diff --git a/packages/cli-kit/src/private/node/testing/ui.ts b/packages/cli-kit/src/private/node/testing/ui.ts
index 13c5019050..66d47e1144 100644
--- a/packages/cli-kit/src/private/node/testing/ui.ts
+++ b/packages/cli-kit/src/private/node/testing/ui.ts
@@ -23,6 +23,17 @@ export class Stdin extends EventEmitter {
   constructor(options: {isTTY?: boolean} = {}) {
     super()
     this.isTTY = options.isTTY ?? true
+
+    // When a 'readable' listener is added and there's pending data,
+    // re-emit 'readable' so the new listener can read it. This mirrors
+    // real Node streams where buffered data is available to new readers,
+    // and prevents dropped input when data is written before Ink's
+    // useInput effect registers its listener.
+    this.on('newListener', (event: string) => {
+      if (event === 'readable' && this.data !== null) {
+        setImmediate(() => this.emit('readable'))
+      }
+    })
   }
 
   write = (data: string) => {
diff --git a/packages/cli-kit/src/private/node/ui/components/AutocompletePrompt.test.tsx b/packages/cli-kit/src/private/node/ui/components/AutocompletePrompt.test.tsx
index 8e04bb76d7..b097057eca 100644
--- a/packages/cli-kit/src/private/node/ui/components/AutocompletePrompt.test.tsx
+++ b/packages/cli-kit/src/private/node/ui/components/AutocompletePrompt.test.tsx
@@ -1,7 +1,6 @@
 import {AutocompletePrompt, SearchResults} from './AutocompletePrompt.js'
 import {
   getLastFrameAfterUnmount,
-  sendInputAndWait,
   sendInputAndWaitForChange,
   sendInputAndWaitForContent,
   waitForInputsToBeReady,
@@ -286,8 +285,9 @@ describe('AutocompletePrompt', async () => {
     await waitForInputsToBeReady()
 
     await sendInputAndWaitForContent(renderInstance, 'No results found', 'a')
-    // prompt doesn't change when enter is pressed
-    await sendInputAndWait(renderInstance, 100, ENTER)
+    // prompt doesn't change when enter is pressed — yield to let React
+    // 19's scheduler process any batched updates from the keypress
+    await sendInputAndWaitForContent(renderInstance, 'No results found', ENTER)
 
     expect(renderInstance.lastFrame()).toMatchInlineSnapshot(`
       "?  Associate your project with the org Castile Ventures?   a█
@@ -328,12 +328,11 @@ describe('AutocompletePrompt', async () => {
   test('has a loading state', async () => {
     const onEnter = vi.fn()
 
+    // Use a promise that never resolves so the loading state persists
+    // for the entire test, eliminating timing races with React 19's
+    // batched rendering on slow CI runners.
     const search = () => {
-      return new Promise<SearchResults<string>>((resolve) => {
-        setTimeout(() => {
-          resolve({data: [{label: 'a', value: 'b'}]})
-        }, 2000)
-      })
+      return new Promise<SearchResults<string>>(() => {})
     }
 
     const renderInstance = render(
@@ -347,9 +346,9 @@ describe('AutocompletePrompt', async () => {
 
     await waitForInputsToBeReady()
     await sendInputAndWaitForContent(renderInstance, 'Loading...', 'a')
-    // prompt doesn't change when enter is pressed
-    await new Promise((resolve) => setTimeout(resolve, 100))
-    await sendInputAndWait(renderInstance, 100, ENTER)
+    // prompt doesn't change when enter is pressed — yield to let React
+    // 19's scheduler process any batched updates from the keypress
+    await sendInputAndWaitForContent(renderInstance, 'Loading...', ENTER)
 
     expect(renderInstance.lastFrame()).toMatchInlineSnapshot(`
       "?  Associate your project with the org Castile Ventures?   a█