diff --git a/apps/admin/src/app/api/admin/analytics/route.ts b/apps/admin/src/app/api/admin/analytics/route.ts
index 638587f..1c0e7c5 100644
--- a/apps/admin/src/app/api/admin/analytics/route.ts
+++ b/apps/admin/src/app/api/admin/analytics/route.ts
@@ -4,6 +4,7 @@ import { getDatabase } from "@/lib/database";
 import { ensureUserSynced } from "@/lib/sync-user";
 import { successResponse } from "@/lib/api/responses";
 import { db as rawDb, sql } from "@fitai/database";
+import { getUsersByGym, getClientsByGym } from "@/lib/gym-context";
 
 interface UserGrowthPoint {
   label: string;
@@ -45,12 +46,36 @@ export async function GET(req: NextRequest) {
     const url = new URL(req.url);
     const months = parseInt(url.searchParams.get("months") || "6");
 
-    const allUsers = await database.getAllUsers();
-    const allClients = await database.getAllClients();
+    // Get target gym based on role
+    const targetGymId =
+      user.role === "superAdmin"
+        ? (url.searchParams.get("gymId") ?? undefined)
+        : (user.gymId ?? undefined);
 
-    const paymentsRaw = await rawDb.all(
-      sql`SELECT * FROM payments WHERE status = 'completed' AND paid_at IS NOT NULL`,
-    );
+    // Validate gym access for non-superAdmins
+    if (user.role !== "superAdmin" && !targetGymId) {
+      return NextResponse.json(
+        { error: "Forbidden - No gym assigned" },
+        { status: 403 },
+      );
+    }
+
+    // Get gym-scoped data
+    const allUsers = targetGymId
+      ? await getUsersByGym(targetGymId)
+      : await database.getAllUsers();
+
+    const allClients = targetGymId
+      ? await getClientsByGym(targetGymId)
+      : await database.getAllClients();
+
+    // For payments, we'd need a similar filter - for now, skip payments if gym-scoped
+    // TODO: Add getPaymentsByGym when needed
+    const paymentsRaw = targetGymId
+      ? [] // Skip payments for gym-scoped for now
+      : await rawDb.all(
+          sql`SELECT * FROM payments WHERE status = 'completed' AND paid_at IS NOT NULL`,
+        );
     const payments: any[] = paymentsRaw || [];
 
     const now = new Date();
diff --git a/apps/admin/src/app/api/admin/attendance/route.ts b/apps/admin/src/app/api/admin/attendance/route.ts
index c540337..03a5d50 100644
--- a/apps/admin/src/app/api/admin/attendance/route.ts
+++ b/apps/admin/src/app/api/admin/attendance/route.ts
@@ -1,23 +1,39 @@
 import { auth } from "@clerk/nextjs/server";
-import { NextResponse } from "next/server";
+import { NextRequest, NextResponse } from "next/server";
 import { getDatabase } from "@/lib/database";
 import { ensureUserSynced } from "@/lib/sync-user";
 import { successResponse } from "@/lib/api/responses";
+import { getAttendanceByGym } from "@/lib/gym-context";
 
-export async function GET(req: Request) {
+export async function GET(req: NextRequest) {
   try {
     const { userId } = await auth();
     if (!userId) return new NextResponse("Unauthorized", { status: 401 });
 
     const db = await getDatabase();
-
     const user = await ensureUserSynced(userId, db);
 
     if (!user || (user.role !== "admin" && user.role !== "superAdmin")) {
       return new NextResponse("Forbidden", { status: 403 });
     }
 
-    const attendance = await db.getAllAttendance();
+    // Get target gym based on role
+    const url = new URL(req.url);
+    const targetGymId =
+      user.role === "superAdmin"
+        ? (url.searchParams.get("gymId") ?? undefined)
+        : (user.gymId ?? undefined);
+
+    // Validate gym access for non-superAdmins
+    if (user.role !== "superAdmin" && !targetGymId) {
+      return new NextResponse("Forbidden - No gym assigned", { status: 403 });
+    }
+
+    // Get attendance filtered by gym
+    const attendance = targetGymId
+      ? await getAttendanceByGym(targetGymId)
+      : await db.getAllAttendance();
+
     return successResponse({ records: attendance });
   } catch (error) {
     console.error("Admin attendance error:", error);
diff --git a/apps/admin/src/app/api/profile/fitness/route.ts b/apps/admin/src/app/api/profile/fitness/route.ts
index e49825b..b4b6867 100644
--- a/apps/admin/src/app/api/profile/fitness/route.ts
+++ b/apps/admin/src/app/api/profile/fitness/route.ts
@@ -1,11 +1,14 @@
 import { NextRequest, NextResponse } from "next/server";
 import { getDatabase } from "../../../../lib/database/index";
+import { auth } from "@clerk/nextjs/server";
 import log from "@/lib/logger";
 import { fitnessProfileSchema } from "@/lib/validation/schemas";
 import {
   validateRequestBody,
   validationErrorResponse,
 } from "@/lib/validation/helpers";
+import { getFitnessProfilesByGym } from "@/lib/gym-context";
+import { ensureUserSynced } from "@/lib/sync-user";
 
 export async function POST(request: NextRequest) {
   try {
@@ -63,12 +66,47 @@ export async function POST(request: NextRequest) {
 
 export async function GET(request: NextRequest) {
   try {
-    const db = await getDatabase();
-    const { searchParams } = new URL(request.url);
-    const userId = searchParams.get("userId");
+    // First authenticate
+    const { userId: clerkUserId } = await auth();
+    if (!clerkUserId) {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
 
