fix: update user fields to match schema

- Replace firstName/lastName with name field in users API route
- Update user formatting in UsersTab component
- Add email fallback when name is not available

package.json

@@ -3,7 +3,7 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "next dev",
+    "dev": "next dev --turbopack",
     "build": "next build",
     "start": "next start",
     "lint": "next lint",
@@ -18,10 +18,12 @@
   "dependencies": {
     "@clerk/nextjs": "^6.4.0",
     "@radix-ui/react-alert-dialog": "^1.1.2",
+    "@radix-ui/react-avatar": "^1.1.1",
     "@radix-ui/react-dialog": "^1.1.2",
     "@radix-ui/react-icons": "^1.3.2",
     "@radix-ui/react-label": "^2.1.0",
     "@radix-ui/react-select": "^2.1.2",
+    "@radix-ui/react-separator": "^1.1.0",
     "@radix-ui/react-slot": "^1.1.0",
     "@radix-ui/react-tabs": "^1.1.1",
     "@types/nodemailer": "^6.4.17",

pnpm-lock.yaml

@@ -14,6 +14,9 @@ importers:
       '@radix-ui/react-alert-dialog':
         specifier: ^1.1.2
         version: 1.1.2(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      '@radix-ui/react-avatar':
+        specifier: ^1.1.1
+        version: 1.1.1(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
       '@radix-ui/react-dialog':
         specifier: ^1.1.2
         version: 1.1.2(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
@@ -26,6 +29,9 @@ importers:
       '@radix-ui/react-select':
         specifier: ^2.1.2
         version: 2.1.2(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      '@radix-ui/react-separator':
+        specifier: ^1.1.0
+        version: 1.1.0(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
       '@radix-ui/react-slot':
         specifier: ^1.1.0
         version: 1.1.0(@types/react@18.3.12)(react@18.3.1)
@@ -889,6 +895,19 @@ packages:
       '@types/react-dom':
         optional: true
 
+  '@radix-ui/react-avatar@1.1.1':
+    resolution: {integrity: sha512-eoOtThOmxeoizxpX6RiEsQZ2wj5r4+zoeqAwO0cBaFQGjJwIH3dIX0OCxNrCyrrdxG+vBweMETh3VziQG7c1kw==}
+    peerDependencies:
+      '@types/react': '*'
+      '@types/react-dom': '*'
+      react: ^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc
+      react-dom: ^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc
+    peerDependenciesMeta:
+      '@types/react':
+        optional: true
+      '@types/react-dom':
+        optional: true
+
   '@radix-ui/react-collection@1.1.0':
     resolution: {integrity: sha512-GZsZslMJEyo1VKm5L1ZJY8tGDxZNPAoUeQUIbKeJfoi7Q4kmig5AsgLMYYuyYbfjd8fBmFORAIwYAkXMnXZgZw==}
     peerDependencies:
@@ -1091,6 +1110,19 @@ packages:
       '@types/react-dom':
         optional: true
 
+  '@radix-ui/react-separator@1.1.0':
+    resolution: {integrity: sha512-3uBAs+egzvJBDZAzvb/n4NxxOYpnspmWxO2u5NbZ8Y6FM/NdrGSF9bop3Cf6F6C71z1rTSn8KV0Fo2ZVd79lGA==}
+    peerDependencies:
+      '@types/react': '*'
+      '@types/react-dom': '*'
+      react: ^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc
+      react-dom: ^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc
+    peerDependenciesMeta:
+      '@types/react':
+        optional: true
+      '@types/react-dom':
+        optional: true
+
   '@radix-ui/react-slot@1.1.0':
     resolution: {integrity: sha512-FUCf5XMfmW4dtYl69pdS4DbxKy8nj4M7SafBgPllysxmdachynNflAdp/gCsnYWNDnge6tI9onzMp5ARYc1KNw==}
     peerDependencies:
@@ -3610,6 +3642,18 @@ snapshots:
       '@types/react': 18.3.12
       '@types/react-dom': 18.3.1
 
+  '@radix-ui/react-avatar@1.1.1(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)':
+    dependencies:
+      '@radix-ui/react-context': 1.1.1(@types/react@18.3.12)(react@18.3.1)
+      '@radix-ui/react-primitive': 2.0.0(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      '@radix-ui/react-use-callback-ref': 1.1.0(@types/react@18.3.12)(react@18.3.1)
+      '@radix-ui/react-use-layout-effect': 1.1.0(@types/react@18.3.12)(react@18.3.1)
+      react: 18.3.1
+      react-dom: 18.3.1(react@18.3.1)
+    optionalDependencies:
+      '@types/react': 18.3.12
+      '@types/react-dom': 18.3.1
+
   '@radix-ui/react-collection@1.1.0(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)':
     dependencies:
       '@radix-ui/react-compose-refs': 1.1.0(@types/react@18.3.12)(react@18.3.1)
@@ -3811,6 +3855,15 @@ snapshots:
       '@types/react': 18.3.12
       '@types/react-dom': 18.3.1
 
+  '@radix-ui/react-separator@1.1.0(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)':
+    dependencies:
+      '@radix-ui/react-primitive': 2.0.0(@types/react-dom@18.3.1)(@types/react@18.3.12)(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      react: 18.3.1
+      react-dom: 18.3.1(react@18.3.1)
+    optionalDependencies:
+      '@types/react': 18.3.12
+      '@types/react-dom': 18.3.1
+
   '@radix-ui/react-slot@1.1.0(@types/react@18.3.12)(react@18.3.1)':
     dependencies:
       '@radix-ui/react-compose-refs': 1.1.0(@types/react@18.3.12)(react@18.3.1)

src/app/api/studies/[id]/participants/route.ts

@@ -7,16 +7,17 @@ import { auth } from "@clerk/nextjs/server";
 
 export async function GET(
   request: Request,
-  { params }: { params: { id: string } }
+  context: { params: { id: string } }
 ) {
   const { userId } = await auth();
+  const { id } = await context.params;
   
   if (!userId) {
     return ApiError.Unauthorized();
   }
 
   try {
-    const studyId = parseInt(params.id);
+    const studyId = parseInt(id);
 
     if (isNaN(studyId)) {
       return ApiError.BadRequest("Invalid study ID");
@@ -27,15 +28,19 @@ export async function GET(
       permission: PERMISSIONS.VIEW_PARTICIPANT_NAMES,
     });
 
-    if (permissionCheck.error) {
-      return permissionCheck.error;
-    }
-
     const participants = await db
       .select()
       .from(participantsTable)
       .where(eq(participantsTable.studyId, studyId));
 
+    if (permissionCheck.error) {
+      const anonymizedParticipants = participants.map((participant, index) => ({
+        ...participant,
+        name: `Participant ${String.fromCharCode(65 + index)}`,
+      }));
+      return createApiResponse(anonymizedParticipants);
+    }
+
     return createApiResponse(participants);
   } catch (error) {
     return ApiError.ServerError(error);
@@ -44,16 +49,17 @@ export async function GET(
 
 export async function POST(
   request: Request,
-  { params }: { params: { id: string } }
+  context: { params: { id: string } }
 ) {
   const { userId } = await auth();
+  const { id } = await context.params;
   
   if (!userId) {
     return ApiError.Unauthorized();
   }
 
   try {
-    const studyId = parseInt(params.id);
+    const studyId = parseInt(id);
     const { name } = await request.json();
 
     if (isNaN(studyId)) {
@@ -89,16 +95,17 @@ export async function POST(
 
 export async function DELETE(
   request: Request,
-  { params }: { params: { id: string } }
+  context: { params: { id: string } }
 ) {
   const { userId } = await auth();
+  const { id } = await context.params;
   
   if (!userId) {
     return ApiError.Unauthorized();
   }
 
   try {
-    const studyId = parseInt(params.id);
+    const studyId = parseInt(id);
     const { participantId } = await request.json();
 
     if (isNaN(studyId)) {

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

@@ -6,7 +6,7 @@ import { ApiError, createApiResponse } from "~/lib/api-utils";
 
 export async function GET(request: Request, { params }: { params: { id: string } }) {
   try {
-    const { id } = params;
+    const id = await Promise.resolve(params.id);
     const studyId = parseInt(id);
 
     if (isNaN(studyId)) {

src/app/api/studies/[id]/stats/route.ts

@@ -0,0 +1,55 @@
+import { eq } from "drizzle-orm";
+import { sql } from "drizzle-orm";
+import { db } from "~/db";
+import { participantsTable } from "~/db/schema";
+import { PERMISSIONS, checkPermissions } from "~/lib/permissions-server";
+import { ApiError, createApiResponse } from "~/lib/api-utils";
+import { auth } from "@clerk/nextjs/server";
+
+export async function GET(
+  request: Request,
+  context: { params: { id: string } }
+) {
+  const { userId } = await auth();
+  const { id } = context.params;
+  
+  if (!userId) {
+    return ApiError.Unauthorized();
+  }
+
+  try {
+    const studyId = parseInt(id);
+
+    if (isNaN(studyId)) {
+      return ApiError.BadRequest("Invalid study ID");
+    }
+
+    const permissionCheck = await checkPermissions({
+      studyId,
+      permission: PERMISSIONS.VIEW_STUDY,
+    });
+
+    if (permissionCheck.error) {
+      return permissionCheck.error;
+    }
+
+    // Get participant count using SQL count
+    const [{ count }] = await db
+      .select({
+        count: sql<number>`count(*)::int`,
+      })
+      .from(participantsTable)
+      .where(eq(participantsTable.studyId, studyId));
+
+    // TODO: Add actual trial and form counts when those tables are added
+    const stats = {
+      participantCount: count,
+      completedTrialsCount: 0,
+      pendingFormsCount: 0,
+    };
+
+    return createApiResponse(stats);
+  } catch (error) {
+    return ApiError.ServerError(error);
+  }
+} 

src/app/api/studies/[id]/users/[userId]/role/route.ts

@@ -0,0 +1,60 @@
+import { eq, and } from "drizzle-orm";
+import { db } from "~/db";
+import { userRolesTable } from "~/db/schema";
+import { PERMISSIONS, checkPermissions } from "~/lib/permissions-server";
+import { ApiError, createApiResponse } from "~/lib/api-utils";
+
+export async function PUT(
+  request: Request,
+  context: { params: { id: string; userId: string } }
+) {
+  try {
+    const { id, userId } = await context.params;
+    const studyId = parseInt(id);
+
+    if (isNaN(studyId)) {
+      return ApiError.BadRequest("Invalid study ID");
+    }
+
+    const permissionCheck = await checkPermissions({
+      studyId,
+      permission: PERMISSIONS.MANAGE_ROLES
+    });
+
+    if (permissionCheck.error) {
+      return permissionCheck.error;
+    }
+
+    const { roleId } = await request.json();
+
+    if (!roleId || typeof roleId !== "number") {
+      return ApiError.BadRequest("Role ID is required");
+    }
+
+    // Update user's role in the study
+    await db.transaction(async (tx) => {
+      // Delete existing roles
+      await tx
+        .delete(userRolesTable)
+        .where(
+          and(
+            eq(userRolesTable.userId, userId),
+            eq(userRolesTable.studyId, studyId)
+          )
+        );
+
+      // Assign new role
+      await tx
+        .insert(userRolesTable)
+        .values({
+          userId,
+          roleId,
+          studyId,
+        });
+    });
+
+    return createApiResponse({ message: "Role updated successfully" });
+  } catch (error) {
+    return ApiError.ServerError(error);
+  }
+} 

