fix(agentmain): reject unknown CLI arguments (v3, re-roll onto current main)

[Kailigithub]

Summary

Reject unsupported command-line arguments before GenericAgent initializes. This makes mistyped launch modes such as --goal fail with argparse's non-zero error instead of falling through to the interactive path.

Problem

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 to interactive mode and hang without dispatching any work — users reported "agent launched but did nothing."

Fix

Single-source change in agentmain.py: when _unknown (leftover from parse_known_args()) is non-empty AND --reflect is not active, call parser.error() to print usage and exit non-zero.

--reflect mode is exempted because reflect scripts receive the extra key/value pairs as parameters and need them forwarded (existing behavior preserved).

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 as parameters.
    # 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)}")
_extra_args = dict(zip([k.lstrip('-') for k in _unknown[::2]], _unknown[1::2])) if _unknown else {}

Verification

• python3 -m py_compile agentmain.py — syntax OK
• Regression harness at /tmp/test_issue_566.py — 4 checks:
  • test_source_has_guard: confirms if _unknown and not args.reflect + parser.error are present.
  • test_unknown_arg_rejected: python3 agentmain.py --goal /tmp/foo.json exits with code 2 and the message unrecognized arguments: --goal /tmp/foo.json.
  • test_help_still_works: --help exits 0 without the new guard firing.
  • test_extra_args_dict_still_populated_for_reflect: the _extra_args dict assignment is untouched.
• Three-step dance (stash → test fails on main → pop → test passes with fix) confirms the test catches the regression.

Scope

• 1 file, +6/-0 lines
• Single argparse guard, no runtime logic change
• Closes Goal Hive can silently hang when launched with unsupported --goal argument #566