-    if (userId) {
-      const profile = await db.getFitnessProfileByUserId(userId);
+    const db = await getDatabase();
+    const currentUser = await ensureUserSynced(clerkUserId, db);
+
+    if (!currentUser) {
+      return NextResponse.json({ error: "Forbidden" }, { status: 403 });
+    }
+
+    const { searchParams } = new URL(request.url);
+    const targetUserId = searchParams.get("userId");
+
+    // If accessing another user's profile, verify gym access
+    if (targetUserId && targetUserId !== clerkUserId) {
+      const isStaff =
+        currentUser.role === "admin" ||
+        currentUser.role === "superAdmin" ||
+        currentUser.role === "trainer";
+
+      if (!isStaff) {
+        return NextResponse.json({ error: "Forbidden" }, { status: 403 });
+      }
+
+      // Staff need to verify target user is in same gym
+      if (currentUser.role !== "superAdmin") {
+        const targetUser = await db.getUserById(targetUserId);
+        if (!targetUser || targetUser.gymId !== currentUser.gymId) {
+          return NextResponse.json(
+            { error: "Forbidden - Cannot access users from other gyms" },
+            { status: 403 },
+          );
+        }
+      }
+    }
+
+    if (targetUserId) {
+      const profile = await db.getFitnessProfileByUserId(targetUserId);
       if (!profile) {
         return NextResponse.json(
           { error: "Profile not found" },
@@ -78,8 +116,28 @@ export async function GET(request: NextRequest) {
       return NextResponse.json({ profile });
     }
 
-    const profiles = await db.getAllFitnessProfiles();
-    return NextResponse.json({ profiles });
+    // Staff get gym-scoped profiles
+    const isStaff =
+      currentUser.role === "admin" ||
+      currentUser.role === "superAdmin" ||
+      currentUser.role === "trainer";
+
+    if (isStaff) {
+      const targetGymId =
+        currentUser.role === "superAdmin"
+          ? (searchParams.get("gymId") ?? undefined)
+          : (currentUser.gymId ?? undefined);
+
+      const profiles = targetGymId
+        ? await getFitnessProfilesByGym(targetGymId)
+        : await db.getAllFitnessProfiles();
+
+      return NextResponse.json({ profiles });
+    }
+
+    // Regular users only get their own
+    const profile = await db.getFitnessProfileByUserId(clerkUserId);
+    return NextResponse.json({ profile: profile ? [profile] : [] });
   } catch (error) {
     log.error("Failed to get fitness profiles", error);
     return NextResponse.json(
diff --git a/apps/admin/src/app/api/recommendations/route.ts b/apps/admin/src/app/api/recommendations/route.ts
index d084d03..d2b9eeb 100644
--- a/apps/admin/src/app/api/recommendations/route.ts
+++ b/apps/admin/src/app/api/recommendations/route.ts
@@ -17,6 +17,8 @@ import {
   badRequestResponse,
   internalErrorResponse,
 } from "@/lib/api/responses";
+import { getRecommendationsByGym } from "@/lib/gym-context";
+import { ensureUserSynced } from "@/lib/sync-user";
 
 export async function GET(request: NextRequest) {
   try {
@@ -25,38 +27,59 @@ export async function GET(request: NextRequest) {
       return unauthorizedResponse();
     }
 
+    const db = await getDatabase();
+    const currentUser = await ensureUserSynced(currentUserId, db);
+
+    if (!currentUser) {
+      return forbiddenResponse("User not found");
+    }
+
     const { searchParams } = new URL(request.url);
     const targetUserId = searchParams.get("userId");
 
-    const db = await getDatabase();
-
-    // If no userId provided, check if staff and return all recommendations
+    // If no userId provided, staff gets gym-scoped recommendations
     if (!targetUserId) {
-      const currentUser = await db.getUserById(currentUserId);
       const isStaff =
-        currentUser?.role === "admin" ||
-        currentUser?.role === "superAdmin" ||
-        currentUser?.role === "trainer";
+        currentUser.role === "admin" ||
+        currentUser.role === "superAdmin" ||
+        currentUser.role === "trainer";
 
       if (!isStaff) {
         return badRequestResponse("User ID is required");
       }
 
-      const recommendations = await db.getAllRecommendations();
+      // Get target gym based on role
+      const targetGymId =
+        currentUser.role === "superAdmin"
+          ? (searchParams.get("gymId") ?? undefined)
+          : (currentUser.gymId ?? undefined);
+
+      // Get recommendations filtered by gym
+      const recommendations = targetGymId
+        ? await getRecommendationsByGym(targetGymId)
+        : await db.getAllRecommendations();
+
       return successResponse({ recommendations });
     }
 
-    // Check permissions: Users can view their own, Admins/Trainers can view anyone's
-    const currentUser = await db.getUserById(currentUserId);
+    // Check permissions: Users can view their own, Admins/Trainers can view anyone's in their gym
     const isStaff =
-      currentUser?.role === "admin" ||
-      currentUser?.role === "superAdmin" ||
-      currentUser?.role === "trainer";
+      currentUser.role === "admin" ||
+      currentUser.role === "superAdmin" ||
+      currentUser.role === "trainer";
 
     if (currentUserId !== targetUserId) {
       if (!isStaff) {
         return forbiddenResponse();
       }
+
+      // Staff need to verify target user is in same gym
+      if (currentUser.role !== "superAdmin") {
+        const targetUser = await db.getUserById(targetUserId);
+        if (!targetUser || targetUser.gymId !== currentUser.gymId) {
+          return forbiddenResponse("Cannot access users from other gyms");
+        }
+      }
     }
 
     let recommendations = await db.getRecommendationsByUserId(targetUserId);
diff --git a/apps/admin/src/app/api/users/route.ts b/apps/admin/src/app/api/users/route.ts
index ee57b71..832b00d 100644
--- a/apps/admin/src/app/api/users/route.ts
+++ b/apps/admin/src/app/api/users/route.ts
@@ -24,14 +24,42 @@ import {
   internalErrorResponse,
   badRequestResponse,
 } from "@/lib/api/responses";
+import { getUsersByGym } from "@/lib/gym-context";
+import { ensureUserSynced } from "@/lib/sync-user";
 
 export async function GET(request: NextRequest) {
   try {
+    // First authenticate the user
+    const { userId: clerkUserId } = await auth();
+    if (!clerkUserId) {
+      return unauthorizedResponse();
+    }
+
     const db = await getDatabase();
+    const currentUser = await ensureUserSynced(clerkUserId, db);
+
+    if (!currentUser) {
+      return forbiddenResponse("User not found");
+    }
+
     const { searchParams } = new URL(request.url);
     const role = searchParams.get("role");
 