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

@@ -0,0 +1,73 @@
+import { eq, and } from "drizzle-orm";
+import { db } from "~/db";
+import { userRolesTable, usersTable, rolesTable } from "~/db/schema";
+import { PERMISSIONS, checkPermissions } from "~/lib/permissions-server";
+import { ApiError, createApiResponse } from "~/lib/api-utils";
+
+export async function GET(
+  request: Request,
+  context: { params: { id: string } }
+) {
+  try {
+    const { id } = await context.params;
+    const studyId = parseInt(id);
+
+    if (isNaN(studyId)) {
+      return ApiError.BadRequest("Invalid study ID");
+    }
+
+    const permissionCheck = await checkPermissions({
+      studyId,
+      permission: PERMISSIONS.VIEW_STUDY
+    });
+
+    if (permissionCheck.error) {
+      return permissionCheck.error;
+    }
+
+    // Get all users in the study with their roles
+    const studyUsers = await db
+      .select({
+        id: usersTable.id,
+        email: usersTable.email,
+        name: usersTable.name,
+        roleId: rolesTable.id,
+        roleName: rolesTable.name,
+      })
+      .from(userRolesTable)
+      .innerJoin(usersTable, eq(usersTable.id, userRolesTable.userId))
+      .innerJoin(rolesTable, eq(rolesTable.id, userRolesTable.roleId))
+      .where(eq(userRolesTable.studyId, studyId));
+
+    // Group roles by user
+    const users = studyUsers.reduce((acc, curr) => {
+      const existingUser = acc.find(u => u.id === curr.id);
+      if (!existingUser) {
+        acc.push({
+          id: curr.id,
+          email: curr.email,
+          name: curr.name,
+          roles: [{
+            id: curr.roleId,
+            name: curr.roleName,
+          }]
+        });
+      } else if (curr.roleName && !existingUser.roles.some(r => r.id === curr.roleId)) {
+        existingUser.roles.push({
+          id: curr.roleId,
+          name: curr.roleName,
+        });
+      }
+      return acc;
+    }, [] as Array<{
+      id: string;
+      email: string;
+      name: string | null;
+      roles: Array<{ id: number; name: string }>;
+    }>);
+
+    return createApiResponse(users);
+  } catch (error) {
+    return ApiError.ServerError(error);
+  }
+} 

src/app/dashboard/layout.tsx

@@ -1,6 +1,7 @@
 import { Sidebar } from "~/components/sidebar";
 import { cn } from "~/lib/utils";
 import { StudyProvider } from "~/context/StudyContext";
+import { ActiveStudyProvider } from "~/context/active-study";
 
 export default function DashboardLayout({
   children,
@@ -8,17 +9,19 @@ export default function DashboardLayout({
   children: React.ReactNode
 }) {
   return (
-    <StudyProvider>
+    <ActiveStudyProvider>
-      <div className="flex h-screen overflow-hidden">
+      <StudyProvider>
-        <Sidebar />
+        <div className="flex h-screen overflow-hidden">
-        <main className={cn(
+          <Sidebar />
-          "flex-1 overflow-y-auto",
+          <main className={cn(
-          "lg:pt-8 p-8",
+            "flex-1 overflow-y-auto",
-          "pt-[calc(3.5rem+2rem)]"
+            "lg:pt-8 p-8",
-        )}>
+            "pt-[calc(3.5rem+2rem)]"
-          {children}
+          )}>
-        </main>
+            {children}
-      </div>
+          </main>
-    </StudyProvider>
+        </div>
+      </StudyProvider>
+    </ActiveStudyProvider>
   );
 }

src/app/dashboard/page.tsx

@@ -4,19 +4,18 @@ import { useEffect, useState } from "react";
 import { useRouter } from "next/navigation";
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
 import { Button } from "~/components/ui/button";
-import { Users, BookOpen, Settings2 } from "lucide-react";
+import { BookOpen, Settings2 } from "lucide-react";
 import { useToast } from "~/hooks/use-toast";
+import { Breadcrumb } from "~/components/breadcrumb";
 
 interface DashboardStats {
   studyCount: number;
-  participantCount: number;
   activeInvitationCount: number;
 }
 
 export default function Dashboard() {
   const [stats, setStats] = useState<DashboardStats>({
     studyCount: 0,
-    participantCount: 0,
     activeInvitationCount: 0,
   });
   const [loading, setLoading] = useState(true);
@@ -34,8 +33,7 @@ export default function Dashboard() {
       
       // For now, just show study count
       setStats({
-        studyCount: studies.length,
+        studyCount: studies.data.length,
-        participantCount: 0,
         activeInvitationCount: 0,
       });
     } catch (error) {
@@ -59,35 +57,26 @@ export default function Dashboard() {
   }
 
   return (
-    <div className="container py-6 space-y-6">
+    <div className="space-y-6">
+      <Breadcrumb />
+      
       <div>
         <h1 className="text-2xl font-bold">Dashboard</h1>
         <p className="text-muted-foreground">Overview of your research studies</p>
       </div>
 
-      <div className="grid gap-4 md:grid-cols-3">
+      <div className="grid gap-4 md:grid-cols-2">
         <Card>
           <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
             <CardTitle className="text-sm font-medium">Total Studies</CardTitle>
             <BookOpen className="h-4 w-4 text-muted-foreground" />
           </CardHeader>
           <CardContent>
-            <div className="text-2xl font-bold">{stats.studyCount ? stats.studyCount : 0}</div>
+            <div className="text-2xl font-bold">{stats.studyCount}</div>
             <p className="text-xs text-muted-foreground">Active research studies</p>
           </CardContent>
         </Card>
 
-        <Card>
-          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
-            <CardTitle className="text-sm font-medium">Total Participants</CardTitle>
-            <Users className="h-4 w-4 text-muted-foreground" />
-          </CardHeader>
-          <CardContent>
-            <div className="text-2xl font-bold">{stats.participantCount}</div>
-            <p className="text-xs text-muted-foreground">Across all studies</p>
-          </CardContent>
-        </Card>
-
         <Card>
           <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
             <CardTitle className="text-sm font-medium">Pending Invitations</CardTitle>
@@ -115,14 +104,6 @@ export default function Dashboard() {
               <BookOpen className="mr-2 h-4 w-4" />
               Manage Studies
             </Button>
-            <Button
-              variant="outline"
-              className="w-full justify-start"
-              onClick={() => router.push('/dashboard/participants')}
-            >
-              <Users className="mr-2 h-4 w-4" />
-              Manage Participants
-            </Button>
           </CardContent>
         </Card>
 
@@ -139,7 +120,7 @@ export default function Dashboard() {
               • Invite collaborators using study settings
             </p>
             <p className="text-sm text-muted-foreground">
-              • Add participants to begin collecting data
+              • Configure study parameters and forms
             </p>
           </CardContent>
         </Card>

src/app/dashboard/participants/page.tsx

@@ -0,0 +1,238 @@
+'use client';
+
+import { PlusIcon, Trash2Icon } from "lucide-react";
+import { useEffect, useState } from "react";
+import { Button } from "~/components/ui/button";
+import { 
+  Card, 
+  CardContent, 
+  CardHeader, 
+  CardTitle, 
+  CardDescription,
+  CardFooter 
+} from "~/components/ui/card";
+import { Input } from "~/components/ui/input";
+import { Label } from "~/components/ui/label";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue
+} from "~/components/ui/select";
+import { usePermissions } from "~/hooks/usePermissions";
+
+interface Study {
+  id: number;
+  title: string;
+}
+
+interface Participant {
+  id: number;
+  name: string;
+  studyId: number;
+}
+
+export default function Participants() {
+  const [studies, setStudies] = useState<Study[]>([]);
+  const [participants, setParticipants] = useState<Participant[]>([]);
+  const [selectedStudyId, setSelectedStudyId] = useState<number | null>(null);
+  const [participantName, setParticipantName] = useState("");
+  const [loading, setLoading] = useState(true);
+  const { hasPermission } = usePermissions();
+
+  useEffect(() => {
+    fetchStudies();
+  }, []);
+
+  const fetchStudies = async () => {
+    try {
+      const response = await fetch('/api/studies');
+      const data = await response.json();
+      setStudies(data);
+    } catch (error) {
+      console.error('Error fetching studies:', error);
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  const fetchParticipants = async (studyId: number) => {
+    try {
+      console.log(`Fetching participants for studyId: ${studyId}`);
+      const response = await fetch(`/api/participants?studyId=${studyId}`);
+      
+      if (!response.ok) {
+        throw new Error(`HTTP error! status: ${response.status}`);
+      }
+
+      const data = await response.json();
+      setParticipants(data);
+    } catch (error) {
+      console.error('Error fetching participants:', error);
+    }
+  };
+
+  const handleStudyChange = (studyId: string) => {
+    const id = parseInt(studyId); // Convert the string to a number
+    setSelectedStudyId(id);
+    fetchParticipants(id);
+  };
+
+  const addParticipant = async (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!selectedStudyId) return;
+
+    try {
+      const response = await fetch(`/api/participants`, {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify({
+          name: participantName,
+          studyId: selectedStudyId,
+        }),
+      });
+
+      if (response.ok) {
+        const newParticipant = await response.json();
+        setParticipants([...participants, newParticipant]);
+        setParticipantName("");
+      } else {
+        console.error('Error adding participant:', response.statusText);
+      }
+    } catch (error) {
+      console.error('Error adding participant:', error);
+    }
+  };
+
+  const deleteParticipant = async (id: number) => {
+    try {
+      const response = await fetch(`/api/participants/${id}`, {
+        method: 'DELETE',
+      });
+
+      if (response.ok) {
+        setParticipants(participants.filter(participant => participant.id !== id));
+      } else {
+        console.error('Error deleting participant:', response.statusText);
+      }
+    } catch (error) {
+      console.error('Error deleting participant:', error);
+    }
+  };
+
+  if (loading) {
+    return <div>Loading...</div>;
+  }
+
+  return (
+    <div className="max-w-4xl mx-auto">
+      <div className="flex justify-between items-center mb-8">
+        <h1 className="text-3xl font-bold">Participants</h1>
+      </div>
+
+      <Card className="mb-8">
+        <CardHeader>
+          <CardTitle>Study Selection</CardTitle>
+          <CardDescription>
+            Select a study to manage its participants
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <div className="space-y-2">
+            <Label htmlFor="study">Select Study</Label>
+            <Select onValueChange={handleStudyChange}>
+              <SelectTrigger>
+                <SelectValue placeholder="Select a study" />
+              </SelectTrigger>
+              <SelectContent>
+                {studies.map((study) => (
+                  <SelectItem key={study.id} value={study.id.toString()}>
+                    {study.title}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+        </CardContent>
+      </Card>
+
+      <Card className="mb-8">
+        <CardHeader>
+          <CardTitle>Add New Participant</CardTitle>
+          <CardDescription>
+            Add a new participant to the selected study
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <form onSubmit={addParticipant} className="space-y-4">
+            <div className="space-y-2">
+              <Label htmlFor="name">Participant Name</Label>
+              <Input
+                type="text"
+                id="name"
+                value={participantName}
+                onChange={(e) => setParticipantName(e.target.value)}
+                required
+              />
+            </div>
+            <Button type="submit" disabled={!selectedStudyId}>
+              <PlusIcon className="w-4 h-4 mr-2" />
+              Add Participant
+            </Button>
+          </form>
+        </CardContent>
+      </Card>
+
+      <div className="grid gap-4">
+        {participants.map((participant) => (
+          <Card key={participant.id}>
+            <CardHeader>
+              <div className="flex justify-between items-start">
+                <div>
+                  <CardTitle>{participant.name}</CardTitle>
+                  <CardDescription className="mt-1.5">
+                    Participant ID: {participant.id}
+                  </CardDescription>
+                </div>
+                {hasPermission('DELETE_PARTICIPANT') && (
+                  <Button 
+                    variant="ghost" 
+                    size="icon"
+                    className="text-destructive"
+                    onClick={() => deleteParticipant(participant.id)}
+                  >
+                    <Trash2Icon className="w-4 h-4" />
+                  </Button>
+                )}
+              </div>
+            </CardHeader>
+            <CardFooter className="text-sm text-muted-foreground">
+              Study ID: {participant.studyId}
+            </CardFooter>
+          </Card>
+        ))}
+        {participants.length === 0 && selectedStudyId && (
+          <Card>
+            <CardContent className="py-8">
+              <p className="text-center text-muted-foreground">
+                No participants found for this study. Add one above to get started.
+              </p>
+            </CardContent>
+          </Card>
+        )}
+        {!selectedStudyId && (
+          <Card>
+            <CardContent className="py-8">
+              <p className="text-center text-muted-foreground">
+                Please select a study to view its participants.
+              </p>
+            </CardContent>
+          </Card>
+        )}
+      </div>
+    </div>
+  );
+}

src/app/dashboard/studies/[id]/layout.tsx

@@ -0,0 +1,43 @@
+'use client';
+
+import { useParams } from "next/navigation";
+import { useEffect } from "react";
+import { useActiveStudy } from "~/context/active-study";
+import { Breadcrumb } from "~/components/breadcrumb";
+import { Skeleton } from "~/components/ui/skeleton";
+
+export default function StudyLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  const { id } = useParams();
+  const { studies, activeStudy, setActiveStudy, isLoading } = useActiveStudy();
+
+  useEffect(() => {
+    if (studies.length > 0 && id) {
+      const study = studies.find(s => s.id === parseInt(id as string));
+      if (study && (!activeStudy || activeStudy.id !== study.id)) {
+        setActiveStudy(study);
+      }
+    }
+  }, [id, studies, activeStudy, setActiveStudy]);
+
+  if (isLoading) {
+    return (
+      <div className="space-y-6">
+        <div className="h-6">
+          <Skeleton className="h-4 w-[250px]" />
+        </div>
+        <Skeleton className="h-[400px]" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-6">
+      <Breadcrumb />
+      {children}
+    </div>
+  );
+} 

