fix(POSTV1-05): 修复生成请求与 Worker 重入

apps/worker/src/generation-polling-loop.ts

@@ -0,0 +1,35 @@
+export interface GenerationPollingProcessor {
+  processNext(): Promise<unknown>;
+}
+
+export class GenerationPollingLoop {
+  private closed = false;
+  private inFlight = false;
+  private readonly timer: ReturnType<typeof setInterval>;
+
+  constructor(
+    private readonly processor: GenerationPollingProcessor,
+    intervalMilliseconds = 250,
+  ) {
+    if (!Number.isSafeInteger(intervalMilliseconds) || intervalMilliseconds <= 0) {
+      throw new Error("generation_polling_interval_invalid");
+    }
+    this.timer = setInterval(() => this.run(), intervalMilliseconds);
+  }
+
+  close() {
+    if (this.closed) return;
+    this.closed = true;
+    clearInterval(this.timer);
+  }
+
+  private run() {
+    if (this.closed || this.inFlight) return;
+    this.inFlight = true;
+    void this.processor.processNext()
+      .catch(() => undefined)
+      .finally(() => {
+        this.inFlight = false;
+      });
+  }
+}