feat: 重连不再等待并精简连接日志，失败才记断开与退避

- 连接曾稳定存活（>= _STABLE_SECONDS）而被服务端要求重连时立刻重连、
  不等待也不记日志：这期间事件由网关按 RESUME 补发，等待只是徒增盲区
- 仅在连接未能稳定存活（握手失败/看门狗超时/限流/抖动）时才记
  "WebSocket 已断开"并按指数退避重试
- 去掉常规的「WebSocket 已连接/已断开」info，只保留「发送 RESUME」等
  有信息量的行，消除每小时一次的日志噪音
- 新增 tests/test_reconnect.py：健康断开零等待零日志、失败退避翻倍、
  限流 60s、抖动不重置退避

tests/test_reconnect.py

@@ -0,0 +1,93 @@
+"""重连循环：健康断开立刻重连（不记连接/断开），失败才退避并记断开。"""
+
+import asyncio
+from typing import Any
+
+import pytest
+from loguru import logger
+
+from qqbotsdk.connecter import RateLimitError, WebsocketConnecter
+
+pytestmark = pytest.mark.asyncio
+
+
+def _make(monkeypatch: pytest.MonkeyPatch, seq: list[Any]) -> WebsocketConnecter:
+    """构造 connecter，并把 _connect 换成按 seq 依次返回（float=存活秒数，
+    Exception=连接失败）。seq 用尽后抛 IndexError 中止 run() 的无限循环。"""
+    conn = WebsocketConnecter.__new__(WebsocketConnecter)
+    remaining = list(seq)
+
+    async def fake_connect() -> float:
+        item = remaining.pop(0)  # 用尽则 IndexError 逃出 run()
+        if isinstance(item, Exception):
+            raise item
+        return float(item)
+
+    monkeypatch.setattr(conn, "_connect", fake_connect)
+    return conn
+
+
+async def _run_capture(
+    monkeypatch: pytest.MonkeyPatch, seq: list[Any]
+) -> tuple[list[float], list[str]]:
+    """跑 run() 直到 seq 用尽，返回 (sleep 延迟序列, 日志消息列表)。"""
+    sleeps: list[float] = []
+    logs: list[str] = []
+    real_sleep = asyncio.sleep
+
+    async def fake_sleep(delay: float) -> None:
+        sleeps.append(delay)
+        await real_sleep(0)  # 让出控制权，避免紧循环
+
+    monkeypatch.setattr(asyncio, "sleep", fake_sleep)
+    sink_id = logger.add(lambda m: logs.append(m.record["message"]), level="INFO")
+    try:
+        conn = _make(monkeypatch, seq)
+        with pytest.raises(IndexError):
+            await conn.run()
+    finally:
+        logger.remove(sink_id)
+    return sleeps, logs
+
+
+async def test_healthy_disconnect_reconnects_without_delay_or_log(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """健康连接（存活 >= 稳定阈值）断开后立刻重连：不 sleep、不记连接/断开。"""
+    sleeps, logs = await _run_capture(monkeypatch, [3600.0, 3600.0])
+
+    assert sleeps == []  # 两次都立刻重连
+    assert not any("已连接" in m or "已断开" in m for m in logs)
+
+
+async def test_failed_reconnect_backs_off_and_logs_disconnect(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """连不上时记断开并按退避等待，退避逐次翻倍。"""
+    sleeps, logs = await _run_capture(
+        monkeypatch, [3600.0, TimeoutError(), 0.0, 0.0]
+    )
+
+    # 健康断开 → 无 sleep；失败后依次 1s、2s、4s
+    assert sleeps == [1, 2, 4]
+    assert sum("已断开" in m for m in logs) == 3
+
+
+async def test_rate_limit_backs_off_hard(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """gateway 限流：退避 60s，且不重复记断开。"""
+    sleeps, logs = await _run_capture(monkeypatch, [RateLimitError(), 3600.0])
+
+    assert sleeps == [60]
+    assert any("频率限制" in m for m in logs)
+    assert not any("已断开" in m for m in logs)
+
+
+async def test_flapping_connection_does_not_reset_backoff(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """连接建立后立刻掉线（存活 < 阈值）视为抖动：退避持续拉长，不归零。"""
+    sleeps, _ = await _run_capture(monkeypatch, [0.5, 0.5, 0.5])
+
+    assert sleeps == [1, 2, 4]  # 每次都等得更久（若归零会是 1,1,1）