fix(auto-reply): coalesce block replies and document streaming toggles (#536) (thanks @mcinteerj)

src/auto-reply/reply/block-reply-coalescer.test.ts

@@ -0,0 +1,71 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { createBlockReplyCoalescer } from "./block-reply-coalescer.js";
+
+describe("block reply coalescer", () => {
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("coalesces chunks within the idle window", async () => {
+    vi.useFakeTimers();
+    const flushes: string[] = [];
+    const coalescer = createBlockReplyCoalescer({
+      config: { minChars: 1, maxChars: 200, idleMs: 100, joiner: " " },
+      shouldAbort: () => false,
+      onFlush: (payload) => {
+        flushes.push(payload.text ?? "");
+      },
+    });
+
+    coalescer.enqueue({ text: "Hello" });
+    coalescer.enqueue({ text: "world" });
+
+    await vi.advanceTimersByTimeAsync(100);
+    expect(flushes).toEqual(["Hello world"]);
+    coalescer.stop();
+  });
+
+  it("waits until minChars before idle flush", async () => {
+    vi.useFakeTimers();
+    const flushes: string[] = [];
+    const coalescer = createBlockReplyCoalescer({
+      config: { minChars: 10, maxChars: 200, idleMs: 50, joiner: " " },
+      shouldAbort: () => false,
+      onFlush: (payload) => {
+        flushes.push(payload.text ?? "");
+      },
+    });
+
+    coalescer.enqueue({ text: "short" });
+    await vi.advanceTimersByTimeAsync(50);
+    expect(flushes).toEqual([]);
+
+    coalescer.enqueue({ text: "message" });
+    await vi.advanceTimersByTimeAsync(50);
+    expect(flushes).toEqual(["short message"]);
+    coalescer.stop();
+  });
+
+  it("flushes buffered text before media payloads", () => {
+    const flushes: Array<{ text?: string; mediaUrls?: string[] }> = [];
+    const coalescer = createBlockReplyCoalescer({
+      config: { minChars: 1, maxChars: 200, idleMs: 0, joiner: " " },
+      shouldAbort: () => false,
+      onFlush: (payload) => {
+        flushes.push({
+          text: payload.text,
+          mediaUrls: payload.mediaUrls,
+        });
+      },
+    });
+
+    coalescer.enqueue({ text: "Hello" });
+    coalescer.enqueue({ text: "world" });
+    coalescer.enqueue({ mediaUrls: ["https://example.com/a.png"] });
+    void coalescer.flush({ force: true });
+
+    expect(flushes[0].text).toBe("Hello world");
+    expect(flushes[1].mediaUrls).toEqual(["https://example.com/a.png"]);
+    coalescer.stop();
+  });
+});