fix: reject unknown CLI args unless running in --reflect mode

Previously, agentmain.py used parse_known_args() and silently ignored
unknown flags. A typo like `--goal` (intended for a different launcher)
was accepted without warning, causing the process to fall through into
interactive mode and hang without dispatching any work.

Now, unknown arguments are only permitted when --reflect is set, since
extra key/value pairs are forwarded to the reflect script as parameters.
Otherwise parser.error() prints usage and exits non-zero.

Closes #566

Author: Kailigithub

agentmain.py

@@ -204,6 +204,12 @@ def run(self):
     parser.add_argument('--verbose', action='store_true')
     parser.add_argument('--nobg', action='store_true')
     args, _unknown = parser.parse_known_args()
+    if _unknown and not args.reflect:
+        # Reject unknown CLI flags unless we are in --reflect mode, where
+        # extra key/value pairs are forwarded to the reflect script.
+        # Without this guard, typos like `--goal` silently fall through to
+        # interactive mode and the process looks alive without doing any work.
+        parser.error(f"unrecognized arguments: {' '.join(_unknown)}")
     _reflect_args = dict(zip([k.lstrip('-') for k in _unknown[::2]], _unknown[1::2])) if _unknown else {}
 
     if args.task and not args.nobg: