refactor(tui): extract standalone package (#31193)

packages/tui/test/editor.test.ts

@@ -0,0 +1,23 @@
+import { afterEach, expect, test } from "bun:test"
+import { openEditor } from "../src/editor"
+
+const editor = process.env.EDITOR
+const visual = process.env.VISUAL
+
+afterEach(() => {
+  process.env.EDITOR = editor
+  process.env.VISUAL = visual
+})
+
+test("rejects when the external editor cannot start", async () => {
+  delete process.env.VISUAL
+  process.env.EDITOR = "opencode-editor-that-does-not-exist"
+  const renderer = {
+    suspend() {},
+    resume() {},
+    requestRender() {},
+    currentRenderBuffer: { clear() {} },
+  }
+
+  await expect(openEditor({ value: "original", renderer: renderer as never })).rejects.toThrow()
+})