diff --git a/features/image-assistant/backend-api/src/modules/classification/classification.logic.spec.ts b/features/image-assistant/backend-api/src/modules/classification/classification.logic.spec.ts
new file mode 100644
index 000000000..31d08a65c
--- /dev/null
+++ b/features/image-assistant/backend-api/src/modules/classification/classification.logic.spec.ts
@@ -0,0 +1,155 @@
+import { describe, it, expect } from 'vitest';
+
+import { determineCategory, SCREENSHOT_SIGLIP_PROMPTS } from './classification.logic';
+import { PhotoCategory } from './classification.types';
+
+import type { ModeratorResult, SiglipResult } from './classification.types';
+
+describe('SCREENSHOT_SIGLIP_PROMPTS', () => {
+  it('contains all expected screenshot categories as keys', () => {
+    const expectedKeys = ['receipt', 'conversation', 'shopping', 'meme', 'event', 'reservation', 'hottie', 'other'];
+    for (const key of expectedKeys) {
+      expect(SCREENSHOT_SIGLIP_PROMPTS).toHaveProperty(key);
+      expect(Array.isArray(SCREENSHOT_SIGLIP_PROMPTS[key])).toBe(true);
+      expect(SCREENSHOT_SIGLIP_PROMPTS[key].length).toBeGreaterThan(0);
+    }
+  });
+});
+
+describe('determineCategory — screenshot path', () => {
+  const screenshotPhoto = { isScreenshot: true, isSelfie: false, storageKey: 'some/key.jpg' };
+
+  it('returns SCREENSHOT_OTHER when no siglipResult provided', () => {
+    expect(determineCategory(screenshotPhoto)).toBe(PhotoCategory.SCREENSHOT_OTHER);
+  });
+
+  it('returns SCREENSHOT_OTHER when siglipResult has empty scores', () => {
+    const siglip: SiglipResult = { scores: {} };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_OTHER);
+  });
+
+  it('picks the key with the highest score', () => {
+    const siglip: SiglipResult = {
+      scores: { receipt: 0.1, conversation: 0.9, shopping: 0.3 },
+    };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_CONVERSATION);
+  });
+
+  it('maps receipt → SCREENSHOT_RECEIPT', () => {
+    const siglip: SiglipResult = { scores: { receipt: 0.95, other: 0.1 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_RECEIPT);
+  });
+
+  it('maps shopping → SCREENSHOT_SHOPPING', () => {
+    const siglip: SiglipResult = { scores: { shopping: 0.8 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_SHOPPING);
+  });
+
+  it('maps meme → SCREENSHOT_MEME', () => {
+    const siglip: SiglipResult = { scores: { meme: 0.7 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_MEME);
+  });
+
+  it('maps event → SCREENSHOT_EVENT', () => {
+    const siglip: SiglipResult = { scores: { event: 0.6 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_EVENT);
+  });
+
+  it('maps reservation → SCREENSHOT_RESERVATION', () => {
+    const siglip: SiglipResult = { scores: { reservation: 0.75 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_RESERVATION);
+  });
+
+  it('maps hottie → SCREENSHOT_HOTTIE', () => {
+    const siglip: SiglipResult = { scores: { hottie: 0.85 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_HOTTIE);
+  });
+
+  it('maps other → SCREENSHOT_OTHER', () => {
+    const siglip: SiglipResult = { scores: { other: 0.6 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_OTHER);
+  });
+
+  it('returns SCREENSHOT_OTHER for an unknown top key', () => {
+    const siglip: SiglipResult = { scores: { unknown_category: 0.99 } };
+    expect(determineCategory(screenshotPhoto, undefined, siglip)).toBe(PhotoCategory.SCREENSHOT_OTHER);
+  });
+
+  it('ignores moderatorResult when photo is a screenshot', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.9, nsfw_category: 'explicit', face_count: 2 };
+    const siglip: SiglipResult = { scores: { meme: 0.9 } };
+    expect(determineCategory(screenshotPhoto, moderator, siglip)).toBe(PhotoCategory.SCREENSHOT_MEME);
+  });
+});
+
+describe('determineCategory — no storage key', () => {
+  it('returns UNCLASSIFIED when storageKey is null and not a screenshot', () => {
+    expect(determineCategory({ isScreenshot: false, isSelfie: false, storageKey: null })).toBe(
+      PhotoCategory.UNCLASSIFIED,
+    );
+  });
+
+  it('returns UNCLASSIFIED when storageKey is undefined and not a screenshot', () => {
+    expect(determineCategory({ isScreenshot: false, isSelfie: false })).toBe(PhotoCategory.UNCLASSIFIED);
+  });
+});
+
+describe('determineCategory — moderator result path', () => {
+  const photo = { isScreenshot: false, isSelfie: false, storageKey: 'photos/original.jpg' };
+  const selfiePhoto = { isScreenshot: false, isSelfie: true, storageKey: 'photos/selfie.jpg' };
+
+  it('returns UNCLASSIFIED when no moderatorResult is provided', () => {
+    expect(determineCategory(photo)).toBe(PhotoCategory.UNCLASSIFIED);
+  });
+
+  it('returns SELF_EXPLICIT for explicit + selfie', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.95, nsfw_category: 'explicit', face_count: 1 };
+    expect(determineCategory(selfiePhoto, moderator)).toBe(PhotoCategory.SELF_EXPLICIT);
+  });
+
+  it('returns SELF_EXPLICIT for explicit + face_count <= 1 even without isSelfie flag', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.95, nsfw_category: 'explicit', face_count: 1 };
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.SELF_EXPLICIT);
+  });
+
+  it('returns SELF_WITH_OTHERS for explicit + face_count > 1 without isSelfie', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.95, nsfw_category: 'explicit', face_count: 3 };
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.SELF_WITH_OTHERS);
+  });
+
+  it('returns SELF_EXPLICIT for explicit + isSelfie even with face_count > 1', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.95, nsfw_category: 'explicit', face_count: 2 };
+    expect(determineCategory(selfiePhoto, moderator)).toBe(PhotoCategory.SELF_EXPLICIT);
+  });
+
+  it('returns SELF_NUDE when nsfw_score > 0.4 and not explicit', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.6, nsfw_category: 'nude', face_count: 0 };
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.SELF_NUDE);
+  });
+
+  it('returns SELF_NUDE at exactly the 0.4 threshold boundary (above)', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.41, nsfw_category: 'suggestive', face_count: 0 };
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.SELF_NUDE);
+  });
+
+  it('does NOT return SELF_NUDE at exactly 0.4 (boundary is strict greater-than)', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.4, nsfw_category: 'safe', face_count: 0 };
+    // Falls through to isSelfie/face_count checks
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.UNCLASSIFIED);
+  });
+
+  it('returns SELF_CLOTHED when isSelfie and nsfw_score <= 0.4', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.1, nsfw_category: 'safe', face_count: 1 };
+    expect(determineCategory(selfiePhoto, moderator)).toBe(PhotoCategory.SELF_CLOTHED);
+  });
+
+  it('returns FRIENDS when face_count > 0 and not selfie and nsfw_score <= 0.4', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.1, nsfw_category: 'safe', face_count: 2 };
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.FRIENDS);
+  });
+
+  it('returns UNCLASSIFIED when safe, no selfie, no faces', () => {
+    const moderator: ModeratorResult = { nsfw_score: 0.05, nsfw_category: 'safe', face_count: 0 };
+    expect(determineCategory(photo, moderator)).toBe(PhotoCategory.UNCLASSIFIED);
+  });
+});