feat: harden remote serve and reuse connections

- Gate TCP serve commands with safe-by-default policies, per-key allow tokens, per-key rate limiting, and audit labels.
- Reuse authenticated encrypted remote sessions and parallelize/caches multi-browser fanout to reduce repeated handshake roundtrips.
- Increase paged native-host batch size with extension-side byte budgeting to speed large tab listings safely.
- Point install output at public Chrome Web Store / Firefox AMO listings by default, with --dev preserving unpacked workflows.
- Share search-engine metadata between CLI and SDK and bump the package/extension version to 0.16.0.
- Cover the new security, pooling, paging, install, and fanout behavior with expanded Python and extension tests.

browser_cli/commands/serve_http.py

@@ -10,6 +10,7 @@ from rich.console import Console
 
 from browser_cli import BrowserCLI
 from browser_cli.command_security import CommandPolicy, assert_command_allowed
+from browser_cli.commands import command_policy_from_options, command_policy_options
 
 console = Console()
 
@@ -24,9 +25,11 @@ class _Handler(BaseHTTPRequestHandler):
   def _authorized(self) -> bool:
     if self.token is None:
       return True
-    if self.headers.get("Authorization", "") == f"Bearer {self.token}":
+    bearer = self.headers.get("Authorization", "")
+    if bearer.startswith("Bearer ") and secrets.compare_digest(bearer[len("Bearer "):], self.token):
       return True
-    return self.headers.get("X-Browser-CLI-Token") == self.token
+    header = self.headers.get("X-Browser-CLI-Token")
+    return header is not None and secrets.compare_digest(header, self.token)
 
   def _require_auth(self) -> bool:
     if self._authorized():
@@ -87,10 +90,8 @@ class _Handler(BaseHTTPRequestHandler):
 @click.option("--key", default=None, help="Remote auth key spec")
 @click.option("--token", default=None, help="Bearer token required for HTTP access (generated by default)")
 @click.option("--no-auth", is_flag=True, help="Disable HTTP auth (only allowed on loopback hosts)")
-@click.option("--allow-read-page", is_flag=True, help="Allow /command to run page-content read commands")
-@click.option("--allow-control", is_flag=True, help="Allow /command to run browser-control commands")
-@click.option("--allow-dangerous", is_flag=True, help="Allow /command to run high-risk commands")
-def cmd_serve_http(host, port, browser, remote, key, token, no_auth, allow_read_page, allow_control, allow_dangerous):
+@command_policy_options
+def cmd_serve_http(host, port, browser, remote, key, token, no_auth, allow_read_page, allow_control, allow_dangerous, allow_keys, allow_all):
   """Expose a tiny local HTTP JSON gateway (/tabs, /clients, /command).
 
   Auth is enabled by default. Pass the printed token as either
@@ -99,7 +100,7 @@ def cmd_serve_http(host, port, browser, remote, key, token, no_auth, allow_read_
   if no_auth and not _is_loopback(host):
     raise click.ClickException("--no-auth is only allowed on loopback hosts")
   auth_token = None if no_auth else (token or secrets.token_urlsafe(32))
-  policy = CommandPolicy(allow_read_page=allow_read_page, allow_control=allow_control, allow_dangerous=allow_dangerous)
+  policy = command_policy_from_options(allow_read_page=allow_read_page, allow_control=allow_control, allow_dangerous=allow_dangerous, allow_keys=allow_keys, allow_all=allow_all)
   handler = type(
     "BrowserCLIHTTPHandler",
     (_Handler,),