feat(tui): add agent interaction workflows

tui/src/prompt-queue.test.ts

@@ -0,0 +1,27 @@
+import { describe, expect, test } from "bun:test"
+
+import { PromptQueue } from "./prompt-queue"
+
+const prompt = (content: string) => ({ content, options: {} })
+
+describe("PromptQueue", () => {
+  test("promotes the newest armed prompt to steering", () => {
+    const queue = new PromptQueue()
+    queue.enqueue(prompt("next one"))
+    queue.enqueue(prompt("steer now"))
+
+    expect(queue.takeSteering()?.content).toBe("steer now")
+    expect(queue.takeSteering()).toBeNull()
+    expect(queue.takeFollowUp()?.content).toBe("next one")
+  })
+
+  test("keeps follow-ups FIFO and restores unsent drafts", () => {
+    const queue = new PromptQueue()
+    queue.enqueue(prompt("first"))
+    queue.enqueue(prompt("second"))
+
+    expect(queue.takeFollowUp()?.content).toBe("first")
+    expect(queue.restore().map(({ content }) => content)).toEqual(["second"])
+    expect(queue.length).toBe(0)
+  })
+})