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

backend/src/utils/read/media.py

@@ -1,7 +1,8 @@
+import json
+
 import asyncpg
 
 from utils.files import media_file_name
-from utils.read.message_view import load_raw
 from utils.read.models import MediaVersionView, MediaView
 
 MEDIA_COLS = (
@@ -40,15 +41,15 @@ async def _web_page_media_stub(
     pool: asyncpg.Pool, account_id: int, chat_id: int, message_id: int
 ) -> MediaView | None:
     row = await pool.fetchrow(
-        "SELECT date, raw FROM messages "
+        "SELECT date, raw->'web_page' AS web_page FROM messages "
         "WHERE account_id = $1 AND chat_id = $2 AND message_id = $3",
         account_id,
         chat_id,
         message_id,
     )
-    if row is None:
+    if row is None or row["web_page"] is None:
         return None
-    web_page = load_raw(row["raw"]).get("web_page")
+    web_page = json.loads(row["web_page"])
     if not isinstance(web_page, dict):
         return None
     kind = next(
@@ -105,7 +106,7 @@ async def get_media_versions(
     rows = await pool.fetch(
         f"SELECT {_VERSION_COLS} FROM media_versions "  # noqa: S608
         "WHERE account_id = $1 AND chat_id = $2 AND message_id = $3 "
-        "ORDER BY observed_at",
+        "ORDER BY observed_at LIMIT 500",
         account_id,
         chat_id,
         message_id,