src/app/dashboard/studies/[id]/page.tsx

@@ -0,0 +1,172 @@
+'use client';
+
+import { useEffect, useState } from "react";
+import { useParams } from "next/navigation";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
+import { Button } from "~/components/ui/button";
+import { 
+  Users, 
+  FileText, 
+  BarChart, 
+  PlayCircle,
+  Plus,
+  Settings2
+} from "lucide-react";
+import { useToast } from "~/hooks/use-toast";
+import Link from "next/link";
+
+interface StudyStats {
+  participantCount: number;
+  completedTrialsCount: number;
+  pendingFormsCount: number;
+}
+
+export default function StudyDashboard() {
+  const [stats, setStats] = useState<StudyStats>({
+    participantCount: 0,
+    completedTrialsCount: 0,
+    pendingFormsCount: 0,
+  });
+  const [loading, setLoading] = useState(true);
+  const { id } = useParams();
+  const { toast } = useToast();
+
+  useEffect(() => {
+    fetchStudyStats();
+  }, [id]);
+
+  const fetchStudyStats = async () => {
+    try {
+      const response = await fetch(`/api/studies/${id}/stats`);
+      if (!response.ok) throw new Error("Failed to fetch study statistics");
+      const data = await response.json();
+      setStats(data.data);
+    } catch (error) {
+      console.error("Error fetching study stats:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load study statistics",
+        variant: "destructive",
+      });
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  if (loading) {
+    return (
+      <div className="flex items-center justify-center min-h-[400px]">
+        <div className="animate-spin h-8 w-8 border-4 border-primary border-t-transparent rounded-full" />
+      </div>
+    );
+  }
+
+  return (
+    <div className="space-y-6">
+      <div className="grid gap-4 md:grid-cols-3">
+        <Card>
+          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
+            <CardTitle className="text-sm font-medium">Participants</CardTitle>
+            <Users className="h-4 w-4 text-muted-foreground" />
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">{stats.participantCount}</div>
+            <p className="text-xs text-muted-foreground">Total participants enrolled</p>
+          </CardContent>
+        </Card>
+
+        <Card>
+          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
+            <CardTitle className="text-sm font-medium">Completed Trials</CardTitle>
+            <PlayCircle className="h-4 w-4 text-muted-foreground" />
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">{stats.completedTrialsCount}</div>
+            <p className="text-xs text-muted-foreground">Successfully completed trials</p>
+          </CardContent>
+        </Card>
+
+        <Card>
+          <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
+            <CardTitle className="text-sm font-medium">Pending Forms</CardTitle>
+            <FileText className="h-4 w-4 text-muted-foreground" />
+          </CardHeader>
+          <CardContent>
+            <div className="text-2xl font-bold">{stats.pendingFormsCount}</div>
+            <p className="text-xs text-muted-foreground">Forms awaiting completion</p>
+          </CardContent>
+        </Card>
+      </div>
+
+      <div className="grid gap-4 md:grid-cols-2">
+        <Card>
+          <CardHeader>
+            <CardTitle>Quick Actions</CardTitle>
+            <CardDescription>Common tasks for this study</CardDescription>
+          </CardHeader>
+          <CardContent className="space-y-2">
+            <Button
+              variant="outline"
+              className="w-full justify-start"
+              asChild
+            >
+              <Link href={`/dashboard/studies/${id}/participants/new`}>
+                <Plus className="mr-2 h-4 w-4" />
+                Add Participant
+              </Link>
+            </Button>
+            <Button
+              variant="outline"
+              className="w-full justify-start"
+              asChild
+            >
+              <Link href={`/dashboard/studies/${id}/trials/new`}>
+                <PlayCircle className="mr-2 h-4 w-4" />
+                Start New Trial
+              </Link>
+            </Button>
+            <Button
+              variant="outline"
+              className="w-full justify-start"
+              asChild
+            >
+              <Link href={`/dashboard/studies/${id}/forms/new`}>
+                <FileText className="mr-2 h-4 w-4" />
+                Create Form
+              </Link>
+            </Button>
+          </CardContent>
+        </Card>
+
+        <Card>
+          <CardHeader>
+            <CardTitle>Recent Activity</CardTitle>
+            <CardDescription>Latest updates and changes</CardDescription>
+          </CardHeader>
+          <CardContent className="space-y-2">
+            <Button
+              variant="outline"
+              className="w-full justify-start"
+              asChild
+            >
+              <Link href={`/dashboard/studies/${id}/analysis`}>
+                <BarChart className="mr-2 h-4 w-4" />
+                View Analytics
+              </Link>
+            </Button>
+            <Button
+              variant="outline"
+              className="w-full justify-start"
+              asChild
+            >
+              <Link href={`/dashboard/studies/${id}/settings`}>
+                <Settings2 className="mr-2 h-4 w-4" />
+                Study Settings
+              </Link>
+            </Button>
+          </CardContent>
+        </Card>
+      </div>
+    </div>
+  );
+} 

src/app/dashboard/studies/[id]/participants/new/page.tsx

@@ -0,0 +1,111 @@
+'use client';
+
+import { useEffect, useState } from "react";
+import { useParams, useRouter } from "next/navigation";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
+import { Button } from "~/components/ui/button";
+import { Input } from "~/components/ui/input";
+import { Label } from "~/components/ui/label";
+import { useToast } from "~/hooks/use-toast";
+import { ArrowLeft } from "lucide-react";
+import Link from "next/link";
+import { useActiveStudy } from "~/context/active-study";
+import { hasPermission } from "~/lib/permissions-client";
+import { PERMISSIONS } from "~/lib/permissions";
+
+export default function NewParticipant() {
+  const [name, setName] = useState("");
+  const [isSubmitting, setIsSubmitting] = useState(false);
+  const { id } = useParams();
+  const router = useRouter();
+  const { toast } = useToast();
+  const { activeStudy } = useActiveStudy();
+
+  useEffect(() => {
+    if (!activeStudy || !hasPermission(activeStudy.permissions, PERMISSIONS.CREATE_PARTICIPANT)) {
+      router.push(`/dashboard/studies/${id}`);
+    }
+  }, [activeStudy, id, router]);
+
+  if (!activeStudy || !hasPermission(activeStudy.permissions, PERMISSIONS.CREATE_PARTICIPANT)) {
+    return null;
+  }
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault();
+    setIsSubmitting(true);
+
+    try {
+      const response = await fetch(`/api/studies/${id}/participants`, {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+        },
+        body: JSON.stringify({ name }),
+      });
+
+      if (!response.ok) {
+        throw new Error("Failed to create participant");
+      }
+
+      toast({
+        title: "Success",
+        description: "Participant created successfully",
+      });
+
+      router.push(`/dashboard/studies/${id}/participants`);
+    } catch (error) {
+      console.error("Error creating participant:", error);
+      toast({
+        title: "Error",
+        description: "Failed to create participant",
+        variant: "destructive",
+      });
+    } finally {
+      setIsSubmitting(false);
+    }
+  };
+
+  return (
+    <div className="space-y-6">
+      <div className="flex items-center justify-between">
+        <Button
+          variant="ghost"
+          className="gap-2"
+          asChild
+        >
+          <Link href={`/dashboard/studies/${id}/participants`}>
+            <ArrowLeft className="h-4 w-4" />
+            Back to Participants
+          </Link>
+        </Button>
+      </div>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Add New Participant</CardTitle>
+          <CardDescription>
+            Create a new participant for {activeStudy?.title}
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <form onSubmit={handleSubmit} className="space-y-4">
+            <div className="space-y-2">
+              <Label htmlFor="name">Participant Name</Label>
+              <Input
+                id="name"
+                value={name}
+                onChange={(e) => setName(e.target.value)}
+                placeholder="Enter participant name"
+                required
+              />
+            </div>
+            <Button type="submit" disabled={isSubmitting}>
+              {isSubmitting ? "Creating..." : "Create Participant"}
+            </Button>
+          </form>
+        </CardContent>
+      </Card>
+    </div>
+  );
+} 

src/app/dashboard/studies/[id]/participants/page.tsx

@@ -0,0 +1,215 @@
+'use client';
+
+import { useEffect, useState } from "react";
+import { useParams } from "next/navigation";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
+import { Button } from "~/components/ui/button";
+import { useToast } from "~/hooks/use-toast";
+import { Plus, Trash2 } from "lucide-react";
+import Link from "next/link";
+import { useActiveStudy } from "~/context/active-study";
+import { hasPermission } from "~/lib/permissions-client";
+import { PERMISSIONS } from "~/lib/permissions";
+import {
+  AlertDialog,
+  AlertDialogAction,
+  AlertDialogCancel,
+  AlertDialogContent,
+  AlertDialogDescription,
+  AlertDialogFooter,
+  AlertDialogHeader,
+  AlertDialogTitle,
+  AlertDialogTrigger,
+} from "~/components/ui/alert-dialog";
+import {
+  Table,
+  TableBody,
+  TableCell,
+  TableHead,
+  TableHeader,
+  TableRow,
+} from "~/components/ui/table";
+
+interface Participant {
+  id: number;
+  name: string;
+  studyId: number;
+  createdAt: string;
+}
+
+export default function ParticipantsList() {
+  const [participants, setParticipants] = useState<Participant[]>([]);
+  const [isLoading, setIsLoading] = useState(true);
+  const { id } = useParams();
+  const { toast } = useToast();
+  const { activeStudy } = useActiveStudy();
+
+  const canCreateParticipant = activeStudy && hasPermission(activeStudy.permissions, PERMISSIONS.CREATE_PARTICIPANT);
+  const canDeleteParticipant = activeStudy && hasPermission(activeStudy.permissions, PERMISSIONS.DELETE_PARTICIPANT);
+  const canViewNames = activeStudy && hasPermission(activeStudy.permissions, PERMISSIONS.VIEW_PARTICIPANT_NAMES);
+
+  useEffect(() => {
+    fetchParticipants();
+  }, [id]);
+
+  const fetchParticipants = async () => {
+    try {
+      const response = await fetch(`/api/studies/${id}/participants`, {
+        method: "GET",
+        headers: {
+          "Content-Type": "application/json",
+        },
+      });
+
+      if (!response.ok) throw new Error("Failed to fetch participants");
+      const data = await response.json();
+      setParticipants(data.data || []);
+    } catch (error) {
+      console.error("Error fetching participants:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load participants",
+        variant: "destructive",
+      });
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  const handleDelete = async (participantId: number) => {
+    try {
+      const response = await fetch(`/api/studies/${id}/participants`, {
+        method: "DELETE",
+        headers: {
+          "Content-Type": "application/json",
+        },
+        body: JSON.stringify({ participantId }),
+      });
+
+      if (!response.ok) throw new Error("Failed to delete participant");
+
+      setParticipants(participants.filter(p => p.id !== participantId));
+      toast({
+        title: "Success",
+        description: "Participant deleted successfully",
+      });
+    } catch (error) {
+      console.error("Error deleting participant:", error);
+      toast({
+        title: "Error",
+        description: "Failed to delete participant",
+        variant: "destructive",
+      });
+    }
+  };
+
+  if (isLoading) {
+    return (
+      <Card>
+        <CardContent className="py-8">
+          <p className="text-center text-muted-foreground">Loading participants...</p>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  return (
+    <div className="space-y-6">
+      <div className="flex items-center justify-between">
+        <div>
+          <h2 className="text-2xl font-bold tracking-tight">Participants</h2>
+          <p className="text-muted-foreground">
+            Manage study participants and their data
+          </p>
+        </div>
+        {canCreateParticipant && (
+          <Button asChild>
+            <Link href={`/dashboard/studies/${id}/participants/new`}>
+              <Plus className="mr-2 h-4 w-4" />
+              Add Participant
+            </Link>
+          </Button>
+        )}
+      </div>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Study Participants</CardTitle>
+          <CardDescription>
+            All participants enrolled in {activeStudy?.title}
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          {participants.length > 0 ? (
+            <Table>
+              <TableHeader>
+                <TableRow>
+                  <TableHead>ID</TableHead>
+                  <TableHead>Name</TableHead>
+                  <TableHead>Added</TableHead>
+                  {canDeleteParticipant && <TableHead className="w-[100px]">Actions</TableHead>}
+                </TableRow>
+              </TableHeader>
+              <TableBody>
+                {participants.map((participant) => (
+                  <TableRow key={participant.id}>
+                    <TableCell>{participant.id}</TableCell>
+                    <TableCell>
+                      {canViewNames ? participant.name : `Participant ${participant.id}`}
+                    </TableCell>
+                    <TableCell>
+                      {new Date(participant.createdAt).toLocaleDateString()}
+                    </TableCell>
+                    {canDeleteParticipant && (
+                      <TableCell>
+                        <AlertDialog>
+                          <AlertDialogTrigger asChild>
+                            <Button variant="ghost" size="icon">
+                              <Trash2 className="h-4 w-4" />
+                            </Button>
+                          </AlertDialogTrigger>
+                          <AlertDialogContent>
+                            <AlertDialogHeader>
+                              <AlertDialogTitle>Delete Participant</AlertDialogTitle>
+                              <AlertDialogDescription>
+                                Are you sure you want to delete this participant? This action cannot be undone.
+                              </AlertDialogDescription>
+                            </AlertDialogHeader>
+                            <AlertDialogFooter>
+                              <AlertDialogCancel>Cancel</AlertDialogCancel>
+                              <AlertDialogAction
+                                onClick={() => handleDelete(participant.id)}
+                                className="bg-destructive text-destructive-foreground hover:bg-destructive/90"
+                              >
+                                Delete
+                              </AlertDialogAction>
+                            </AlertDialogFooter>
+                          </AlertDialogContent>
+                        </AlertDialog>
+                      </TableCell>
+                    )}
+                  </TableRow>
+                ))}
+              </TableBody>
+            </Table>
+          ) : (
+            <div className="py-8 text-center text-muted-foreground">
+              No participants added yet
+              {canCreateParticipant && (
+                <>
+                  .{" "}
+                  <Link
+                    href={`/dashboard/studies/${id}/participants/new`}
+                    className="font-medium text-primary hover:underline"
+                  >
+                    Add your first participant
+                  </Link>
+                </>
+              )}
+            </div>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+} 

