diff --git a/src/components/editorAccessibility.ts b/src/components/editorAccessibility.ts
index 376a9a0b..aa5b6471 100644
--- a/src/components/editorAccessibility.ts
+++ b/src/components/editorAccessibility.ts
@@ -51,6 +51,30 @@ function validateEditorTextDirection(
   }
 }
 
+/** Reject runtime `aria-invalid` values outside Inkspan's finite contract. */
+function validateEditorAriaInvalid(
+  value: EditorAriaInvalid | undefined,
+): void {
+  if (
+    value !== undefined &&
+    value !== false &&
+    value !== true &&
+    value !== 'grammar' &&
+    value !== 'spelling'
+  ) {
+    throw new RangeError(
+      'Editor aria-invalid must be false, true, grammar, or spelling.',
+    );
+  }
+}
+
+/** Reject runtime `aria-required` values outside Inkspan's boolean contract. */
+function validateEditorAriaRequired(value: boolean | undefined): void {
+  if (value !== undefined && value !== false && value !== true) {
+    throw new RangeError('Editor aria-required must be false or true.');
+  }
+}
+
 /**
  * Normalize the shared visual and semantic empty-editor guidance.
  *
@@ -76,6 +100,8 @@ export function buildEditorAccessibilityAttributes(
   options: EditorAccessibilityOptions,
 ): Record<string, string> {
   validateEditorTextDirection(options.textDirection);
+  validateEditorAriaInvalid(options.ariaInvalid);
+  validateEditorAriaRequired(options.ariaRequired);
   const placeholder = normalizeEditorPlaceholder(options.placeholder);
   const languageTag = normalizedAccessibilityValue(options.languageTag);
   const labelledBy = normalizedAccessibilityValue(options.ariaLabelledBy);
diff --git a/src/components/editorAccessibilityRuntime.test.ts b/src/components/editorAccessibilityRuntime.test.ts
index 04ce1ea4..b00b5e09 100644
--- a/src/components/editorAccessibilityRuntime.test.ts
+++ b/src/components/editorAccessibilityRuntime.test.ts
@@ -26,4 +26,56 @@ describe('editor accessibility runtime contracts', () => {
       new RangeError('Editor text direction must be ltr, rtl, or auto.'),
     );
   });
+
+  it.each([false, true, 'grammar', 'spelling'] as const)(
+    'preserves the valid %s aria-invalid state',
+    (ariaInvalid) => {
+      expect(
+        buildEditorAccessibilityAttributes({
+          defaultLabel: 'Editor',
+          editable: true,
+          ariaInvalid,
+        })['aria-invalid'],
+      ).toBe(String(ariaInvalid));
+    },
+  );
+
+  it('rejects a runtime aria-invalid value outside the public states', () => {
+    expect(() =>
+      buildEditorAccessibilityAttributes({
+        defaultLabel: 'Editor',
+        editable: true,
+        ariaInvalid: 'unknown' as never,
+      }),
+    ).toThrowError(
+      new RangeError(
+        'Editor aria-invalid must be false, true, grammar, or spelling.',
+      ),
+    );
+  });
+
+  it.each([false, true] as const)(
+    'preserves the valid %s aria-required state',
+    (ariaRequired) => {
+      expect(
+        buildEditorAccessibilityAttributes({
+          defaultLabel: 'Editor',
+          editable: true,
+          ariaRequired,
+        })['aria-required'],
+      ).toBe(String(ariaRequired));
+    },
+  );
+
+  it('rejects a runtime aria-required value outside the public states', () => {
+    expect(() =>
+      buildEditorAccessibilityAttributes({
+        defaultLabel: 'Editor',
+        editable: true,
+        ariaRequired: 'maybe' as never,
+      }),
+    ).toThrowError(
+      new RangeError('Editor aria-required must be false or true.'),
+    );
+  });
 });