fix: --yolo and other flags silently dropped when placed before 'chat' subcommand

When --yolo, -w, -s, -r, -c, and --pass-session-id exist on both the parent
parser and the 'chat' subparser with explicit defaults (default=False or
default=None), argparse's subparser initialization overwrites the parent's
parsed value. So 'hermes --yolo chat' silently drops --yolo, making it appear
broken.

Fix: use default=argparse.SUPPRESS on all duplicated arguments in the chat
subparser. SUPPRESS means 'don't set this attribute if the user didn't
explicitly provide it', so the parent parser's value survives through.

Affected flags: --yolo, --worktree/-w, --skills/-s, --pass-session-id,
--resume/-r, --continue/-c.

Adds 15 regression tests covering flag-before-subcommand, flag-after-subcommand,
no-subcommand, and env var propagation scenarios.

hermes_cli/main.py

@@ -4033,7 +4033,7 @@ For more help on a command:
     chat_parser.add_argument(
         "-s", "--skills",
         action="append",
-        default=None,
+        default=argparse.SUPPRESS,
         help="Preload one or more skills for the session (repeat flag or comma-separate)"
     )
     chat_parser.add_argument(
@@ -4055,6 +4055,7 @@ For more help on a command:
     chat_parser.add_argument(
         "--resume", "-r",
         metavar="SESSION_ID",
+        default=argparse.SUPPRESS,
         help="Resume a previous session by ID (shown on exit)"
     )
     chat_parser.add_argument(
@@ -4062,14 +4063,14 @@ For more help on a command:
         dest="continue_last",
         nargs="?",
         const=True,
-        default=None,
+        default=argparse.SUPPRESS,
         metavar="SESSION_NAME",
         help="Resume a session by name, or the most recent if no name given"
     )
     chat_parser.add_argument(
         "--worktree", "-w",
         action="store_true",
-        default=False,
+        default=argparse.SUPPRESS,
         help="Run in an isolated git worktree (for parallel agents on the same repo)"
     )
     chat_parser.add_argument(
@@ -4088,13 +4089,13 @@ For more help on a command:
     chat_parser.add_argument(
         "--yolo",
         action="store_true",
-        default=False,
+        default=argparse.SUPPRESS,
         help="Bypass all dangerous command approval prompts (use at your own risk)"
     )
     chat_parser.add_argument(
         "--pass-session-id",
         action="store_true",
-        default=False,
+        default=argparse.SUPPRESS,
         help="Include the session ID in the agent's system prompt"
     )
     chat_parser.add_argument(

