From 1f72b0dffbfde8736da4459c744ffcf508118c31 Mon Sep 17 00:00:00 2001
From: Floze <88098863+floze-the-genius@users.noreply.github.com>
Date: Sun, 19 Jul 2026 17:33:15 +0400
Subject: [PATCH 1/2] fix(Qobuz): restore missing GTIN check digits

---
 providers/Qobuz/mod.test.ts | 12 +++++++++++-
 providers/Qobuz/mod.ts      | 12 ++++++++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/providers/Qobuz/mod.test.ts b/providers/Qobuz/mod.test.ts
index fef74344..568b90ad 100644
--- a/providers/Qobuz/mod.test.ts
+++ b/providers/Qobuz/mod.test.ts
@@ -6,7 +6,7 @@ import { assert } from 'std/assert/assert.ts';
 import { afterAll, describe, it } from '@std/testing/bdd';
 import { assertSnapshot } from '@std/testing/snapshot';
 
-import QobuzProvider from './mod.ts';
+import QobuzProvider, { normalizeQobuzGtin } from './mod.ts';
 import { assertEquals } from 'std/assert/assert_equals.ts';
 
 describe('Qobuz provider', () => {
@@ -129,6 +129,16 @@ describe('Qobuz provider', () => {
 		);
 	});
 
+	describe('GTIN normalization', () => {
+		it('appends a missing check digit to legacy 13-digit UPC values', () => {
+			assertEquals(normalizeQobuzGtin('0001589171735'), '00015891717357');
+		});
+
+		it('preserves UPC values which already have a valid check digit', () => {
+			assertEquals(normalizeQobuzGtin('0198884774947'), '0198884774947');
+		});
+	});
+
 	afterAll(() => {
 		lookupStub.restore();
 	});
diff --git a/providers/Qobuz/mod.ts b/providers/Qobuz/mod.ts
index 1b662912..1bb6d59b 100644
--- a/providers/Qobuz/mod.ts
+++ b/providers/Qobuz/mod.ts
@@ -5,7 +5,7 @@ import { DurationPrecision, FeatureQuality, FeatureQualityMap } from '@/provider
 import { getFromEnv } from '@/utils/config.ts';
 import { parseHyphenatedDate, PartialDate } from '@/utils/date.ts';
 import { ResponseError } from '@/utils/errors.ts';
-import { isEqualGTIN } from '@/utils/gtin.ts';
+import { checkDigit, isEqualGTIN, isValidGTIN } from '@/utils/gtin.ts';
 import type {
 	ArtistCreditName,
 	Artwork,
@@ -29,6 +29,14 @@ import { ResponseError as SnapResponseError } from 'snap-storage';
 
 const qobuzAppId = getFromEnv('HARMONY_QOBUZ_APP_ID') || '';
 
+export function normalizeQobuzGtin(upc: string): string {
+	if (isValidGTIN(upc) || !/^\d{13}$/.test(upc)) {
+		return upc;
+	}
+
+	return `${upc}${checkDigit(`${upc}0`)}`;
+}
+
 export default class QobuzProvider extends MetadataApiProvider {
 	readonly name = 'Qobuz';
 
@@ -245,7 +253,7 @@ export class QobuzReleaseLookup extends ReleaseApiLookup<QobuzProvider, QobuzAlb
 				types: linkTypes,
 			}],
 			info: this.generateReleaseInfo(),
-			gtin: rawRelease.upc,
+			gtin: normalizeQobuzGtin(rawRelease.upc),
 		};
 	}
 

From 1db810f76d664dec1660c2972f5f8d4ed860e78e Mon Sep 17 00:00:00 2001
From: David Kellner <52860029+kellnerd@users.noreply.github.com>
Date: Sun, 9 Aug 2026 21:59:20 +0200
Subject: [PATCH 2/2] Apply suggestions from code review

Co-authored-by: David Kellner <52860029+kellnerd@users.noreply.github.com>
---
 providers/Qobuz/mod.test.ts | 4 ++--
 providers/Qobuz/mod.ts      | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/providers/Qobuz/mod.test.ts b/providers/Qobuz/mod.test.ts
index 568b90ad..ed688475 100644
--- a/providers/Qobuz/mod.test.ts
+++ b/providers/Qobuz/mod.test.ts
@@ -130,11 +130,11 @@ describe('Qobuz provider', () => {
 	});
 
 	describe('GTIN normalization', () => {
-		it('appends a missing check digit to legacy 13-digit UPC values', () => {
+		it('appends a missing check digit to invalid 13-digit barcodes, turning them into valid GTIN-14', () => {
 			assertEquals(normalizeQobuzGtin('0001589171735'), '00015891717357');
 		});
 
-		it('preserves UPC values which already have a valid check digit', () => {
+		it('preserves GTIN-13 values which already have a valid check digit', () => {
 			assertEquals(normalizeQobuzGtin('0198884774947'), '0198884774947');
 		});
 	});
diff --git a/providers/Qobuz/mod.ts b/providers/Qobuz/mod.ts
index 1bb6d59b..432934ce 100644
--- a/providers/Qobuz/mod.ts
+++ b/providers/Qobuz/mod.ts
@@ -29,6 +29,7 @@ import { ResponseError as SnapResponseError } from 'snap-storage';
 
 const qobuzAppId = getFromEnv('HARMONY_QOBUZ_APP_ID') || '';
 
+/** Appends the missing check digit to invalid 13 digit barcodes from older Qobuz releases. */
 export function normalizeQobuzGtin(upc: string): string {
 	if (isValidGTIN(upc) || !/^\d{13}$/.test(upc)) {
 		return upc;