diff --git a/browse/src/server.ts b/browse/src/server.ts
index d70c98c2..1e054d2c 100644
--- a/browse/src/server.ts
+++ b/browse/src/server.ts
@@ -480,8 +480,8 @@ function spawnClaude(userMessage: string, extensionUrl?: string | null, forTabId
   const prompt = `${systemPrompt}\n\n<user-message>\n${escapedMessage}\n</user-message>`;
   // Never resume — each message is a fresh context. Resuming carries stale
   // page URLs and old navigation state that makes the agent fight the user.
-  const args = ['-p', prompt, '--output-format', 'stream-json', '--verbose',
-    '--allowedTools', 'Bash,Read,Glob,Grep'];
+  const args = ['-p', prompt, '--model', 'opus', '--output-format', 'stream-json', '--verbose',
+    '--allowedTools', 'Bash,Read,Glob,Grep,Write'];
 
   addChatEntry({ ts: new Date().toISOString(), role: 'agent', type: 'agent_start' });
 
diff --git a/browse/test/sidebar-security.test.ts b/browse/test/sidebar-security.test.ts
index 33c64b49..71f2190a 100644
--- a/browse/test/sidebar-security.test.ts
+++ b/browse/test/sidebar-security.test.ts
@@ -110,7 +110,7 @@ describe('Sidebar prompt injection defense', () => {
     // It should NOT rebuild args from scratch (the old bug)
     expect(AGENT_SRC).toContain('args || [');
     // Verify the destructured args come from queueEntry
-    expect(AGENT_SRC).toContain('const { prompt, args, stateFile, cwd } = queueEntry');
+    expect(AGENT_SRC).toContain('const { prompt, args, stateFile, cwd, tabId } = queueEntry');
   });
 
   test('sidebar-agent falls back to defaults if queue has no args', () => {
diff --git a/browse/test/sidebar-ux.test.ts b/browse/test/sidebar-ux.test.ts
index bc595e7a..fe96006e 100644
--- a/browse/test/sidebar-ux.test.ts
+++ b/browse/test/sidebar-ux.test.ts
@@ -221,14 +221,14 @@ describe('sidebar agent queue poll (sidebar-agent.ts)', () => {
 describe('system prompt size', () => {
   const serverSrc = fs.readFileSync(path.join(ROOT, 'src', 'server.ts'), 'utf-8');
 
-  test('system prompt is compact (under 20 lines)', () => {
+  test('system prompt is compact (under 30 lines)', () => {
     const start = serverSrc.indexOf('const systemPrompt = [');
     const end = serverSrc.indexOf("].join('\\n');", start);
     const promptBlock = serverSrc.slice(start, end);
     const lines = promptBlock.split('\n').length;
     // Compact prompt = fewer input tokens = faster first response
-    // Slightly higher limit because of per-tab instruction line
-    expect(lines).toBeLessThan(20);
+    // Higher limit accommodates security lines (prompt injection defense, allowed commands)
+    expect(lines).toBeLessThan(30);
   });
 
   test('system prompt does not contain verbose narration examples', () => {