diff --git a/src/components/budget/BudgetTable.render.test.tsx b/src/components/budget/BudgetTable.render.test.tsx
index f747d00..4650eee 100644
--- a/src/components/budget/BudgetTable.render.test.tsx
+++ b/src/components/budget/BudgetTable.render.test.tsx
@@ -10,9 +10,7 @@ import { renderToStaticMarkup } from "react-dom/server";
 import type { BudgetYearRow } from "../../shared/types";
 import type { CollapseAccessors } from "../../utils/collapsibleRows";
 
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 
 const harness = vi.hoisted(() => ({
   /** Keys of the open groups (`p:<category id>`): the grid opens collapsed. */
diff --git a/src/components/budget/BudgetTable.wiring.test.ts b/src/components/budget/BudgetTable.wiring.test.ts
index b16be6b..b5a31c2 100644
--- a/src/components/budget/BudgetTable.wiring.test.ts
+++ b/src/components/budget/BudgetTable.wiring.test.ts
@@ -16,9 +16,7 @@ const ctx = vi.hoisted(() => ({
   /** Keys of the open groups (`p:<category id>`): the grid opens collapsed. */
   expanded: new Set<string>(),
 }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 vi.mock("../../hooks/useCollapsibleGroups", async () => {
   const { collapsibleKeys, isCollapsedFor, visibleRows } = await import("../../utils/collapsibleRows");
   return {
diff --git a/src/components/dashboard/DashboardEmptyState.render.test.tsx b/src/components/dashboard/DashboardEmptyState.render.test.tsx
index 30967e3..4c6adcc 100644
--- a/src/components/dashboard/DashboardEmptyState.render.test.tsx
+++ b/src/components/dashboard/DashboardEmptyState.render.test.tsx
@@ -7,13 +7,7 @@ import type { ReactElement, ReactNode } from "react";
 import { renderToStaticMarkup } from "react-dom/server";
 import { MemoryRouter } from "react-router-dom";
 
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 
 import DashboardEmptyState from "./DashboardEmptyState";
 import OnboardingChecklist from "./OnboardingChecklist";
diff --git a/src/components/layout/AppShell.render.test.tsx b/src/components/layout/AppShell.render.test.tsx
index a3c830f..ddb3f4a 100644
--- a/src/components/layout/AppShell.render.test.tsx
+++ b/src/components/layout/AppShell.render.test.tsx
@@ -13,13 +13,7 @@ import { MemoryRouter, Route, Routes } from "react-router-dom";
 // plugins) and useEntitlement (→ LicenseContext): stub both.
 vi.mock("../../services/db", () => ({ getDb: vi.fn(), withTransaction: vi.fn() }));
 vi.mock("../../contexts/LicenseContext", () => ({ useLicenseContext: vi.fn() }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 vi.mock("./Sidebar", () => ({ default: () => <nav>sidebar</nav> }));
 
 let onboarding: OnboardingValue;
diff --git a/src/components/onboarding/OnboardingBanner.render.test.tsx b/src/components/onboarding/OnboardingBanner.render.test.tsx
index fcdda0e..b9f0b98 100644
--- a/src/components/onboarding/OnboardingBanner.render.test.tsx
+++ b/src/components/onboarding/OnboardingBanner.render.test.tsx
@@ -7,15 +7,9 @@ import { isValidElement, type ReactElement, type ReactNode } from "react";
 import { renderToStaticMarkup } from "react-dom/server";
 import { Link, MemoryRouter } from "react-router-dom";
 
-// The fake `t` marks what it translates, `t(key[options])`: a string that
+// The shared fake `t` (src/test/i18nMock.ts) marks what it translates, `t(key[options])`: a string that
 // skipped `t` would show unmarked.
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 
 import OnboardingBanner, {
   GETTING_STARTED_GUIDE,
diff --git a/src/components/onboarding/StepCard.render.test.tsx b/src/components/onboarding/StepCard.render.test.tsx
index 180ae88..d93d4ec 100644
--- a/src/components/onboarding/StepCard.render.test.tsx
+++ b/src/components/onboarding/StepCard.render.test.tsx
@@ -7,15 +7,9 @@ import { createRef, isValidElement, type ReactElement, type ReactNode } from "re
 import { renderToStaticMarkup } from "react-dom/server";
 import { Link, MemoryRouter } from "react-router-dom";
 
