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src/data/__tests__/exportService.test.ts

@@ -187,13 +187,23 @@ describe('generateReportHTML — currency-aware amounts', () => {
         expect(html).toContain(`${kwd.symbol}1.500`);
     });
 
-    it('applies the user decimal separator (comma)', () => {
+    it('applies the user number-format profile (comma: dot groups, symbol suffixed)', () => {
         const html = generateReportHTML(
             2026, 2,
             [makeTx({ amount: 200050, type: TransactionType.INCOME })],
             wallets, categories, usd, 'comma',
         );
-        expect(html).toContain(`${usd.symbol}2.000,50`);
+        // The comma profile suffixes the symbol behind a U+00A0 gap.
+        expect(html).toContain(`2.000,50\u00A0${usd.symbol}`);
+    });
+
+    it('applies the user number-format profile (space: U+00A0 groups, symbol suffixed)', () => {
+        const html = generateReportHTML(
+            2026, 2,
+            [makeTx({ amount: 200050, type: TransactionType.INCOME })],
+            wallets, categories, usd, 'space',
+        );
+        expect(html).toContain(`2\u00A0000,50\u00A0${usd.symbol}`);
     });
 
     // DoD-5: totals use the same exponent as the line items (no mixed scaling).

src/data/__tests__/numberFormatDerivation.test.ts

@@ -0,0 +1,214 @@
+/**
+ * Number-format profile derivation tests (V-20 / F-14).
+ *
+ * Two things are under test and they are not the same thing:
+ *
+ *  1. numberFormatForLocale - a pure locale-tag -> profile mapping.
+ *  2. WHEN that mapping is allowed to run. It runs on first launch and never
+ *     again, so a user's explicit choice can never be overwritten by their
+ *     device locale. That guarantee is the point of the feature, and the second
+ *     half of this file exists to hold it in place.
+ */
+
+// ─── Mocks ────────────────────────────────────────────────────────────
+
+jest.mock('@react-native-async-storage/async-storage', () =>
+    require('@react-native-async-storage/async-storage/jest/async-storage-mock')
+);
+
+// Mutable so a test can change the device locale between launches. The getter
+// means every read of NativeModules picks up the current value rather than a
+// value captured when the module was first imported.
+const mockDeviceLocale = { value: 'en_US' };
+
+jest.mock('react-native', () => ({
+    Platform: { OS: 'ios' },
+    NativeModules: {
+        SettingsManager: {
+            get settings() {
+                return {
+                    AppleLocale: mockDeviceLocale.value,
+                    AppleLanguages: [mockDeviceLocale.value],
+                };
+            },
+        },
+    },
+}));
+
+import AsyncStorage from '@react-native-async-storage/async-storage';
+import {
+    getDefaultSettings,
+    getInitialSettings,
+    loadSettings,
+    updateSetting,
+} from '../../data/services/settingsService';
+import { getDeviceLocale } from '../../domain/constants/languages';
+import { numberFormatForLocale } from '../../domain/constants/numberFormats';
+
+const SETTINGS_KEY = '@valto:settings';
+
+beforeEach(async () => {
+    await AsyncStorage.clear();
+    mockDeviceLocale.value = 'en_US';
+    jest.clearAllMocks();
+});
+
+// ─── The pure mapping ─────────────────────────────────────────────────
+
+describe('numberFormatForLocale', () => {
+    it('maps French locales to the space profile', () => {
+        expect(numberFormatForLocale('fr')).toBe('space');
+        expect(numberFormatForLocale('fr-FR')).toBe('space');
+        expect(numberFormatForLocale('fr_CI')).toBe('space');
+        expect(numberFormatForLocale('fr-SN')).toBe('space');
+    });
+
+    it('maps English locales to the dot profile', () => {
+        expect(numberFormatForLocale('en')).toBe('dot');
+        expect(numberFormatForLocale('en_US')).toBe('dot');
+        expect(numberFormatForLocale('en-GB')).toBe('dot');
+    });
+
+    it('maps continental European locales to the comma profile', () => {
+        expect(numberFormatForLocale('de')).toBe('comma');
+        expect(numberFormatForLocale('es-ES')).toBe('comma');
+        expect(numberFormatForLocale('pt-BR')).toBe('comma');
+        expect(numberFormatForLocale('it')).toBe('comma');
+    });
+
+    it('applies region overrides where the language default is wrong', () => {
+        expect(numberFormatForLocale('es-MX')).toBe('dot');
+        expect(numberFormatForLocale('es_US')).toBe('dot');
+        expect(numberFormatForLocale('pt-PT')).toBe('space');
+        expect(numberFormatForLocale('de-CH')).toBe('dot');
+    });
+
+    it('skips a script subtag when looking for the region', () => {
+        expect(numberFormatForLocale('zh-Hans-CN')).toBe('dot');
+        expect(numberFormatForLocale('sr-Latn-RS')).toBe('comma');
+    });
+
+    it('falls back to the dot profile for anything unrecognised', () => {
