fix(tui): restore reverted prompt in v2

packages/tui/test/util/revert-prompt.test.ts

@@ -0,0 +1,61 @@
+import { describe, expect, test } from "bun:test"
+import type { SessionMessageUser } from "@opencode-ai/sdk/v2"
+import { revertedPrompt } from "../../src/util/revert-prompt"
+
+const message: SessionMessageUser = {
+  id: "message-1",
+  type: "user",
+  text: "Fix the tests",
+  time: { created: 1 },
+  files: [
+    {
+      uri: "file:///repo/test.ts",
+      mime: "text/typescript",
+      name: "test.ts",
+      source: { start: 0, end: 8, text: "@test.ts" },
+    },
+  ],
+  agents: [{ name: "review", source: { start: 9, end: 16, text: "@review" } }],
+}
+
+describe("reverted prompt", () => {
+  test("restores the reverted user message into an empty prompt", () => {
+    expect(revertedPrompt({ input: "", parts: [] }, message)).toEqual({
+      input: "Fix the tests",
+      parts: [
+        {
+          type: "file",
+          mime: "text/typescript",
+          filename: "test.ts",
+          url: "file:///repo/test.ts",
+          source: {
+            type: "file",
+            path: "test.ts",
+            text: { start: 0, end: 8, value: "@test.ts" },
+          },
+        },
+        {
+          type: "agent",
+          name: "review",
+          source: { start: 9, end: 16, value: "@review" },
+        },
+      ],
+    })
+  })
+
+  test("preserves an existing text draft", () => {
+    expect(revertedPrompt({ input: "Keep this", parts: [] }, message)).toBeUndefined()
+  })
+
+  test("preserves an existing attachment draft", () => {
+    expect(
+      revertedPrompt(
+        {
+          input: "",
+          parts: [{ type: "agent", name: "build" }],
+        },
+        message,
+      ),
+    ).toBeUndefined()
+  })
+})