fix(watcher): resume the bot backlog from a saved cursor instead of restarting it

backend/src/utils/read/bots.py

@@ -35,6 +35,28 @@ SET enabled = false, status = 'removed', status_detail = NULL, updated_at = now(
 WHERE bot_id = $1 AND enabled
 """
 
+_BACKLOG_CURSOR = """
+SELECT backfill_pts, backfill_qts, backfill_date
+FROM watched_bots
+WHERE bot_id = $1 AND backfill_pts IS NOT NULL
+"""
+
+_SAVE_BACKLOG_CURSOR = """
+UPDATE watched_bots SET
+    backfill_pts = $2, backfill_qts = $3, backfill_date = $4, updated_at = now()
+WHERE bot_id = $1
+"""
+
+_MARK_BACKFILLED = """
+UPDATE watched_bots SET
+    backfilled_at = now(),
+    backfill_pts = NULL,
+    backfill_qts = NULL,
+    backfill_date = NULL,
+    updated_at = now()
+WHERE bot_id = $1
+"""
+
 _SET_STATUS = """
 UPDATE watched_bots SET
     status = $2,
@@ -116,9 +138,20 @@ async def needs_backfill(pool: asyncpg.Pool, bot_id: int) -> bool:
     )
 
 
+async def backlog_cursor(
+    pool: asyncpg.Pool, bot_id: int
+) -> tuple[int, int, int] | None:
+    row = await pool.fetchrow(_BACKLOG_CURSOR, bot_id)
+    if row is None:
+        return None
+    return row["backfill_pts"], row["backfill_qts"], row["backfill_date"]
+
+
+async def save_backlog_cursor(
+    pool: asyncpg.Pool, bot_id: int, pts: int, qts: int, date: int
+) -> None:
+    await pool.execute(_SAVE_BACKLOG_CURSOR, bot_id, pts, qts, date)
+
+
 async def mark_backfilled(pool: asyncpg.Pool, bot_id: int) -> None:
-    await pool.execute(
-        "UPDATE watched_bots SET backfilled_at = now(), updated_at = now() "
-        "WHERE bot_id = $1",
-        bot_id,
-    )
+    await pool.execute(_MARK_BACKFILLED, bot_id)