the average buying price, and reports purchases separately", async () => {
+  it("costs only the units sold, first-in-first-out, and reports purchases separately", async () => {
     const t = await makeTenant();
     const buy = (quantity: number, unitCost: number) =>
       purchases.POST(req("POST", "/x", { as: t.managerA, body: { supplierName: "Kiwanja", productId: t.water20, quantity, unitCost } }));
     await buy(20, 10);
-    await buy(10, 13); // average (200 + 130) / 30 = 11
+    await buy(10, 13);
     await cash.POST(
       req("POST", "/x", {
         as: t.cashierA,
@@ -116,9 +116,9 @@ describe("F-07 cost of goods sold", () => {
     expect(body).toMatchObject({
       revenue: 660, // 3 x 200 + 1 x 60
       unitsSold: 4,
-      costOfGoodsSold: 33, // 3 x 11; the 5L was never purchased
+      costOfGoodsSold: 30, // 3 x 10 from the oldest purchase; the 5L was never purchased
       unitsWithoutCost: 1,
-      grossProfit: 627,
+      grossProfit: 630,
       stockPurchases: 330,
       cashSurplus: 330,
     });
@@ -152,7 +152,7 @@ describe("F-04 / F-05 / CAT-12 catalogue", () => {
     await adjustments.POST(
       req("POST", "/x", { as: t.owner, body: { clientUuid: uuid(), branchId: t.branchA, productId: t.water5, mode: "DELTA", quantity: 7 } })
     );
-    await Product.updateOne({ _id: t.water5 }, { isActive: false });
+    await db(() => Product.updateOne({ _id: t.water5 }, { isActive: false }));
 
     const forManager = await json(await products.GET(req("GET", "/api/products?includeInactive=1", { as: t.managerA })));
     const forCashier = await json(await products.GET(req("GET", "/api/products?includeInactive=1", { as: t.cashierA })));
@@ -228,13 +228,13 @@ describe("STA-04 staff invites", () => {
     expect((await invites.GET(req("GET", "/x"), params({ token }))).status).toBe(404);
     expect((await invites.GET(req("GET", "/x"), params({ token: fresh }))).status).toBe(200);
 
-    await User.updateOne({ _id: new mongoose.Types.ObjectId(userId) }, { inviteExpiresAt: new Date(Date.now() - 1000) });
+    await db(() => User.updateOne({ _id: new mongoose.Types.ObjectId(userId) }, { inviteExpiresAt: new Date(Date.now() - 1000) }));
     expect((await invites.GET(req("GET", "/x"), params({ token: fresh }))).status).toBe(404);
   });
 
   it("does not let a manager re-invite another branch's staff", async () => {
     const t = await makeTenant();
-    await User.updateOne({ _id: t.cashierB.id }, { inviteExpiresAt: new Date(Date.now() + 60_000) });
+    await db(() => User.updateOne({ _id: t.cashierB.id }, { inviteExpiresAt: new Date(Date.now() + 60_000) }));
     const res = await reinvite.POST(req("POST", "/x", { as: t.managerA }), params({ id: t.cashierB.id }));
     expect(res.status).toBe(403);
   });

tests/helpers.ts

@@ -7,6 +7,7 @@ import { User, UserRole } from "@/lib/server/models/User";
 import { Product } from "@/lib/server/models/Product";
 import { signAccessToken } from "@/lib/server/jwt";
 import { ACCESS_COOKIE } from "@/lib/server/auth";
+import { crossTenant } from "@/lib/server/tenantGuard";
 
 let phoneSeq = 0;
 function nextPhone(): string {
@@ -131,3 +132,8 @@ export async function json<T = any>(res: Response): Promise<{ status: number; bo
 export function uuid(): string {
   return randomUUID();
 }
+
+/** Tests may inspect and arrange any business's data directly. */
+export function db<T>(fn: () => PromiseLike<T>): Promise<T> {
+  return crossTenant("test inspects the database directly", fn);
+}

tests/identity.test.ts

@@ -6,7 +6,7 @@ import * as login from "@/app/api/auth/login/route";
 import * as me from "@/app/api/auth/me/route";
 import * as platformBusinesses from "@/app/api/platform/businesses/route";
 import { ACCESS_COOKIE } from "@/lib/server/auth";
-import { json, makeTenant, req, uuid, type Actor, type Tenant } from "./helpers";
+import { json, makeTenant, req, uuid, type Actor, type Tenant, db } from "./helpers";
 
