diff --git a/browse/src/sidebar-agent.ts b/browse/src/sidebar-agent.ts
index 6f28f5f4..6eb2cebb 100644
--- a/browse/src/sidebar-agent.ts
+++ b/browse/src/sidebar-agent.ts
@@ -13,7 +13,7 @@ import { spawn } from 'child_process';
 import * as fs from 'fs';
 import * as path from 'path';
 
-const QUEUE = path.join(process.env.HOME || '/tmp', '.gstack', 'sidebar-agent-queue.jsonl');
+const QUEUE = process.env.SIDEBAR_QUEUE_PATH || path.join(process.env.HOME || '/tmp', '.gstack', 'sidebar-agent-queue.jsonl');
 const SERVER_PORT = parseInt(process.env.BROWSE_SERVER_PORT || '34567', 10);
 const SERVER_URL = `http://127.0.0.1:${SERVER_PORT}`;
 const POLL_MS = 500;  // Fast polling — server already did the user-facing response
@@ -205,14 +205,15 @@ async function askClaude(queueEntry: any): Promise<void> {
       });
     });
 
-    // Timeout after 300 seconds (5 min — multi-page tasks need time)
+    // Timeout (default 300s / 5 min — multi-page tasks need time)
+    const timeoutMs = parseInt(process.env.SIDEBAR_AGENT_TIMEOUT || '300000', 10);
     setTimeout(() => {
       try { proc.kill(); } catch {}
-      sendEvent({ type: 'agent_error', error: 'Timed out after 300s' }).then(() => {
+      sendEvent({ type: 'agent_error', error: `Timed out after ${timeoutMs / 1000}s` }).then(() => {
         isProcessing = false;
         resolve();
       });
-    }, 300000);
+    }, timeoutMs);
   });
 }
 
diff --git a/browse/src/sidebar-utils.ts b/browse/src/sidebar-utils.ts
new file mode 100644
index 00000000..c5ff201d
--- /dev/null
+++ b/browse/src/sidebar-utils.ts
@@ -0,0 +1,21 @@
+/**
+ * Shared sidebar utilities — extracted for testability.
+ */
+
+/**
+ * Sanitize a URL from the Chrome extension before embedding in a prompt.
+ * Only accepts http/https, strips control characters, truncates to 2048 chars.
+ * Returns null if the URL is invalid or uses a non-http scheme.
+ */
+export function sanitizeExtensionUrl(url: string | null | undefined): string | null {
+  if (!url) return null;
+  try {
+    const u = new URL(url);
+    if (u.protocol === 'http:' || u.protocol === 'https:') {
+      return u.href.replace(/[\x00-\x1f\x7f]/g, '').slice(0, 2048);
+    }
+    return null;
+  } catch {
+    return null;
+  }
+}
diff --git a/browse/test/sidebar-integration.test.ts b/browse/test/sidebar-integration.test.ts
new file mode 100644
index 00000000..bcafe052
--- /dev/null
+++ b/browse/test/sidebar-integration.test.ts
@@ -0,0 +1,320 @@
+/**
+ * Layer 2: Server HTTP integration tests for sidebar endpoints.
+ * Starts the browse server as a subprocess (no browser via BROWSE_HEADLESS_SKIP),
+ * exercises sidebar HTTP endpoints with fetch(). No Chrome, no Claude, no sidebar-agent.
+ */
+
+import { describe, test, expect, beforeAll, afterAll, beforeEach } from 'bun:test';
+import { spawn, type Subprocess } from 'bun';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+
+let serverProc: Subprocess | null = null;
+let serverPort: number = 0;
+let authToken: string = '';
+let tmpDir: string = '';
+let stateFile: string = '';
+let queueFile: string = '';
+
+async function api(pathname: string, opts: RequestInit & { noAuth?: boolean } = {}): Promise<Response> {
+  const { noAuth, ...fetchOpts } = opts;
+  const headers: Record<string, string> = {
+    'Content-Type': 'application/json',
+    ...(fetchOpts.headers as Record<string, string> || {}),
+  };
+  if (!noAuth && !headers['Authorization'] && authToken) {
+    headers['Authorization'] = `Bearer ${authToken}`;
+  }
+  return fetch(`http://127.0.0.1:${serverPort}${pathname}`, { ...fetchOpts, headers });
+}
+
+beforeAll(async () => {
+  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'sidebar-integ-'));
+  stateFile = path.join(tmpDir, 'browse.json');
+  queueFile = path.join(tmpDir, 'sidebar-queue.jsonl');
+
+  // Ensure queue dir exists
+  fs.mkdirSync(path.dirname(queueFile), { recursive: true });
+
+  const serverScript = path.resolve(__dirname, '..', 'src', 'server.ts');
+  serverProc = spawn(['bun', 'run', serverScript], {
+    env: {
+      ...process.env,
+      BROWSE_STATE_FILE: stateFile,
+      BROWSE_HEADLESS_SKIP: '1',
+      BROWSE_PORT: '0',
+      SIDEBAR_QUEUE_PATH: queueFile,
+      BROWSE_IDLE_TIMEOUT: '300',
+    },
+    stdio: ['ignore', 'pipe', 'pipe'],
+  });
+
+  // Wait for state file
+  const deadline = Date.now() + 15000;
+  while (Date.now() < deadline) {
+    if (fs.existsSync(stateFile)) {
+      try {
+        const state = JSON.parse(fs.readFileSync(stateFile, 'utf-8'));
+        if (state.port && state.token) {
+          serverPort = state.port;
+          authToken = state.token;
+          break;
+        }
+      } catch {}
+    }
+    await new Promise(r => setTimeout(r, 100));
+  }
+  if (!serverPort) throw new Error('Server did not start in time');
+}, 20000);
+
+afterAll(() => {
+  if (serverProc) { try { serverProc.kill(); } catch {} }
+  try { fs.rmSync(tmpDir, { recursive: true, force: true }); } catch {}
+});
+
+// Reset state between tests — creates a fresh session, clears all queues
+async function resetState() {
+  await api('/sidebar-session/new', { method: 'POST' });
+  fs.writeFileSync(queueFile, '');
+}
+
+describe('sidebar auth', () => {
+  test('rejects request without auth token', async () => {
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      noAuth: true,
+      body: JSON.stringify({ message: 'test' }),
+    });
+    expect(resp.status).toBe(401);
+  });
+
+  test('rejects request with wrong token', async () => {
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      headers: { 'Authorization': 'Bearer wrong-token' },
+      body: JSON.stringify({ message: 'test' }),
+    });
+    expect(resp.status).toBe(401);
+  });
+
+  test('accepts request with correct token', async () => {
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'hello' }),
+    });
+    expect(resp.status).toBe(200);
+    // Clean up
+    await api('/sidebar-agent/kill', { method: 'POST' });
+  });
+});
+
+describe('sidebar-command → queue', () => {
+  test('writes queue entry with activeTabUrl', async () => {
+    await resetState();
+
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({
+        message: 'what is on this page?',
+        activeTabUrl: 'https://example.com/test-page',
+      }),
+    });
+    expect(resp.status).toBe(200);
+    const data = await resp.json();
+    expect(data.ok).toBe(true);
+
+    // Give server a moment to write queue
+    await new Promise(r => setTimeout(r, 100));
+
+    const content = fs.readFileSync(queueFile, 'utf-8').trim();
+    const lines = content.split('\n').filter(Boolean);
+    expect(lines.length).toBeGreaterThan(0);
+    const entry = JSON.parse(lines[lines.length - 1]);
+    expect(entry.pageUrl).toBe('https://example.com/test-page');
+    expect(entry.prompt).toContain('https://example.com/test-page');
+
+    await api('/sidebar-agent/kill', { method: 'POST' });
+  });
+
+  test('falls back when activeTabUrl is null', async () => {
+    await resetState();
+
+    await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'test', activeTabUrl: null }),
+    });
+    await new Promise(r => setTimeout(r, 100));
+
+    const lines = fs.readFileSync(queueFile, 'utf-8').trim().split('\n').filter(Boolean);
+    expect(lines.length).toBeGreaterThan(0);
+    const entry = JSON.parse(lines[lines.length - 1]);
+    // No browser → playwright URL is 'about:blank'
+    expect(entry.pageUrl).toBe('about:blank');
+
+    await api('/sidebar-agent/kill', { method: 'POST' });
+  });
+
+  test('rejects chrome:// activeTabUrl and falls back', async () => {
+    await resetState();
+
