diff --git a/src/notifications/notification-runner.service.ts b/src/notifications/notification-runner.service.ts
index b4f4b3b..883bd4f 100644
--- a/src/notifications/notification-runner.service.ts
+++ b/src/notifications/notification-runner.service.ts
@@ -17,6 +17,7 @@ import {
   type NotificationRule,
   type Severity,
 } from './notification-rules';
+import { quietHoursDelay } from './quiet-hours';
 
 const BATCH_SIZE = 200;
 const SAFETY_LAG_MS = 60_000;
@@ -96,6 +97,11 @@ export class NotificationRunnerService {
 
       // Agregare: daca exista deja o notificare necitita cu aceeasi cheie in
       // fereastra, o incrementam in loc sa cream a doua (spec §12).
+      //
+      // Nota deliberata: agregarea NU reevalueaza quiet hours. Incrementarea
+      // unui contor pe o notificare deja vizibila nu e o intrerupere noua, deci
+      // decision.scheduledAt se aplica doar randurilor nou create. Daca
+      // notificarea existenta e SCHEDULED, ramane SCHEDULED.
       if (rule.aggregationWindowMinutes) {
         const windowStart = new Date(Date.now() - rule.aggregationWindowMinutes * 60_000);
         const existing = await db.query.notifications.findFirst({
@@ -210,37 +216,15 @@ export class NotificationRunnerService {
       return { deliver: false, scheduledAt: null };
     }
 
-    const scheduledAt = this.quietHoursDelay(
-      prefs.quietHoursStart,
-      prefs.quietHoursEnd,
-      rule.severity,
-      prefs.criticalBypassesQuietHours === 1,
-    );
+    const scheduledAt = quietHoursDelay({
+      start: prefs.quietHoursStart,
+      end: prefs.quietHoursEnd,
+      severity: rule.severity,
+      criticalBypasses: prefs.criticalBypassesQuietHours === 1,
+    });
     return { deliver: true, scheduledAt };
   }
 