src/app/dashboard/studies/[id]/settings/page.tsx

@@ -1,11 +1,15 @@
 'use client';
 
 import { useState } from "react";
-import { useParams, useRouter, useSearchParams } from "next/navigation";
+import { useParams, useRouter } from "next/navigation";
-import { Tabs, TabsContent, TabsList, TabsTrigger } from "~/components/ui/tabs";
 import { SettingsTab } from "~/components/studies/settings-tab";
 import { ParticipantsTab } from "~/components/studies/participants-tab";
+import { UsersTab } from "~/components/studies/users-tab";
 import { useEffect } from "react";
+import { PERMISSIONS } from "~/lib/permissions-client";
+import { Button } from "~/components/ui/button";
+import { Settings2Icon, UsersIcon, UserIcon } from "lucide-react";
+import { cn } from "~/lib/utils";
 
 interface Study {
   id: number;
@@ -18,17 +22,32 @@ export default function StudySettings() {
   const [study, setStudy] = useState<Study | null>(null);
   const [isLoading, setIsLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
+  const [activeTab, setActiveTab] = useState<'settings' | 'participants' | 'users'>('settings');
   const { id } = useParams();
   const router = useRouter();
-  const searchParams = useSearchParams();
-  const tab = searchParams.get('tab') || 'settings';
 
   useEffect(() => {
     const fetchStudy = async () => {
       try {
         const response = await fetch(`/api/studies/${id}`);
-        if (!response.ok) throw new Error("Failed to fetch study");
+        if (!response.ok) {
+          if (response.status === 403) {
+            router.push('/dashboard/studies');
+            return;
+          }
+          throw new Error("Failed to fetch study");
+        }
         const data = await response.json();
+        
+        // Check if user has any required permissions
+        const requiredPermissions = [PERMISSIONS.EDIT_STUDY, PERMISSIONS.MANAGE_ROLES];
+        const hasAccess = data.data.permissions.some(p => requiredPermissions.includes(p));
+
+        if (!hasAccess) {
+          router.push('/dashboard/studies');
+          return;
+        }
+
         setStudy(data.data);
       } catch (error) {
         console.error("Error fetching study:", error);
@@ -39,43 +58,65 @@ export default function StudySettings() {
     };
 
     fetchStudy();
-  }, [id]);
+  }, [id, router]);
-
-  const handleTabChange = (value: string) => {
-    router.push(`/dashboard/studies/${id}/settings?tab=${value}`);
-  };
 
   if (isLoading) {
-    return <div className="container py-6">Loading...</div>;
+    return <div>Loading...</div>;
   }
 
   if (error || !study) {
-    return <div className="container py-6 text-destructive">{error || "Study not found"}</div>;
+    return <div>Error: {error}</div>;
   }
 
   return (
-    <div className="container py-6 space-y-6">
+    <div className="container py-6">
-      <div className="flex flex-col gap-2">
+      <div className="flex flex-col gap-2 mb-6">
         <h1 className="text-3xl font-bold tracking-tight">{study.title}</h1>
         <p className="text-muted-foreground">
-          Manage study settings and participants
+          Manage study settings, participants, and team members
         </p>
       </div>
 
-      <Tabs value={tab} onValueChange={handleTabChange} className="space-y-6">
+      <div className="flex gap-6">
-        <TabsList>
+        <div className="w-48 flex flex-col gap-2">
-          <TabsTrigger value="settings">Settings</TabsTrigger>
+          <Button
-          <TabsTrigger value="participants">Participants</TabsTrigger>
+            variant={activeTab === 'settings' ? 'secondary' : 'ghost'}
-        </TabsList>
+            className="justify-start"
+            onClick={() => setActiveTab('settings')}
+          >
+            <Settings2Icon className="mr-2 h-4 w-4" />
+            Settings
+          </Button>
+          <Button
+            variant={activeTab === 'participants' ? 'secondary' : 'ghost'}
+            className="justify-start"
+            onClick={() => setActiveTab('participants')}
+          >
+            <UserIcon className="mr-2 h-4 w-4" />
+            Participants
+          </Button>
+          <Button
+            variant={activeTab === 'users' ? 'secondary' : 'ghost'}
+            className="justify-start"
+            onClick={() => setActiveTab('users')}
+          >
+            <UsersIcon className="mr-2 h-4 w-4" />
+            Users
+          </Button>
+        </div>
 
-        <TabsContent value="settings" className="space-y-6">
+        <div className="flex-1">
-          <SettingsTab study={study} />
+          <div className={cn(activeTab === 'settings' ? 'block' : 'hidden')}>
-        </TabsContent>
+            <SettingsTab study={study} />
-
+          </div>
-        <TabsContent value="participants" className="space-y-6">
+          <div className={cn(activeTab === 'participants' ? 'block' : 'hidden')}>
-          <ParticipantsTab studyId={study.id} permissions={study.permissions} />
+            <ParticipantsTab studyId={study.id} permissions={study.permissions} />
-        </TabsContent>
+          </div>
-      </Tabs>
+          <div className={cn(activeTab === 'users' ? 'block' : 'hidden')}>
+            <UsersTab studyId={study.id} permissions={study.permissions} />
+          </div>
+        </div>
+      </div>
     </div>
   );
 } 

src/app/dashboard/studies/new/page.tsx

@@ -0,0 +1,116 @@
+'use client';
+
+import { useState } from "react";
+import { useRouter } from "next/navigation";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
+import { Button } from "~/components/ui/button";
+import { Input } from "~/components/ui/input";
+import { Label } from "~/components/ui/label";
+import { Textarea } from "~/components/ui/textarea";
+import { useToast } from "~/hooks/use-toast";
+import { ArrowLeft } from "lucide-react";
+import Link from "next/link";
+import { useActiveStudy } from "~/context/active-study";
+import { hasPermission } from "~/lib/permissions-client";
+import { PERMISSIONS } from "~/lib/permissions";
+
+export default function NewStudy() {
+  const [title, setTitle] = useState("");
+  const [description, setDescription] = useState("");
+  const [isSubmitting, setIsSubmitting] = useState(false);
+  const router = useRouter();
+  const { toast } = useToast();
+  const { refreshStudies } = useActiveStudy();
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault();
+    setIsSubmitting(true);
+
+    try {
+      const response = await fetch('/api/studies', {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+        },
+        body: JSON.stringify({ title, description }),
+      });
+
+      if (!response.ok) {
+        throw new Error("Failed to create study");
+      }
+
+      const data = await response.json();
+      
+      toast({
+        title: "Success",
+        description: "Study created successfully",
+      });
+
+      // Refresh studies list and redirect to the new study
+      await refreshStudies();
+      router.push(`/dashboard/studies/${data.data.id}`);
+    } catch (error) {
+      console.error("Error creating study:", error);
+      toast({
+        title: "Error",
+        description: "Failed to create study",
+        variant: "destructive",
+      });
+    } finally {
+      setIsSubmitting(false);
+    }
+  };
+
+  return (
+    <div className="space-y-6">
+      <div className="flex items-center justify-between">
+        <Button
+          variant="ghost"
+          className="gap-2"
+          asChild
+        >
+          <Link href="/dashboard/studies">
+            <ArrowLeft className="h-4 w-4" />
+            Back to Studies
+          </Link>
+        </Button>
+      </div>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Create New Study</CardTitle>
+          <CardDescription>
+            Set up a new research study
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <form onSubmit={handleSubmit} className="space-y-4">
+            <div className="space-y-2">
+              <Label htmlFor="title">Study Title</Label>
+              <Input
+                id="title"
+                value={title}
+                onChange={(e) => setTitle(e.target.value)}
+                placeholder="Enter study title"
+                required
+              />
+            </div>
+            <div className="space-y-2">
+              <Label htmlFor="description">Description</Label>
+              <Textarea
+                id="description"
+                value={description}
+                onChange={(e) => setDescription(e.target.value)}
+                placeholder="Enter study description"
+                rows={4}
+              />
+            </div>
+            <Button type="submit" disabled={isSubmitting}>
+              {isSubmitting ? "Creating..." : "Create Study"}
+            </Button>
+          </form>
+        </CardContent>
+      </Card>
+    </div>
+  );
+} 

src/app/dashboard/studies/page.tsx

@@ -250,7 +250,11 @@ export default function Studies() {
           <Card>
             <CardContent className="py-8">
               <p className="text-center text-muted-foreground">
-                No studies created yet. Create your first study above.
+                No studies created yet.{' '}
+                {hasPermission(studies[0]?.permissions || [], PERMISSIONS.CREATE_STUDY) 
+                  ? "Create your first study above."
+                  : "Ask your administrator to create your first study."
+                }
               </p>
             </CardContent>
           </Card>

src/app/globals.css

@@ -10,8 +10,8 @@ body {
   :root {
     --background: 210 50% 98%;
     --foreground: 215 25% 27%;
-    --card: 210 50% 98%; /* Card background color */
+    --card: 210 50% 98%;
-    --card-foreground: 215 25% 27%; /* Card text color */
+    --card-foreground: 215 25% 27%;
     --popover: 210 50% 98%;
     --popover-foreground: 215 25% 27%;
     --primary: 215 60% 40%;
@@ -33,34 +33,36 @@ body {
     --gradient-start: 210 50% 96%;
     --gradient-end: 210 50% 98%;
 
-    /* Update sidebar variables */
+    /* Updated sidebar variables for a clean, light look */
-    --sidebar-background-top: 210 55% 92%;
+    --sidebar-background: 210 50% 98%;
-    --sidebar-background-bottom: 210 55% 88%;
     --sidebar-foreground: 215 25% 27%;
     --sidebar-muted: 215 20% 50%;
-    --sidebar-hover: 210 60% 86%;
+    --sidebar-hover: 210 50% 94%;
+    --sidebar-border: 214 32% 91%;
+    --sidebar-separator: 214 32% 91%;
+    --sidebar-active: 210 50% 92%;
     
-    --card-level-1: 210 50% 95%; /* Level 1 card background color */
+    --card-level-1: 210 50% 95%;
-    --card-level-2: 210 50% 90%; /* Level 2 card background color */
+    --card-level-2: 210 50% 90%;
-    --card-level-3: 210 50% 85%; /* Level 3 card background color */
+    --card-level-3: 210 50% 85%;
   }
 
   .dark {
-    --background: 220 20% 15%; /* Dark mode background */
+    --background: 220 20% 15%;
-    --foreground: 220 20% 90%; /* Dark mode foreground */
+    --foreground: 220 20% 90%;
-    --card: 220 20% 15%; /* Dark mode card background color */
+    --card: 220 20% 15%;
-    --card-foreground: 220 20% 90%; /* Dark mode card text color */
+    --card-foreground: 220 20% 90%;
     --popover: 220 20% 15%;
     --popover-foreground: 220 20% 90%;
     --primary: 220 60% 50%;
     --primary-foreground: 220 20% 90%;
-    --secondary: 220 30% 20%; /* Darker secondary */
+    --secondary: 220 30% 20%;
     --secondary-foreground: 220 20% 90%;
     --muted: 220 30% 20%;
     --muted-foreground: 220 20% 70%;
     --accent: 220 30% 20%;
     --accent-foreground: 220 20% 90%;
-    --destructive: 0 62% 40%; /* Darker destructive */
+    --destructive: 0 62% 40%;
     --destructive-foreground: 220 20% 90%;
     --border: 220 30% 20%;
     --input: 220 30% 20%;
@@ -70,16 +72,18 @@ body {
     --gradient-start: 220 20% 12%;
     --gradient-end: 220 20% 15%;
 
-    /* Update sidebar variables for dark mode */
+    /* Updated sidebar variables for dark mode */
     --sidebar-background-top: 220 20% 15%;
-    --sidebar-background-bottom: 220 20% 12%;
+    --sidebar-background-bottom: 220 20% 15%;
     --sidebar-foreground: 220 20% 90%;
-    --sidebar-muted: 220 20% 70%;
+    --sidebar-muted: 220 20% 60%;
-    --sidebar-hover: 220 30% 20%;
+    --sidebar-hover: 220 20% 20%;
+    --sidebar-border: 220 20% 25%;
+    --sidebar-separator: 220 20% 22%;
     
-    --card-level-1: 220 20% 12%; /* Dark mode Level 1 card background color */
+    --card-level-1: 220 20% 12%;
-    --card-level-2: 220 20% 10%; /* Dark mode Level 2 card background color */
+    --card-level-2: 220 20% 10%;
-    --card-level-3: 220 20% 8%; /* Dark mode Level 3 card background color */
+    --card-level-3: 220 20% 8%;
   }
 
   /* Add these utility classes */
@@ -104,3 +108,20 @@ body {
     @apply bg-background text-foreground;
   }
 }
+
+/* Sidebar specific styles */
+.sidebar-separator {
+  @apply my-3 border-t border-[hsl(var(--sidebar-separator))] opacity-60;
+}
+
+.sidebar-dropdown-content {
+  @apply bg-[hsl(var(--sidebar-background))] border-[hsl(var(--sidebar-border))];
+}
+
+.sidebar-button {
+  @apply hover:bg-[hsl(var(--sidebar-hover))] text-[hsl(var(--sidebar-foreground))];
+}
+
+.sidebar-button[data-active="true"] {
+  @apply bg-[hsl(var(--sidebar-active))] font-medium;
+}

src/components/breadcrumb.tsx

@@ -0,0 +1,93 @@
+'use client';
+
+import { ChevronRight } from "lucide-react";
+import Link from "next/link";
+import { usePathname } from "next/navigation";
+import { useActiveStudy } from "~/context/active-study";
+
+interface BreadcrumbItem {
+  label: string;
+  href?: string;
+}
+
+export function Breadcrumb() {
+  const pathname = usePathname();
+  const { activeStudy } = useActiveStudy();
+
+  const getBreadcrumbs = (): BreadcrumbItem[] => {
+    const items: BreadcrumbItem[] = [{ label: 'Dashboard', href: '/dashboard' }];
+    const path = pathname.split('/').filter(Boolean);
+
+    // Handle studies list page
+    if (path[1] === 'studies' && !activeStudy) {
+      items.push({ label: 'Studies', href: '/dashboard/studies' });
+      if (path[2] === 'new') {
+        items.push({ label: 'New Study' });
+      }
+      return items;
+    }
+
+    // Handle active study pages
+    if (activeStudy) {
+      items.push({ 
+        label: 'Studies', 
+        href: '/dashboard/studies' 
+      });
+      
+      items.push({ 
+        label: activeStudy.title,
+        href: `/dashboard/studies/${activeStudy.id}`
+      });
+
+      // Add section based on URL
+      if (path.length > 3) {
+        const section = path[3];
+        const sectionLabel = section.charAt(0).toUpperCase() + section.slice(1);
+        
+        if (section === 'new') {
+          items.push({ 
+            label: `New ${path[2].slice(0, -1)}`,
+            href: `/dashboard/studies/${activeStudy.id}/${path[2]}/new`
+          });
+        } else {
+          items.push({ 
+            label: sectionLabel,
+            href: `/dashboard/studies/${activeStudy.id}/${section}`
+          });
+        }
+      }
+    }
+
+    return items;
+  };
+
+  const breadcrumbs = getBreadcrumbs();
+
+  if (breadcrumbs.length <= 1) return null;
+
+  return (
+    <div className="flex items-center space-x-2 text-sm text-muted-foreground mb-6">
+      {breadcrumbs.map((item, index) => {
+        const isLast = index === breadcrumbs.length - 1;
+
+        return (
+          <div key={item.label} className="flex items-center">
+            {index > 0 && <ChevronRight className="h-4 w-4 mx-2" />}
+            {item.href && !isLast ? (
+              <Link
+                href={item.href}
+                className="hover:text-foreground transition-colors"
+              >
+                {item.label}
+              </Link>
+            ) : (
+              <span className={isLast ? "text-foreground font-medium" : ""}>
+                {item.label}
+              </span>
+            )}
+          </div>
+        );
+      })}
+    </div>
+  );
+} 

src/components/layout/dashboard-layout.tsx

@@ -0,0 +1 @@
+ 

src/components/layout/sidebar.tsx

@@ -0,0 +1 @@
+ 

src/components/sidebar.tsx

@@ -5,50 +5,172 @@ import {
   BarChartIcon,
   UsersRoundIcon,
   LandPlotIcon,
-  BotIcon,
-  FolderIcon,
   FileTextIcon,
   LayoutDashboard,
   Menu,
-  Settings
+  Settings,
+  ChevronDown,
+  FolderIcon,
+  PlusIcon
 } from "lucide-react"
 import Link from "next/link"
-import { usePathname } from "next/navigation"
+import { usePathname, useRouter } from "next/navigation"
 import { useState } from "react"
 import { Button } from "~/components/ui/button"
 import { Sheet, SheetContent, SheetTrigger, SheetTitle } from "~/components/ui/sheet"
 import { cn } from "~/lib/utils"
 import { Logo } from "~/components/logo"
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "~/components/ui/select"
+import { Separator } from "~/components/ui/separator"
+import { useActiveStudy } from "~/context/active-study"
 
-const navItems = [
+const getNavItems = (studyId?: number) => [
-  { name: "Dashboard", href: "/dashboard", icon: LayoutDashboard },
+  { 
-  { name: "Studies", href: "/dashboard/studies", icon: FolderIcon },
+    name: "Dashboard", 
-  { name: "Trials", href: "/dashboard/trials", icon: LandPlotIcon },
+    href: studyId ? `/dashboard/studies/${studyId}` : "/dashboard", 
-  { name: "Forms", href: "/dashboard/forms", icon: FileTextIcon },
+    icon: LayoutDashboard,
-  { name: "Data Analysis", href: "/dashboard/analysis", icon: BarChartIcon },
+    exact: true,
-  { name: "Settings", href: "/dashboard/settings", icon: Settings },
+    requiresStudy: false
+  },
+  { 
+    name: "Participants", 
+    href: `/dashboard/studies/${studyId}/participants`, 
+    icon: UsersRoundIcon,
+    requiresStudy: true,
+    baseRoute: "participants"
+  },
+  { 
+    name: "Trials", 
+    href: `/dashboard/studies/${studyId}/trials`, 
+    icon: LandPlotIcon,
+    requiresStudy: true,
+    baseRoute: "trials"
+  },
+  { 
+    name: "Forms", 
+    href: `/dashboard/studies/${studyId}/forms`, 
+    icon: FileTextIcon,
+    requiresStudy: true,
+    baseRoute: "forms"
+  },
+  { 
+    name: "Data Analysis", 
+    href: `/dashboard/studies/${studyId}/analysis`, 
+    icon: BarChartIcon,
+    requiresStudy: true,
+    baseRoute: "analysis"
+  },
+  { 
+    name: "Settings", 
+    href: `/dashboard/studies/${studyId}/settings`, 
+    icon: Settings,
+    requiresStudy: true,
+    baseRoute: "settings"
+  },
 ];
 
 export function Sidebar() {
   const pathname = usePathname()
+  const router = useRouter()
   const [isOpen, setIsOpen] = useState(false)
   const { user } = useUser()
+  const { activeStudy, setActiveStudy, studies, isLoading } = useActiveStudy()
+
+  const navItems = getNavItems(activeStudy?.id)
+  const visibleNavItems = activeStudy 
+    ? navItems 
+    : navItems.filter(item => !item.requiresStudy)
+
+  const isActiveRoute = (item: { href: string, exact?: boolean, baseRoute?: string }) => {
+    if (item.exact) {
+      return pathname === item.href;
+    }
+    if (item.baseRoute && activeStudy) {
+      const pattern = new RegExp(`/dashboard/studies/\\d+/${item.baseRoute}`);
+      return pattern.test(pathname);
+    }
+    return pathname.startsWith(item.href);
+  };
+
+  const handleStudyChange = (value: string) => {
+    if (value === "all") {
+      setActiveStudy(null);
+      router.push("/dashboard/studies");
+    } else {
+      const study = studies.find(s => s.id.toString() === value);
+      if (study) {
+        setActiveStudy(study);
+        router.push(`/dashboard/studies/${study.id}`);
+      }
+    }
+  };
 
   const SidebarContent = () => (
-    <div className="flex h-full flex-col bg-gradient-to-b from-[hsl(var(--sidebar-background-top))] to-[hsl(var(--sidebar-background-bottom))]">
+    <div className="flex h-full flex-col">
+      <div className="p-4">
+        <Select
+          value={activeStudy?.id?.toString() || "all"}
+          onValueChange={handleStudyChange}
+        >
+          <SelectTrigger className="w-full sidebar-button">
+            <div className="flex items-center justify-between">
+              <span className="truncate">
+                {activeStudy?.title || "All Studies"}
+              </span>
+              <ChevronDown className="h-4 w-4 opacity-50" />
+            </div>
+          </SelectTrigger>
+          <SelectContent className="sidebar-dropdown-content">
+            <SelectItem value="all" className="sidebar-button">
+              <div className="flex items-center">
+                <FolderIcon className="h-4 w-4 mr-2" />
+                All Studies
+              </div>
+            </SelectItem>
+            <Separator className="sidebar-separator" />
+            {studies.map((study) => (
+              <SelectItem 
+                key={study.id} 
+                value={study.id.toString()}
+                className="sidebar-button"
+              >
+                {study.title}
+              </SelectItem>
+            ))}
+            <Separator className="sidebar-separator" />
+            <Button
+              variant="ghost"
+              className="w-full justify-start sidebar-button"
+              asChild
+            >
+              <Link href="/dashboard/studies/new">
+                <PlusIcon className="h-4 w-4 mr-2" />
+                Create New Study
+              </Link>
+            </Button>
+          </SelectContent>
+        </Select>
+      </div>
+
       <nav className="flex-1 overflow-y-auto p-4">
         <ul className="space-y-2">
-          {navItems.map((item) => {
+          {visibleNavItems.map((item) => {
             const IconComponent = item.icon;
+            const isActive = isActiveRoute(item);
+            
             return (
               <li key={item.href}>
                 <Button
                   asChild
                   variant="ghost"
-                  className={cn(
+                  className="w-full justify-start sidebar-button"
-                    "w-full justify-start text-[hsl(var(--sidebar-foreground))] hover:bg-[hsl(var(--sidebar-hover))]",
+                  data-active={isActive}
-                    pathname === item.href && "bg-[hsl(var(--sidebar-hover))] font-semibold"
-                  )}
                 >
                   <Link href={item.href} onClick={() => setIsOpen(false)}>
                     <IconComponent className="h-5 w-5 mr-3" />
@@ -60,13 +182,20 @@ export function Sidebar() {
           })}
         </ul>
       </nav>
-      <div className="border-t p-4">
+
-        <div className="flex items-center justify-between">
+      <div className="p-4">
-          <div className="flex items-center space-x-4">
+        <div className="border-t border-[hsl(var(--sidebar-separator))]">
-            <UserButton />
+          <div className="flex items-center justify-between pt-4">
-            <div>
+            <div className="flex items-center space-x-4">
-              <p className="text-sm font-medium text-[hsl(var(--sidebar-foreground))]">{user?.fullName ?? 'User'}</p>
+              <UserButton />
-              <p className="text-xs text-[hsl(var(--sidebar-muted))]">{user?.primaryEmailAddress?.emailAddress ?? 'user@example.com'}</p>
+              <div>
+                <p className="text-sm font-medium text-[hsl(var(--sidebar-foreground))]">
+                  {user?.fullName ?? user?.username ?? 'User'}
+                </p>
+                <p className="text-xs text-[hsl(var(--sidebar-muted))]">
+                  {user?.primaryEmailAddress?.emailAddress ?? 'user@example.com'}
+                </p>
+              </div>
             </div>
           </div>
         </div>
@@ -77,7 +206,7 @@ export function Sidebar() {
   return (
     <>
       <div className="lg:hidden fixed top-0 left-0 right-0 z-50">
-        <div className="flex h-14 items-center justify-between border-b px-4 bg-background">
+        <div className="flex h-14 items-center justify-between border-b border-[hsl(var(--sidebar-border))]">
           <Logo 
             href="/dashboard"
             className="text-[hsl(var(--sidebar-foreground))]"
@@ -85,19 +214,22 @@ export function Sidebar() {
           />
           <Sheet open={isOpen} onOpenChange={setIsOpen}>
             <SheetTrigger asChild>
-              <Button variant="ghost" className="h-14 w-14 px-0">
+              <Button variant="ghost" className="h-14 w-14 px-0 sidebar-button">
                 <Menu className="h-6 w-6" />
               </Button>
             </SheetTrigger>
-            <SheetContent side="top" className="w-full">
+            <SheetContent 
+              side="left" 
+              className="w-full p-0 border-[hsl(var(--sidebar-border))]"
+            >
               <SheetTitle className="sr-only">Navigation Menu</SheetTitle>
               <SidebarContent />
             </SheetContent>
           </Sheet>
         </div>
       </div>
-      <div className="hidden lg:flex lg:w-64 lg:flex-col lg:border-r lg:bg-gradient-to-b lg:from-[hsl(var(--sidebar-background-top))] lg:to-[hsl(var(--sidebar-background-bottom))]">
+      <div className="hidden lg:flex lg:w-64 lg:flex-col lg:border-r lg:border-[hsl(var(--sidebar-border))]">
-        <div className="flex h-14 items-center border-b px-4">
+        <div className="flex h-14 items-center border-b border-[hsl(var(--sidebar-border))] px-4">
           <Logo 
             href="/dashboard"
             className="text-[hsl(var(--sidebar-foreground))]"

