perf(*): bound list queries, batch fetches, harden media downloads

backend/src/userbot/modules/jobs/handlers/enrich_chat.py

@@ -65,16 +65,28 @@ async def _enrich_members(client: Client, ctx: CaptureContext, chat_id: int) ->
         return
 
 
+async def _fetch_users(client: Client, ids: list[int]) -> list[User]:
+    try:
+        users = await client.get_users(ids)
+    except BadRequest:
+        users = []
+        for sender_id in ids:
+            try:
+                users.append(await client.get_users(sender_id))
+            except BadRequest:
+                continue
+    if isinstance(users, User):
+        return [users]
+    return [user for user in users if isinstance(user, User)]
+
+
 async def _enrich_senders(client: Client, ctx: CaptureContext, chat_id: int) -> None:
     rows = await ctx.pool.fetch(_MISSING_SENDERS, ctx.account_id, chat_id)
     ids = [row["sender_id"] for row in rows]
-    for sender_id in ids:
-        try:
-            user = await client.get_users(sender_id)
-        except BadRequest:
-            continue
-        if isinstance(user, User):
-            await _save_user(ctx, user)
+    if not ids:
+        return
+    for user in await _fetch_users(client, ids):
+        await _save_user(ctx, user)
 
 
 @register("enrich_chat")