diff --git a/packages/email-threads-api/.env.example b/packages/email-threads-api/.env.example
new file mode 100644
index 00000000..c3056692
--- /dev/null
+++ b/packages/email-threads-api/.env.example
@@ -0,0 +1,9 @@
+# Email Threads API - Environment Configuration
+# Copy this file to .env and fill in the values
+
+# Database
+DATABASE_URL="postgresql://user:password@localhost:5432/email_threads?schema=public"
+
+# Server
+PORT=3000
+NODE_ENV=development
diff --git a/packages/email-threads-api/API.md b/packages/email-threads-api/API.md
new file mode 100644
index 00000000..b975361e
--- /dev/null
+++ b/packages/email-threads-api/API.md
@@ -0,0 +1,81 @@
+# Email Threads API - Tests
+
+## Thread List
+
+### GET /api/threads
+Returns paginated list of email threads.
+
+Query Parameters:
+- `page` (number, default: 1) - Page number
+- `limit` (number, default: 20, max: 100) - Items per page
+- `category` (string: INBOX|SENT|DRAFT|SPAM|TRASH|ARCHIVE) - Filter by category
+- `priority` (string: LOW|NORMAL|HIGH|URGENT) - Filter by priority
+- `isRead` (boolean) - Filter by read status
+- `isStarred` (boolean) - Filter by starred status
+- `search` (string) - Search in subject, snippet, and message body
+- `label` (string) - Filter by label name
+- `tag` (string) - Filter by tag name
+- `sortBy` (string: createdAt|updatedAt|subject, default: createdAt)
+- `sortOrder` (string: asc|desc, default: desc)
+
+### Response
+```json
+{
+  "threads": [
+    {
+      "id": "clx...",
+      "subject": "Meeting tomorrow",
+      "snippet": "Hi, just confirming our meeting...",
+      "isRead": false,
+      "isStarred": true,
+      "category": "INBOX",
+      "priority": "HIGH",
+      "createdAt": "2024-01-15T10:30:00Z",
+      "updatedAt": "2024-01-15T11:00:00Z",
+      "messageCount": 3,
+      "lastMessageFrom": "Alice",
+      "labels": [{ "id": "...", "name": "Work", "color": "#007AFF" }],
+      "tags": [{ "id": "...", "name": "Important", "color": "#FF3B30" }]
+    }
+  ],
+  "total": 42,
+  "page": 1,
+  "limit": 20,
+  "totalPages": 3
+}
+```
+
+## Thread Detail
+
+### GET /api/threads/:id
+Returns a single thread with all its messages.
+
+### Response
+```json
+{
+  "id": "clx...",
+  "subject": "Meeting tomorrow",
+  "snippet": "Hi, just confirming our meeting...",
+  "isRead": false,
+  "isStarred": true,
+  "category": "INBOX",
+  "priority": "HIGH",
+  "createdAt": "2024-01-15T10:30:00Z",
+  "updatedAt": "2024-01-15T11:00:00Z",
+  "messages": [
+    {
+      "id": "...",
+      "fromName": "Alice",
+      "fromEmail": "alice@example.com",
+      "to": "bob@example.com",
+      "cc": null,
+      "subject": "Meeting tomorrow",
+      "body": "Hi, just confirming our meeting...",
+      "isRead": true,
+      "createdAt": "2024-01-15T10:30:00Z"
+    }
+  ],
+  "labels": [...],
+  "tags": [...]