+    await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'test', activeTabUrl: 'chrome://extensions' }),
+    });
+    await new Promise(r => setTimeout(r, 100));
+
+    const lines = fs.readFileSync(queueFile, 'utf-8').trim().split('\n').filter(Boolean);
+    expect(lines.length).toBeGreaterThan(0);
+    const entry = JSON.parse(lines[lines.length - 1]);
+    expect(entry.pageUrl).toBe('about:blank');
+
+    await api('/sidebar-agent/kill', { method: 'POST' });
+  });
+
+  test('rejects empty message', async () => {
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: '' }),
+    });
+    expect(resp.status).toBe(400);
+  });
+});
+
+describe('sidebar-agent/event → chat buffer', () => {
+  test('agent events appear in /sidebar-chat', async () => {
+    await resetState();
+
+    // Post mock agent events using Claude's streaming format
+    await api('/sidebar-agent/event', {
+      method: 'POST',
+      body: JSON.stringify({
+        type: 'assistant',
+        message: { content: [{ type: 'text', text: 'Hello from mock agent' }] },
+      }),
+    });
+
+    const chatData = await (await api('/sidebar-chat?after=0')).json();
+    const textEntry = chatData.entries.find((e: any) => e.type === 'text');
+    expect(textEntry).toBeDefined();
+    expect(textEntry.text).toBe('Hello from mock agent');
+  });
+
+  test('agent_done transitions status to idle', async () => {
+    await resetState();
+    // Start a command so agent is processing
+    await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'test' }),
+    });
+
+    // Verify processing
+    let session = await (await api('/sidebar-session')).json();
+    expect(session.agent.status).toBe('processing');
+
+    // Send agent_done
+    await api('/sidebar-agent/event', {
+      method: 'POST',
+      body: JSON.stringify({ type: 'agent_done' }),
+    });
+
+    session = await (await api('/sidebar-session')).json();
+    expect(session.agent.status).toBe('idle');
+  });
+});
+
+describe('message queuing', () => {
+  test('queues message when agent is processing', async () => {
+    await resetState();
+
+    // First message starts processing
+    await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'first' }),
+    });
+
+    // Second message gets queued
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'second' }),
+    });
+    const data = await resp.json();
+    expect(data.ok).toBe(true);
+    expect(data.queued).toBe(true);
+    expect(data.position).toBe(1);
+
+    await api('/sidebar-agent/kill', { method: 'POST' });
+  });
+
+  test('returns 429 when queue is full', async () => {
+    await resetState();
+
+    // First message starts processing
+    await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'first' }),
+    });
+
+    // Fill queue (max 5)
+    for (let i = 0; i < 5; i++) {
+      await api('/sidebar-command', {
+        method: 'POST',
+        body: JSON.stringify({ message: `fill-${i}` }),
+      });
+    }
+
+    // 7th message should be rejected
+    const resp = await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'overflow' }),
+    });
+    expect(resp.status).toBe(429);
+
+    await api('/sidebar-agent/kill', { method: 'POST' });
+  });
+});
+
+describe('chat clear', () => {
+  test('clears chat buffer', async () => {
+    await resetState();
+    // Add some entries
+    await api('/sidebar-agent/event', {
+      method: 'POST',
+      body: JSON.stringify({ type: 'text', text: 'to be cleared' }),
+    });
+
+    await api('/sidebar-chat/clear', { method: 'POST' });
+
+    const data = await (await api('/sidebar-chat?after=0')).json();
+    expect(data.entries.length).toBe(0);
+    expect(data.total).toBe(0);
+  });
+});
+
+describe('agent kill', () => {
+  test('kill adds error entry and returns to idle', async () => {
+    await resetState();
+
+    // Start a command so agent is processing
+    await api('/sidebar-command', {
+      method: 'POST',
+      body: JSON.stringify({ message: 'kill me' }),
+    });
+
+    let session = await (await api('/sidebar-session')).json();
+    expect(session.agent.status).toBe('processing');
+
+    // Kill the agent
+    const killResp = await api('/sidebar-agent/kill', { method: 'POST' });
+    expect(killResp.status).toBe(200);
+
+    // Check chat for error entry
+    const chatData = await (await api('/sidebar-chat?after=0')).json();
+    const errorEntry = chatData.entries.find((e: any) => e.error === 'Killed by user');
+    expect(errorEntry).toBeDefined();
+
+    // Agent should be idle (no queue items to auto-process)
+    session = await (await api('/sidebar-session')).json();
+    expect(session.agent.status).toBe('idle');
+  });
+});
diff --git a/browse/test/sidebar-unit.test.ts b/browse/test/sidebar-unit.test.ts
new file mode 100644
index 00000000..3c0459a0
--- /dev/null
+++ b/browse/test/sidebar-unit.test.ts
@@ -0,0 +1,96 @@
+/**
+ * Layer 1: Unit tests for sidebar utilities.
