fix(form-core): ignore aborted async form-level validation results

.changeset/quiet-forms-ignore-stale.md

@@ -0,0 +1,5 @@
+---
+"@tanstack/form-core": patch
+---
+
+Ignore aborted async form-level validation results so a slower previous run cannot overwrite newer form state.

packages/form-core/src/FormApi.ts

@@ -2232,6 +2232,7 @@ export class FormApi<
           } catch (e: unknown) {
             rawError = e as ValidationError
           }
+          if (controller.signal.aborted) return resolve(undefined)
           const { formError, fieldErrors: fieldErrorsFromNormalizeError } =
             normalizeError<TFormData>(rawError)
 

packages/form-core/tests/FormApi.spec.ts

@@ -1420,6 +1420,47 @@ describe('form api', () => {
     })
   })
 
+  it('should ignore aborted async form-level validation results', async () => {
+    vi.useFakeTimers()
+
+    try {
+      const form = new FormApi({
+        defaultValues: {
+          name: 'valid',
+        },
+        validators: {
+          onChangeAsyncDebounceMs: 0,
+          onChangeAsync: async ({ value }) => {
+            if (value.name === 'slow-invalid') {
+              await sleep(2000)
+              return 'Stale validation result'
+            }
+            await sleep(50)
+            return undefined
+          },
+        },
+      })
+      const field = new FieldApi({
+        form,
+        name: 'name',
+      })
+      form.mount()
+      field.mount()
+
+      field.setValue('slow-invalid')
+      await vi.advanceTimersByTimeAsync(0)
+      field.setValue('valid')
+      await vi.advanceTimersByTimeAsync(50)
+      expect(form.state.errors).toEqual([])
+
+      await vi.advanceTimersByTimeAsync(2000)
+      expect(form.state.errors).toEqual([])
+      expect(form.state.errorMap.onChange).toBeUndefined()
+    } finally {
+      vi.useRealTimers()
+    }
+  })
+
   it('should run validation onBlur', () => {
     const form = new FormApi({
       defaultValues: {