+}
+```
diff --git a/packages/email-threads-api/package.json b/packages/email-threads-api/package.json
new file mode 100644
index 00000000..baf0ebf3
--- /dev/null
+++ b/packages/email-threads-api/package.json
@@ -0,0 +1,32 @@
+{
+  "name": "@warpspeed/email-threads-api",
+  "version": "0.1.0",
+  "description": "Email Threads API - list, detail, search, and filter email threads",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "build": "tsc",
+    "start": "node dist/index.js",
+    "dev": "tsx watch src/index.ts",
+    "db:generate": "prisma generate",
+    "db:push": "prisma db push",
+    "db:migrate": "prisma migrate dev",
+    "test": "vitest run",
+    "lint": "eslint src/ --ext .ts"
+  },
+  "dependencies": {
+    "@prisma/client": "^5.18.0",
+    "express": "^4.19.2",
+    "cors": "^2.8.5",
+    "zod": "^3.23.8"
+  },
+  "devDependencies": {
+    "@types/express": "^4.17.21",
+    "@types/cors": "^2.8.17",
+    "@types/node": "^20.14.11",
+    "prisma": "^5.18.0",
+    "tsx": "^4.16.2",
+    "typescript": "^5.5.3",
+    "vitest": "^2.0.3"
+  }
+}
diff --git a/packages/email-threads-api/prisma/schema.prisma b/packages/email-threads-api/prisma/schema.prisma
new file mode 100644
index 00000000..39175999
--- /dev/null
+++ b/packages/email-threads-api/prisma/schema.prisma
@@ -0,0 +1,73 @@
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "postgresql"
+  url      = env("DATABASE_URL")
+}
+
+model EmailThread {
+  id        String    @id @default(cuid())
+  subject   String
+  snippet   String?
+  isRead    Boolean   @default(false)
+  isStarred Boolean   @default(false)
+  category  Category  @default(INBOX)
+  priority  Priority  @default(NORMAL)
+  createdAt DateTime  @default(now())
+  updatedAt DateTime  @updatedAt
+  messages  EmailMessage[]
+  labels    Label[]
+  tags      Tag[]
+}
+
+model EmailMessage {
+  id        String   @id @default(cuid())
+  threadId  String
+  thread    EmailThread @relation(fields: [threadId], references: [id], onDelete: Cascade)
+  fromName  String
+  fromEmail String
+  to        String
+  cc        String?
+  bcc       String?
+  subject   String
+  body      String
+  isRead    Boolean  @default(false)
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@index([threadId])
+  @@index([fromEmail])
+  @@index([createdAt])
+}
+
+model Label {
+  id        String        @id @default(cuid())
+  name      String        @unique
+  color     String        @default("#007AFF")
+  threads   EmailThread[]
+}
+
+model Tag {
+  id        String        @id @default(cuid())
+  name      String        @unique
+  color     String        @default("#8E8E93")
+  threads   EmailThread[]
+}
+
+enum Category {
+  INBOX
+  SENT
+  DRAFT
+  SPAM
+  TRASH
+  ARCHIVE
+}
+
+enum Priority {
+  LOW
+  NORMAL
+  HIGH
+  URGENT
+}
diff --git a/packages/email-threads-api/src/index.ts b/packages/email-threads-api/src/index.ts
new file mode 100644
index 00000000..51a3802c
--- /dev/null
+++ b/packages/email-threads-api/src/index.ts
@@ -0,0 +1,25 @@
+import express from 'express';
+import cors from 'cors';
+import threadRoutes from './routes/threads.js';
+
+const app = express();
+const PORT = parseInt(process.env.PORT ?? '3000', 10);
+
+// Middleware
+app.use(cors());
+app.use(express.json());
+
+// Routes
+app.use('/api', threadRoutes);
+
+// Health check
+app.get('/health', (_req, res) => {
+  res.json({ status: 'ok', timestamp: new Date().toISOString() });
+});
+
+// Start server
+app.listen(PORT, () => {
+  console.log(`Email Threads API running on http://localhost:${PORT}`);
+});
+
+export default app;
diff --git a/packages/email-threads-api/src/lib/prisma.ts b/packages/email-threads-api/src/lib/prisma.ts
new file mode 100644
index 00000000..89f754f8
--- /dev/null
+++ b/packages/email-threads-api/src/lib/prisma.ts
@@ -0,0 +1,13 @@
+import { PrismaClient } from '@prisma/client';
+
+const globalForPrisma = globalThis as unknown as { prisma: PrismaClient | undefined };
+
+export const prisma =
+  globalForPrisma.prisma ??