-    let users = await db.getAllUsers();
+    // Get target gym based on role
+    const targetGymId =
+      currentUser.role === "superAdmin"
+        ? (searchParams.get("gymId") ?? undefined)
+        : (currentUser.gymId ?? undefined);
+
+    // Validate gym access for non-superAdmins
+    if (currentUser.role !== "superAdmin" && !targetGymId) {
+      return forbiddenResponse("No gym assigned");
+    }
+
+    // Get users filtered by gym
+    let users = targetGymId
+      ? await getUsersByGym(targetGymId)
+      : await db.getAllUsers();
 
     // Hydrate gymId from raw DB to ensure consistency with writes
     const rawUserRows = await rawDb.all(sql`SELECT id, gym_id FROM users`);
diff --git a/apps/admin/src/app/page.tsx b/apps/admin/src/app/page.tsx
index 76278eb..2a00a55 100644
--- a/apps/admin/src/app/page.tsx
+++ b/apps/admin/src/app/page.tsx
@@ -14,11 +14,26 @@ import { AnalyticsDashboard } from "@/components/analytics/AnalyticsDashboard";
 import { useDashboardStats } from "@/hooks/use-api";
 import { useQueryClient } from "@tanstack/react-query";
 import { Button } from "@/components/ui/button";
+import { useUser } from "@clerk/nextjs";
+import { useSearchParams } from "next/navigation";
+import { GymSelector } from "@/components/gym/GymSelector";
 
 export default function Home() {
-  const { data: stats, isLoading, refetch, isFetching } = useDashboardStats();
+  const { user } = useUser();
+  const searchParams = useSearchParams();
+  const gymId = searchParams.get("gymId") ?? undefined;
+
+  const {
+    data: stats,
+    isLoading,
+    refetch,
+    isFetching,
+  } = useDashboardStats(gymId);
   const queryClient = useQueryClient();
 
+  // Get user role from metadata
+  const userRole = (user?.publicMetadata?.role as string) ?? "client";
+
   const handleRefresh = () => {
     queryClient.invalidateQueries({ queryKey: ["dashboard-stats"] });
     queryClient.invalidateQueries({ queryKey: ["analytics"] });
@@ -40,18 +55,21 @@ export default function Home() {
         title="Dashboard"
         description="Welcome back! Here's what's happening with your gym today."
         actions={
-          <Button
-            variant="outline"
-            size="sm"
-            onClick={handleRefresh}
-            disabled={isFetching}
-            className="gap-2"
-          >
-            <RefreshCw
-              className={`h-4 w-4 ${isFetching ? "animate-spin" : ""}`}
-            />
-            Refresh
-          </Button>
+          <div className="flex items-center gap-3">
+            <GymSelector userRole={userRole} />
+            <Button
+              variant="outline"
+              size="sm"
+              onClick={handleRefresh}
+              disabled={isFetching}
+              className="gap-2"
+            >
+              <RefreshCw
+                className={`h-4 w-4 ${isFetching ? "animate-spin" : ""}`}
+              />
+              Refresh
+            </Button>
+          </div>
         }
       />
 
@@ -125,7 +143,7 @@ export default function Home() {
                 Overview of your gym metrics
               </p>
             </div>
-            <AnalyticsDashboard />
+            <AnalyticsDashboard gymId={gymId} />
           </div>
         </div>
       </div>
diff --git a/apps/admin/src/app/users/page.tsx b/apps/admin/src/app/users/page.tsx
index f631cb4..e5eed4a 100644
--- a/apps/admin/src/app/users/page.tsx
+++ b/apps/admin/src/app/users/page.tsx
@@ -1,17 +1,29 @@
+"use client";
+
 import { UserManagement } from "@/components/users/UserManagement";
 import { PageHeader } from "@/components/ui/PageHeader";
+import { useUser } from "@clerk/nextjs";
+import { useSearchParams } from "next/navigation";
+import { GymSelector } from "@/components/gym/GymSelector";
 
 export default function UsersPage() {
+  const { user } = useUser();
+  const searchParams = useSearchParams();
+
+  const userRole = (user?.publicMetadata?.role as string) ?? "client";
+  const gymId = searchParams.get("gymId") ?? undefined;
+
   return (
     <div className="space-y-8">
       <PageHeader
         title="Users"
         description="Manage your gym members, trainers, and administrators"
         breadcrumbs={[{ label: "Users", href: "/users" }]}
+        actions={<GymSelector userRole={userRole} />}
       />
 
       <div className="card-modern">
-        <UserManagement />
+        <UserManagement gymId={gymId} />
       </div>
     </div>
   );
diff --git a/apps/admin/src/components/analytics/AnalyticsDashboard.tsx b/apps/admin/src/components/analytics/AnalyticsDashboard.tsx
index 3b3ec94..e94f828 100644
--- a/apps/admin/src/components/analytics/AnalyticsDashboard.tsx
+++ b/apps/admin/src/components/analytics/AnalyticsDashboard.tsx
@@ -6,8 +6,12 @@ import { RevenueChart } from "@/components/charts/RevenueChart";
 import { Card, CardHeader, CardContent } from "@/components/ui/card";
 import { useAnalytics } from "@/hooks/use-api";
 