 const PERSON = { name: "Wanjiru", email: "wanjiru@aquaflow.test", phoneNumber: "0722000111" };
 const OPERATOR = "operator@aquaflow.test"; // listed in PLATFORM_ADMIN_EMAILS by tests/setup.ts
@@ -35,7 +35,7 @@ describe("email and phone are unique per business", () => {
     const b = await makeTenant("Beta");
     expect((await hire(a, a.owner)).status).toBe(201);
     expect((await hire(b, b.owner)).status).toBe(201);
-    expect(await User.countDocuments({ email: PERSON.email })).toBe(2);
+    expect(await db(() => User.countDocuments({ email: PERSON.email }))).toBe(2);
   });
 
   it("still refuses a duplicate inside the same business", async () => {

tests/isolation.test.ts

@@ -0,0 +1,172 @@
+import { describe, expect, it } from "vitest";
+import mongoose from "mongoose";
+import { readdirSync } from "fs";
+import path from "path";
+import { crossTenant, isTenantGuarded, TenantScopeError } from "@/lib/server/tenantGuard";
+import { User } from "@/lib/server/models/User";
+import { Transaction } from "@/lib/server/models/Transaction";
+import { Expense } from "@/lib/server/models/Expense";
+import { StockMovement } from "@/lib/server/models/StockMovement";
+import { stockOf } from "@/lib/server/stock";
+import * as cash from "@/app/api/transactions/cash/route";
+import * as transactions from "@/app/api/transactions/route";
+import * as expenses from "@/app/api/expenses/route";
+import * as purchases from "@/app/api/purchases/route";
+import * as stock from "@/app/api/stock/route";
+import * as movements from "@/app/api/stock/movements/route";
+import * as transfers from "@/app/api/stock/transfers/route";
+import * as adjustments from "@/app/api/stock/adjustments/route";
+import * as summary from "@/app/api/dashboard/summary/route";
+import * as reconciliation from "@/app/api/dashboard/reconciliation/route";
+import * as profit from "@/app/api/reports/profit/route";
+import * as users from "@/app/api/users/route";
+import * as userById from "@/app/api/users/[id]/route";
+import * as reinvite from "@/app/api/users/[id]/invite/route";
+import * as branchById from "@/app/api/branches/[id]/route";
+import * as productById from "@/app/api/products/[id]/route";
+import * as branchPrices from "@/app/api/branch-prices/route";
+import * as dispatch from "@/app/api/inventory/dispatch/route";
+import * as eveningCount from "@/app/api/inventory/evening-count/route";
+import { db, json, makeTenant, params, req, uuid, type Tenant } from "./helpers";
+
+// Models that hold one business's data but are deliberately unguarded (see tenantGuard.ts).
+const UNGUARDED = new Set(["Business", "UserSession", "MpesaCallbackLog", "StockLock"]);
+
+describe("the tenant guard", () => {
+  it("is on every model that stores a businessId", async () => {
+    // Load every model file so none can be skipped by accident.
+    const dir = path.resolve(__dirname, "../src/lib/server/models");
+    for (const file of readdirSync(dir)) await import(path.join(dir, file));
+
+    const scoped = Object.values(mongoose.models).filter((m) => m.schema.path("businessId") && !UNGUARDED.has(m.modelName));
+    expect(scoped.length).toBeGreaterThanOrEqual(10);
+    const unguarded = scoped.filter((m) => !isTenantGuarded(m.schema)).map((m) => m.modelName);
+    expect(unguarded).toEqual([]);
+  });
+
+  it("refuses queries that do not name exactly one business", async () => {
+    const t = await makeTenant();
+    const attempts: [string, () => PromiseLike<unknown>][] = [
+      ["find", () => Transaction.find({ branchId: t.branchA })],
+      ["findById", () => User.findById(t.cashierA.id)],
+      ["exists", () => StockMovement.exists({ type: "SALE" })],
+      ["updateMany", () => Expense.updateMany({}, { amount: 0 })],
+      ["deleteMany", () => Transaction.deleteMany({ paymentMethod: "CASH" })],
+      ["countDocuments", () => User.countDocuments({})],