tests/hermes_cli/test_argparse_flag_propagation.py

@@ -0,0 +1,172 @@
+"""Tests for parent→subparser flag propagation.
+
+When flags like --yolo, -w, -s exist on both the parent parser and the 'chat'
+subparser, placing the flag BEFORE the subcommand (e.g. 'hermes --yolo chat')
+must not silently drop the flag value.
+
+Regression test for: argparse subparser default=False overwriting parent's
+parsed True when the same argument is defined on both parsers.
+
+Fix: chat subparser uses default=argparse.SUPPRESS for all duplicated flags,
+so the subparser only sets the attribute when the user explicitly provides it.
+"""
+
+import argparse
+import os
+import sys
+from unittest.mock import patch
+
+import pytest
+
+
+def _build_parser():
+    """Build the hermes argument parser from the real code.
+
+    We import the real main() and extract the parser it builds.
+    Since main() is a large function that does much more than parse args,
+    we replicate just the parser structure here to avoid side effects.
+    """
+    parser = argparse.ArgumentParser(prog="hermes")
+    parser.add_argument("--resume", "-r", metavar="SESSION", default=None)
+    parser.add_argument(
+        "--continue", "-c", dest="continue_last", nargs="?",
+        const=True, default=None, metavar="SESSION_NAME",
+    )
+    parser.add_argument("--worktree", "-w", action="store_true", default=False)
+    parser.add_argument("--skills", "-s", action="append", default=None)
+    parser.add_argument("--yolo", action="store_true", default=False)
+    parser.add_argument("--pass-session-id", action="store_true", default=False)
+
+    subparsers = parser.add_subparsers(dest="command")
+    chat = subparsers.add_parser("chat")
+    # These MUST use argparse.SUPPRESS to avoid overwriting parent values
+    chat.add_argument("--yolo", action="store_true",
+                      default=argparse.SUPPRESS)
+    chat.add_argument("--worktree", "-w", action="store_true",
+                      default=argparse.SUPPRESS)
+    chat.add_argument("--skills", "-s", action="append",
+                      default=argparse.SUPPRESS)
+    chat.add_argument("--pass-session-id", action="store_true",
+                      default=argparse.SUPPRESS)
+    chat.add_argument("--resume", "-r", metavar="SESSION_ID",
+                      default=argparse.SUPPRESS)
+    chat.add_argument(
+        "--continue", "-c", dest="continue_last", nargs="?",
+        const=True, default=argparse.SUPPRESS, metavar="SESSION_NAME",
+    )
+    return parser
+
+
+class TestFlagBeforeSubcommand:
+    """Flags placed before 'chat' must propagate through."""
+
+    def test_yolo_before_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["--yolo", "chat"])
+        assert getattr(args, "yolo", False) is True
+
+    def test_worktree_before_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["-w", "chat"])
+        assert getattr(args, "worktree", False) is True
+
+    def test_skills_before_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["-s", "myskill", "chat"])
+        assert getattr(args, "skills", None) == ["myskill"]
+
+    def test_pass_session_id_before_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["--pass-session-id", "chat"])
+        assert getattr(args, "pass_session_id", False) is True
+
+    def test_resume_before_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["-r", "abc123", "chat"])
+        assert getattr(args, "resume", None) == "abc123"
+
+
+class TestFlagAfterSubcommand:
+    """Flags placed after 'chat' must still work."""
+
+    def test_yolo_after_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat", "--yolo"])
+        assert getattr(args, "yolo", False) is True
+
+    def test_worktree_after_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat", "-w"])
+        assert getattr(args, "worktree", False) is True
+
+    def test_skills_after_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat", "-s", "myskill"])
+        assert getattr(args, "skills", None) == ["myskill"]
+
+    def test_resume_after_chat(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat", "-r", "abc123"])
+        assert getattr(args, "resume", None) == "abc123"
+
+
+class TestNoSubcommandDefaults:
+    """When no subcommand is given, flags must work and defaults must hold."""
+
+    def test_yolo_no_subcommand(self):
+        parser = _build_parser()
+        args = parser.parse_args(["--yolo"])
+        assert args.yolo is True
+        assert args.command is None
+
+    def test_defaults_no_flags(self):
+        parser = _build_parser()
+        args = parser.parse_args([])
+        assert getattr(args, "yolo", False) is False
+        assert getattr(args, "worktree", False) is False
+        assert getattr(args, "skills", None) is None
+        assert getattr(args, "resume", None) is None
+
+    def test_defaults_chat_no_flags(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat"])
+        # With SUPPRESS, these fall through to parent defaults
+        assert getattr(args, "yolo", False) is False
+        assert getattr(args, "worktree", False) is False
+        assert getattr(args, "skills", None) is None
+
+
+class TestYoloEnvVar:
+    """Verify --yolo sets HERMES_YOLO_MODE regardless of flag position.
+
+    This tests the actual cmd_chat logic pattern (getattr → os.environ).
+    """
+
+    @pytest.fixture(autouse=True)
+    def _clean_env(self):
+        os.environ.pop("HERMES_YOLO_MODE", None)
+        yield
+        os.environ.pop("HERMES_YOLO_MODE", None)
+
+    def _simulate_cmd_chat_yolo_check(self, args):
+        """Replicate the exact check from cmd_chat in main.py."""
+        if getattr(args, "yolo", False):
+            os.environ["HERMES_YOLO_MODE"] = "1"
+
+    def test_yolo_before_chat_sets_env(self):
+        parser = _build_parser()
+        args = parser.parse_args(["--yolo", "chat"])
+        self._simulate_cmd_chat_yolo_check(args)
+        assert os.environ.get("HERMES_YOLO_MODE") == "1"
+
+    def test_yolo_after_chat_sets_env(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat", "--yolo"])
+        self._simulate_cmd_chat_yolo_check(args)
+        assert os.environ.get("HERMES_YOLO_MODE") == "1"
+
+    def test_no_yolo_no_env(self):
+        parser = _build_parser()
+        args = parser.parse_args(["chat"])
+        self._simulate_cmd_chat_yolo_check(args)
+        assert os.environ.get("HERMES_YOLO_MODE") is None