-export function AnalyticsDashboard() {
-  const { data: analytics, isLoading } = useAnalytics(6);
+interface AnalyticsDashboardProps {
+  gymId?: string;
+}
+
+export function AnalyticsDashboard({ gymId }: AnalyticsDashboardProps) {
+  const { data: analytics, isLoading } = useAnalytics(6, gymId);
 
   const userGrowthData = analytics?.userGrowth ?? [];
   const membershipData = analytics?.membershipDistribution ?? [];
diff --git a/apps/admin/src/components/gym/GymSelector.tsx b/apps/admin/src/components/gym/GymSelector.tsx
new file mode 100644
index 0000000..7907e79
--- /dev/null
+++ b/apps/admin/src/components/gym/GymSelector.tsx
@@ -0,0 +1,91 @@
+"use client";
+
+import { useRouter, useSearchParams } from "next/navigation";
+import { useEffect, useState } from "react";
+
+interface Gym {
+  id: string;
+  name: string;
+}
+
+interface GymSelectorProps {
+  currentGymId?: string;
+  userRole: string;
+}
+
+export function GymSelector({ userRole }: GymSelectorProps) {
+  const router = useRouter();
+  const searchParams = useSearchParams();
+  const [gyms, setGyms] = useState<Gym[]>([]);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    // Only fetch gyms for superAdmin
+    if (userRole !== "superAdmin") {
+      setLoading(false);
+      return;
+    }
+
+    async function fetchGyms() {
+      try {
+        const response = await fetch("/api/gyms");
+        const data = await response.json();
+
+        // API returns array directly
+        if (Array.isArray(data)) {
+          setGyms(data);
+        }
+      } catch (error) {
+        console.error("Failed to fetch gyms:", error);
+      } finally {
+        setLoading(false);
+      }
+    }
+
+    fetchGyms();
+  }, [userRole]);
+
+  const handleGymChange = (gymId: string) => {
+    const params = new URLSearchParams(searchParams.toString());
+
+    if (gymId === "all") {
+      params.delete("gymId");
+    } else {
+      params.set("gymId", gymId);
+    }
+
+    router.push(`?${params.toString()}`);
+  };
+
+  // Only show for superAdmin
+  if (userRole !== "superAdmin") {
+    return null;
+  }
+
+  const selectedGymId = searchParams.get("gymId") ?? "all";
+
+  if (loading) {
+    return (
+      <div className="flex items-center gap-2">
+        <div className="h-9 w-40 animate-pulse rounded-md bg-muted" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="flex items-center gap-2">
+      <select
+        value={selectedGymId}
+        onChange={(e) => handleGymChange(e.target.value)}
+        className="h-9 rounded-md border border-input bg-background px-3 py-1 text-sm shadow-sm transition-colors focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring"
+      >
+        <option value="all">All Gyms</option>
+        {gyms.map((gym) => (
+          <option key={gym.id} value={gym.id}>
+            {gym.name}
+          </option>
+        ))}
+      </select>
+    </div>
+  );
+}
diff --git a/apps/admin/src/components/users/UserManagement.tsx b/apps/admin/src/components/users/UserManagement.tsx
index 24a1fa4..a5ce0a7 100644
--- a/apps/admin/src/components/users/UserManagement.tsx
+++ b/apps/admin/src/components/users/UserManagement.tsx
@@ -16,7 +16,11 @@ import {
   useSendInvitation,
 } from "@/hooks/use-api";
 
-export function UserManagement() {
+interface UserManagementProps {
+  gymId?: string;
+}
+
+export function UserManagement({ gymId }: UserManagementProps) {
   const { user } = useUser();
   const [filter, setFilter] = useState<string>("all");
   const [selectedUser, setSelectedUser] = useState<User | null>(null);
@@ -38,6 +42,7 @@ export function UserManagement() {
     refetch,
   } = useUsers({
     role: filter !== "all" ? filter : undefined,
+    gymId,
   });
   const { data: gyms = [] } = useGyms();
   const updateUser = useUpdateUser();
diff --git a/apps/admin/src/hooks/use-api.ts b/apps/admin/src/hooks/use-api.ts
index 87be6d3..287eab0 100644
--- a/apps/admin/src/hooks/use-api.ts
+++ b/apps/admin/src/hooks/use-api.ts
@@ -370,12 +370,16 @@ export interface AnalyticsData {
   revenue: { label: string; value: number; color: string }[];
 }
 
