Localize restored answer state to native numeral system

When restoring saved answer state into widgets, convert ASCII digits
back to the content locale's native numeral system. This ensures users
who typed ٤٢ (stored as "42" by Phase 1 normalization) see ٤٢ when
returning to an exercise, not the ASCII representation.

Adds localizeNumerals and localizeUserInput as inverses of the existing
normalize functions, with a roundtrip test confirming they are proper
inverses.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rtibbles

kolibri/plugins/perseus_viewer/frontend/__tests__/numeralNormalization.spec.js

@@ -3,6 +3,8 @@ import {
   normalizeUserInput,
   getLocalizedDigits,
   localizeKeypadDigits,
+  localizeNumerals,
+  localizeUserInput,
 } from '../numeralNormalization';
 
 describe('normalizeNumerals', () => {
@@ -225,3 +227,109 @@ describe('localizeKeypadDigits', () => {
     expect(localizeKeypadDigits(container, null)).toBeNull();
   });
 });
+
+describe('localizeNumerals', () => {
+  it('converts ASCII digits to Eastern Arabic for ar-EG', () => {
+    expect(localizeNumerals('42', 'ar-EG')).toBe('٤٢');
+  });
+
+  it('converts all 10 digits for Arabic locale', () => {
+    expect(localizeNumerals('0123456789', 'ar-EG')).toBe('٠١٢٣٤٥٦٧٨٩');
+  });
+
+  it('leaves non-digit characters unchanged', () => {
+    expect(localizeNumerals('x+y', 'ar-EG')).toBe('x+y');
+  });
+
+  it('handles mixed digits and text', () => {
+    expect(localizeNumerals('2x+3', 'ar-EG')).toBe('٢x+٣');
+  });
+
+  it('handles decimal numbers', () => {
+    expect(localizeNumerals('3.14', 'ar-EG')).toBe('٣.١٤');
+  });
+
+  it('returns string unchanged for English locale', () => {
+    expect(localizeNumerals('42', 'en')).toBe('42');
+  });
+
+  it('returns string unchanged for null locale', () => {
+    expect(localizeNumerals('42', null)).toBe('42');
+  });
+
+  it('returns non-string values unchanged', () => {
+    expect(localizeNumerals(42, 'ar-EG')).toBe(42);
+    expect(localizeNumerals(null, 'ar-EG')).toBe(null);
+    expect(localizeNumerals(undefined, 'ar-EG')).toBe(undefined);
+  });
+
+  it('returns empty string unchanged', () => {
+    expect(localizeNumerals('', 'ar-EG')).toBe('');
+  });
+});
+
+describe('localizeUserInput', () => {
+  it('localizes numeric-input widget state', () => {
+    const input = {
+      'numeric-input 1': { currentValue: '42' },
+    };
+    expect(localizeUserInput(input, 'ar-EG')).toEqual({
+      'numeric-input 1': { currentValue: '٤٢' },
+    });
+  });
+
+  it('localizes expression widget state (plain string)', () => {
+    const input = {
+      'expression 1': '2x+3',
+    };
+    expect(localizeUserInput(input, 'ar-EG')).toEqual({
+      'expression 1': '٢x+٣',
+    });
+  });
+
+  it('leaves dropdown widget state unchanged (numeric value)', () => {
+    const input = {
+      'dropdown 1': { value: 2 },
+    };
+    expect(localizeUserInput(input, 'ar-EG')).toEqual({
+      'dropdown 1': { value: 2 },
+    });
+  });
+
+  it('handles multiple widgets', () => {
+    const input = {
+      'numeric-input 1': { currentValue: '21' },
+      'numeric-input 2': { currentValue: '7' },
+      'expression 1': '5x',
+    };
+    expect(localizeUserInput(input, 'ar-EG')).toEqual({
+      'numeric-input 1': { currentValue: '٢١' },
+      'numeric-input 2': { currentValue: '٧' },
+      'expression 1': '٥x',
+    });
+  });
+
+  it('returns input unchanged for English locale', () => {
+    const input = { 'numeric-input 1': { currentValue: '42' } };
+    expect(localizeUserInput(input, 'en')).toEqual(input);
+  });
+
+  it('handles null and undefined gracefully', () => {
+    expect(localizeUserInput(null, 'ar-EG')).toBe(null);
+    expect(localizeUserInput(undefined, 'ar-EG')).toBe(undefined);
+  });
+
+  it('handles nested arrays', () => {
+    const input = ['4', ['2', '3']];
+    expect(localizeUserInput(input, 'ar-EG')).toEqual(['٤', ['٢', '٣']]);
+  });
+
+  it('is the inverse of normalizeUserInput for Arabic', () => {
+    const original = {
+      'numeric-input 1': { currentValue: '42' },
+      'expression 1': '2x+3',
+    };
+    const localized = localizeUserInput(original, 'ar-EG');
+    expect(normalizeUserInput(localized)).toEqual(original);
+  });
+});

kolibri/plugins/perseus_viewer/frontend/numeralNormalization.js

@@ -170,9 +170,42 @@ function localizeKeypadDigits(keypadContainer, locale) {
   return observer;
 }
 
+/**
+ * Convert ASCII digits in a string to localized digits for a given locale.
+ * The reverse of normalizeNumerals: "42" → "٤٢" for Arabic.
+ * Returns the string unchanged if the locale uses Western digits.
+ */
+function localizeNumerals(str, locale) {
+  if (typeof str !== 'string') {
+    return str;
+  }
+  const digits = getLocalizedDigits(locale);
+  if (!digits) {
+    return str;
+  }
+  return str.replace(/[0-9]/g, d => digits[Number(d)]);
+}
+
+/**
+ * Recursively localize all string values in a user input object.
+ * The reverse of normalizeUserInput: converts ASCII digits back to
+ * the locale's native numeral system for display in widgets.
+ *
+ * Used when restoring saved answer state so that users see their
+ * answers in their native numeral format, not as ASCII digits.
+ */
+function localizeUserInput(input, locale) {
+  if (!getLocalizedDigits(locale)) {
+    return input;
+  }
+  return deepMapStrings(input, s => localizeNumerals(s, locale));
+}
+
 export {
   normalizeNumerals,
   normalizeUserInput,
   getLocalizedDigits,
   localizeKeypadDigits,
+  localizeNumerals,
+  localizeUserInput,
 };

kolibri/plugins/perseus_viewer/frontend/views/PerseusRendererIndex.vue

@@ -58,7 +58,11 @@
   import perseusTranslator from '../translator';
   import { wrapPerseusMessages } from '../translationUtils';
   import widgetSolver from '../widgetSolver';
-  import { normalizeUserInput, localizeKeypadDigits } from '../numeralNormalization';
+  import {
+    normalizeUserInput,
+    localizeKeypadDigits,
+    localizeUserInput,
+  } from '../numeralNormalization';
   import imageMissing from './image_missing.svg';
   import TeX from './Tex';
 
@@ -585,6 +589,11 @@
         if (userInput) {
           // Restore image URLs from placeholders to blob URLs
           userInput = JSON.parse(replaceImageUrls(JSON.stringify(userInput), this.perseusFileUrl));
+          // Localize ASCII digits back to the content locale's numeral system
+          // so users see their saved answers in their native format.
+          // (Phase 1 normalized input to ASCII for scoring/storage.)
+          const locale = this.lang && this.lang.id;
+          userInput = localizeUserInput(userInput, locale);
           // Restore each widget's user input via the Renderer's handleUserInput callback
           const widgetIds = this.itemRenderer.getWidgetIds();
           for (const id of widgetIds) {