-  private quietHoursDelay(
-    start: number | null,
-    end: number | null,
-    severity: Severity,
-    criticalBypasses: boolean,
-  ): Date | null {
-    if (start === null || end === null || start === end) return null;
-    if (severity === 'CRITICAL' && criticalBypasses) return null;
-
-    const now = new Date();
-    const hour = now.getUTCHours();
-    // Fereastra poate traversa miezul noptii (ex. 22 -> 7).
-    const inQuiet = start < end ? hour >= start && hour < end : hour >= start || hour < end;
-    if (!inQuiet) return null;
-
-    const deliverAt = new Date(now);
-    deliverAt.setUTCMinutes(0, 0, 0);
-    if (hour >= end) deliverAt.setUTCDate(deliverAt.getUTCDate() + 1);
-    deliverAt.setUTCHours(end);
-    return deliverAt;
-  }
-
   private deduplicationKey(
     rule: NotificationRule,
     event: NotificationEvent,
diff --git a/src/notifications/quiet-hours.spec.ts b/src/notifications/quiet-hours.spec.ts
new file mode 100644
index 0000000..d2b0c69
--- /dev/null
+++ b/src/notifications/quiet-hours.spec.ts
@@ -0,0 +1,68 @@
+import { quietHoursDelay } from './quiet-hours';
+
+const at = (hourUtc: number) => new Date(Date.UTC(2026, 6, 29, hourUtc, 30, 0));
+
+describe('quietHoursDelay', () => {
+  it('livreaza imediat cand userul n-a configurat quiet hours', () => {
+    expect(
+      quietHoursDelay({ start: null, end: null, severity: 'INFORMATION', criticalBypasses: true, now: at(3) }),
+    ).toBeNull();
+  });
+
+  it('trateaza start === end ca fiind fara quiet hours, nu ca 24h de liniste', () => {
+    expect(
+      quietHoursDelay({ start: 9, end: 9, severity: 'INFORMATION', criticalBypasses: true, now: at(9) }),
+    ).toBeNull();
+  });
+
+  describe('fereastra simpla, in aceeasi zi (9 -> 17)', () => {
+    it('amana pana la sfarsitul ferestrei cand suntem inauntru', () => {
+      const result = quietHoursDelay({ start: 9, end: 17, severity: 'INFORMATION', criticalBypasses: true, now: at(13) });
+      expect(result?.toISOString()).toBe('2026-07-29T17:00:00.000Z');
+    });
+
+    it('livreaza imediat inainte de inceputul ferestrei', () => {
+      expect(
+        quietHoursDelay({ start: 9, end: 17, severity: 'INFORMATION', criticalBypasses: true, now: at(8) }),
+      ).toBeNull();
+    });
+
+    it('livreaza imediat exact la ora de sfarsit -- capatul e exclusiv', () => {
+      expect(
+        quietHoursDelay({ start: 9, end: 17, severity: 'INFORMATION', criticalBypasses: true, now: at(17) }),
+      ).toBeNull();
+    });
+  });
+
+  describe('fereastra care traverseaza miezul noptii (22 -> 7)', () => {
+    it('seara amana pana dimineata ZILEI URMATOARE', () => {
+      const result = quietHoursDelay({ start: 22, end: 7, severity: 'INFORMATION', criticalBypasses: true, now: at(23) });
+      expect(result?.toISOString()).toBe('2026-07-30T07:00:00.000Z');
+    });
+
+    it('noaptea tarziu amana pana dimineata ACELEIASI zi', () => {
+      const result = quietHoursDelay({ start: 22, end: 7, severity: 'INFORMATION', criticalBypasses: true, now: at(3) });
+      expect(result?.toISOString()).toBe('2026-07-29T07:00:00.000Z');
+    });
+
+    it('la pranz livreaza imediat -- suntem in afara ferestrei', () => {
+      expect(
+        quietHoursDelay({ start: 22, end: 7, severity: 'INFORMATION', criticalBypasses: true, now: at(12) }),
+      ).toBeNull();
+    });
+  });
+
+  describe('CRITICAL', () => {
+    it('depaseste quiet hours cand politica userului permite', () => {
+      expect(
+        quietHoursDelay({ start: 22, end: 7, severity: 'CRITICAL', criticalBypasses: true, now: at(3) }),
+      ).toBeNull();
+    });
+
+    it('respecta quiet hours cand userul a dezactivat bypass-ul', () => {
+      // Nu presupunem ca "critical" invinge mereu preferinta explicita a userului.
+      const result = quietHoursDelay({ start: 22, end: 7, severity: 'CRITICAL', criticalBypasses: false, now: at(3) });
+      expect(result?.toISOString()).toBe('2026-07-29T07:00:00.000Z');
+    });
+  });
+});
diff --git a/src/notifications/quiet-hours.ts b/src/notifications/quiet-hours.ts
new file mode 100644
index 0000000..1db3d66
--- /dev/null
+++ b/src/notifications/quiet-hours.ts
@@ -0,0 +1,38 @@
+import type { Severity } from './notification-rules';
+
+/**
+ * Calculeaza cand se poate livra o notificare data fiind fereastra de liniste
+ * a userului. Intoarce null cand se poate livra imediat.
+ *
+ * Functie pura, separata de runner, ca sa fie testabila: aritmetica de ore cu
+ * fereastra care traverseaza miezul noptii e locul unde apar erorile.
+ */
+export function quietHoursDelay(params: {
+  start: number | null;
+  end: number | null;
+  severity: Severity;
+  criticalBypasses: boolean;
+  now?: Date;
+}): Date | null {
+  const { start, end, severity, criticalBypasses } = params;
+  const now = params.now ?? new Date();
+
+  // start === end ar insemna fereastra de 24h sau de 0h -- ambiguu, deci o
+  // tratam ca "fara quiet hours" in loc sa ghicim.
+  if (start === null || end === null || start === end) return null;
+  if (severity === 'CRITICAL' && criticalBypasses) return null;
+
+  const hour = now.getUTCHours();
+  const crossesMidnight = start > end;
+  const inQuiet = crossesMidnight ? hour >= start || hour < end : hour >= start && hour < end;
+  if (!inQuiet) return null;
+
+  const deliverAt = new Date(now);
+  deliverAt.setUTCMinutes(0, 0, 0);
+  // Daca ora curenta e deja peste ora de sfarsit, sfarsitul ferestrei e maine.
+  if (hour >= end) {
+    deliverAt.setUTCDate(deliverAt.getUTCDate() + 1);
+  }
+  deliverAt.setUTCHours(end);
+  return deliverAt;
+}