-export function useAnalytics(months: number = 6) {
+export function useAnalytics(months: number = 6, gymId?: string) {
   return useQuery({
-    queryKey: ["analytics", months],
-    queryFn: () =>
-      fetchApi<{ data: { analytics: AnalyticsData } }>(
-        `/api/admin/analytics?months=${months}`,
-      ).then((res) => res.data?.analytics),
+    queryKey: ["analytics", months, gymId],
+    queryFn: () => {
+      const url = gymId
+        ? `/api/admin/analytics?months=${months}&gymId=${gymId}`
+        : `/api/admin/analytics?months=${months}`;
+      return fetchApi<{ data: { analytics: AnalyticsData } }>(url).then(
+        (res) => res.data?.analytics,
+      );
+    },
   });
 }
diff --git a/apps/admin/src/lib/auth/context.ts b/apps/admin/src/lib/auth/context.ts
new file mode 100644
index 0000000..50f1333
--- /dev/null
+++ b/apps/admin/src/lib/auth/context.ts
@@ -0,0 +1,231 @@
+import { NextRequest, NextResponse } from "next/server";
+import { auth } from "@clerk/nextjs/server";
+import { USER_ROLES, type UserRole } from "@fitai/shared";
+import { getDatabase } from "../database";
+
+export interface AuthContext {
+  userId: string;
+  role: UserRole;
+  gymId: string | null;
+}
+
+export interface AuthResult extends AuthContext {}
+
+/**
+ * Get the full authentication context including gymId
+ * Combines Clerk session claims with database lookup for accurate gym assignment
+ *
+ * @returns AuthContext with userId, role, and gymId
+ *
+ * @example
+ * const { userId, role, gymId } = await getAuthContext();
+ * // userId: "user_abc123"
+ * // role: "admin"
+ * // gymId: "gym_xyz"
+ */
+export async function getAuthContext(): Promise<AuthContext> {
+  const { userId, sessionClaims } = await auth();
+
+  if (!userId) {
+    throw new Error("Unauthorized: No authenticated user");
+  }
+
+  // Get role from Clerk metadata
+  const role = (sessionClaims?.metadata as { role?: UserRole })?.role;
+
+  if (!role || !USER_ROLES.includes(role)) {
+    throw new Error(`Forbidden: Invalid or missing role - ${role}`);
+  }
+
+  // Get gymId from Clerk metadata or database
+  let gymId: string | null = null;
+
+  // First try Clerk metadata (faster path)
+  const clerkGymId = (sessionClaims?.metadata as { gymId?: string })?.gymId;
+  if (clerkGymId) {
+    gymId = clerkGymId;
+  } else {
+    // Fallback to database lookup
+    try {
+      const db = await getDatabase();
+      const user = await db.getUserById(userId);
+      gymId = user?.gymId ?? null;
+    } catch (error) {
+      console.error("Failed to get gymId from database:", error);
+      gymId = null;
+    }
+  }
+
+  return { userId, role, gymId };
+}
+
+/**
+ * Middleware to require authentication and optionally check user role
+ * Enhanced version that also retrieves gymId
+ *
+ * @param allowedRoles - Array of roles allowed to access the endpoint (optional)
+ * @returns Authentication result with userId, role, and gymId, or NextResponse error
+ *
+ * @example
+ * export async function DELETE(request: NextRequest) {
+ *   const authResult = await requireAuth(["admin", "superAdmin"]);
+ *   if (authResult instanceof NextResponse) return authResult;
+ *   const { userId, role, gymId } = authResult;
+ *   // ... proceed with authorized logic
+ * }
+ */
+export async function requireAuth(
+  allowedRoles?: UserRole[],
+): Promise<AuthResult | NextResponse> {
+  try {
+    const context = await getAuthContext();
+
+    // Check if user has required role
+    if (allowedRoles && allowedRoles.length > 0) {
+      if (!allowedRoles.includes(context.role)) {
+        return NextResponse.json(
+          {
+            error: `Forbidden - Requires one of: ${allowedRoles.join(", ")}`,
+            requiredRoles: allowedRoles,
+            userRole: context.role,
+          },
+          { status: 403 },
+        );
+      }
+    }
+
+    return context;
+  } catch (error) {
+    const message = error instanceof Error ? error.message : "Unknown error";
+
+    if (message.includes("Unauthorized")) {
+      return NextResponse.json(
+        { error: "Unauthorized - Authentication required" },
+        { status: 401 },
+      );
+    }
+
+    if (message.includes("Forbidden")) {
+      return NextResponse.json({ error: message }, { status: 403 });
+    }
+
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
+  }
+}
+
+/**
+ * Require authentication with gym access validation
+ * Use this for endpoints that need to verify the user can access a specific gym
+ *
+ * @param allowedRoles - Roles allowed to access this endpoint
+ * @param requiredGymId - Gym ID that must be accessed (optional - uses user's gym if not provided)
+ * @returns AuthResult with full context, or NextResponse error
+ *
+ * @example
+ * // Admin accessing their own gym
+ * const result = await requireGymAccess(["admin"]);
+ *
+ * // SuperAdmin accessing specific gym
+ * const result = await requireGymAccess(["superAdmin"], "gym_123");
+ */
+export async function requireGymAccess(
+  allowedRoles: UserRole[],
+  requiredGymId?: string,
+): Promise<AuthResult | NextResponse> {
+  const authResult = await requireAuth(allowedRoles);
+
+  if (authResult instanceof NextResponse) {
+    return authResult;
+  }
+
+  const { role, gymId: userGymId } = authResult;
+
+  // Determine target gym
+  const targetGymId = requiredGymId ?? userGymId;
+
+  // SuperAdmin can access any gym
+  if (role === "superAdmin") {
+    return { ...authResult, gymId: targetGymId };
+  }
+
+  // Other roles must have matching gym
+  if (!targetGymId) {
+    return NextResponse.json(
+      { error: "Forbidden - User is not assigned to a gym" },
+      { status: 403 },
+    );
+  }
+
+  if (userGymId !== targetGymId) {
+    return NextResponse.json(
+      { error: "Forbidden - Cannot access other gym's data" },
+      { status: 403 },
+    );
+  }
+