+      ["$in over businesses", () => User.find({ businessId: { $in: [t.businessId, new mongoose.Types.ObjectId()] } })],
+      ["$exists", () => User.find({ businessId: { $exists: true } })],
+      ["aggregate without $match", () => Transaction.aggregate([{ $group: { _id: "$businessId" } }])],
+      ["aggregate matching later", () => Transaction.aggregate([{ $sort: { createdAt: -1 } }, { $match: { businessId: t.businessId } }])],
+      ["unscoped populate", () => Expense.find({ businessId: t.businessId }).populate("branchId")],
+    ];
+    await Expense.create({ businessId: t.businessId, branchId: t.branchA, category: "Rent", amount: 1, description: "x", recordedBy: t.owner.id });
+    for (const [label, run] of attempts) {
+      await expect(Promise.resolve().then(run), label).rejects.toBeInstanceOf(TenantScopeError);
+    }
+  });
+
+  it("allows scoped queries, and cross-business ones only with a stated reason", async () => {
+    const t = await makeTenant();
+    expect(await User.countDocuments({ businessId: t.businessId })).toBe(4);
+    expect(await User.countDocuments({ $and: [{ businessId: t.businessId }, { role: "DELIVERY" }] })).toBe(2);
+    expect(await crossTenant("test", () => User.countDocuments({}))).toBe(4);
+    expect(() => crossTenant(" ", () => User.countDocuments({}))).toThrow(/reason/);
+    // The exemption ends with the callback.
+    await expect(Promise.resolve().then(() => User.countDocuments({}))).rejects.toBeInstanceOf(TenantScopeError);
+  });
+});
+
+/** Give tenant B one of everything, so a leak into tenant A's view would show. */
+async function seedVictim(b: Tenant) {
+  await adjustments.POST(
+    req("POST", "/x", { as: b.owner, body: { clientUuid: uuid(), branchId: b.branchA, productId: b.water20, mode: "DELTA", quantity: 50 } })
+  );
+  await cash.POST(
+    req("POST", "/x", { as: b.cashierA, body: { sales: [{ clientUuid: uuid(), lines: [{ productId: b.water20, quantity: 3 }] }] } })
+  );
+  await expenses.POST(req("POST", "/x", { as: b.owner, body: { branchId: b.branchA, category: "Rent", amount: 7777, description: "B rent" } }));
+  await purchases.POST(
+    req("POST", "/x", { as: b.owner, body: { branchId: b.branchA, supplierName: "B supplier", productId: b.water20, quantity: 5, unitCost: 99 } })
+  );
+  await transfers.POST(
+    req("POST", "/x", { as: b.owner, body: { clientUuid: uuid(), fromBranchId: b.branchA, toBranchId: b.branchB, productId: b.water20, quantity: 2 } })
+  );
+}
+
+describe("route sweep: another business's ids get nothing", () => {
+  it("every read route returns none of business B's data to business A, whatever ids A sends", async () => {
+    const a = await makeTenant("Alpha");
+    const b = await makeTenant("Beta");
+    await seedVictim(b);
+
+    const reads: [string, Response][] = [];
+    const get = async (label: string, handler: (r: any) => Promise<Response>, url: string) =>
+      reads.push([label, await handler(req("GET", url, { as: a.owner }))]);
+    const q = "?branchId=" + b.branchA;
+    await get("transactions", transactions.GET, "/api/transactions" + q);
+    await get("expenses", expenses.GET, "/api/expenses" + q);
+    await get("purchases", purchases.GET, "/api/purchases" + q);
+    await get("stock", stock.GET, "/api/stock" + q);
+    await get("movements", movements.GET, "/api/stock/movements" + q);
+    await get("transfers", transfers.GET, "/api/stock/transfers" + q);
+    await get("summary", summary.GET, "/api/dashboard/summary" + q);
+    await get("reconciliation", reconciliation.GET, "/api/dashboard/reconciliation" + q);
+    await get("profit", profit.GET, "/api/reports/profit" + q);
+    await get("users", users.GET, "/api/users" + q);
+    await get("branch prices", branchPrices.GET, "/api/branch-prices" + q);
+
+    const bIds = [b.businessId, b.branchA, b.branchB, b.water20, b.owner.id, b.cashierA.id];
+    for (const [label, res] of reads) {
