Fix recovery Telegram dedup and unify Beijing time display.

Store alert metrics without per-value Redis members to stop duplicate recovery pushes; format all operator-facing timestamps in Asia/Shanghai across Web UI and Telegram.

tests/test_agent_recovery_dedup.py

@@ -0,0 +1,38 @@
+"""Recovery detection must emit one notification per metric, not per Redis entry."""
+
+from server.api.agent import _alert_metric_key, _detect_recovery
+
+
+def test_alert_metric_key_parses_legacy_and_new_formats():
+    assert _alert_metric_key("mem") == "mem"
+    assert _alert_metric_key("mem:92.1") == "mem"
+    assert _alert_metric_key("cpu:85.0") == "cpu"
+    assert _alert_metric_key("") is None
+
+
+def test_detect_recovery_dedupes_legacy_metric_value_entries():
+    thresholds = {"cpu": 80, "mem": 80, "disk": 80}
+    prev_alerts = {"mem:88.0", "mem:91.2", "mem:93.5"}
+    system_info = {"mem_usage": 55.0}
+
+    recoveries = _detect_recovery(system_info, prev_alerts, thresholds)
+
+    assert recoveries == [("mem", 55.0)]
+
+
+def test_detect_recovery_one_per_metric_when_multiple_metrics():
+    thresholds = {"cpu": 80, "mem": 80, "disk": 80}
+    prev_alerts = {"cpu:90.0", "mem:88.0", "mem:92.0"}
+    system_info = {"cpu_usage": 40.0, "mem_usage": 50.0}
+
+    recoveries = _detect_recovery(system_info, prev_alerts, thresholds)
+
+    assert sorted(recoveries) == [("cpu", 40.0), ("mem", 50.0)]
+
+
+def test_detect_recovery_skips_still_alerting_metric():
+    thresholds = {"cpu": 80, "mem": 80, "disk": 80}
+    prev_alerts = {"mem:88.0", "mem:91.0"}
+    system_info = {"mem_usage": 85.0}
+
+    assert _detect_recovery(system_info, prev_alerts, thresholds) == []