+  return { ...authResult, gymId: targetGymId };
+}
+
+/**
+ * Get the target gym ID from request for superAdmin context switching
+ * SuperAdmins can pass ?gymId to view specific gym data
+ *
+ * @param request - NextRequest with query params
+ * @param userRole - Current user's role
+ * @param userGymId - Current user's gym ID
+ * @returns Target gym ID or undefined for superAdmin viewing all
+ *
+ * @example
+ * const targetGymId = getTargetGymId(request, role, gymId);
+ * // For superAdmin with ?gymId=abc -> "abc"
+ * // For superAdmin without param -> undefined (all gyms)
+ * // For admin -> always returns their gymId
+ */
+export function getTargetGymId(
+  request: NextRequest,
+  userRole: UserRole,
+  userGymId: string | null,
+): string | undefined {
+  // For superAdmin, allow gymId query param for context switching
+  if (userRole === "superAdmin") {
+    const queryGymId = request.nextUrl.searchParams.get("gymId");
+    return queryGymId ?? undefined;
+  }
+
+  // For other roles, they can only access their own gym
+  return userGymId ?? undefined;
+}
+
+/**
+ * Check if the authenticated user is trying to modify their own account
+ * Useful for preventing self-deletion or self-demotion
+ */
+export function isSelfModification(
+  userId: string,
+  targetUserId: string,
+): boolean {
+  return userId === targetUserId;
+}
+
+/**
+ * Validate that an admin isn't demoting themselves or deleting their own account
+ */
+export function preventSelfModification(
+  userId: string,
+  targetUserId: string,
+  action: string,
+): NextResponse | undefined {
+  if (isSelfModification(userId, targetUserId)) {
+    return NextResponse.json(
+      {
+        error: `Cannot ${action} your own account`,
+        hint: "Ask another administrator to perform this action",
+      },
+      { status: 403 },
+    );
+  }
+  return undefined;
+}
diff --git a/apps/admin/src/lib/auth/permissions.ts b/apps/admin/src/lib/auth/permissions.ts
new file mode 100644
index 0000000..907106d
--- /dev/null
+++ b/apps/admin/src/lib/auth/permissions.ts
@@ -0,0 +1,249 @@
+import type { UserRole } from "@fitai/shared";
+import { NextResponse } from "next/server";
+
+/**
+ * Check if a user can access data from a specific gym
+ *
+ * @param userRole - The role of the requesting user
+ * @param userGymId - The gym ID of the requesting user (null for superAdmin)
+ * @param targetGymId - The gym ID being accessed (undefined means all gyms)
+ * @returns true if access is allowed
+ *
+ * @example
+ * // SuperAdmin accessing any gym
+ * canAccessGym("superAdmin", null, "gym_123") // true
+ *
+ * // Admin accessing their own gym
+ * canAccessGym("admin", "gym_abc", "gym_abc") // true
+ *
+ * // Admin trying to access other gym
+ * canAccessGym("admin", "gym_abc", "gym_xyz") // false
+ */
+export function canAccessGym(
+  userRole: UserRole,
+  userGymId: string | null,
+  targetGymId: string | undefined,
+): boolean {
+  // SuperAdmin can access any gym
+  if (userRole === "superAdmin") {
+    return true;
+  }
+
+  // If no target gym specified, allow access to own gym
+  if (targetGymId === undefined) {
+    return true;
+  }
+
+  // Non-superAdmins must have a gymId
+  if (!userGymId) {
+    return false;
+  }
+
+  // Must match the gym
+  return userGymId === targetGymId;
+}
+
+/**
+ * Check if a user can manage (create/update/delete) another user
+ * Based on role hierarchy and gym membership
+ *
+ * @param requesterRole - Role of the user making the request
+ * @param requesterGymId - Gym ID of the requesting user
+ * @param targetRole - Role of the user being managed
+ * @param targetGymId - Gym ID of the user being managed
+ * @returns true if management is allowed
+ *
+ * @example
+ * // SuperAdmin can manage anyone
+ * canManageUser("superAdmin", null, "admin", "gym_abc") // true
+ *
+ * // Admin can manage trainers and clients in their gym
+ * canManageUser("admin", "gym_abc", "trainer", "gym_abc") // true
+ * canManageUser("admin", "gym_abc", "client", "gym_abc") // true
+ *
+ * // Admin cannot manage users in other gyms
+ * canManageUser("admin", "gym_abc", "trainer", "gym_xyz") // false
+ *
+ * // Trainer can manage clients in their gym
+ * canManageUser("trainer", "gym_abc", "client", "gym_abc") // true
+ */
+export function canManageUser(
+  requesterRole: UserRole,
+  requesterGymId: string | null,
+  targetRole: UserRole,
+  targetGymId: string | null,
+): boolean {
+  // SuperAdmin can manage anyone
+  if (requesterRole === "superAdmin") {
+    return true;
+  }
+
+  // Role hierarchy: admin > trainer > client
+  const roleHierarchy: Record<UserRole, number> = {
+    superAdmin: 4,
+    admin: 3,
+    trainer: 2,
+    client: 1,
+  };
+
+  const requesterLevel = roleHierarchy[requesterRole];
+  const targetLevel = roleHierarchy[targetRole];
+
+  // Cannot manage users at same or higher level
+  if (requesterLevel <= targetLevel) {
+    return false;
+  }
+
+  // Must have gym access
+  if (!requesterGymId) {
+    return false;
+  }
+
+  // For admin/trainer, target must be in same gym
+  if (requesterRole === "admin" || requesterRole === "trainer") {
+    return requesterGymId === targetGymId;
+  }
+
+  return false;
+}
+
+/**
+ * Check if a trainer can access a specific client's data
+ * Trainer must be assigned to that client via trainerClients table
+ *
+ * @param trainerGymId - Gym ID of the trainer
+ * @param clientGymId - Gym ID of the client
+ * @returns true if in same gym
+ *
+ * @note In a more complex system, this would query trainerClients table
+ * For now, we use gym-based access (trainer and client in same gym)
+ */
+export function canTrainerAccessClient(
+  trainerGymId: string | null,
+  clientGymId: string | null,
+): boolean {
+  if (!trainerGymId || !clientGymId) {
+    return false;
+  }
+  return trainerGymId === clientGymId;
+}
+
+/**