+  new PrismaClient({
+    log: process.env.NODE_ENV === 'development' ? ['query'] : [],
+  });
+
+if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma;
+
+export default prisma;
diff --git a/packages/email-threads-api/src/routes/threads.ts b/packages/email-threads-api/src/routes/threads.ts
new file mode 100644
index 00000000..1abcbcf0
--- /dev/null
+++ b/packages/email-threads-api/src/routes/threads.ts
@@ -0,0 +1,57 @@
+import { Router, Request, Response } from 'express';
+import { threadListQuerySchema, threadParamsSchema } from '../schemas.js';
+import { listThreads, getThreadById } from '../services/thread-service.js';
+
+const router = Router();
+
+/**
+ * GET /api/threads
+ * List email threads with optional filtering, search, and pagination.
+ */
+router.get('/threads', async (req: Request, res: Response) => {
+  try {
+    const query = threadListQuerySchema.parse(req.query);
+    const result = await listThreads(query);
+    res.json(result);
+  } catch (error: any) {
+    if (error?.name === 'ZodError') {
+      res.status(400).json({
+        error: 'Invalid query parameters',
+        details: error.errors ?? error,
+      });
+      return;
+    }
+    console.error('Error listing threads:', error);
+    res.status(500).json({ error: 'Internal server error' });
+  }
+});
+
+/**
+ * GET /api/threads/:id
+ * Get a single thread with all its messages.
+ */
+router.get('/threads/:id', async (req: Request, res: Response) => {
+  try {
+    const { id } = threadParamsSchema.parse(req.params);
+    const thread = await getThreadById(id);
+
+    if (!thread) {
+      res.status(404).json({ error: 'Thread not found' });
+      return;
+    }
+
+    res.json(thread);
+  } catch (error: any) {
+    if (error?.name === 'ZodError') {
+      res.status(400).json({
+        error: 'Invalid thread ID',
+        details: error.errors ?? error,
+      });
+      return;
+    }
+    console.error('Error getting thread:', error);
+    res.status(500).json({ error: 'Internal server error' });
+  }
+});
+
+export default router;
diff --git a/packages/email-threads-api/src/schemas.ts b/packages/email-threads-api/src/schemas.ts
new file mode 100644
index 00000000..b6efa6a0
--- /dev/null
+++ b/packages/email-threads-api/src/schemas.ts
@@ -0,0 +1,33 @@
+import { z } from 'zod';
+
+export const CategoryEnum = z.enum(['INBOX', 'SENT', 'DRAFT', 'SPAM', 'TRASH', 'ARCHIVE']);
+export const PriorityEnum = z.enum(['LOW', 'NORMAL', 'HIGH', 'URGENT']);
+
+export const threadListQuerySchema = z.object({
+  page: z.coerce.number().int().positive().default(1),
+  limit: z.coerce.number().int().positive().max(100).default(20),
+  category: CategoryEnum.optional(),
+  priority: PriorityEnum.optional(),
+  isRead: z.coerce.boolean().optional(),
+  isStarred: z.coerce.boolean().optional(),
+  search: z.string().optional(),
+  label: z.string().optional(),
+  tag: z.string().optional(),
+  sortBy: z.enum(['createdAt', 'updatedAt', 'subject']).default('createdAt'),
+  sortOrder: z.enum(['asc', 'desc']).default('desc'),
+});
+
+export const threadParamsSchema = z.object({
+  id: z.string().min(1),
+});
+
+export const paginationSchema = z.object({
+  page: z.number().int().positive(),
+  limit: z.number().int().positive().max(100),
+  total: z.number().int().min(0),
+  totalPages: z.number().int().min(0),
+});
+
+export type ThreadListQuery = z.infer<typeof threadListQuerySchema>;
+export type Category = z.infer<typeof CategoryEnum>;
+export type Priority = z.infer<typeof PriorityEnum>;
diff --git a/packages/email-threads-api/src/services/thread-service.ts b/packages/email-threads-api/src/services/thread-service.ts
new file mode 100644
index 00000000..33508f41
--- /dev/null