src/components/studies/invitations-tab.tsx

@@ -0,0 +1,136 @@
+'use client';
+
+import { useState, useEffect } from "react";
+import { Button } from "~/components/ui/button";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
+import { useToast } from "~/hooks/use-toast";
+import { PERMISSIONS } from "~/lib/permissions-client";
+import { InviteUserDialog } from "./invite-user-dialog";
+
+interface Invitation {
+  id: string;
+  email: string;
+  roleName: string;
+  accepted: boolean;
+  expiresAt: string;
+}
+
+interface InvitationsTabProps {
+  studyId: number;
+  permissions: string[];
+}
+
+export function InvitationsTab({ studyId, permissions }: InvitationsTabProps) {
+  const [invitations, setInvitations] = useState<Invitation[]>([]);
+  const [isLoading, setIsLoading] = useState(true);
+  const { toast } = useToast();
+
+  const hasPermission = (permission: string) => permissions.includes(permission);
+  const canManageRoles = hasPermission(PERMISSIONS.MANAGE_ROLES);
+
+  useEffect(() => {
+    fetchInvitations();
+  }, [studyId]);
+
+  const fetchInvitations = async () => {
+    try {
+      const response = await fetch(`/api/invitations?studyId=${studyId}`);
+      if (!response.ok) throw new Error("Failed to fetch invitations");
+      const data = await response.json();
+      setInvitations(data.data || []);
+    } catch (error) {
+      console.error("Error fetching invitations:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load invitations",
+        variant: "destructive",
+      });
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  const handleDeleteInvitation = async (invitationId: string) => {
+    try {
+      const response = await fetch(`/api/invitations/${invitationId}`, {
+        method: "DELETE",
+      });
+
+      if (!response.ok) {
+        throw new Error("Failed to delete invitation");
+      }
+
+      setInvitations(invitations.filter(inv => inv.id !== invitationId));
+      toast({
+        title: "Success",
+        description: "Invitation deleted successfully",
+      });
+    } catch (error) {
+      console.error("Error deleting invitation:", error);
+      toast({
+        title: "Error",
+        description: "Failed to delete invitation",
+        variant: "destructive",
+      });
+    }
+  };
+
+  if (isLoading) {
+    return (
+      <Card>
+        <CardContent className="py-8">
+          <p className="text-center text-muted-foreground">Loading invitations...</p>
+        </CardContent>
+      </Card>
+    );
+  }
+
+  return (
+    <div className="space-y-6">
+      <Card>
+        <CardHeader>
+          <div className="flex items-center justify-between">
+            <div>
+              <CardTitle>Manage Invitations</CardTitle>
+              <CardDescription>
+                Invite researchers and participants to collaborate on this study
+              </CardDescription>
+            </div>
+            <InviteUserDialog studyId={studyId} onInviteSent={fetchInvitations} />
+          </div>
+        </CardHeader>
+        <CardContent className="space-y-6">
+          {invitations.length > 0 ? (
+            <div className="space-y-4">
+              {invitations.map((invitation) => (
+                <div
+                  key={invitation.id}
+                  className="flex items-center justify-between p-4 border rounded-lg bg-card"
+                >
+                  <div>
+                    <p className="font-medium">{invitation.email}</p>
+                    <p className="text-sm text-muted-foreground">
+                      Role: {invitation.roleName}
+                      {invitation.accepted ? " • Accepted" : " • Pending"}
+                    </p>
+                  </div>
+                  {!invitation.accepted && (
+                    <Button
+                      variant="outline"
+                      size="sm"
+                      onClick={() => handleDeleteInvitation(invitation.id)}
+                    >
+                      Cancel
+                    </Button>
+                  )}
+                </div>
+              ))}
+            </div>
+          ) : (
+            <p className="text-muted-foreground">No invitations sent yet.</p>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+} 

src/components/studies/invite-user-dialog.tsx

@@ -0,0 +1,167 @@
+'use client';
+
+import { useState, useEffect } from "react";
+import { Button } from "~/components/ui/button";
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+  DialogTrigger,
+} from "~/components/ui/dialog";
+import { Input } from "~/components/ui/input";
+import { Label } from "~/components/ui/label";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "~/components/ui/select";
+import { useToast } from "~/hooks/use-toast";
+
+interface Role {
+  id: number;
+  name: string;
+  description: string;
+}
+
+interface InviteUserDialogProps {
+  studyId: number;
+  onInviteSent: () => void;
+}
+
+export function InviteUserDialog({ studyId, onInviteSent }: InviteUserDialogProps) {
+  const [email, setEmail] = useState("");
+  const [roleId, setRoleId] = useState<string>("");
+  const [isOpen, setIsOpen] = useState(false);
+  const [isLoading, setIsLoading] = useState(false);
+  const [roles, setRoles] = useState<Role[]>([]);
+  const { toast } = useToast();
+
+  // Fetch available roles when dialog opens
+  useEffect(() => {
+    if (isOpen) {
+      fetchRoles();
+    }
+  }, [isOpen]);
+
+  const fetchRoles = async () => {
+    try {
+      const response = await fetch("/api/roles");
+      if (!response.ok) {
+        throw new Error("Failed to fetch roles");
+      }
+      const data = await response.json();
+      // Filter out admin and PI roles
+      setRoles(data.filter((role: Role) => 
+        !['admin', 'principal_investigator'].includes(role.name)
+      ));
+    } catch (error) {
+      console.error("Error fetching roles:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load roles",
+        variant: "destructive",
+      });
+    }
+  };
+
+  const handleSubmit = async (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!email || !roleId) return;
+
+    setIsLoading(true);
+    try {
+      const response = await fetch("/api/invitations", {
+        method: "POST",
+        headers: {
+          "Content-Type": "application/json",
+        },
+        body: JSON.stringify({
+          email,
+          roleId: parseInt(roleId, 10),
+          studyId,
+        }),
+      });
+
+      if (!response.ok) {
+        throw new Error("Failed to send invitation");
+      }
+
+      toast({
+        title: "Success",
+        description: "Invitation sent successfully",
+      });
+      setIsOpen(false);
+      setEmail("");
+      setRoleId("");
+      onInviteSent();
+    } catch (error) {
+      console.error("Error sending invitation:", error);
+      toast({
+        title: "Error",
+        description: "Failed to send invitation",
+        variant: "destructive",
+      });
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  return (
+    <Dialog open={isOpen} onOpenChange={setIsOpen}>
+      <DialogTrigger asChild>
+        <Button>Invite User</Button>
+      </DialogTrigger>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>Invite User</DialogTitle>
+          <DialogDescription>
+            Send an invitation to collaborate on this study
+          </DialogDescription>
+        </DialogHeader>
+        <form onSubmit={handleSubmit} className="space-y-4">
+          <div className="space-y-2">
+            <Label htmlFor="email">Email</Label>
+            <Input
+              id="email"
+              type="email"
+              placeholder="Enter email address"
+              value={email}
+              onChange={(e) => setEmail(e.target.value)}
+              required
+            />
+          </div>
+          <div className="space-y-2">
+            <Label htmlFor="role">Role</Label>
+            <Select value={roleId} onValueChange={setRoleId} required>
+              <SelectTrigger>
+                <SelectValue placeholder="Select a role" />
+              </SelectTrigger>
+              <SelectContent>
+                {roles.map((role) => (
+                  <SelectItem key={role.id} value={role.id.toString()}>
+                    {role.name.split('_').map(word => 
+                      word.charAt(0).toUpperCase() + word.slice(1).toLowerCase()
+                    ).join(' ')}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+          </div>
+          <DialogFooter>
+            <Button type="button" variant="outline" onClick={() => setIsOpen(false)}>
+              Cancel
+            </Button>
+            <Button type="submit" disabled={isLoading}>
+              {isLoading ? "Sending..." : "Send Invitation"}
+            </Button>
+          </DialogFooter>
+        </form>
+      </DialogContent>
+    </Dialog>
+  );
+} 

src/components/studies/participants-tab.tsx

@@ -38,6 +38,11 @@ export function ParticipantsTab({ studyId, permissions }: ParticipantsTabProps)
   const [error, setError] = useState<string | null>(null);
   const { toast } = useToast();
 
+  const hasPermission = (permission: string) => permissions.includes(permission);
+  const canCreateParticipant = hasPermission(PERMISSIONS.CREATE_PARTICIPANT);
+  const canDeleteParticipant = hasPermission(PERMISSIONS.DELETE_PARTICIPANT);
+  const canViewNames = hasPermission(PERMISSIONS.VIEW_PARTICIPANT_NAMES);
+
   useEffect(() => {
     fetchParticipants();
   }, [studyId]);
@@ -121,8 +126,6 @@ export function ParticipantsTab({ studyId, permissions }: ParticipantsTabProps)
     }
   };
 
-  const hasPermission = (permission: string) => permissions.includes(permission);
-
   if (isLoading) {
     return (
       <Card>
@@ -133,19 +136,9 @@ export function ParticipantsTab({ studyId, permissions }: ParticipantsTabProps)
     );
   }
 
-  if (error) {
-    return (
-      <Card>
-        <CardContent className="py-8">
-          <p className="text-center text-destructive">{error}</p>
-        </CardContent>
-      </Card>
-    );
-  }
-
   return (
     <div className="space-y-6">
-      {hasPermission(PERMISSIONS.CREATE_PARTICIPANT) && (
+      {canCreateParticipant && (
         <Card>
           <CardHeader>
             <CardTitle>Add New Participant</CardTitle>
@@ -181,12 +174,13 @@ export function ParticipantsTab({ studyId, permissions }: ParticipantsTabProps)
                   <div>
                     <h3 className="font-semibold">
                       {participant.name}
+                      {!canViewNames && <span className="text-sm text-muted-foreground ml-2">(ID: {participant.id})</span>}
                     </h3>
                     <p className="text-sm text-muted-foreground">
                       Added {new Date(participant.createdAt).toLocaleDateString()}
                     </p>
                   </div>
-                  {hasPermission(PERMISSIONS.DELETE_PARTICIPANT) && (
+                  {canDeleteParticipant && (
                     <AlertDialog>
                       <AlertDialogTrigger asChild>
                         <Button variant="outline" size="sm">
@@ -222,7 +216,7 @@ export function ParticipantsTab({ studyId, permissions }: ParticipantsTabProps)
           <Card>
             <CardContent className="py-8">
               <p className="text-center text-muted-foreground">
-                No participants added yet. Add your first participant above.
+                No participants added yet{canCreateParticipant ? ". Add your first participant above" : ""}.
               </p>
             </CardContent>
           </Card>

src/components/studies/settings-tab.tsx

@@ -8,6 +8,7 @@ import { Button } from "~/components/ui/button";
 import { useToast } from "~/hooks/use-toast";
 import { useState } from "react";
 import { PERMISSIONS } from "~/lib/permissions-client";
+import { useRouter } from "next/navigation";
 
 interface SettingsTabProps {
   study: {
@@ -21,13 +22,18 @@ interface SettingsTabProps {
 export function SettingsTab({ study }: SettingsTabProps) {
   const [title, setTitle] = useState(study.title);
   const [description, setDescription] = useState(study.description || "");
+  const [isLoading, setIsLoading] = useState(false);
   const { toast } = useToast();
+  const router = useRouter();
 
   const hasPermission = (permission: string) => study.permissions.includes(permission);
   const canEditStudy = hasPermission(PERMISSIONS.EDIT_STUDY);
 
   const updateStudy = async (e: React.FormEvent) => {
     e.preventDefault();
+    if (!canEditStudy) return;
+
+    setIsLoading(true);
     try {
       const response = await fetch(`/api/studies/${study.id}`, {
         method: "PATCH",
@@ -37,7 +43,13 @@ export function SettingsTab({ study }: SettingsTabProps) {
         body: JSON.stringify({ title, description }),
       });
 
-      if (!response.ok) throw new Error("Failed to update study");
+      if (!response.ok) {
+        if (response.status === 403) {
+          router.push('/dashboard/studies');
+          return;
+        }
+        throw new Error("Failed to update study");
+      }
 
       toast({
         title: "Success",
@@ -47,12 +59,26 @@ export function SettingsTab({ study }: SettingsTabProps) {
       console.error("Error updating study:", error);
       toast({
         title: "Error",
-        description: "Failed to update study",
+        description: error instanceof Error ? error.message : "Failed to update study",
         variant: "destructive",
       });
+    } finally {
+      setIsLoading(false);
     }
   };
 