+        expect(numberFormatForLocale(null)).toBe('dot');
+        expect(numberFormatForLocale(undefined)).toBe('dot');
+        expect(numberFormatForLocale('')).toBe('dot');
+        expect(numberFormatForLocale('xx-YY')).toBe('dot');
+    });
+});
+
+// ─── Reading the device locale ────────────────────────────────────────
+
+describe('getDeviceLocale', () => {
+    it('returns the full tag, region included', () => {
+        mockDeviceLocale.value = 'fr_CI';
+        expect(getDeviceLocale()).toBe('fr_CI');
+    });
+});
+
+// ─── First launch only ────────────────────────────────────────────────
+
+describe('first-launch profile derivation', () => {
+    it('derives the space profile on a French device', async () => {
+        mockDeviceLocale.value = 'fr_FR';
+        const settings = await loadSettings();
+        expect(settings.decimalSeparator).toBe('space');
+    });
+
+    it('derives the dot profile on an English device', async () => {
+        mockDeviceLocale.value = 'en_US';
+        const settings = await loadSettings();
+        expect(settings.decimalSeparator).toBe('dot');
+    });
+
+    it('derives from the region, not only the language', async () => {
+        mockDeviceLocale.value = 'fr_CI';
+        expect((await loadSettings()).decimalSeparator).toBe('space');
+
+        await AsyncStorage.clear();
+        mockDeviceLocale.value = 'es_MX';
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+    });
+
+    it('getInitialSettings is the only entry point that reads the device', () => {
+        mockDeviceLocale.value = 'fr_FR';
+        // getDefaultSettings stays static, so nothing that merges over defaults
+        // can accidentally pull the device locale in.
+        expect(getDefaultSettings().decimalSeparator).toBe('dot');
+        expect(getInitialSettings().decimalSeparator).toBe('space');
+    });
+});
+
+// ─── Never again ──────────────────────────────────────────────────────
+
+describe('a stored choice always wins over the device locale', () => {
+    it('does not overwrite an explicit choice on the next launch', async () => {
+        // Launch 1 on a French device: derived.
+        mockDeviceLocale.value = 'fr_FR';
+        expect((await loadSettings()).decimalSeparator).toBe('space');
+
+        // The user disagrees and picks dot.
+        await updateSetting('decimalSeparator', 'dot');
+
+        // Launch 2, same French device: the stored choice stands.
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+
+        // Launch 3, and a fourth for good measure - still no drift.
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+    });
+
+    it('does not re-derive when the device locale changes under a stored choice', async () => {
+        mockDeviceLocale.value = 'en_US';
+        await updateSetting('decimalSeparator', 'dot');
+
+        // User travels, changes phone language, restores a backup - whatever.
+        mockDeviceLocale.value = 'fr_FR';
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+    });
+
+    it('keeps a stored space choice on an English device', async () => {
+        mockDeviceLocale.value = 'fr_FR';
+        await updateSetting('decimalSeparator', 'space');
+
+        mockDeviceLocale.value = 'en_US';
+        expect((await loadSettings()).decimalSeparator).toBe('space');
+    });
+
+    it('does not derive for an existing install whose stored settings predate the field', async () => {
+        // Storage exists but carries no decimalSeparator. This is NOT a first
+        // launch, so the static default applies rather than the device locale -
+        // an upgrade must not silently restyle every amount in the app.
+        mockDeviceLocale.value = 'fr_FR';
+        await AsyncStorage.setItem(SETTINGS_KEY, JSON.stringify({
+            theme: 'system',
+            currency: 'XOF',
+            currencyLocked: true,
+            notificationsEnabled: false,
+            language: 'fr',
+            dateFormat: 'DD/MM/YYYY',
+            firstDayOfWeek: 'monday',
+            onboardingCompleted: true,
+        }));
+
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+    });
+
+    it('sanitises a corrupted profile to the static default, not to the device locale', async () => {
+        mockDeviceLocale.value = 'fr_FR';
+        await AsyncStorage.setItem(SETTINGS_KEY, JSON.stringify({
+            ...getDefaultSettings(),
+            decimalSeparator: 'semicolon',
+        }));
+
+        expect((await loadSettings()).decimalSeparator).toBe('dot');
+    });
+
+    it('accepts a stored space profile through sanitisation', async () => {
+        await AsyncStorage.setItem(SETTINGS_KEY, JSON.stringify({
+            ...getDefaultSettings(),
+            decimalSeparator: 'space',
+        }));
+
+        expect((await loadSettings()).decimalSeparator).toBe('space');
+    });
+});

