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

backend/src/watcher/registry.py

@@ -22,11 +22,13 @@ from utils.read import accounts, bots
 from utils.storage import ContentAddressedStorage
 from watcher import tokens
 from watcher.context import build_bot_capture_context
-from watcher.drain import drain_backlog
+from watcher.drain import DrainCursor, drain_backlog, first_cursor
 
 DEVICE_MODEL = "Beavergram Bot"
 TOKEN_MISSING = "Токен не найден на диске"  # noqa: S105
 INVALID_TOKEN_ERRORS = ("ACCESS_TOKEN_INVALID", "ACCESS_TOKEN_EXPIRED")
+BACKLOG_ATTEMPTS = 3
+BACKLOG_RETRY_PAUSE = 60
 
 
 @dataclass
@@ -184,10 +186,30 @@ class BotRegistry:
         )
 
     async def _backlog(self, client: PyroClient, bot_id: int, account_id: int) -> None:
-        stored = await drain_backlog(client, account_id)
-        if stored is None:
-            return
-        await bots.mark_backfilled(self._pool, bot_id)
+        async def save(at: DrainCursor) -> None:
+            await bots.save_backlog_cursor(self._pool, bot_id, at.pts, at.qts, at.date)
+
+        saved = await bots.backlog_cursor(self._pool, bot_id)
+        cursor = DrainCursor(*saved) if saved else first_cursor()
+        stored = 0
+        for attempt in range(BACKLOG_ATTEMPTS):
+            if attempt:
+                await asyncio.sleep(BACKLOG_RETRY_PAUSE)
+            walk = await drain_backlog(client, account_id, cursor, save)
+            stored += walk.stored
+            cursor = walk.cursor
+            if walk.done:
+                await bots.mark_backfilled(self._pool, bot_id)
+                logger.info(
+                    f"[green]Account {account_id}: backlog complete,[/] "
+                    f"{stored} messages stored"
+                )
+                break
+        else:
+            logger.warning(
+                f"[yellow]Account {account_id}: backlog unfinished at "
+                f"pts={cursor.pts},[/] {stored} messages stored, resumes on restart"
+            )
         if stored:
             await accounts.notify_accounts_changed(self._pool)