+ * Get the roles that a specific role can invite
+ * Based on role hierarchy
+ *
+ * @param role - The role wanting to invite
+ * @returns Array of roles that can be invited
+ *
+ * @example
+ * getInvitableRoles("superAdmin") // ["admin", "trainer", "client"]
+ * getInvitableRoles("admin")      // ["trainer", "client"]
+ * getInvitableRoles("trainer")    // ["client"]
+ * getInvitableRoles("client")     // []
+ */
+export function getInvitableRoles(role: UserRole): UserRole[] {
+  const invitationRules: Record<UserRole, UserRole[]> = {
+    superAdmin: ["admin", "trainer", "client"],
+    admin: ["trainer", "client"],
+    trainer: ["client"],
+    client: [],
+  };
+
+  return invitationRules[role] ?? [];
+}
+
+/**
+ * Validate gym access and return error response if denied
+ * Use this in API routes to enforce gym-based access control
+ *
+ * @param request - NextRequest for getting query params
+ * @param userRole - Current user's role
+ * @param userGymId - Current user's gym ID
+ * @param targetGymId - Gym being accessed (optional)
+ * @returns NextResponse if denied, undefined if allowed
+ *
+ * @example
+ * export async function GET(request: NextRequest) {
+ *   const error = await validateGymAccess(request, role, gymId);
+ *   if (error) return error;
+ *   // ... proceed
+ * }
+ */
+export function validateGymAccess(
+  userRole: UserRole,
+  userGymId: string | null,
+  targetGymId?: string,
+): NextResponse | undefined {
+  if (!canAccessGym(userRole, userGymId, targetGymId)) {
+    return NextResponse.json(
+      { error: "Forbidden - Cannot access this gym's data" },
+      { status: 403 },
+    );
+  }
+  return undefined;
+}
+
+/**
+ * Get filter condition for gym-scoped queries
+ * Returns appropriate filter based on user role
+ *
+ * @param userRole - Current user's role
+ * @param userGymId - Current user's gym ID
+ * @returns Filter object or undefined (no filter = all gyms)
+ *
+ * @example
+ * // For superAdmin: returns undefined (no filter)
+ * getGymFilter("superAdmin", null) // undefined
+ *
+ * // For admin: returns { gymId: "gym_abc" }
+ * getGymFilter("admin", "gym_abc") // { gymId: "gym_abc" }
+ */
+export function getGymFilter(
+  userRole: UserRole,
+  userGymId: string | null,
+): { gymId: string } | undefined {
+  // SuperAdmin sees all gyms
+  if (userRole === "superAdmin") {
+    return undefined;
+  }
+
+  // Other roles filtered by their gym
+  if (userGymId) {
+    return { gymId: userGymId };
+  }
+
+  // No gym assigned - return filter that matches nothing
+  return { gymId: "" };
+}
+
+/**
+ * Get all gym IDs a user can access
+ * SuperAdmin gets all gyms, others get only their own
+ *
+ * @param userRole - Current user's role
+ * @param userGymId - Current user's gym ID
+ * @param allGymIds - List of all gym IDs in system (for superAdmin)
+ * @returns Array of accessible gym IDs
+ *
+ * @example
+ * getAccessibleGymIds("admin", "gym_abc", ["gym_abc", "gym_xyz"])
+ * // Returns: ["gym_abc"]
+ *
+ * getAccessibleGymIds("superAdmin", null, ["gym_abc", "gym_xyz"])
+ * // Returns: ["gym_abc", "gym_xyz"]
+ */
+export function getAccessibleGymIds(
+  userRole: UserRole,
+  userGymId: string | null,
+  allGymIds: string[],
+): string[] {
+  if (userRole === "superAdmin") {
+    return allGymIds;
+  }
+
+  if (userGymId) {
+    return [userGymId];
+  }
+
+  return [];
+}
diff --git a/apps/admin/src/lib/gym-context.ts b/apps/admin/src/lib/gym-context.ts
new file mode 100644
index 0000000..049b733
--- /dev/null
+++ b/apps/admin/src/lib/gym-context.ts
@@ -0,0 +1,149 @@
+import { getDatabase } from "@/lib/database";
+
+/**
+ * Get users filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by (undefined returns all users for superAdmin)
+ * @returns Array of users in the gym
+ */
+export async function getUsersByGym(gymId?: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+
+  if (!gymId) {
+    return allUsers;
+  }
+
+  return allUsers.filter((u) => u.gymId === gymId);
+}
+
+/**
+ * Get clients filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by
+ * @returns Array of clients in the gym
+ */
+export async function getClientsByGym(gymId: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+  const allClients = await db.getAllClients();
+
+  const gymClientUserIds = allUsers
+    .filter((u) => u.gymId === gymId && u.role === "client")
+    .map((u) => u.id);
+
+  if (gymClientUserIds.length === 0) {
+    return [];
+  }
+
+  return allClients.filter((c) => gymClientUserIds.includes(c.userId));
+}
+
+/**
+ * Get trainers filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by
+ * @returns Array of trainers in the gym
+ */
+export async function getTrainersByGym(gymId: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+
+  return allUsers.filter((u) => u.gymId === gymId && u.role === "trainer");
+}
+
+/**
+ * Get attendance filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by
+ * @returns Array of attendance records in the gym
+ */
+export async function getAttendanceByGym(gymId: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+  const allAttendance = await db.getAllAttendance();
+
+  const gymUserIds = allUsers.filter((u) => u.gymId === gymId).map((u) => u.id);
+
+  if (gymUserIds.length === 0) {
+    return [];
+  }
+
+  return allAttendance.filter((a) => gymUserIds.includes(a.userId));
+}
+
+/**
+ * Get recommendations filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by
+ * @returns Array of recommendations in the gym
+ */
+export async function getRecommendationsByGym(gymId: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+  const allRecommendations = await db.getAllRecommendations();
+
+  const gymUserIds = allUsers.filter((u) => u.gymId === gymId).map((u) => u.id);
+
+  if (gymUserIds.length === 0) {
+    return [];
+  }
+
+  return allRecommendations.filter((r) => gymUserIds.includes(r.userId));
