cli: add first-party launchd install/uninstall commands for autostart

Introduce built-in launchd management to remove shell-wrapper indirection and
make macOS autostart reliable.

- Add `install-launchagent` and `uninstall-launchagent` CLI subcommands.
- Create launchd helper module to:
  - write `~/Library/LaunchAgents/<label>.plist`
  - invoke app via `sys.executable -m mpd_now_playable.cli` (absolute interpreter path)
  - set `RunAtLoad`, `KeepAlive`
  - run `launchctl bootout/bootstrap/kickstart` for install and `bootout` for uninstall
  - support `--label` and `--force`
- Add tests for subcommand dispatch, plist generation, and launchctl flow.
- Document the new launchd workflow in README.
  - Run markdownlint

This keeps the setup DRY/KISS, avoids PATH/shell expansion pitfalls in launchd,
and gives users a supported and easy autostart path out of the box.

tests/test_cli.py

@@ -1,5 +1,7 @@
 from types import SimpleNamespace
 
+import pytest
+
 import mpd_now_playable.cli as cli
 
 
@@ -11,12 +13,15 @@ def test_main_help_prints_usage(monkeypatch, capsys) -> None:
 
 	monkeypatch.setattr(cli, "loadConfig", fail_load)
 
-	cli.main()
+	with pytest.raises(SystemExit) as exc:
+		cli.main()
+	assert exc.value.code == 0
 	output = capsys.readouterr().out
 
-	assert "Usage: mpd-now-playable [OPTIONS]" in output
-	assert "-h, --help" in output
-	assert "-v, --version" in output
+	assert "usage: mpd-now-playable" in output
+	assert "--version" in output
+	assert "install-launchagent" in output
+	assert "uninstall-launchagent" in output
 
 
 def test_main_version_prints_version(monkeypatch, capsys) -> None:
@@ -93,3 +98,43 @@ def test_main_starts_listener_and_receivers(monkeypatch) -> None:
 	assert seen["receivers"] == (receiver_1, receiver_2)
 	assert seen["listen_args"] == (config, listener, (receiver_1, receiver_2))
 	assert seen["run"] == (fake_coroutine, FakeLoopFactory.make_loop, False)
+
+
+def test_main_install_launchagent(monkeypatch, capsys) -> None:
+	seen = {}
+
+	def fake_install(*, label: str, force: bool) -> str:
+		seen["args"] = (label, force)
+		return "/tmp/example.plist"
+
+	monkeypatch.setattr(
+		cli.sys,
+		"argv",
+		["mpd-now-playable", "install-launchagent", "--label", "com.example.test", "--force"],
+	)
+	monkeypatch.setattr(cli, "install_launchagent", fake_install)
+
+	cli.main()
+	output = capsys.readouterr().out
+	assert seen["args"] == ("com.example.test", True)
+	assert "Installed LaunchAgent at /tmp/example.plist" in output
+
+
+def test_main_uninstall_launchagent(monkeypatch, capsys) -> None:
+	seen = {}
+
+	def fake_uninstall(*, label: str) -> str:
+		seen["label"] = label
+		return "/tmp/example.plist"
+
+	monkeypatch.setattr(
+		cli.sys,
+		"argv",
+		["mpd-now-playable", "uninstall-launchagent", "--label", "com.example.test"],
+	)
+	monkeypatch.setattr(cli, "uninstall_launchagent", fake_uninstall)
+
+	cli.main()
+	output = capsys.readouterr().out
+	assert seen["label"] == "com.example.test"
+	assert "Uninstalled LaunchAgent at /tmp/example.plist" in output

tests/test_launchd.py

@@ -0,0 +1,77 @@
+import plistlib
+from pathlib import Path
+
+import pytest
+
+import mpd_now_playable.launchd as launchd
+
+
+def test_plist_bytes_uses_absolute_python(monkeypatch, tmp_path) -> None:
+	monkeypatch.setattr(launchd.sys, "executable", "/abs/python")
+	monkeypatch.setattr(Path, "home", lambda: tmp_path)
+
+	payload = plistlib.loads(launchd._plist_bytes("com.example.test"))
+
+	assert payload["Label"] == "com.example.test"
+	assert payload["ProgramArguments"] == ["/abs/python", "-m", "mpd_now_playable.cli"]
+	assert payload["RunAtLoad"] is True
+	assert payload["KeepAlive"] is True
+
+
+def test_install_launchagent_writes_plist_and_bootstraps(monkeypatch, tmp_path) -> None:
+	monkeypatch.setattr(launchd.sys, "platform", "darwin")
+	monkeypatch.setattr(launchd.sys, "executable", "/abs/python")
+	monkeypatch.setattr(Path, "home", lambda: tmp_path)
+	monkeypatch.setattr(launchd.os, "getuid", lambda: 501)
+
+	seen: list[tuple[tuple[str, ...], bool]] = []
+
+	def fake_run_launchctl(*args: str, check: bool = True) -> object:
+		seen.append((args, check))
+		return object()
+
+	monkeypatch.setattr(launchd, "_run_launchctl", fake_run_launchctl)
+
+	plist_path = launchd.install_launchagent(label="com.example.test", force=False)
+	assert plist_path == tmp_path / "Library" / "LaunchAgents" / "com.example.test.plist"
+	assert plist_path.exists()
+	assert seen == [
+		(("bootout", "gui/501/com.example.test"), False),
+		(("bootstrap", "gui/501", str(plist_path)), True),
+		(("kickstart", "-k", "gui/501/com.example.test"), True),
+	]
+
+
+def test_install_launchagent_refuses_existing_without_force(monkeypatch, tmp_path) -> None:
+	monkeypatch.setattr(launchd.sys, "platform", "darwin")
+	monkeypatch.setattr(Path, "home", lambda: tmp_path)
+
+	plist = tmp_path / "Library" / "LaunchAgents" / "com.example.test.plist"
+	plist.parent.mkdir(parents=True, exist_ok=True)
+	plist.write_text("already here")
+
+	with pytest.raises(FileExistsError):
+		launchd.install_launchagent(label="com.example.test")
+
+
+def test_uninstall_launchagent_boots_out_and_removes_file(monkeypatch, tmp_path) -> None:
+	monkeypatch.setattr(launchd.sys, "platform", "darwin")
+	monkeypatch.setattr(Path, "home", lambda: tmp_path)
+	monkeypatch.setattr(launchd.os, "getuid", lambda: 501)
+
+	seen: list[tuple[tuple[str, ...], bool]] = []
+
+	def fake_run_launchctl(*args: str, check: bool = True) -> object:
+		seen.append((args, check))
+		return object()
+
+	monkeypatch.setattr(launchd, "_run_launchctl", fake_run_launchctl)
+
+	plist = tmp_path / "Library" / "LaunchAgents" / "com.example.test.plist"
+	plist.parent.mkdir(parents=True, exist_ok=True)
+	plist.write_text("x")
+
+	removed = launchd.uninstall_launchagent(label="com.example.test")
+	assert removed == plist
+	assert not plist.exists()
+	assert seen == [(("bootout", "gui/501/com.example.test"), False)]