fix: remove auth token from /health, secure extension bootstrap (CRITICAL-02 + HIGH-03)

- Remove token from /health response (was leaked to any localhost process)
- Write .auth.json to extension dir for Manifest V3 bootstrap
- sidebar-agent reads token from state file via BROWSE_STATE_FILE env var
- Remove getToken handler from extension (token via health broadcast)
- Extension loads token before first health poll to prevent race condition

extension/background.js

@@ -30,6 +30,19 @@ function getBaseUrl() {
   return serverPort ? `http://127.0.0.1:${serverPort}` : null;
 }
 
+// ─── Auth Token Bootstrap ─────────────────────────────────────
+
+async function loadAuthToken() {
+  if (authToken) return;
+  try {
+    const resp = await fetch(chrome.runtime.getURL('.auth.json'));
+    if (resp.ok) {
+      const data = await resp.json();
+      if (data.token) authToken = data.token;
+    }
+  } catch {}
+}
+
 // ─── Health Polling ────────────────────────────────────────────
 
 async function checkHealth() {
@@ -39,13 +52,14 @@ async function checkHealth() {
     return;
   }
 
+  // Retry loading auth token if we don't have one yet
+  if (!authToken) await loadAuthToken();
+
   try {
     const resp = await fetch(`${base}/health`, { signal: AbortSignal.timeout(3000) });
     if (!resp.ok) { setDisconnected(); return; }
     const data = await resp.json();
     if (data.status === 'healthy') {
-      // Capture auth token from health response
-      if (data.token) authToken = data.token;
       // Forward chatEnabled so sidepanel can show/hide chat tab
       setConnected({ ...data, chatEnabled: !!data.chatEnabled });
     } else {
@@ -62,8 +76,8 @@ function setConnected(healthData) {
   chrome.action.setBadgeBackgroundColor({ color: '#F59E0B' });
   chrome.action.setBadgeText({ text: ' ' });
 
-  // Broadcast health to popup and side panel
-  chrome.runtime.sendMessage({ type: 'health', data: healthData }).catch(() => {});
+  // Broadcast health to popup and side panel (include token for sidepanel auth)
+  chrome.runtime.sendMessage({ type: 'health', data: { ...healthData, token: authToken } }).catch(() => {});
 
   // Notify content scripts on connection change
   if (wasDisconnected) {
@@ -74,7 +88,7 @@ function setConnected(healthData) {
 function setDisconnected() {
   const wasConnected = isConnected;
   isConnected = false;
-  authToken = null;
+  // Keep authToken — it comes from .auth.json, not /health
   chrome.action.setBadgeText({ text: '' });
 
   chrome.runtime.sendMessage({ type: 'health', data: null }).catch(() => {});
@@ -128,7 +142,9 @@ async function fetchAndRelayRefs() {
   if (!base || !isConnected) return;
 
   try {
-    const resp = await fetch(`${base}/refs`, { signal: AbortSignal.timeout(3000) });
+    const headers = {};
+    if (authToken) headers['Authorization'] = `Bearer ${authToken}`;
+    const resp = await fetch(`${base}/refs`, { signal: AbortSignal.timeout(3000), headers });
     if (!resp.ok) return;
     const data = await resp.json();
 
@@ -163,10 +179,7 @@ chrome.runtime.onMessage.addListener((msg, sender, sendResponse) => {
     return true;
   }
 
-  if (msg.type === 'getToken') {
-    sendResponse({ token: authToken });
-    return true;
-  }
+  // getToken handler removed — token distributed via health broadcast
 
   if (msg.type === 'fetchRefs') {
     fetchAndRelayRefs().then(() => sendResponse({ ok: true }));
@@ -237,7 +250,10 @@ chrome.runtime.onInstalled.addListener(async () => {
 
 // ─── Startup ────────────────────────────────────────────────────
 
-loadPort().then(() => {
-  checkHealth();
-  healthInterval = setInterval(checkHealth, 10000);
+// Load auth token BEFORE first health poll (token no longer in /health response)
+loadAuthToken().then(() => {
+  loadPort().then(() => {
+    checkHealth();
+    healthInterval = setInterval(checkHealth, 10000);
+  });
 });

extension/sidepanel.js

@@ -413,7 +413,7 @@ function createEntryElement(entry) {
   div.innerHTML = `
     <div class="entry-header">
       <span class="entry-time">${formatTime(entry.timestamp)}</span>
-      <span class="entry-command">${entry.command || entry.type}</span>
+      <span class="entry-command">${escapeHtml(entry.command || entry.type)}</span>
     </div>
     ${argsText ? `<div class="entry-args">${escapeHtml(argsText)}</div>` : ''}
     ${entry.type === 'command_end' ? `
@@ -469,7 +469,8 @@ function connectSSE() {
   if (!serverUrl) return;
   if (eventSource) { eventSource.close(); eventSource = null; }
 
-  const url = `${serverUrl}/activity/stream?after=${lastId}`;
+  const tokenParam = serverToken ? `&token=${serverToken}` : '';
+  const url = `${serverUrl}/activity/stream?after=${lastId}${tokenParam}`;
   eventSource = new EventSource(url);
 
   eventSource.addEventListener('activity', (e) => {
@@ -493,7 +494,9 @@ function connectSSE() {
 async function fetchRefs() {
   if (!serverUrl) return;
   try {
-    const resp = await fetch(`${serverUrl}/refs`, { signal: AbortSignal.timeout(3000) });
+    const headers = {};
+    if (serverToken) headers['Authorization'] = `Bearer ${serverToken}`;
+    const resp = await fetch(`${serverUrl}/refs`, { signal: AbortSignal.timeout(3000), headers });
     if (!resp.ok) return;
     const data = await resp.json();
 
@@ -594,10 +597,8 @@ function tryConnect() {
   chrome.runtime.sendMessage({ type: 'getPort' }, (resp) => {
     if (resp && resp.port && resp.connected) {
       const url = `http://127.0.0.1:${resp.port}`;
-      // Get the token from background
-      chrome.runtime.sendMessage({ type: 'getToken' }, (tokenResp) => {
-        updateConnection(url, tokenResp?.token);
-      });
+      // Token arrives via health broadcast from background.js
+      updateConnection(url, null);
     } else {
       setTimeout(tryConnect, 2000);
     }