diff --git a/packages/api/src/__tests__/bounty_detail.test.ts b/packages/api/src/__tests__/bounty_detail.test.ts
new file mode 100644
index 0000000..1bf6485
--- /dev/null
+++ b/packages/api/src/__tests__/bounty_detail.test.ts
@@ -0,0 +1,78 @@
+import { describe, it, expect, beforeAll, vi, beforeEach } from 'vitest';
+import { createApp } from '../app';
+import { verify } from 'hono/jwt';
+import { db } from '../db';
+
+vi.mock('hono/jwt', () => ({ verify: vi.fn() }));
+
+vi.mock('../db', () => ({
+  db: {
+    query: {
+      bounties: { findMany: vi.fn(), findFirst: vi.fn() },
+      users: { findFirst: vi.fn() },
+    },
+    select: vi.fn(() => ({ from: vi.fn(() => ({ where: vi.fn() })) })),
+  },
+}));
+
+describe('GET /api/bounties/:id', () => {
+  let app: ReturnType<typeof createApp>;
+
+  beforeAll(() => {
+    app = createApp();
+    vi.mocked(verify).mockResolvedValue({
+      sub: 'test-user-id',
+      username: 'testuser',
+      exp: Math.floor(Date.now() / 1000) + 3600,
+    });
+    process.env.JWT_PUBLIC_KEY = '-----BEGIN PUBLIC KEY-----\nfake\n-----END PUBLIC KEY-----';
+  });
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('returns enriched bounty detail with creator, assignee and application_count', async () => {
+    vi.mocked(db.query.bounties.findFirst).mockResolvedValue({
+      id: 'b1',
+      title: 'Test',
+      creatorId: 'u1',
+      assigneeId: 'u2',
+      status: 'assigned',
+    } as any);
+
+    vi.mocked(db.query.users.findFirst)
+      .mockResolvedValueOnce({ id: 'u1', username: 'creator', avatarUrl: 'creator.png' } as any)
+      .mockResolvedValueOnce({ id: 'u2', username: 'assignee', avatarUrl: 'assignee.png' } as any);
+
+    (db.select as any).mockReturnValue({
+      from: () => ({
+        where: () => Promise.resolve([{ count: 3 }]),
+      }),
+    });
+
+    const res = await app.request('/api/bounties/b1', {
+      headers: { Authorization: 'Bearer valid.token' },
+    });
+
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.id).toBe('b1');
+    expect(body.creator).toEqual({ username: 'creator', avatar_url: 'creator.png' });
+    expect(body.assignee).toEqual({ username: 'assignee', avatar_url: 'assignee.png' });
+    expect(body.application_count).toBe(3);
+    expect(body.status).toBe('assigned');
+  });
+
+  it('returns 404 when bounty does not exist', async () => {
+    vi.mocked(db.query.bounties.findFirst).mockResolvedValue(undefined as any);
+
+    const res = await app.request('/api/bounties/missing', {
+      headers: { Authorization: 'Bearer valid.token' },
+    });
+
+    expect(res.status).toBe(404);
+    const body = await res.json();
+    expect(body.error).toBe('Bounty not found');
+  });
+});
diff --git a/packages/api/src/routes/bounties.ts b/packages/api/src/routes/bounties.ts
index 2f4f6e6..3407e86 100644
--- a/packages/api/src/routes/bounties.ts
+++ b/packages/api/src/routes/bounties.ts
@@ -2,8 +2,8 @@ import { Hono } from 'hono';
 import { Variables } from '../middleware/auth';
 import { ensureBountyCreator, ensureBountyAssignee } from '../middleware/resource-auth';
 import { db } from '../db';
-import { bounties } from '../db/schema';
-import { eq, and, gte, lte, sql, desc, or, lt } from 'drizzle-orm';
+import { bounties, users, applications } from '../db/schema';
+import { eq, and, gte, lte, sql, desc, or, lt, count } from 'drizzle-orm';
 
 const bountiesRouter = new Hono<{ Variables: Variables }>();
 
@@ -136,7 +136,34 @@ bountiesRouter.get('/:id', async (c) => {
         return c.json({ error: 'Bounty not found' }, 404);
     }
 
-    return c.json(bounty);
+    const [creator, assignee, applicationCountRows] = await Promise.all([
+        db.query.users.findFirst({
+            where: eq(users.id, bounty.creatorId),
+            columns: { username: true, avatarUrl: true },
+        }),
+        bounty.assigneeId
+            ? db.query.users.findFirst({
+                where: eq(users.id, bounty.assigneeId),
+                columns: { username: true, avatarUrl: true },
+            })
+            : Promise.resolve(null),
+        db.select({ count: count() }).from(applications).where(eq(applications.bountyId, bounty.id)),
+    ]);
+
+    return c.json({
+        ...bounty,
+        creator: {
+            username: creator?.username ?? null,
+            avatar_url: creator?.avatarUrl ?? null,
+        },
+        assignee: assignee
+            ? {
+                username: assignee.username ?? null,
+                avatar_url: assignee.avatarUrl ?? null,
+            }
+            : null,
+        application_count: Number(applicationCountRows[0]?.count ?? 0),
+    });
 });
 
 /**