+ * Tests pure functions — no server, no processes, no network.
+ */
+
+import { describe, test, expect } from 'bun:test';
+import { sanitizeExtensionUrl } from '../src/sidebar-utils';
+
+describe('sanitizeExtensionUrl', () => {
+  test('passes valid http URL', () => {
+    expect(sanitizeExtensionUrl('http://example.com')).toBe('http://example.com/');
+  });
+
+  test('passes valid https URL', () => {
+    expect(sanitizeExtensionUrl('https://example.com/page?q=1')).toBe('https://example.com/page?q=1');
+  });
+
+  test('rejects chrome:// URLs', () => {
+    expect(sanitizeExtensionUrl('chrome://extensions')).toBeNull();
+  });
+
+  test('rejects chrome-extension:// URLs', () => {
+    expect(sanitizeExtensionUrl('chrome-extension://abcdef/popup.html')).toBeNull();
+  });
+
+  test('rejects javascript: URLs', () => {
+    expect(sanitizeExtensionUrl('javascript:alert(1)')).toBeNull();
+  });
+
+  test('rejects file:// URLs', () => {
+    expect(sanitizeExtensionUrl('file:///etc/passwd')).toBeNull();
+  });
+
+  test('rejects data: URLs', () => {
+    expect(sanitizeExtensionUrl('data:text/html,<h1>hi</h1>')).toBeNull();
+  });
+
+  test('strips raw control characters from URL', () => {
+    // URL constructor percent-encodes \x00 as %00, which is safe
+    // The regex strips any remaining raw control chars after .href normalization
+    const result = sanitizeExtensionUrl('https://example.com/\x00page\x1f');
+    expect(result).not.toBeNull();
+    expect(result!).not.toMatch(/[\x00-\x1f\x7f]/);
+  });
+
+  test('strips newlines (prompt injection vector)', () => {
+    const result = sanitizeExtensionUrl('https://evil.com/%0AUser:%20ignore');
+    // URL constructor normalizes %0A, control char stripping removes any raw newlines
+    expect(result).not.toBeNull();
+    expect(result!).not.toContain('\n');
+  });
+
+  test('truncates URLs longer than 2048 chars', () => {
+    const longUrl = 'https://example.com/' + 'a'.repeat(3000);
+    const result = sanitizeExtensionUrl(longUrl);
+    expect(result).not.toBeNull();
+    expect(result!.length).toBeLessThanOrEqual(2048);
+  });
+
+  test('returns null for null input', () => {
+    expect(sanitizeExtensionUrl(null)).toBeNull();
+  });
+
+  test('returns null for undefined input', () => {
+    expect(sanitizeExtensionUrl(undefined)).toBeNull();
+  });
+
+  test('returns null for empty string', () => {
+    expect(sanitizeExtensionUrl('')).toBeNull();
+  });
+
+  test('returns null for invalid URL string', () => {
+    expect(sanitizeExtensionUrl('not a url at all')).toBeNull();
+  });
+
+  test('does not crash on weird input', () => {
+    expect(sanitizeExtensionUrl(':///')).toBeNull();
+    expect(sanitizeExtensionUrl('   ')).toBeNull();
+    expect(sanitizeExtensionUrl('\x00\x01\x02')).toBeNull();
+  });
+
+  test('preserves query parameters and fragments', () => {
+    const url = 'https://example.com/search?q=test&page=2#results';
+    expect(sanitizeExtensionUrl(url)).toBe(url);
+  });
+
+  test('preserves port numbers', () => {
+    expect(sanitizeExtensionUrl('http://localhost:3000/api')).toBe('http://localhost:3000/api');
+  });
+
+  test('handles URL with auth (user:pass@host)', () => {
+    const result = sanitizeExtensionUrl('https://user:pass@example.com/');
+    expect(result).not.toBeNull();
+    expect(result).toContain('example.com');
+  });
+});
diff --git a/package.json b/package.json
index de2b664f..dd8c200d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "gstack",
-  "version": "0.12.0.0",
+  "version": "0.12.2.0",
   "description": "Garry's Stack — Claude Code skills + fast headless browser. One repo, one install, entire AI engineering workflow.",
   "license": "MIT",
   "type": "module",