新增热重载：文件变更自动重启（开发用，默认关）

- musicbot/reload.py：轮询监控 musicbot/ 下的 .py 与 intents.toml/.env，
  变更后重启 bot 子进程；跳过 logs/、__pycache__/、.venv/
- 进程级重启而非模块重载：长连接 + 模块级状态 + handler 闭包，
  就地重载易留幽灵 handler，重启子进程状态干净
- 子进程用 _MUSICBOT_RELOAD_CHILD 标记，不会套娃自我复制
- Windows 用 taskkill /T 收整棵进程树，实测连续重载无进程泄漏
- 开启方式：`uv run musicbot --reload`（start.bat 已带）或 RELOAD=on
- 监督者不配日志，避免与子进程抢写同一日志文件

tests/test_music.py

@@ -663,6 +663,101 @@ def test_setup_logging_writes_file(tmp_path: Path):
     lg.remove()
 
 
+def test_config_reload_flag(monkeypatch):
+    """RELOAD 默认关（生产不受影响），on 可开启，非法值按关处理。"""
+    from musicbot.config import BotConfig
+
+    monkeypatch.delenv("RELOAD", raising=False)
+    assert BotConfig.load().reload is False
+
+    monkeypatch.setenv("RELOAD", "on")
+    assert BotConfig.load().reload is True
+
+    monkeypatch.setenv("RELOAD", "随便写")
+    assert BotConfig.load().reload is False
+
+
+# ---- 热重载：文件监听与进程监督 ----
+
+def test_watched_files_and_skip_rules(tmp_path: Path):
+    """监控 .py/.toml 与 .env；跳过 logs/、__pycache__/、.venv/ 与无关文件。"""
+    from musicbot import reload
+
+    (tmp_path / "musicbot").mkdir()
+    (tmp_path / "musicbot" / "music.py").write_text("", encoding="utf-8")
+    (tmp_path / "tests").mkdir()
+    (tmp_path / "tests" / "test_x.py").write_text("", encoding="utf-8")
+    (tmp_path / "intents.toml").write_text("", encoding="utf-8")
+    (tmp_path / ".env").write_text("", encoding="utf-8")
+    (tmp_path / "README.md").write_text("", encoding="utf-8")  # 无关后缀
+    (tmp_path / "logs").mkdir()
+    (tmp_path / "logs" / "musicbot.log").write_text("", encoding="utf-8")
+    (tmp_path / "musicbot" / "__pycache__").mkdir()
+    (tmp_path / "musicbot" / "__pycache__" / "x.py").write_text("", encoding="utf-8")
+
+    watched = reload.iter_watched_files(tmp_path)
+    names = {p.relative_to(tmp_path).as_posix() for p in watched}
+    assert names == {"musicbot/music.py", "tests/test_x.py", "intents.toml", ".env"}
+
+
+def test_changed_files_detects_edit_add_remove(tmp_path: Path):
+    """快照比对：改动/新增/删除都能识别，未变则返回空。"""
+    from musicbot import reload
+
+    f = tmp_path / "musicbot"
+    f.mkdir()
+    mod = f / "music.py"
+    mod.write_text("a", encoding="utf-8")
+
+    before = reload.snapshot(tmp_path)
+    assert reload.changed_files(before, reload.snapshot(tmp_path)) == []
+
+    mod.write_text("bb", encoding="utf-8")
+    assert reload.changed_files(before, reload.snapshot(tmp_path)) == [mod]
+
+
+def test_is_child_guard(monkeypatch):
+    """子进程标记生效：带标记的进程不再做监督，避免 --reload 无限自我复制。"""
+    from musicbot import reload
+
+    monkeypatch.delenv(reload.CHILD_ENV, raising=False)
+    assert reload.is_child() is False
+    monkeypatch.setenv(reload.CHILD_ENV, "1")
+    assert reload.is_child() is True
+
+
+def test_main_child_does_not_supervise(monkeypatch):
+    """子进程即使带 --reload / RELOAD=on 也只跑 bot，不起监督
+    （否则 --reload 会无限自我复制）。"""
+    from musicbot import main as mb_main
+    from musicbot import reload
+
+    called: dict[str, bool] = {}
+
+    async def fake_amain() -> None:
+        called["bot"] = True
+
+    monkeypatch.setattr(reload, "is_child", lambda: True)
+    monkeypatch.setattr(mb_main, "amain", fake_amain)
+    monkeypatch.setattr(
+        reload, "run_supervisor",
+        lambda *a, **k: called.setdefault("supervisor", True),
+    )
+    monkeypatch.setattr(mb_main.BotConfig, "load", staticmethod(
+        lambda: replace(
+            BotConfig(
+                music_server_url="http://127.0.0.1:1",
+                music_quality="128k",
+                music_source="tx",
+            ),
+            reload=True,
+        )
+    ))
+
+    mb_main.main(["--reload"])
+    assert called == {"bot": True}  # 跑的是 bot，没有起监督
+
+
 # ---- 全量模式（不 @ 也能用）与去重 ----
 
 def make_emitter(api, http, config) -> EventEmitter: