feat(tmux-monitor): add a unified multi-host view (#1520)

plugins/tmux-monitor/tests/frontend/poll-queue.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, it, vi } from "vitest";
+import { createPollQueue } from "../../src/frontend/poll-queue";
+
+describe("background host polling queue", () => {
+  it("bounds concurrent hosts and releases a slot after failure", async () => {
+    const run = createPollQueue(2);
+    let release!: () => void;
+    const held = new Promise<void>((resolve) => {
+      release = resolve;
+    });
+    const first = run(() => held);
+    const second = run(async () => {
+      throw new Error("offline");
+    });
+    const thirdTask = vi.fn(async () => "third");
+    const third = run(thirdTask);
+    expect(thirdTask).not.toHaveBeenCalled();
+    await expect(second).rejects.toThrow("offline");
+    await expect(third).resolves.toBe("third");
+    expect(thirdTask).toHaveBeenCalledOnce();
+    release();
+    await first;
+  });
+});