src/data/__tests__/settingsFeatures.test.ts

@@ -366,7 +366,12 @@ describe('Formatting Utilities', () => {
     });
 
     it('formatAmount with comma separator', () => {
-        expect(formatAmount(200050, '$', 'comma')).toBe('$2.000,50');
+        // The comma profile suffixes the symbol behind a U+00A0 gap.
+        expect(formatAmount(200050, '$', 'comma')).toBe('2.000,50\u00A0$');
+    });
+
+    it('formatAmount with space separator', () => {
+        expect(formatAmount(200050, '$', 'space')).toBe('2\u00A0000,50\u00A0$');
     });
 
     it('formatDate DD/MM/YYYY', () => {

src/data/services/settingsService.ts

@@ -6,7 +6,8 @@
  */
 
 import { DEFAULT_CURRENCY_CODE } from '../../domain/constants/currencies';
-import { DEFAULT_LANGUAGE_CODE, getDeviceLanguage, isSupportedLanguage } from '../../domain/constants/languages';
+import { DEFAULT_LANGUAGE_CODE, getDeviceLanguage, getDeviceLocale, isSupportedLanguage } from '../../domain/constants/languages';
+import { DEFAULT_NUMBER_FORMAT, NUMBER_FORMAT_PROFILES, numberFormatForLocale } from '../../domain/constants/numberFormats';
 import { asyncStorageAdapter, StorageKeys } from '../storage';
 
 // ─── Types ────────────────────────────────────────────────────────────
@@ -34,16 +35,37 @@ export function getDefaultSettings(): AppSettings {
         language: getDeviceLanguage(),
         dateFormat: 'MM/DD/YYYY',
         firstDayOfWeek: 'monday',
-        decimalSeparator: 'dot',
+        decimalSeparator: DEFAULT_NUMBER_FORMAT,
         onboardingCompleted: false,
     };
 }
 
