diff --git a/app/api/clips.py b/app/api/clips.py
index 2b4db99..b261a4a 100644
--- a/app/api/clips.py
+++ b/app/api/clips.py
@@ -214,8 +214,20 @@ def _load_affinity(session: Session, device_id: str) -> tuple[ClipAffinity | Non
 
 def _save_affinity(session: Session, device_id: str, row: ClipAffinity | None, aff: cf.Affinity, events: int) -> None:
     if row is None:
-        row = ClipAffinity(device_id=device_id)
-        session.add(row)
+        # Pierwszy zapis dla urzadzenia. Onboarding i zdarzenia z pierwszych klipow
+        # przychodza naraz, oba widzialy brak wiersza i oba robily INSERT, drugi konczyl
+        # sie UniqueViolation i bledem 500 (GOON-7X). Wstawiamy pusty wiersz z ON CONFLICT
+        # i bierzemy go z blokada. Nasze wagi liczylismy od zera, wiec to same przyrosty:
+        # dodajemy je do tego, co zdazylo zapisac rownolegle zadanie.
+        session.execute(
+            pg_insert(ClipAffinity)
+            .values(device_id=device_id, tag_weights={}, niche_weights={}, creator_weights={}, events_seen=0)
+            .on_conflict_do_nothing(index_elements=["device_id"])
+        )
+        row = session.get(ClipAffinity, device_id, with_for_update=True, populate_existing=True)
+        for mine, theirs in ((aff.tags, row.tag_weights), (aff.niches, row.niche_weights), (aff.creators, row.creator_weights)):
+            for k, v in (theirs or {}).items():
+                mine[k] = round(mine.get(k, 0.0) + v, 3)
     row.tag_weights = aff.tags
     row.niche_weights = aff.niches
     row.creator_weights = aff.creators