diff --git a/client/src/lib/stats.test.ts b/client/src/lib/stats.test.ts
new file mode 100644
index 0000000..2146059
--- /dev/null
+++ b/client/src/lib/stats.test.ts
@@ -0,0 +1,11 @@
+import { describe, it, expect } from "vitest";
+import { sumUpdates } from "./stats.js";
+
+describe("sumUpdates", () => {
+  it("somme les compteurs", () => {
+    expect(sumUpdates({ a: 2, b: 3, c: 0 })).toBe(5);
+  });
+  it("retourne 0 pour un objet vide", () => {
+    expect(sumUpdates({})).toBe(0);
+  });
+});
diff --git a/client/src/lib/stats.ts b/client/src/lib/stats.ts
new file mode 100644
index 0000000..cfeeb7c
--- /dev/null
+++ b/client/src/lib/stats.ts
@@ -0,0 +1,4 @@
+// client/src/lib/stats.ts
+export function sumUpdates(counts: Record<string, number>): number {
+  return Object.values(counts).reduce((acc, n) => acc + n, 0);
+}