diff --git a/app/backend/src/lib/persian.ts b/app/backend/src/lib/persian.ts
new file mode 100644
index 0000000..d79d4f7
--- /dev/null
+++ b/app/backend/src/lib/persian.ts
@@ -0,0 +1,34 @@
+export function normalizeFa(input: string) {
+  return input
+    .replace(/[\u200c\u0640]/g, '')
+    .replace(/[\u064b-\u0652]/g, '')
+    .replace(/[يى]/g, 'ی')
+    .replace(/ك/g, 'ک')
+    .replace(/[أإآٱ]/g, 'ا')
+    .replace(/\s+/g, ' ')
+    .trim()
+    .toLowerCase();
+}
+
+export function computeStreak(streakCount: number, lastReadAt: Date | null, now: Date): number {
+  if (!lastReadAt) return 1;
+  const lastDate = new Date(lastReadAt);
+  lastDate.setHours(0, 0, 0, 0);
+  const today = new Date(now);
+  today.setHours(0, 0, 0, 0);
+  const diffDays = Math.floor((today.getTime() - lastDate.getTime()) / (1000 * 60 * 60 * 24));
+  if (diffDays === 1) return streakCount + 1;
+  if (diffDays > 1) return 1;
+  return streakCount;
+}
+
+export function currentStreakIfAlive(streakCount: number, lastReadAt: Date | null, now: Date): number {
+  if (!lastReadAt) return 0;
+  const lastDate = new Date(lastReadAt);
+  lastDate.setHours(0, 0, 0, 0);
+  const today = new Date(now);
+  today.setHours(0, 0, 0, 0);
+  const diffDays = Math.floor((today.getTime() - lastDate.getTime()) / (1000 * 60 * 60 * 24));
+  if (diffDays > 1) return 0;
+  return streakCount;
+}