+      const text = await res.text();
+      for (const id of bIds) expect(text.includes(id), `${label} leaked ${id}`).toBe(false);
+      expect(text.includes("7777") || text.includes("B supplier"), `${label} leaked B's figures`).toBe(false);
+    }
+    // Totals A sees are A's own (zero), not B's sale.
+    const totals = JSON.parse(await (await summary.GET(req("GET", "/api/dashboard/summary" + q, { as: a.owner }))).text());
+    expect(totals.totals.cashTotal).toBe(0);
+  });
+
+  it("every write route refuses business B's ids and leaves B's data untouched", async () => {
+    const a = await makeTenant("Alpha");
+    const b = await makeTenant("Beta");
+    await seedVictim(b);
+    const before = {
+      stockA: await stockOf(b.businessId, b.branchA, b.water20),
+      cashier: await db(() => User.findById(b.cashierA.id).lean()),
+      sales: await Transaction.countDocuments({ businessId: b.businessId }),
+    };
+
+    const as = a.owner;
+    const writes: [string, Response][] = [
+      ["deactivate B's cashier", await userById.PATCH(req("PATCH", "/x", { as, body: { isActive: false } }), params({ id: b.cashierA.id }))],
+      ["move B's cashier", await userById.PATCH(req("PATCH", "/x", { as, body: { branchId: a.branchA } }), params({ id: b.cashierA.id }))],
+      ["re-invite B's cashier", await reinvite.POST(req("POST", "/x", { as }), params({ id: b.cashierA.id }))],
+      ["rename B's branch", await branchById.PATCH(req("PATCH", "/x", { as, body: { branchName: "Pwned" } }), params({ id: b.branchA }))],
+      ["reprice B's product", await productById.PATCH(req("PATCH", "/x", { as, body: { unitPrice: 1 } }), params({ id: b.water20 }))],
+      ["branch price on B", await branchPrices.PUT(req("PUT", "/x", { as, body: { branchId: b.branchA, productId: b.water20, unitPrice: 1 } }))],
+      ["adjust B's stock", await adjustments.POST(req("POST", "/x", { as, body: { clientUuid: uuid(), branchId: b.branchA, productId: b.water20, mode: "COUNT", quantity: 0 } }))],
+      ["transfer out of B", await transfers.POST(req("POST", "/x", { as, body: { clientUuid: uuid(), fromBranchId: b.branchA, toBranchId: a.branchA, productId: b.water20, quantity: 1 } }))],
+      ["transfer into B", await transfers.POST(req("POST", "/x", { as, body: { clientUuid: uuid(), fromBranchId: a.branchA, toBranchId: b.branchA, productId: a.water20, quantity: 1 } }))],
+      ["expense on B", await expenses.POST(req("POST", "/x", { as, body: { branchId: b.branchA, category: "Rent", amount: 1, description: "x" } }))],
+      ["purchase into B", await purchases.POST(req("POST", "/x", { as, body: { branchId: b.branchA, supplierName: "x", productId: b.water20, quantity: 1, unitCost: 1 } }))],
+      ["dispatch at B", await dispatch.POST(req("POST", "/x", { as, body: { branchId: b.branchA, productId: b.water20, morningDispatched: 1 } }))],
+      ["count at B", await eveningCount.POST(req("POST", "/x", { as, body: { branchId: b.branchA, productId: b.water20, eveningPhysicalCount: 1 } }))],
+      ["sale of B's product", await cash.POST(req("POST", "/x", { as: a.cashierA, body: { sales: [{ clientUuid: uuid(), lines: [{ productId: b.water20, quantity: 1 }] }] } }))],
+    ];
+    for (const [label, res] of writes) {
+      if (label.startsWith("sale")) {
+        expect((await json(res)).body.results[0].status, label).toBe("rejected");
+      } else {
+        expect(res.status, label).toBeGreaterThanOrEqual(400);
+      }
+    }
+
+    expect(await stockOf(b.businessId, b.branchA, b.water20)).toBe(before.stockA);
+    expect(await db(() => User.findById(b.cashierA.id).lean())).toMatchObject({
+      isActive: before.cashier!.isActive,
+      branchId: before.cashier!.branchId,
+    });
+    expect(await Transaction.countDocuments({ businessId: b.businessId })).toBe(before.sales);
+    expect(await Expense.countDocuments({ businessId: b.businessId })).toBe(1);
+  });
+});

