Test that a failed start keeps a waiting steer until its run is cleared

packages/server/src/server/agent/agent-run-state.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, test } from "vitest";
+
+import { AgentRunState } from "./agent-run-state.js";
+
+function track(promise: Promise<void>): { readonly resolved: boolean } {
+  const state = { resolved: false };
+  void (async () => {
+    await promise;
+    state.resolved = true;
+  })();
+  return state;
+}
+
+async function flushMicrotasks(): Promise<void> {
+  await new Promise<void>((resolve) => setImmediate(resolve));
+}
+
+describe("waitForForegroundStart", () => {
+  test("resolves once the starting turn has an id", async () => {
+    const runs = new AgentRunState();
+    const run = runs.createPendingRun("agent");
+    const wait = track(runs.waitForForegroundStart("agent"));
+
+    await flushMicrotasks();
+    expect(wait.resolved).toBe(false);
+
+    runs.settleForegroundStart(run, { status: "started", turnId: "turn-1" });
+    await flushMicrotasks();
+    expect(wait.resolved).toBe(true);
+  });
+
+  test("waits for a failed start's run to be cleared", async () => {
+    const runs = new AgentRunState();
+    const run = runs.createPendingRun("agent");
+    const wait = track(runs.waitForForegroundStart("agent"));
+
+    runs.settleForegroundStart(run, { status: "failed", error: "start failed" });
+    await flushMicrotasks();
+    expect(wait.resolved).toBe(false);
+    expect(runs.hasPendingRun("agent")).toBe(true);
+
+    runs.settleForegroundRun("agent", run.token);
+    await flushMicrotasks();
+    expect(wait.resolved).toBe(true);
+  });
+
+  test("resolves at once when no turn is starting", async () => {
+    const runs = new AgentRunState();
+    await expect(runs.waitForForegroundStart("agent")).resolves.toBeUndefined();
+  });
+});