Improve timestamp handling and event navigation

server/monlet_server/api/events.py

@@ -16,12 +16,13 @@ from ..schemas import (
     StoredCheckResultEvent,
 )
 from ..services.ingestion import ingest_event
+from ..timeutil import to_utc
 
 router = APIRouter()
 
 
 def _encode_cursor(received_at: datetime, event_id) -> str:
-    raw = f"{received_at.isoformat()}|{event_id}".encode()
+    raw = f"{to_utc(received_at).isoformat()}|{event_id}".encode()
     return base64.urlsafe_b64encode(raw).decode().rstrip("=")
 
 
@@ -30,7 +31,7 @@ def _decode_cursor(cursor: str) -> tuple[datetime, str]:
     try:
         raw = base64.urlsafe_b64decode(cursor + pad).decode()
         ts_str, eid = raw.split("|", 1)
-        return datetime.fromisoformat(ts_str), eid
+        return to_utc(datetime.fromisoformat(ts_str)), eid
     except (binascii.Error, ValueError) as exc:
         raise HTTPException(status_code=400, detail="invalid cursor") from exc
 
@@ -87,8 +88,8 @@ async def query_events(
             event_id=str(r.event_id),
             agent_id=r.agent_id,
             check_id=r.check_id,
-            observed_at=r.observed_at,
-            received_at=r.received_at,
+            observed_at=to_utc(r.observed_at),
+            received_at=to_utc(r.received_at),
             status=r.status,
             exit_code=r.exit_code,
             duration_ms=r.duration_ms,