feat: exit() accepts result value, waitUntilExit resolves with it

Change exit(error?: Error) to exit(errorOrResult?: unknown). When an
Error is passed, waitUntilExit rejects; otherwise it resolves with the
value. This matches Ink's behavior where exit("hello") resolves the
promise with "hello".

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/runtime-tests/integration/lifecycle/exit.test.tsx

@@ -82,10 +82,9 @@ test("exit() called multiple times is idempotent", async () => {
   await waitUntilExit();
 });
 
-test("waitUntilExit() resolves after exit() with result value", async () => {
-  // Mirrors Ink's "exit on exit() with result value" — vue-tui's exit()
-  // resolves cleanly (no value); just verifies the promise resolves.
-  let exitFn!: () => void;
+test("waitUntilExit() resolves with result value passed to exit()", async () => {
+  // Mirrors Ink's "exit on exit() with result value"
+  let exitFn!: (errorOrResult?: unknown) => void;
 
   const App = defineComponent(() => {
     exitFn = useExit();
@@ -95,6 +94,34 @@ test("waitUntilExit() resolves after exit() with result value", async () => {
   const { lastFrame, waitUntilExit } = await render(App);
   expect(lastFrame()).toContain("hello from vue-tui");
 
+  exitFn("hello from ink");
+  await expect(waitUntilExit()).resolves.toBe("hello from ink");
+});
+
+test("waitUntilExit() resolves with object result value", async () => {
+  // Mirrors Ink's "exit on exit() with object result"
+  let exitFn!: (errorOrResult?: unknown) => void;
+
+  const App = defineComponent(() => {
+    exitFn = useExit();
+    return () => <Text>hello</Text>;
+  });
+
+  const { waitUntilExit } = await render(App);
+  const resultObj = { message: "hello from ink object" };
+  exitFn(resultObj);
+  await expect(waitUntilExit()).resolves.toBe(resultObj);
+});
+
+test("waitUntilExit() resolves with undefined when exit() called with no args", async () => {
+  let exitFn!: (errorOrResult?: unknown) => void;
+
+  const App = defineComponent(() => {
+    exitFn = useExit();
+    return () => <Text>hello</Text>;
+  });
+
+  const { waitUntilExit } = await render(App);
   exitFn();
   await expect(waitUntilExit()).resolves.toBeUndefined();
 });

packages/runtime/src/composables/useExit.ts

@@ -3,10 +3,11 @@ import { AppContextKey } from "../context.ts";
 
 /**
  * Returns the exit function so a component can end the app from inside the
- * tree. Pass an Error to reject `app.waitUntilExit()` (and any awaiter); call
- * with no args to resolve cleanly.
+ * tree. Pass an Error to reject `app.waitUntilExit()` (and any awaiter); pass
+ * any other value to resolve with it as the result; call with no args to
+ * resolve with undefined.
  */
-export function useExit(): (error?: Error) => void {
+export function useExit(): (errorOrResult?: unknown) => void {
   const ctx = inject(AppContextKey);
   if (!ctx) throw new Error("useExit() must be called inside a vue-tui render tree");
   return ctx.exit;

packages/runtime/src/context.ts

@@ -2,7 +2,7 @@ import type { InjectionKey, ShallowRef } from "vue";
 import type { EventEmitter } from "node:events";
 
 export interface AppContext {
-  exit: (error?: Error) => void;
+  exit: (errorOrResult?: unknown) => void;
   stdout: NodeJS.WriteStream;
   stderr: NodeJS.WriteStream;
   stdin: NodeJS.ReadStream;

packages/runtime/src/render.ts

@@ -31,7 +31,7 @@ export interface MountOptions {
 
 export interface TuiApp extends Omit<VueApp<TuiNode>, "mount"> {
   mount(options?: MountOptions): ComponentPublicInstance;
-  waitUntilExit(): Promise<void>;
+  waitUntilExit(): Promise<unknown>;
 }
 
 type RootProps = Record<string, unknown>;
@@ -39,9 +39,9 @@ type RootProps = Record<string, unknown>;
 export function createApp(root: Component, rootProps?: RootProps | null): TuiApp {
   // exit promise — created at createApp time so waitUntilExit() works even
   // before mount (it just hangs until mount + exit).
-  let exitResolve!: () => void;
+  let exitResolve!: (result?: unknown) => void;
   let exitReject!: (e: Error) => void;
-  const exitPromise = new Promise<void>((res, rej) => {
+  const exitPromise = new Promise<unknown>((res, rej) => {
     exitResolve = res;
     exitReject = rej;
   });
@@ -120,14 +120,17 @@ export function createApp(root: Component, rootProps?: RootProps | null): TuiApp
     mountedDebug = debug;
 
     const appContext: AppContext = {
-      exit(err?: Error) {
-        if (err) exitReject(err);
+      exit(errorOrResult?: unknown) {
         // Defer teardown to a microtask: exit() is frequently called from
         // inside the Vue update cycle (useInput handler, setup(), errorHandler)
         // and unmounting synchronously would tear Vue down mid-flush.
         queueMicrotask(() => {
           teardown();
-          exitResolve();
+          if (errorOrResult instanceof Error) {
+            exitReject(errorOrResult);
+          } else {
+            exitResolve(errorOrResult);
+          }
         });
       },
       stdout,
@@ -238,7 +241,7 @@ export function createApp(root: Component, rootProps?: RootProps | null): TuiApp
     exitResolve();
   };
 
-  app.waitUntilExit = function waitUntilExit(): Promise<void> {
+  app.waitUntilExit = function waitUntilExit(): Promise<unknown> {
     return exitPromise;
   };
 

packages/testing/src/render.ts

@@ -31,7 +31,7 @@ export interface RenderResult {
   };
   terminal: Terminal;
   unmount(this: void): void;
-  waitUntilExit(this: void): Promise<void>;
+  waitUntilExit(this: void): Promise<unknown>;
 }
 
 function trimFrame(raw: string): string {