Add site definition worker inference

tests/inference-worker.test.ts

@@ -0,0 +1,50 @@
+import { describe, expect, it } from "vitest";
+import { InferenceWorkerHost, type InferenceWorker } from "../src/background/inference-worker";
+import type { InferenceRequest } from "../src/shared/types";
+
+const request: InferenceRequest = { id: "post", text: "text", site: "threads", navigationId: "nav", priority: 0, requestId: "request" };
+class FakeWorker implements InferenceWorker {
+  readonly listeners = new Map<string, EventListener[]>();
+  readonly requests: Array<{ requests: InferenceRequest[]; modelBaseUrl: string }> = [];
+  terminated = false;
+
+  addEventListener(type: "message" | "error", listener: EventListener): void {
+    this.listeners.set(type, [...(this.listeners.get(type) ?? []), listener]);
+  }
+
+  removeEventListener(type: "message" | "error", listener: EventListener): void {
+    this.listeners.set(type, (this.listeners.get(type) ?? []).filter((candidate) => candidate !== listener));
+  }
+
+  postMessage(message: { requests: InferenceRequest[]; modelBaseUrl: string }): void {
+    this.requests.push(message);
+  }
+
+  terminate(): void { this.terminated = true; }
+
+  reply(): void {
+    const event = new MessageEvent("message", { data: { results: [{ requestId: request.requestId, id: request.id, textHash: "hash", label: "not_toxic", probability: .1, navigationId: request.navigationId }] } });
+    this.listeners.get("message")?.forEach((listener) => listener(event));
+  }
+}
+
+describe("InferenceWorkerHost", () => {
+  it("reuses its worker", async () => {
+    const workers: FakeWorker[] = [];
+    const host = new InferenceWorkerHost(() => {
+      const worker = new FakeWorker();
+      workers.push(worker);
+      return worker;
+    }, "chrome-extension://id/models/toxicity/");
+
+    const first = host.run([request]);
+    workers[0]!.reply();
+    await first;
+    const second = host.run([request]);
+    workers[0]!.reply();
+    await second;
+    expect(workers).toHaveLength(1);
+
+    expect(workers[0]!.requests).toHaveLength(2);
+  });
+});