+}
+
+/**
+ * Get fitness profiles filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by
+ * @returns Array of fitness profiles in the gym
+ */
+export async function getFitnessProfilesByGym(gymId: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+  const allProfiles = await db.getAllFitnessProfiles();
+
+  const gymUserIds = allUsers.filter((u) => u.gymId === gymId).map((u) => u.id);
+
+  if (gymUserIds.length === 0) {
+    return [];
+  }
+
+  return allProfiles.filter((p) => gymUserIds.includes(p.userId));
+}
+
+/**
+ * Get fitness goals filtered by gym ID
+ *
+ * @param gymId - Gym ID to filter by
+ * @returns Array of fitness goals in the gym
+ */
+export async function getFitnessGoalsByGym(gymId: string) {
+  const db = await getDatabase();
+  const allUsers = await db.getAllUsers();
+
+  const gymUserIds = allUsers.filter((u) => u.gymId === gymId).map((u) => u.id);
+
+  if (gymUserIds.length === 0) {
+    return [];
+  }
+
+  const allGoals: any[] = [];
+  for (const userId of gymUserIds) {
+    const goals = await db.getFitnessGoalsByUserId(userId);
+    allGoals.push(...goals);
+  }
+
+  return allGoals.sort(
+    (a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime(),
+  );
+}
+
+/**
+ * Get user by ID and check if they belong to a specific gym
+ */
+export async function getUserGymId(userId: string): Promise<string | null> {
+  const db = await getDatabase();
+  const user = await db.getUserById(userId);
+  return user?.gymId ?? null;
+}
diff --git a/apps/admin/src/lib/migrations/fix-gym-assignments.js b/apps/admin/src/lib/migrations/fix-gym-assignments.js
new file mode 100644
index 0000000..8e466b4
--- /dev/null
+++ b/apps/admin/src/lib/migrations/fix-gym-assignments.js
@@ -0,0 +1,138 @@
+/**
+ * Migration Script: Fix gym assignments for users without gymId
+ *
+ * This script:
+ * 1. Finds all users with null gymId
+ * 2. For admins: Assigns them to gym where they are adminUserId
+ * 3. For trainers: Gets gymId from their trainerClients records
+ * 4. For clients: Gets gymId from trainerClients or leaves as null for manual review
+ *
+ * Run with: node apps/admin/src/lib/migrations/fix-gym-assignments.js
+ *
+ * Note: Run this AFTER setting up the database, before starting the app
+ */
+
+const Database = require("better-sqlite3");
+
+// Use absolute path to the database - this is where the app stores data
+const dbPath = "/home/echo/dev/prototype/apps/admin/data/fitai.db";
+
+function fixGymAssignments() {
+  console.log("Starting gym assignment migration...\n");
+  console.log(`Database path: ${dbPath}\n`);
+
+  const db = new Database(dbPath);
+
+  // Step 1: Find all users without gymId
+  const usersWithoutGym = db
+    .prepare(
+      `
+    SELECT id, email, role FROM users WHERE gym_id IS NULL
+  `,
+    )
+    .all();
+
+  console.log(`Found ${usersWithoutGym.length} users without gymId`);
+
+  let adminsFixed = 0;
+  let trainersFixed = 0;
+  let clientsFixed = 0;
+  const unableToFix = [];
+
+  for (const user of usersWithoutGym) {
+    try {
+      if (user.role === "admin") {
+        // Find gym where this user is admin
+        const gym = db
+          .prepare(
+            `
+          SELECT id, name FROM gyms WHERE admin_user_id = ?
+        `,
+          )
+          .get(user.id);
+
+        if (gym) {
+          db.prepare(
+            `
+            UPDATE users SET gym_id = ? WHERE id = ?
+          `,
+          ).run(gym.id, user.id);
+
+          console.log(`  ✓ Fixed admin ${user.email} -> gym ${gym.name}`);
+          adminsFixed++;
+        } else {
+          unableToFix.push(`Admin ${user.email} (no gym found)`);
+        }
+      } else if (user.role === "trainer") {
+        // Get gym from trainerClients
+        const tc = db
+          .prepare(
+            `
+          SELECT gym_id FROM trainer_clients WHERE trainer_user_id = ? LIMIT 1
+        `,
+          )
+          .get(user.id);
+
+        if (tc) {
+          db.prepare(
+            `
+            UPDATE users SET gym_id = ? WHERE id = ?
+          `,
+          ).run(tc.gym_id, user.id);
+
+          console.log(`  ✓ Fixed trainer ${user.email} -> gym ${tc.gym_id}`);
+          trainersFixed++;
+        } else {
+          unableToFix.push(`Trainer ${user.email} (no trainerClients record)`);
+        }
+      } else if (user.role === "client") {
+        // Get gym from trainerClients
+        const tc = db
+          .prepare(
+            `
+          SELECT gym_id FROM trainer_clients WHERE client_user_id = ? LIMIT 1
+        `,
+          )
+          .get(user.id);
+
+        if (tc) {
+          db.prepare(
+            `
+            UPDATE users SET gym_id = ? WHERE id = ?
+          `,
+          ).run(tc.gym_id, user.id);
+
+          console.log(`  ✓ Fixed client ${user.email} -> gym ${tc.gym_id}`);
+          clientsFixed++;
+        } else {
+          unableToFix.push(`Client ${user.email} (no trainer assignment)`);
+        }
+      }
+    } catch (error) {
+      console.error(`  ✗ Error fixing user ${user.email}:`, error.message);
+      unableToFix.push(`User ${user.email} (error: ${error.message})`);
+    }
+  }
+
+  db.close();
+
+  console.log("\n=== Migration Summary ===");
+  console.log(`Admins fixed: ${adminsFixed}`);
+  console.log(`Trainers fixed: ${trainersFixed}`);
+  console.log(`Clients fixed: ${clientsFixed}`);
+  console.log(`Unable to fix: ${unableToFix.length}`);
+
+  if (unableToFix.length > 0) {
+    console.log("\nUsers requiring manual review:");
+    unableToFix.forEach((u) => console.log(`  - ${u}`));
+  }
+
+  console.log("\nMigration complete!");
+}
+
+// Run if called directly
+if (require.main === module) {
+  fixGymAssignments();
+}
+
+module.exports = { fixGymAssignments };
diff --git a/data/fitai.db b/data/fitai.db
new file mode 100644
index 0000000..e69de29