feat: backfill missing PnL for submitted alphas

backend/app/jobs.py

@@ -412,21 +412,28 @@ class Runner:
             await db.commit()
 
     async def sync_ids(self, job_id, kind, alpha_ids):
+        """Process fixed IDs, preserving existing PnL during a missing-only backfill.
+
+        Successful items commit individually so cancellation and retries keep
+        completed work. Cache presence is rechecked when a queued item runs.
+        """
+        pnl_job = kind in ("pnl_refresh", "pnl_backfill")
         await self.checkpoint(job_id, {"total": len(alpha_ids)})
         for alpha_id in alpha_ids:
             async with self.sessions() as db:
                 previous = await db.get(JobItem, (job_id, alpha_id))
                 if previous and not previous.error:
                     continue
-            await self.checkpoint(job_id, {"next_retry_at": None})
+                cached = await db.get(Pnl, alpha_id) if kind == "pnl_backfill" else None
+            await self.checkpoint(job_id, {"next_retry_at": None, "checkpoint": {"alpha_id": alpha_id}})
             error = None
             try:
-                raw = await (
-                    self.client.pnl(alpha_id) if kind == "pnl_refresh" else self.client.alpha(alpha_id)
+                raw = cached.raw if cached is not None else await (
+                    self.client.pnl(alpha_id) if pnl_job else self.client.alpha(alpha_id)
                 )
-                if kind != "pnl_refresh" and raw.get("id") != alpha_id:
+                if not pnl_job and raw.get("id") != alpha_id:
                     raise ValueError("平台返回的 Alpha ID 与请求不一致")
-                points = pnl_points(raw) if kind == "pnl_refresh" else None
+                points = cached.points if cached is not None else pnl_points(raw) if pnl_job else None
             except VerificationRequired:
                 raise
             except WqError as exc:
@@ -446,10 +453,10 @@ class Runner:
                     previous = JobItem(job_id=job_id, alpha_id=alpha_id)
                     db.add(previous)
                 if not error:
-                    if kind == "pnl_refresh":
+                    if pnl_job:
                         if not await db.get(Alpha, alpha_id):
                             error = "请先导入此 Alpha"
-                        else:
+                        elif kind != "pnl_backfill" or await db.get(Pnl, alpha_id) is None:
                             await self.save_pnl(db, alpha_id, raw, points)
                     else:
                         await db.scalar(select(Account).where(Account.id == 1).with_for_update())