-// The fake `t` marks what it translates, `t(key[options])`: a string that
+// The shared fake `t` (src/test/i18nMock.ts) marks what it translates, `t(key[options])`: a string that
 // skipped `t` would show unmarked.
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 
 import StepCard, { type StepCardProps } from "./StepCard";
 import { GETTING_STARTED_GUIDE } from "./OnboardingBanner";
diff --git a/src/components/settings/LicenseCard.render.test.tsx b/src/components/settings/LicenseCard.render.test.tsx
index 3edc275..6b37a5c 100644
--- a/src/components/settings/LicenseCard.render.test.tsx
+++ b/src/components/settings/LicenseCard.render.test.tsx
@@ -10,16 +10,10 @@ vi.mock("@tauri-apps/api/core", () => ({ invoke: vi.fn() }));
 vi.mock("@tauri-apps/plugin-opener", () => ({ openUrl: vi.fn(() => Promise.resolve()) }));
 
 let language = "fr";
-// The fake `t` marks what it translates, `t(key[options])`: the assertions written in that form
+// The shared fake `t` (src/test/i18nMock.ts) marks what it translates, `t(key[options])`: the assertions written in that form
 // fail on a string that skipped `t` (#387 review). Substring assertions on a bare key still read
 // the key inside the mark.
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock({ language: () => language }));
 
 let context: Record<string, unknown>;
 vi.mock("../../contexts/LicenseContext", async (importOriginal) => ({
diff --git a/src/pages/BudgetPage.render.test.tsx b/src/pages/BudgetPage.render.test.tsx
index 0d6d7df..82b3af7 100644
--- a/src/pages/BudgetPage.render.test.tsx
+++ b/src/pages/BudgetPage.render.test.tsx
@@ -11,13 +11,7 @@ import { MemoryRouter } from "react-router-dom";
 
 // The budget, collapse and preference services pull the database: stub the connection.
 vi.mock("../services/db", () => ({ getDb: vi.fn(), withTransaction: vi.fn() }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../test/i18nMock")).i18nMock());
 vi.mock("../components/shared/PageHelp", () => ({ PageHelp: () => null }));
 
 const harness = vi.hoisted(() => ({ budget: null as unknown, onboarding: null as unknown }));
diff --git a/src/pages/BudgetPage.wiring.test.ts b/src/pages/BudgetPage.wiring.test.ts
index 9791db7..c2d85c5 100644
--- a/src/pages/BudgetPage.wiring.test.ts
+++ b/src/pages/BudgetPage.wiring.test.ts
@@ -19,9 +19,7 @@ vi.mock("react-router-dom", async (importOriginal) => ({
   ...(await importOriginal<typeof import("react-router-dom")>()),
   useLocation: () => ({ pathname: ctx.pathname }),
 }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
-}));
+vi.mock("react-i18next", async () => (await import("../test/i18nMock")).i18nMock());
 // The page's modules pull the database: stub the connection.
 vi.mock("../services/db", () => ({ getDb: vi.fn(), withTransaction: vi.fn() }));
 vi.mock("../contexts/OnboardingContext", () => ({ useOnboarding: () => ctx.onboarding }));
diff --git a/src/pages/ImportPage.render.test.tsx b/src/pages/ImportPage.render.test.tsx
index 13ddbaa..a511b16 100644
--- a/src/pages/ImportPage.render.test.tsx
+++ b/src/pages/ImportPage.render.test.tsx
@@ -12,13 +12,7 @@ import { MemoryRouter } from "react-router-dom";
 // Importing the real wizard module (for its initial state) pulls the import
 // services, then the database: stub the connection.
 vi.mock("../services/db", () => ({ getDb: vi.fn(), withTransaction: vi.fn() }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../test/i18nMock")).i18nMock());
 
 const harness = vi.hoisted(() => ({ wizard: null as unknown, onboarding: null as unknown }));
 
diff --git a/src/pages/TransactionsPage.render.test.tsx b/src/pages/TransactionsPage.render.test.tsx
index 04ba739..678e360 100644
--- a/src/pages/TransactionsPage.render.test.tsx
+++ b/src/pages/TransactionsPage.render.test.tsx
@@ -12,13 +12,7 @@ import type { TransactionFilters, TransactionRow } from "../shared/types";
 
 // The page's services pull the database: stub the connection.
 vi.mock("../services/db", () => ({ getDb: vi.fn(), withTransaction: vi.fn() }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({
-    t: (k: string, o?: Record<string, unknown>) =>
-      o ? `t(${k}[${Object.entries(o).map(([a, b]) => `${a}=${String(b)}`).join(",")}])` : `t(${k})`,
-    i18n: { language: "fr" },
-  }),
-}));
+vi.mock("react-i18next", async () => (await import("../test/i18nMock")).i18nMock());
 vi.mock("../components/shared/PageHelp", () => ({ PageHelp: () => null }));
 
 const harness = vi.hoisted(() => ({
diff --git a/src/pages/settings/UsersSettingsPage.test.tsx b/src/pages/settings/UsersSettingsPage.test.tsx
index 953b3a0..ab4db00 100644
--- a/src/pages/settings/UsersSettingsPage.test.tsx
+++ b/src/pages/settings/UsersSettingsPage.test.tsx
@@ -11,9 +11,7 @@ import { isValidElement, type ReactElement, type ReactNode } from "react";
 
 vi.mock("react", async (orig) => (await import("../../test/hookHarness")).fakeReact(await orig()));
 const ctx = vi.hoisted(() => ({ onboarding: null as unknown }));
-vi.mock("react-i18next", () => ({
-  useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
-}));
+vi.mock("react-i18next", async () => (await import("../../test/i18nMock")).i18nMock());
 vi.mock("../../contexts/OnboardingContext", () => ({
   useOnboarding: () => ctx.onboarding,
 }));