+  if (!canEditStudy) {
+    return (
+      <Card>
+        <CardContent className="py-8">
+          <p className="text-center text-muted-foreground">
+            You don't have permission to edit this study.
+          </p>
+        </CardContent>
+      </Card>
+    );
+  }
+
   return (
     <Card>
       <CardHeader>
@@ -69,7 +95,7 @@ export function SettingsTab({ study }: SettingsTabProps) {
               onChange={(e) => setTitle(e.target.value)}
               placeholder="Enter study title"
               required
-              disabled={!canEditStudy}
+              disabled={isLoading}
             />
           </div>
           <div className="space-y-2">
@@ -79,14 +105,12 @@ export function SettingsTab({ study }: SettingsTabProps) {
               value={description}
               onChange={(e) => setDescription(e.target.value)}
               placeholder="Enter study description"
-              disabled={!canEditStudy}
+              disabled={isLoading}
             />
           </div>
-          {canEditStudy && (
+          <Button type="submit" disabled={isLoading}>
-            <Button type="submit">
+            {isLoading ? "Saving..." : "Save Changes"}
-              Save Changes
+          </Button>
-            </Button>
-          )}
         </form>
       </CardContent>
     </Card>

src/components/studies/users-tab.tsx

@@ -0,0 +1,336 @@
+'use client';
+
+import { useState, useEffect } from "react";
+import { UserAvatar } from "~/components/user-avatar";
+import { Button } from "~/components/ui/button";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "~/components/ui/card";
+import { useToast } from "~/hooks/use-toast";
+import { PERMISSIONS } from "~/lib/permissions-client";
+import { InviteUserDialog } from "./invite-user-dialog";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "~/components/ui/select";
+import {
+  Table,
+  TableBody,
+  TableCell,
+  TableHead,
+  TableHeader,
+  TableRow,
+} from "~/components/ui/table";
+import { Trash2Icon } from "lucide-react";
+import {
+  AlertDialog,
+  AlertDialogAction,
+  AlertDialogCancel,
+  AlertDialogContent,
+  AlertDialogDescription,
+  AlertDialogFooter,
+  AlertDialogHeader,
+  AlertDialogTitle,
+  AlertDialogTrigger,
+} from "~/components/ui/alert-dialog";
+
+interface User {
+  id: string;
+  email: string;
+  firstName: string | null;
+  lastName: string | null;
+  roles: Array<{ id: number; name: string }>;
+}
+
+interface Invitation {
+  id: string;
+  email: string;
+  roleName: string;
+  accepted: boolean;
+  expiresAt: string;
+}
+
+interface Role {
+  id: number;
+  name: string;
+  description: string;
+}
+
+interface UsersTabProps {
+  studyId: number;
+  permissions: string[];
+}
+
+export function UsersTab({ studyId, permissions }: UsersTabProps) {
+  const [users, setUsers] = useState<User[]>([]);
+  const [invitations, setInvitations] = useState<Invitation[]>([]);
+  const [roles, setRoles] = useState<Role[]>([]);
+  const [isLoading, setIsLoading] = useState(true);
+  const { toast } = useToast();
+
+  const hasPermission = (permission: string) => permissions.includes(permission);
+  const canManageRoles = hasPermission(PERMISSIONS.MANAGE_ROLES);
+
+  useEffect(() => {
+    fetchData();
+  }, [studyId]);
+
+  const fetchData = async () => {
+    try {
+      await Promise.all([
+        fetchUsers(),
+        fetchInvitations(),
+        fetchRoles(),
+      ]);
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  const fetchUsers = async () => {
+    try {
+      const response = await fetch(`/api/studies/${studyId}/users`);
+      if (!response.ok) throw new Error("Failed to fetch users");
+      const data = await response.json();
+      setUsers(data.data || []);
+    } catch (error) {
+      console.error("Error fetching users:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load users",
+        variant: "destructive",
+      });
+    }
+  };
+
+  const fetchInvitations = async () => {
+    try {
+      const response = await fetch(`/api/invitations?studyId=${studyId}`);
+      if (!response.ok) throw new Error("Failed to fetch invitations");
+      const data = await response.json();
+      setInvitations(data.data || []);
+    } catch (error) {
+      console.error("Error fetching invitations:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load invitations",
+        variant: "destructive",
+      });
+    }
+  };
+
+  const fetchRoles = async () => {
+    try {
+      const response = await fetch("/api/roles");
+      if (!response.ok) throw new Error("Failed to fetch roles");
+      const data = await response.json();
+      setRoles(data.filter((role: Role) => 
+        !['admin'].includes(role.name)
+      ));
+    } catch (error) {
+      console.error("Error fetching roles:", error);
+      toast({
+        title: "Error",
+        description: "Failed to load roles",
+        variant: "destructive",
+      });
+    }
+  };
+
+  const handleRoleChange = async (userId: string, newRoleId: string) => {
+    try {
+      const response = await fetch(`/api/studies/${studyId}/users/${userId}/role`, {
+        method: "PUT",
+        headers: {
+          "Content-Type": "application/json",
+        },
+        body: JSON.stringify({
+          roleId: parseInt(newRoleId, 10),
+        }),
+      });
+
+      if (!response.ok) throw new Error("Failed to update role");
+
+      toast({
+        title: "Success",
+        description: "User role updated successfully",
+      });
+
+      // Refresh users list
+      fetchUsers();
+    } catch (error) {
+      console.error("Error updating role:", error);
+      toast({
+        title: "Error",
+        description: "Failed to update user role",
+        variant: "destructive",
+      });
+    }
+  };
+
+  const handleDeleteInvitation = async (invitationId: string) => {
+    try {
+      const response = await fetch(`/api/invitations/${invitationId}`, {
+        method: "DELETE",
+      });
+
+      if (!response.ok) throw new Error("Failed to delete invitation");
+
+      setInvitations(invitations.filter(inv => inv.id !== invitationId));
+      toast({
+        title: "Success",
+        description: "Invitation deleted successfully",
+      });
+    } catch (error) {
+      console.error("Error deleting invitation:", error);
+      toast({
+        title: "Error",
+        description: "Failed to delete invitation",
+        variant: "destructive",
+      });
+    }
+  };
+
+  const formatName = (user: User) => {
+    return user.name || user.email;
+  };
+
+  const formatRoleName = (name: string) => {
+    return name
+      .split('_')
+      .map(word => word.charAt(0).toUpperCase() + word.slice(1).toLowerCase())
+      .join(' ');
+  };
+
+  if (isLoading) {
+    return <div>Loading...</div>;
+  }
+
+  const pendingInvitations = invitations.filter(inv => !inv.accepted);
+
+  return (
+    <div className="space-y-6">
+      <div className="flex justify-between items-center">
+        <h2 className="text-2xl font-bold tracking-tight">Team Members</h2>
+        {canManageRoles && <InviteUserDialog studyId={studyId} onInviteSent={fetchInvitations} />}
+      </div>
+
+      <Card>
+        <CardHeader>
+          <CardTitle>Study Members</CardTitle>
+          <CardDescription>
+            Manage users and their roles in this study
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <Table>
+            <TableHeader>
+              <TableRow>
+                <TableHead>User</TableHead>
+                <TableHead>Email</TableHead>
+                <TableHead>Role</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {users.map((user) => (
+                <TableRow key={user.id}>
+                  <TableCell className="flex items-center gap-2">
+                    <UserAvatar
+                      user={{
+                        name: formatName(user),
+                        email: user.email,
+                      }}
+                    />
+                    <span>{formatName(user)}</span>
+                  </TableCell>
+                  <TableCell>{user.email}</TableCell>
+                  <TableCell>
+                    {canManageRoles ? (
+                      <Select
+                        value={user.roles[0]?.id.toString()}
+                        onValueChange={(value) => handleRoleChange(user.id, value)}
+                      >
+                        <SelectTrigger className="w-[180px]">
+                          <SelectValue />
+                        </SelectTrigger>
+                        <SelectContent>
+                          {roles.map((role) => (
+                            <SelectItem key={role.id} value={role.id.toString()}>
+                              {formatRoleName(role.name)}
+                            </SelectItem>
+                          ))}
+                        </SelectContent>
+                      </Select>
+                    ) : (
+                      <span>{formatRoleName(user.roles[0]?.name || '')}</span>
+                    )}
+                  </TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </CardContent>
+      </Card>
+
+      {pendingInvitations.length > 0 && (
+        <Card>
+          <CardHeader>
+            <CardTitle>Pending Invitations</CardTitle>
+            <CardDescription>
+              Outstanding invitations to join the study
+            </CardDescription>
+          </CardHeader>
+          <CardContent>
+            <Table>
+              <TableHeader>
+                <TableRow>
+                  <TableHead>Email</TableHead>
+                  <TableHead>Role</TableHead>
+                  <TableHead>Expires</TableHead>
+                  {canManageRoles && <TableHead className="w-[100px]">Actions</TableHead>}
+                </TableRow>
+              </TableHeader>
+              <TableBody>
+                {pendingInvitations.map((invitation) => (
+                  <TableRow key={invitation.id}>
+                    <TableCell>{invitation.email}</TableCell>
+                    <TableCell>{formatRoleName(invitation.roleName)}</TableCell>
+                    <TableCell>{new Date(invitation.expiresAt).toLocaleDateString()}</TableCell>
+                    {canManageRoles && (
+                      <TableCell>
+                        <AlertDialog>
+                          <AlertDialogTrigger asChild>
+                            <Button variant="ghost" size="icon">
+                              <Trash2Icon className="h-4 w-4" />
+                            </Button>
+                          </AlertDialogTrigger>
+                          <AlertDialogContent>
+                            <AlertDialogHeader>
+                              <AlertDialogTitle>Delete Invitation</AlertDialogTitle>
+                              <AlertDialogDescription>
+                                Are you sure you want to delete this invitation? This action cannot be undone.
+                              </AlertDialogDescription>
+                            </AlertDialogHeader>
+                            <AlertDialogFooter>
+                              <AlertDialogCancel>Cancel</AlertDialogCancel>
+                              <AlertDialogAction
+                                onClick={() => handleDeleteInvitation(invitation.id)}
+                              >
+                                Delete
+                              </AlertDialogAction>
+                            </AlertDialogFooter>
+                          </AlertDialogContent>
+                        </AlertDialog>
+                      </TableCell>
+                    )}
+                  </TableRow>
+                ))}
+              </TableBody>
+            </Table>
+          </CardContent>
+        </Card>
+      )}
+    </div>
+  );
+} 

src/components/ui/avatar.tsx

@@ -0,0 +1,50 @@
+"use client"
+
+import * as React from "react"
+import * as AvatarPrimitive from "@radix-ui/react-avatar"
+
+import { cn } from "~/lib/utils"
+
+const Avatar = React.forwardRef<
+  React.ElementRef<typeof AvatarPrimitive.Root>,
+  React.ComponentPropsWithoutRef<typeof AvatarPrimitive.Root>
+>(({ className, ...props }, ref) => (
+  <AvatarPrimitive.Root
+    ref={ref}
+    className={cn(
+      "relative flex h-10 w-10 shrink-0 overflow-hidden rounded-full",
+      className
+    )}
+    {...props}
+  />
+))
+Avatar.displayName = AvatarPrimitive.Root.displayName
+
+const AvatarImage = React.forwardRef<
+  React.ElementRef<typeof AvatarPrimitive.Image>,
+  React.ComponentPropsWithoutRef<typeof AvatarPrimitive.Image>
+>(({ className, ...props }, ref) => (
+  <AvatarPrimitive.Image
+    ref={ref}
+    className={cn("aspect-square h-full w-full", className)}
+    {...props}
+  />
+))
+AvatarImage.displayName = AvatarPrimitive.Image.displayName
+
+const AvatarFallback = React.forwardRef<
+  React.ElementRef<typeof AvatarPrimitive.Fallback>,
+  React.ComponentPropsWithoutRef<typeof AvatarPrimitive.Fallback>
+>(({ className, ...props }, ref) => (
+  <AvatarPrimitive.Fallback
+    ref={ref}
+    className={cn(
+      "flex h-full w-full items-center justify-center rounded-full bg-muted",
+      className
+    )}
+    {...props}
+  />
+))
+AvatarFallback.displayName = AvatarPrimitive.Fallback.displayName
+
+export { Avatar, AvatarImage, AvatarFallback }