tests/sync.test.ts

@@ -4,7 +4,7 @@ import { Product, BranchPricing } from "@/lib/server/models/Product";
 import { stockOf } from "@/lib/server/stock";
 import * as cash from "@/app/api/transactions/cash/route";
 import type { SaleResult } from "@/lib/syncProtocol";
-import { json, makeTenant, req, uuid, type Actor, type Tenant } from "./helpers";
+import { json, makeTenant, req, uuid, type Actor, type Tenant, db } from "./helpers";
 
 function sale(t: Tenant, cashier: Actor, lines: { productId: string; quantity: number; unitPrice?: number }[], extra = {}) {
   return {
@@ -31,7 +31,7 @@ describe("offline sale sync", () => {
     const { status, body } = await post(t.cashierA, [s]);
     expect(status).toBe(200);
     expect(body.results).toEqual([{ clientUuid: s.clientUuid, status: "saved", amountTotal: 580, priceMismatch: false }]);
-    expect(await Transaction.countDocuments({ saleId: s.clientUuid })).toBe(2);
+    expect(await db(() => Transaction.countDocuments({ saleId: s.clientUuid }))).toBe(2);
     expect(await stockOf(t.businessId, t.branchA, t.water20)).toBe(-2);
     expect(await stockOf(t.businessId, t.branchA, t.water5)).toBe(-3);
   });
@@ -42,7 +42,7 @@ describe("offline sale sync", () => {
     await post(t.cashierA, [s]);
     const replay = await post(t.cashierA, [s]);
     expect(replay.body.results[0]).toMatchObject({ clientUuid: s.clientUuid, status: "duplicate" });
-    expect(await Transaction.countDocuments({ saleId: s.clientUuid })).toBe(1);
+    expect(await db(() => Transaction.countDocuments({ saleId: s.clientUuid }))).toBe(1);
     expect(await stockOf(t.businessId, t.branchA, t.water20)).toBe(-1);
   });
 
@@ -78,7 +78,7 @@ describe("offline sale sync", () => {
     const otherCashiersSale = sale(t, t.cashierB, [{ productId: t.water20, quantity: 1 }]);
     const { body } = await post(t.cashierA, [otherCashiersSale]);
     expect(body.results[0].status).toBe("rejected");
-    expect(await Transaction.countDocuments({})).toBe(0);
+    expect(await db(() => Transaction.countDocuments({}))).toBe(0);
   });
 
   it("keeps a sale at the branch where it happened after the cashier is moved", async () => {
@@ -86,7 +86,7 @@ describe("offline sale sync", () => {
     const s = sale(t, t.cashierA, [{ productId: t.water20, quantity: 1 }]); // recorded at branch A
     const moved = { ...t.cashierA, branchId: t.branchB };
     await post(moved, [s]);
-    const txn = await Transaction.findOne({ saleId: s.clientUuid });
+    const txn = await db(() => Transaction.findOne({ saleId: s.clientUuid }));
     expect(txn!.branchId.toString()).toBe(t.branchA);
   });
 
@@ -97,13 +97,13 @@ describe("offline sale sync", () => {
     const foreignBranch = sale(t, t.cashierA, [{ productId: t.water20, quantity: 1 }], { branchId: other.branchA });
     const { body } = await post(t.cashierA, [foreignProduct, foreignBranch]);
     expect(body.results.map((r) => r.status)).toEqual(["rejected", "rejected"]);
-    expect(await Transaction.countDocuments({})).toBe(0);
+    expect(await db(() => Transaction.countDocuments({}))).toBe(0);
   });
 
   it("uses the branch price, flags a price the device showed differently, and keeps deactivated products sellable", async () => {
     const t = await makeTenant();
     await BranchPricing.create({ businessId: t.businessId, branchId: t.branchA, productId: t.water20, unitPrice: 180 });
-    await Product.updateOne({ _id: t.water5 }, { isActive: false });
+    await db(() => Product.updateOne({ _id: t.water5 }, { isActive: false }));
     const s = sale(t, t.cashierA, [
       { productId: t.water20, quantity: 1, unitPrice: 200 }, // stale price on the device
       { productId: t.water5, quantity: 1, unitPrice: 60 },