refactor: consolidate typing lifecycle and queue policy

src/channels/typing.test.ts

@@ -0,0 +1,88 @@
+import { describe, expect, it, vi } from "vitest";
+import { createTypingCallbacks } from "./typing.js";
+
+const flushMicrotasks = async () => {
+  await Promise.resolve();
+  await Promise.resolve();
+};
+
+describe("createTypingCallbacks", () => {
+  it("invokes start on reply start", async () => {
+    const start = vi.fn().mockResolvedValue(undefined);
+    const onStartError = vi.fn();
+    const callbacks = createTypingCallbacks({ start, onStartError });
+
+    await callbacks.onReplyStart();
+
+    expect(start).toHaveBeenCalledTimes(1);
+    expect(onStartError).not.toHaveBeenCalled();
+  });
+
+  it("reports start errors", async () => {
+    const start = vi.fn().mockRejectedValue(new Error("fail"));
+    const onStartError = vi.fn();
+    const callbacks = createTypingCallbacks({ start, onStartError });
+
+    await callbacks.onReplyStart();
+
+    expect(onStartError).toHaveBeenCalledTimes(1);
+  });
+
+  it("invokes stop on idle and reports stop errors", async () => {
+    const start = vi.fn().mockResolvedValue(undefined);
+    const stop = vi.fn().mockRejectedValue(new Error("stop"));
+    const onStartError = vi.fn();
+    const onStopError = vi.fn();
+    const callbacks = createTypingCallbacks({ start, stop, onStartError, onStopError });
+
+    callbacks.onIdle?.();
+    await flushMicrotasks();
+
+    expect(stop).toHaveBeenCalledTimes(1);
+    expect(onStopError).toHaveBeenCalledTimes(1);
+  });
+
+  it("sends typing keepalive pings until idle cleanup", async () => {
+    vi.useFakeTimers();
+    try {
+      const start = vi.fn().mockResolvedValue(undefined);
+      const stop = vi.fn().mockResolvedValue(undefined);
+      const onStartError = vi.fn();
+      const callbacks = createTypingCallbacks({ start, stop, onStartError });
+
+      await callbacks.onReplyStart();
+      expect(start).toHaveBeenCalledTimes(1);
+
+      await vi.advanceTimersByTimeAsync(2_999);
+      expect(start).toHaveBeenCalledTimes(1);
+
+      await vi.advanceTimersByTimeAsync(1);
+      expect(start).toHaveBeenCalledTimes(2);
+
+      await vi.advanceTimersByTimeAsync(3_000);
+      expect(start).toHaveBeenCalledTimes(3);
+
+      callbacks.onIdle?.();
+      await flushMicrotasks();
+      expect(stop).toHaveBeenCalledTimes(1);
+
+      await vi.advanceTimersByTimeAsync(9_000);
+      expect(start).toHaveBeenCalledTimes(3);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it("deduplicates stop across idle and cleanup", async () => {
+    const start = vi.fn().mockResolvedValue(undefined);
+    const stop = vi.fn().mockResolvedValue(undefined);
+    const onStartError = vi.fn();
+    const callbacks = createTypingCallbacks({ start, stop, onStartError });
+
+    callbacks.onIdle?.();
+    callbacks.onCleanup?.();
+    await flushMicrotasks();
+
+    expect(stop).toHaveBeenCalledTimes(1);
+  });
+});