refactor: share sync reservation join rule (WealthLedger/backend#119)

src/integrations/tbank/tbank-access.service.ts

@@ -25,6 +25,22 @@ export type TbankSyncAttempt = {
   userId: string;
 };
 
+// Join rule shared by sync reservations: the same process joins its own running attempt
+// only while that attempt is still active in memory. Set and Map both satisfy `has`.
+export function isJoinableRunningAttempt<
+  T extends { attemptId: string; processRunId: string; state: string },
+>(
+  previous: null | T,
+  processRunId: string,
+  active: { has(attemptId: string): boolean },
+): previous is T {
+  return (
+    previous?.state === 'running' &&
+    previous.processRunId === processRunId &&
+    active.has(previous.attemptId)
+  );
+}
+
 @Injectable()
 export class TbankAccessService {
   constructor(
@@ -62,11 +78,7 @@ export class TbankAccessService {
       const previous = await tx.tbankSyncWork.findUnique({
         where: { userId_revision_scopeKey: scope },
       });
-      if (
-        previous?.state === 'running' &&
-        previous.processRunId === processRunId &&
-        active.has(previous.attemptId)
-      ) {
+      if (isJoinableRunningAttempt(previous, processRunId, active)) {
         return { work: previous, launch: false };
       }
       const data = {