fix: 12h cooldown before reopening manually closed host_silence (0.9.9)

Track resolved_by on problems; suppress scan/ingest recreate after manual
resolve; reopen same problem after cooldown; auto-close via heartbeat unchanged.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_host_silence_scan.py

@@ -95,6 +95,85 @@ def test_scan_skips_host_without_heartbeat(db_session, scan_settings):
     assert results == []
 
 
+def test_scan_suppresses_after_manual_resolve_within_cooldown(db_session, scan_settings, monkeypatch):
+    monkeypatch.setenv("SAC_HOST_SILENCE_MANUAL_RESOLVE_COOLDOWN_HOURS", "12")
+    get_settings.cache_clear()
+
+    hb = _ingest(
+        db_session,
+        type="agent.heartbeat",
+        category="agent",
+        severity="info",
+        title="hb",
+        summary="heartbeat",
+    )
+    hb.received_at = datetime.now(timezone.utc) - timedelta(hours=2)
+    db_session.flush()
+
+    now = datetime.now(timezone.utc)
+    first = run_host_silence_scan(db_session, now=now)
+    assert first[0].created is True
+    problem = first[0].problem
+    problem.status = "resolved"
+    problem.resolved_by = "manual"
+    problem.updated_at = now
+    db_session.flush()
+
+    second = run_host_silence_scan(db_session, now=now + timedelta(minutes=10))
+    assert second == []
+
+    open_count = db_session.scalar(
+        select(Problem).where(
+            Problem.host_id == hb.host_id,
+            Problem.rule_id == RULE_HOST_SILENCE,
+            Problem.status == "open",
+        )
+    )
+    assert open_count is None
+
+    resolved_count = len(
+        db_session.scalars(
+            select(Problem).where(
+                Problem.host_id == hb.host_id,
+                Problem.rule_id == RULE_HOST_SILENCE,
+                Problem.status == "resolved",
+            )
+        ).all()
+    )
+    assert resolved_count == 1
+
+
+def test_scan_reopens_after_manual_cooldown_expires(db_session, scan_settings, monkeypatch):
+    monkeypatch.setenv("SAC_HOST_SILENCE_MANUAL_RESOLVE_COOLDOWN_HOURS", "12")
+    get_settings.cache_clear()
+
+    hb = _ingest(
+        db_session,
+        type="agent.heartbeat",
+        category="agent",
+        severity="info",
+        title="hb",
+        summary="heartbeat",
+    )
+    hb.received_at = datetime.now(timezone.utc) - timedelta(hours=2)
+    db_session.flush()
+
+    now = datetime.now(timezone.utc)
+    first = run_host_silence_scan(db_session, now=now)
+    problem = first[0].problem
+    problem.status = "resolved"
+    problem.resolved_by = "manual"
+    problem.updated_at = now - timedelta(hours=13)
+    db_session.flush()
+
+    later = run_host_silence_scan(db_session, now=now)
+    assert len(later) == 1
+    assert later[0].created is True
+    assert later[0].problem.id == problem.id
+    assert later[0].problem.status == "open"
+    assert later[0].problem.resolved_by is None
+
+
 def test_scan_notifies_only_on_create(db_session, scan_settings):
     hb = _ingest(
         db_session,