diff --git a/drb-frontend/lib/useIncidents.ts b/drb-frontend/lib/useIncidents.ts
index 5619b61..62d8602 100644
--- a/drb-frontend/lib/useIncidents.ts
+++ b/drb-frontend/lib/useIncidents.ts
@@ -42,11 +42,17 @@ export function useIncidents(limitCount = 100, dateFrom?: Date, dateTo?: Date) {
       }
 
       // A range on the ordered field rides the existing org_id/started_at index.
+      // Incident started_at is stored as a Python isoformat() STRING
+      // ("2026-09-20T12:00:00.123456+00:00", incident_correlator.py), not a
+      // Firestore timestamp — unlike calls. A Date bound compares by type and
+      // matches nothing, so the bounds go in as UTC ISO strings in the same
+      // shape, which then compare lexicographically in time order.
+      const isoBound = (ms: number) => new Date(ms).toISOString().replace("Z", "+00:00");
       const q = query(
         collection(db, "incidents"),
         where("org_id", "==", orgId),
-        ...(dateFromMs != null ? [where("started_at", ">=", new Date(dateFromMs))] : []),
-        ...(dateToMs != null ? [where("started_at", "<=", new Date(dateToMs))] : []),
+        ...(dateFromMs != null ? [where("started_at", ">=", isoBound(dateFromMs))] : []),
+        ...(dateToMs != null ? [where("started_at", "<=", isoBound(dateToMs))] : []),
         orderBy("started_at", "desc"),
         limit(limitCount)
       );