Sample least-recently-fetched friends instead of random

Replaces random.sample with a staleness-ordered pick: friends never
fetched sort first (epoch timestamp), then oldest fetched_at. Ensures
full following list coverage over successive nightly runs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

blueprints/beli/logic.py

@@ -15,6 +15,8 @@ from utils.beli_service import (
     refresh_access_token,
 )
 
+from tortoise.functions import Max
+
 from .models import BeliProfile, BeliRestaurant, BeliStatus
 
 logger = logging.getLogger(__name__)
@@ -55,7 +57,22 @@ async def _refresh_friend_sample(profile: BeliProfile, access_token: str) -> int
     if not following:
         return 0
 
-    sample = random.sample(following, min(FRIEND_SAMPLE_SIZE, len(following)))
+    # Pick the FRIEND_SAMPLE_SIZE stalest friends — never-fetched first, then oldest
+    fetched_rows = (
+        await BeliRestaurant.filter(profile=profile)
+        .exclude(friend_beli_user_id="")
+        .group_by("friend_beli_user_id")
+        .annotate(last_fetched=Max("fetched_at"))
+        .values("friend_beli_user_id", "last_fetched")
+    )
+    last_fetched: dict[str, datetime] = {
+        r["friend_beli_user_id"]: r["last_fetched"] for r in fetched_rows
+    }
+    _epoch = datetime.fromtimestamp(0, tz=timezone.utc)
+    sample = sorted(
+        following,
+        key=lambda f: last_fetched.get(str(f.get("id") or ""), _epoch),
+    )[:FRIEND_SAMPLE_SIZE]
     upserted = 0
 
     for friend in sample: