feat(tui): make follow-up queue explicit

tui/src/queue-preview.test.ts

@@ -0,0 +1,36 @@
+import { afterEach, describe, expect, test } from "bun:test"
+import { createTestRenderer, type TestRendererSetup } from "@opentui/core/testing"
+
+import { QueuePreview } from "./queue-preview"
+
+describe("QueuePreview", () => {
+  let setup: TestRendererSetup | undefined
+
+  afterEach(() => {
+    if (setup && !setup.renderer.isDestroyed) setup.renderer.destroy()
+    setup = undefined
+  })
+
+  test("shows the latest follow-ups without becoming another card", async () => {
+    setup = await createTestRenderer({ width: 64, height: 12, screenMode: "alternate-screen" })
+    const preview = new QueuePreview(setup.renderer, {
+      accent: "#EF8E30",
+      muted: "#A1A1AA",
+      faint: "#71717A",
+    })
+    setup.renderer.root.add(preview.root)
+
+    preview.update(["first\nline", "second", "third", "fourth"])
+    await setup.renderOnce()
+    const frame = setup.captureCharFrame()
+
+    expect(frame).toContain("Queued next  4")
+    expect(frame).not.toContain("first line")
+    expect(frame).toContain("↳ second")
+    expect(frame).toContain("↳ fourth")
+
+    preview.update([])
+    await setup.renderOnce()
+    expect(setup.captureCharFrame()).not.toContain("Queued next")
+  })
+})