Add tests and docs for '--' argument separator requirement

- Add TestArgumentSeparator class with 8 tests verifying that script
  arguments must come after '--' separator
- Update create and edit command docstrings with examples showing
  correct usage of '--' separator
- Update argument help text to indicate "(must come after '--')"
- Add "Passing Arguments to Your Script" section to README

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -28,7 +28,7 @@ mcquack list
 # Create and load an executable as a LaunchAgent
 mcquack create /path/to/your/script
 
-# Create with additional arguments for the script
+# Create with additional arguments for the script (note the -- separator)
 mcquack create /path/to/your/script -- --arg1 value1 --arg2
 
 # Kickstart (immediately run) the LaunchAgent
@@ -37,7 +37,7 @@ mcquack launch /path/to/your/script
 # Show the current arguments configured in the plist
 mcquack show /path/to/your/script
 
-# Edit the arguments in the plist
+# Edit the arguments in the plist (note the -- separator)
 mcquack edit /path/to/your/script -- --new-arg1 --new-arg2
 
 # Unload (stop) the LaunchAgent
@@ -47,6 +47,25 @@ mcquack unload /path/to/your/script
 mcquack delete /path/to/your/script
 ```
 
+### Passing Arguments to Your Script
+
+When passing arguments to your script with `create` or `edit`, you **must** use `--` to
+separate mcquack's options from arguments intended for your script:
+
+```bash
+# Correct: passes --config and --debug to your script
+mcquack create my_script.sh -- --config /path/to/config --debug
+
+# Wrong: --help is interpreted as mcquack's --help flag, shows help instead
+mcquack create my_script.sh --help
+
+# Correct: passes --help as an argument to your script
+mcquack create my_script.sh -- --help
+```
+
+The `--` separator ensures that flags like `--help`, `--verbose`, etc. are passed to your
+script rather than being interpreted by mcquack itself.
+
 ## How it works
 
 mcquack creates plist files in `~/Library/LaunchAgents/` with the naming convention:

mcquack.py

@@ -74,9 +74,23 @@ def list_agents() -> None:
 @app.command()
 def create(
     script: Annotated[Path, typer.Argument(help="Path to the executable script")],
-    script_args: Annotated[list[str] | None, typer.Argument(help="Arguments to pass to the script")] = None,
+    script_args: Annotated[
+        list[str] | None,
+        typer.Argument(help="Arguments to pass to the script (must come after '--')"),
+    ] = None,
 ) -> None:
-    """Create and load a LaunchAgent for a script."""
+    """Create and load a LaunchAgent for a script.
+
+    To pass arguments to your script, use '--' to separate mcquack options from
+    script arguments. For example:
+
+        mcquack create my_script.sh -- --config /path/to/config
+
+    Without '--', options like --help apply to mcquack itself:
+
+        mcquack create my_script.sh --help    # Shows this help
+        mcquack create my_script.sh -- --help # Passes --help to the script
+    """
     script_path = script.resolve()
 
     if not script_path.exists():
@@ -170,9 +184,22 @@ def show(
 @app.command()
 def edit(
     script: Annotated[Path, typer.Argument(help="Path to the executable script")],
-    script_args: Annotated[list[str] | None, typer.Argument(help="New arguments for the script")] = None,
+    script_args: Annotated[
+        list[str] | None,
+        typer.Argument(help="New arguments for the script (must come after '--')"),
+    ] = None,
 ) -> None:
-    """Edit the arguments in a plist."""
+    """Edit the arguments in a plist.
+
+    To update script arguments, use '--' to separate mcquack options from
+    script arguments. For example:
+
+        mcquack edit my_script.sh -- --verbose --debug
+
+    This replaces all existing script arguments. To clear arguments, omit them:
+
+        mcquack edit my_script.sh
+    """
     script_path = script.resolve()
     plist_path = get_plist_path(script_path)
 

test_mcquack.py

@@ -214,6 +214,99 @@ class TestDelete:
         assert "does not exist" in result.output
 
 
+class TestArgumentSeparator:
+    """Tests verifying that '--' separator is required for passing arguments to scripts.
+
+    This ensures that:
+    - 'mcquack create script.sh --help' shows help for the create command
+    - 'mcquack create script.sh -- --help' creates a plist with --help as a script arg
