diff --git a/apps/agent-worker/src/terminal-token.ts b/apps/agent-worker/src/terminal-token.ts
index 29a70fb..98aeace 100644
--- a/apps/agent-worker/src/terminal-token.ts
+++ b/apps/agent-worker/src/terminal-token.ts
@@ -27,3 +27,28 @@ export const verifyTerminalToken = (
     timingSafeEqual(providedBuf, expectedBuf)
   );
 };
+
+// User-scoped variant authorizing a terminal connection to a user's box.
+// Embeds a literal `box` segment so its four parts never collide with the
+// three-part job token above. Format:
+//   `${expiresAtMs}.box.${username}.${hmacSha256Hex}`
+export const verifyBoxTerminalToken = (
+  token: string,
+  username: string,
+  secret: string,
+): boolean => {
+  if (!token || !secret) return false;
+  const parts = token.split('.');
+  if (parts.length !== 4 || parts[1] !== 'box') return false;
+  const [expRaw, , tokenUsername, provided] = parts;
+  if (tokenUsername !== username) return false;
+  const exp = Number.parseInt(expRaw ?? '', 10);
+  if (!Number.isFinite(exp) || Date.now() > exp) return false;
+  const expected = signature(`${expRaw}.box.${tokenUsername}`, secret);
+  const providedBuf = Buffer.from(provided ?? '', 'hex');
+  const expectedBuf = Buffer.from(expected, 'hex');
+  return (
+    providedBuf.length === expectedBuf.length &&
+    timingSafeEqual(providedBuf, expectedBuf)
+  );
+};
diff --git a/apps/agent-worker/tests/unit/box-terminal-token.test.ts b/apps/agent-worker/tests/unit/box-terminal-token.test.ts
new file mode 100644
index 0000000..147aeaf
--- /dev/null
+++ b/apps/agent-worker/tests/unit/box-terminal-token.test.ts
@@ -0,0 +1,49 @@
+import { createHmac } from 'node:crypto';
+import { describe, expect, test } from 'vitest';
+
+import { verifyBoxTerminalToken } from '../../src/terminal-token';
+
+const mintBox = (username: string, expiresAt: number, secret: string) => {
+  const payload = `${expiresAt}.box.${username}`;
+  const sig = createHmac('sha256', secret).update(payload).digest('hex');
+  return `${payload}.${sig}`;
+};
+
+describe('verifyBoxTerminalToken', () => {
+  const secret = 'test-secret';
+
+  test('accepts a valid, unexpired, username-matched token', () => {
+    const token = mintBox('alice', Date.now() + 60_000, secret);
+    expect(verifyBoxTerminalToken(token, 'alice', secret)).toBe(true);
+  });
+
+  test('rejects an expired token', () => {
+    const token = mintBox('alice', Date.now() - 1, secret);
+    expect(verifyBoxTerminalToken(token, 'alice', secret)).toBe(false);
+  });
+
+  test('rejects a token minted for another username', () => {
+    const token = mintBox('alice', Date.now() + 60_000, secret);
+    expect(verifyBoxTerminalToken(token, 'bob', secret)).toBe(false);
+  });
+
+  test('rejects a token signed with a different secret', () => {
+    const token = mintBox('alice', Date.now() + 60_000, 'other-secret');
+    expect(verifyBoxTerminalToken(token, 'alice', secret)).toBe(false);
+  });
+
+  test('rejects malformed input and an empty secret', () => {
+    expect(verifyBoxTerminalToken('garbage', 'alice', secret)).toBe(false);
+    expect(verifyBoxTerminalToken('', 'alice', secret)).toBe(false);
+    expect(
+      verifyBoxTerminalToken(mintBox('alice', Date.now() + 1000, ''), 'alice', ''),
+    ).toBe(false);
+  });
+
+  test('rejects a 3-part job token (cross-scheme confusion guard)', () => {
+    const payload = `${Date.now() + 60_000}.alice`;
+    const sig = createHmac('sha256', secret).update(payload).digest('hex');
+    const jobToken = `${payload}.${sig}`;
+    expect(verifyBoxTerminalToken(jobToken, 'alice', secret)).toBe(false);
+  });
+});