+/**
+ * Settings for an install that has never stored any.
+ *
+ * This is the ONLY place the device locale reaches the number-format profile, and
+ * it runs on exactly one condition: the settings storage key is absent, which by
+ * definition is first launch. Every later load takes the merge path in
+ * loadSettings, where a stored `decimalSeparator` overrides the default, so a
+ * user's explicit choice can never be overwritten by their device locale - not on
+ * a language change, not on a device migration, not on an app update.
+ *
+ * Deliberately NOT used by the catch path in loadSettings: a transient storage
+ * read failure is not a first launch, and re-deriving there could flip a chosen
+ * format on a bad read.
+ */
+export function getInitialSettings(): AppSettings {
+    return {
+        ...getDefaultSettings(),
+        decimalSeparator: numberFormatForLocale(getDeviceLocale()),
+    };
+}
+
 // ─── Validation Helpers ───────────────────────────────────────────────
 
 const VALID_DATE_FORMATS: DateFormatPreference[] = ['DD/MM/YYYY', 'MM/DD/YYYY', 'YYYY-MM-DD'];
 const VALID_FIRST_DAYS: FirstDayOfWeek[] = ['monday', 'sunday'];
-const VALID_DECIMAL_SEPS: DecimalSeparator[] = ['dot', 'comma'];
+const VALID_DECIMAL_SEPS: DecimalSeparator[] = NUMBER_FORMAT_PROFILES;
 
 // ─── Load ─────────────────────────────────────────────────────────────
 
@@ -56,7 +78,9 @@ export async function loadSettings(): Promise<AppSettings> {
     try {
         const stored = await asyncStorageAdapter.get<Partial<AppSettings>>(StorageKeys.SETTINGS);
         if (!stored) {
-            return getDefaultSettings();
+            // Nothing has ever been persisted: first launch, and the only moment
+            // the device locale is allowed to choose the number-format profile.
+            return getInitialSettings();
         }
         const defaults = getDefaultSettings();
         const merged = { ...defaults, ...stored };
@@ -87,7 +111,7 @@ export async function loadSettings(): Promise<AppSettings> {
             merged.firstDayOfWeek = 'monday';
         }
         if (!VALID_DECIMAL_SEPS.includes(merged.decimalSeparator)) {
-            merged.decimalSeparator = 'dot';
+            merged.decimalSeparator = DEFAULT_NUMBER_FORMAT;
         }
 
         // Validate onboardingCompleted

src/domain/__tests__/validators.test.ts

@@ -209,7 +209,16 @@ describe('validateSettings', () => {
     });
 
     it('throws for invalid decimalSeparator', () => {
-        expect(() => validateSettings({ ...validSettings, decimalSeparator: 'space' as any }))
+        expect(() => validateSettings({ ...validSettings, decimalSeparator: 'semicolon' as any }))
             .toThrow(ValidationError);
     });
+
+    it('accepts every number-format profile', () => {
+        // 'space' became a real profile (grouping U+00A0, comma decimal, suffixed
+        // symbol), so it must validate rather than throw.
+        for (const profile of ['dot', 'comma', 'space'] as const) {
+            expect(() => validateSettings({ ...validSettings, decimalSeparator: profile }))
+                .not.toThrow();
+        }
+    });
 });

src/domain/constants/currencies.ts

@@ -166,7 +166,7 @@ export const SUPPORTED_CURRENCIES: CurrencyDefinition[] = [
     { code: 'WST', symbol: 'WS$', name: 'Samoan Tala', decimals: 2 },
     { code: 'XAF', symbol: 'FCFA', name: 'Central African CFA Franc', decimals: 0 },
     { code: 'XCD', symbol: 'EC$', name: 'East Caribbean Dollar', decimals: 2 },
-    { code: 'XOF', symbol: 'CFA', name: 'West African CFA Franc', decimals: 0 },
+    { code: 'XOF', symbol: 'FCFA', name: 'West African CFA Franc', decimals: 0 },
     { code: 'XPF', symbol: '₣', name: 'CFP Franc', decimals: 0 },
     { code: 'YER', symbol: '﷼', name: 'Yemeni Rial', decimals: 2 },
     { code: 'ZAR', symbol: 'R', name: 'South African Rand', decimals: 2 },