fix: make grocery and reference ordering deterministic

Every list query lacked a tiebreak, so rows sharing a sort key (same-ms
createdAt inserts, tied or NULL quality scores) came back in unspecified
order and bestRef flipped between loads. Add explicit tiebreaks: items
createdAt desc, id desc (newest first); references qualityScore desc,
id asc (first inserted wins ties). Categories were already total
(order, name unique).

Pin the rules with service tests.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/lib/server/services/references.test.ts b/src/lib/server/services/references.test.ts
index 49c5c94..bcefbd0 100644
--- a/src/lib/server/services/references.test.ts
+++ b/src/lib/server/services/references.test.ts
@@ -34,6 +34,25 @@ describe('references service', () => {
 		expect(refs[0].reference).toBe('Brand A');
 	});
 
+	it('loadForGrocery orders refs by score desc, then insertion', async () => {
+		const now = Temporal.Now.instant().toString({
+			smallestUnit: 'millisecond',
+		});
+		const [g] = await db
+			.insert(groceries)
+			.values({ name: 'coffee', checked: false, createdAt: now })
+			.returning();
+		await db.insert(references).values([
+			{ groceryId: g.id, reference: 'A' },
+			{ groceryId: g.id, reference: 'B', qualityScore: 50 },
+			{ groceryId: g.id, reference: 'C' },
+			{ groceryId: g.id, reference: 'D', qualityScore: 50 },
+		]);
+
+		const refs = await loadForGrocery(g.id, db);
+		expect(refs.map((r) => r.reference)).toEqual(['B', 'D', 'A', 'C']);
+	});
+
 	it('add creates a reference', async () => {
 		const now = Temporal.Now.instant().toString({
 			smallestUnit: 'millisecond',