src/components/ui/breadcrumb.tsx

@@ -0,0 +1,114 @@
+import * as React from "react"
+import { Slot } from "@radix-ui/react-slot"
+import { cn } from "~/lib/utils"
+import { ChevronRightIcon, DotsHorizontalIcon } from "@radix-ui/react-icons"
+
+const Breadcrumb = React.forwardRef<
+  HTMLElement,
+  React.ComponentPropsWithoutRef<"nav"> & {
+    separator?: React.ReactNode
+  }
+>(({ ...props }, ref) => <nav ref={ref} aria-label="breadcrumb" {...props} />)
+Breadcrumb.displayName = "Breadcrumb"
+
+const BreadcrumbList = React.forwardRef<
+  HTMLOListElement,
+  React.ComponentPropsWithoutRef<"ol">
+>(({ className, ...props }, ref) => (
+  <ol
+    ref={ref}
+    className={cn(
+      "flex flex-wrap items-center gap-1.5 break-words text-sm text-muted-foreground sm:gap-2.5",
+      className
+    )}
+    {...props}
+  />
+))
+BreadcrumbList.displayName = "BreadcrumbList"
+
+const BreadcrumbItem = React.forwardRef<
+  HTMLLIElement,
+  React.ComponentPropsWithoutRef<"li">
+>(({ className, ...props }, ref) => (
+  <li
+    ref={ref}
+    className={cn("inline-flex items-center gap-1.5", className)}
+    {...props}
+  />
+))
+BreadcrumbItem.displayName = "BreadcrumbItem"
+
+const BreadcrumbLink = React.forwardRef<
+  HTMLAnchorElement,
+  React.ComponentPropsWithoutRef<"a"> & {
+    asChild?: boolean
+  }
+>(({ asChild, className, ...props }, ref) => {
+  const Comp = asChild ? Slot : "a"
+
+  return (
+    <Comp
+      ref={ref}
+      className={cn("transition-colors hover:text-foreground", className)}
+      {...props}
+    />
+  )
+})
+BreadcrumbLink.displayName = "BreadcrumbLink"
+
+const BreadcrumbPage = React.forwardRef<
+  HTMLSpanElement,
+  React.ComponentPropsWithoutRef<"span">
+>(({ className, ...props }, ref) => (
+  <span
+    ref={ref}
+    role="link"
+    aria-disabled="true"
+    aria-current="page"
+    className={cn("font-normal text-foreground", className)}
+    {...props}
+  />
+))
+BreadcrumbPage.displayName = "BreadcrumbPage"
+
+const BreadcrumbSeparator = ({
+  children,
+  className,
+  ...props
+}: React.ComponentProps<"li">) => (
+  <li
+    role="presentation"
+    aria-hidden="true"
+    className={cn("[&>svg]:w-3.5 [&>svg]:h-3.5", className)}
+    {...props}
+  >
+    {children ?? <ChevronRightIcon />}
+  </li>
+)
+BreadcrumbSeparator.displayName = "BreadcrumbSeparator"
+
+const BreadcrumbEllipsis = ({
+  className,
+  ...props
+}: React.ComponentProps<"span">) => (
+  <span
+    role="presentation"
+    aria-hidden="true"
+    className={cn("flex h-9 w-9 items-center justify-center", className)}
+    {...props}
+  >
+    <DotsHorizontalIcon className="h-4 w-4" />
+    <span className="sr-only">More</span>
+  </span>
+)
+BreadcrumbEllipsis.displayName = "BreadcrumbElipssis"
+
+export {
+  Breadcrumb,
+  BreadcrumbList,
+  BreadcrumbItem,
+  BreadcrumbLink,
+  BreadcrumbPage,
+  BreadcrumbSeparator,
+  BreadcrumbEllipsis,
+}

src/components/ui/separator.tsx

@@ -0,0 +1,31 @@
+"use client"
+
+import * as React from "react"
+import * as SeparatorPrimitive from "@radix-ui/react-separator"
+
+import { cn } from "~/lib/utils"
+
+const Separator = React.forwardRef<
+  React.ElementRef<typeof SeparatorPrimitive.Root>,
+  React.ComponentPropsWithoutRef<typeof SeparatorPrimitive.Root>
+>(
+  (
+    { className, orientation = "horizontal", decorative = true, ...props },
+    ref
+  ) => (
+    <SeparatorPrimitive.Root
+      ref={ref}
+      decorative={decorative}
+      orientation={orientation}
+      className={cn(
+        "shrink-0 bg-border",
+        orientation === "horizontal" ? "h-[1px] w-full" : "h-full w-[1px]",
+        className
+      )}
+      {...props}
+    />
+  )
+)
+Separator.displayName = SeparatorPrimitive.Root.displayName
+
+export { Separator }

src/components/ui/skeleton.tsx

@@ -0,0 +1,15 @@
+import { cn } from "~/lib/utils"
+
+function Skeleton({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) {
+  return (
+    <div
+      className={cn("animate-pulse rounded-md bg-primary/10", className)}
+      {...props}
+    />
+  )
+}
+
+export { Skeleton }

src/components/ui/table.tsx

@@ -0,0 +1,120 @@
+import * as React from "react"
+
+import { cn } from "~/lib/utils"
+
+const Table = React.forwardRef<
+  HTMLTableElement,
+  React.HTMLAttributes<HTMLTableElement>
+>(({ className, ...props }, ref) => (
+  <div className="relative w-full overflow-auto">
+    <table
+      ref={ref}
+      className={cn("w-full caption-bottom text-sm", className)}
+      {...props}
+    />
+  </div>
+))
+Table.displayName = "Table"
+
+const TableHeader = React.forwardRef<
+  HTMLTableSectionElement,
+  React.HTMLAttributes<HTMLTableSectionElement>
+>(({ className, ...props }, ref) => (
+  <thead ref={ref} className={cn("[&_tr]:border-b", className)} {...props} />
+))
+TableHeader.displayName = "TableHeader"
+
+const TableBody = React.forwardRef<
+  HTMLTableSectionElement,
+  React.HTMLAttributes<HTMLTableSectionElement>
+>(({ className, ...props }, ref) => (
+  <tbody
+    ref={ref}
+    className={cn("[&_tr:last-child]:border-0", className)}
+    {...props}
+  />
+))
+TableBody.displayName = "TableBody"
+
+const TableFooter = React.forwardRef<
+  HTMLTableSectionElement,
+  React.HTMLAttributes<HTMLTableSectionElement>
+>(({ className, ...props }, ref) => (
+  <tfoot
+    ref={ref}
+    className={cn(
+      "border-t bg-muted/50 font-medium [&>tr]:last:border-b-0",
+      className
+    )}
+    {...props}
+  />
+))
+TableFooter.displayName = "TableFooter"
+
+const TableRow = React.forwardRef<
+  HTMLTableRowElement,
+  React.HTMLAttributes<HTMLTableRowElement>
+>(({ className, ...props }, ref) => (
+  <tr
+    ref={ref}
+    className={cn(
+      "border-b transition-colors hover:bg-muted/50 data-[state=selected]:bg-muted",
+      className
+    )}
+    {...props}
+  />
+))
+TableRow.displayName = "TableRow"
+
+const TableHead = React.forwardRef<
+  HTMLTableCellElement,
+  React.ThHTMLAttributes<HTMLTableCellElement>
+>(({ className, ...props }, ref) => (
+  <th
+    ref={ref}
+    className={cn(
+      "h-10 px-2 text-left align-middle font-medium text-muted-foreground [&:has([role=checkbox])]:pr-0 [&>[role=checkbox]]:translate-y-[2px]",
+      className
+    )}
+    {...props}
+  />
+))
+TableHead.displayName = "TableHead"
+
+const TableCell = React.forwardRef<
+  HTMLTableCellElement,
+  React.TdHTMLAttributes<HTMLTableCellElement>
+>(({ className, ...props }, ref) => (
+  <td
+    ref={ref}
+    className={cn(
+      "p-2 align-middle [&:has([role=checkbox])]:pr-0 [&>[role=checkbox]]:translate-y-[2px]",
+      className
+    )}
+    {...props}
+  />
+))
+TableCell.displayName = "TableCell"
+
+const TableCaption = React.forwardRef<
+  HTMLTableCaptionElement,
+  React.HTMLAttributes<HTMLTableCaptionElement>
+>(({ className, ...props }, ref) => (
+  <caption
+    ref={ref}
+    className={cn("mt-4 text-sm text-muted-foreground", className)}
+    {...props}
+  />
+))
+TableCaption.displayName = "TableCaption"
+
+export {
+  Table,
+  TableHeader,
+  TableBody,
+  TableFooter,
+  TableHead,
+  TableRow,
+  TableCell,
+  TableCaption,
+}

src/components/user-avatar.tsx

@@ -0,0 +1,27 @@
+import { Avatar, AvatarFallback } from "~/components/ui/avatar";
+
+interface UserAvatarProps {
+  user: {
+    name?: string | null;
+    email: string;
+  };
+  className?: string;
+}
+
+export function UserAvatar({ user, className }: UserAvatarProps) {
+  function getInitials(name: string) {
+    return name
+      .split(' ')
+      .map(part => part[0])
+      .join('')
+      .toUpperCase();
+  }
+
+  const initials = user.name ? getInitials(user.name) : user.email[0].toUpperCase();
+
+  return (
+    <Avatar className={className}>
+      <AvatarFallback>{initials}</AvatarFallback>
+    </Avatar>
+  );
+} 

src/context/active-study.tsx

@@ -0,0 +1,106 @@
+'use client';
+
+import { createContext, useContext, useEffect, useState } from 'react';
+import { useRouter, usePathname } from 'next/navigation';
+
+interface Study {
+  id: number;
+  title: string;
+  description: string | null;
+  userId: string;
+  environment: string;
+  createdAt: Date;
+  updatedAt: Date | null;
+  permissions: string[];
+}
+
+interface ActiveStudyContextType {
+  activeStudy: Study | null;
+  setActiveStudy: (study: Study | null) => void;
+  studies: Study[];
+  isLoading: boolean;
+  error: string | null;
+  refreshStudies: () => Promise<void>;
+}
+
+const ActiveStudyContext = createContext<ActiveStudyContextType | undefined>(undefined);
+
+export function ActiveStudyProvider({ children }: { children: React.ReactNode }) {
+  const [activeStudy, setActiveStudy] = useState<Study | null>(null);
+  const [studies, setStudies] = useState<Study[]>([]);
+  const [isLoading, setIsLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const router = useRouter();
+  const pathname = usePathname();
+
+  const fetchStudies = async () => {
+    try {
+      const response = await fetch('/api/studies', {
+        method: 'GET',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+      });
+      
+      if (!response.ok) throw new Error('Failed to fetch studies');
+      const data = await response.json();
+      
+      const studiesWithDates = (data.data || []).map((study: any) => ({
+        ...study,
+        createdAt: new Date(study.createdAt),
+        updatedAt: study.updatedAt ? new Date(study.updatedAt) : null,
+      }));
+      
+      setStudies(studiesWithDates);
+      
+      if (studiesWithDates.length === 1 && !activeStudy) {
+        setActiveStudy(studiesWithDates[0]);
+      }
+    } catch (error) {
+      console.error('Error fetching studies:', error);
+      setError(error instanceof Error ? error.message : 'Failed to load studies');
+    } finally {
+      setIsLoading(false);
+    }
+  };
+
+  useEffect(() => {
+    fetchStudies();
+  }, []);
+
+  useEffect(() => {
+    const studyIdMatch = pathname.match(/\/dashboard\/studies\/(\d+)/);
+    if (studyIdMatch) {
+      const studyId = parseInt(studyIdMatch[1]);
+      const study = studies.find(s => s.id === studyId);
+      if (study && (!activeStudy || activeStudy.id !== study.id)) {
+        setActiveStudy(study);
+      }
+    } else if (!pathname.includes('/studies/new')) {
+      setActiveStudy(null);
+    }
+  }, [pathname, studies]);
+
+  const value = {
+    activeStudy,
+    setActiveStudy,
+    studies,
+    isLoading,
+    error,
+    refreshStudies: fetchStudies,
+  };
+
+  return (
+    <ActiveStudyContext.Provider value={value}>
+      {children}
+    </ActiveStudyContext.Provider>
+  );
+}
+
+export function useActiveStudy() {
+  const context = useContext(ActiveStudyContext);
+  if (context === undefined) {
+    throw new Error('useActiveStudy must be used within an ActiveStudyProvider');
+  }
+  return context;
+} 

src/db/drop.ts

@@ -7,16 +7,9 @@ config({ path: '.env.local' });
 
 async function dropAllTables() {
   try {
+    // drop all tables, regardless of name
     await sql`
-      DROP TABLE IF EXISTS 
+      DROP TABLE IF EXISTS ${sql.raw(Object.values(tables).map(table => table.name).join(', '))}
-        user_roles,
-        role_permissions,
-        permissions,
-        roles,
-        participant,
-        study,
-        users
-      CASCADE;
     `;
     console.log('All tables dropped successfully');
   } catch (error) {

src/lib/roles.ts

@@ -34,7 +34,6 @@ export const ROLE_PERMISSIONS: Record<RoleCode, Array<keyof typeof PERMISSIONS>>
   
   RESEARCHER: [
     'VIEW_STUDY',
-    'VIEW_PARTICIPANT_NAMES',
     'CREATE_PARTICIPANT',
     'EDIT_PARTICIPANT',
     'VIEW_ROBOT_STATUS',
@@ -46,7 +45,6 @@ export const ROLE_PERMISSIONS: Record<RoleCode, Array<keyof typeof PERMISSIONS>>
   
   WIZARD: [
     'VIEW_STUDY',
-    'VIEW_PARTICIPANT_NAMES',
     'VIEW_ROBOT_STATUS',
     'CONTROL_ROBOT',
     'RECORD_EXPERIMENT',