+++ b/packages/email-threads-api/src/services/thread-service.ts
@@ -0,0 +1,109 @@
+import { Prisma } from '@prisma/client';
+import prisma from '../lib/prisma.js';
+import type { ThreadListQuery } from '../schemas.js';
+
+export interface ThreadListResult {
+  threads: Array<{
+    id: string;
+    subject: string;
+    snippet: string | null;
+    isRead: boolean;
+    isStarred: boolean;
+    category: string;
+    priority: string;
+    createdAt: Date;
+    updatedAt: Date;
+    messageCount: number;
+    lastMessageFrom: string;
+    labels: Array<{ id: string; name: string; color: string }>;
+    tags: Array<{ id: string; name: string; color: string }>;
+  }>;
+  total: number;
+  page: number;
+  limit: number;
+  totalPages: number;
+}
+
+export async function listThreads(query: ThreadListQuery): Promise<ThreadListResult> {
+  const where: Prisma.EmailThreadWhereInput = {};
+
+  if (query.category) {
+    where.category = query.category;
+  }
+  if (query.priority) {
+    where.priority = query.priority;
+  }
+  if (query.isRead !== undefined) {
+    where.isRead = query.isRead;
+  }
+  if (query.isStarred !== undefined) {
+    where.isStarred = query.isStarred;
+  }
+  if (query.search) {
+    where.OR = [
+      { subject: { contains: query.search, mode: 'insensitive' } },
+      { snippet: { contains: query.search, mode: 'insensitive' } },
+      { messages: { some: { body: { contains: query.search, mode: 'insensitive' } } } },
+    ];
+  }
+  if (query.label) {
+    where.labels = { some: { name: query.label } };
+  }
+  if (query.tag) {
+    where.tags = { some: { name: query.tag } };
+  }
+
+  const [threads, total] = await Promise.all([
+    prisma.emailThread.findMany({
+      where,
+      include: {
+        messages: {
+          orderBy: { createdAt: 'desc' },
+          take: 1,
+          select: { fromName: true, createdAt: true },
+        },
+        labels: { select: { id: true, name: true, color: true } },
+        tags: { select: { id: true, name: true, color: true } },
+        _count: { select: { messages: true } },
+      },
+      orderBy: { [query.sortBy]: query.sortOrder },
+      skip: (query.page - 1) * query.limit,
+      take: query.limit,
+    }),
+    prisma.emailThread.count({ where }),
+  ]);
+
+  return {
+    threads: threads.map((t) => ({
+      id: t.id,
+      subject: t.subject,
+      snippet: t.snippet,
+      isRead: t.isRead,
+      isStarred: t.isStarred,
+      category: t.category,
+      priority: t.priority,
+      createdAt: t.createdAt,
+      updatedAt: t.updatedAt,
+      messageCount: t._count.messages,
+      lastMessageFrom: t.messages[0]?.fromName ?? '',
+      labels: t.labels,
+      tags: t.tags,
+    })),
+    total,
+    page: query.page,
+    limit: query.limit,
+    totalPages: Math.ceil(total / query.limit),
+  };
+}
+
+export async function getThreadById(id: string) {
+  const thread = await prisma.emailThread.findUnique({
+    where: { id },
+    include: {
+      messages: { orderBy: { createdAt: 'asc' } },
+      labels: { select: { id: true, name: true, color: true } },
+      tags: { select: { id: true, name: true, color: true } },
+    },
+  });
+  return thread;
+}
diff --git a/packages/email-threads-api/tsconfig.json b/packages/email-threads-api/tsconfig.json
new file mode 100644
index 00000000..dcf76e55
--- /dev/null
+++ b/packages/email-threads-api/tsconfig.json
@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022"],
+    "outDir": "./dist",
+    "rootDir": "./src",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "declaration": true,
+    "sourceMap": true,
+    "allowSyntheticDefaultImports": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}