+    """
+
+    def test_create_help_without_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that --help without -- shows create command help, not passed to script."""
+        result = runner.invoke(app, ["create", str(mock_script), "--help"])
+        assert result.exit_code == 0
+        # Should show help text for create command
+        assert "Create and load a LaunchAgent" in result.stdout or "Usage:" in result.stdout
+        # Should NOT have created a plist
+        plist_path = get_plist_path(mock_dirs)
+        assert not plist_path.exists()
+
+    def test_create_help_with_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that -- --help passes --help as an argument to the script."""
+        result = runner.invoke(app, ["create", str(mock_script), "--", "--help"])
+        assert result.exit_code == 0
+        assert "Created:" in result.stdout
+
+        # Verify --help is in the plist as a script argument
+        plist_path = get_plist_path(mock_dirs)
+        assert plist_path.exists()
+        program_args = read_plist_args(plist_path)
+        assert "--help" in program_args
+        assert program_args[1] == "--help"
+
+    def test_create_verbose_without_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that --verbose without -- is treated as unknown option, not script arg."""
+        result = runner.invoke(app, ["create", str(mock_script), "--verbose"])
+        # Typer should reject unknown options
+        assert result.exit_code != 0
+        assert "No such option" in result.output or "no such option" in result.output.lower()
+        # Should NOT have created a plist
+        plist_path = get_plist_path(mock_dirs)
+        assert not plist_path.exists()
+
+    def test_create_verbose_with_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that -- --verbose passes --verbose as an argument to the script."""
+        result = runner.invoke(app, ["create", str(mock_script), "--", "--verbose"])
+        assert result.exit_code == 0
+
+        plist_path = get_plist_path(mock_dirs)
+        program_args = read_plist_args(plist_path)
+        assert "--verbose" in program_args
+
+    def test_edit_help_without_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that edit --help shows edit command help."""
+        # First create an agent
+        runner.invoke(app, ["create", str(mock_script)])
+
+        result = runner.invoke(app, ["edit", str(mock_script), "--help"])
+        assert result.exit_code == 0
+        assert "Edit the arguments" in result.stdout or "Usage:" in result.stdout
+
+    def test_edit_help_with_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that edit -- --help passes --help as a new argument."""
+        # First create an agent
+        runner.invoke(app, ["create", str(mock_script)])
+
+        result = runner.invoke(app, ["edit", str(mock_script), "--", "--help"])
+        assert result.exit_code == 0
+
+        plist_path = get_plist_path(mock_dirs)
+        program_args = read_plist_args(plist_path)
+        assert "--help" in program_args
+
+    def test_create_mixed_args_with_separator(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify multiple dash-prefixed args after -- are all passed to script."""
+        result = runner.invoke(app, ["create", str(mock_script), "--", "--config", "/path", "--debug", "-v"])
+        assert result.exit_code == 0
+
+        plist_path = get_plist_path(mock_dirs)
+        program_args = read_plist_args(plist_path)
+        # All args after -- should be in the plist
+        assert program_args[1:] == ["--config", "/path", "--debug", "-v"]
+
+    def test_create_double_dash_as_argument(self, mock_dirs, mock_script, mock_launchctl):
+        """Verify that -- can be passed as a script argument using -- --."""
+        result = runner.invoke(app, ["create", str(mock_script), "--", "--", "arg_after_double_dash"])
+        assert result.exit_code == 0
+
+        plist_path = get_plist_path(mock_dirs)
+        program_args = read_plist_args(plist_path)
+        # The first -- is consumed by typer, the second becomes an argument
+        assert "--" in program_args
+        assert "arg_after_double_dash" in program_args
+
+
 class TestPlistFormat:
     """Tests verifying plist file format independently of plistlib."""