fix: prevent duplicate host_silence problems per host (0.4.8)

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

backend/app/services/host_silence_scan.py

@@ -12,7 +12,6 @@ from sqlalchemy.orm import Session
 from app.config import get_settings
 from app.models import Host, Problem
 from app.services.problem_rules import RuleMatch, build_fingerprint, host_silence_match_for_host
-from app.services.problems import _correlation_cutoff
 
 logger = logging.getLogger(__name__)
 
@@ -44,15 +43,13 @@ def open_or_refresh_host_silence_problem(
         match.rule_id,
         match.fingerprint_suffix,
     )
-    cutoff = _correlation_cutoff(ref)
 
     open_problem = db.scalar(
         select(Problem)
         .where(
             Problem.status == "open",
-            Problem.fingerprint == fingerprint,
+            Problem.rule_id == match.rule_id,
             Problem.host_id == host_id,
-            Problem.last_seen_at >= cutoff,
         )
         .order_by(Problem.last_seen_at.desc())
         .limit(1)
@@ -60,6 +57,7 @@ def open_or_refresh_host_silence_problem(
     if open_problem:
         open_problem.summary = match.summary
         open_problem.title = match.title
+        open_problem.fingerprint = fingerprint
         open_problem.last_seen_at = ref
         open_problem.updated_at = ref
         db.flush()