Fold only sidecar-only releases (sidecar_only at insert); no queue-wide scan for gone releases

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/functional/batch_store.spec.ts

@@ -146,4 +146,17 @@ test.group('BatchStore', (group) => {
     const keys = (await releasesOf()).filter((r) => r.identity_key === first.identity_key).map((r) => r.release_key)
     assert.deepEqual(keys, [first.identity_key, `${first.identity_key}:3`])
   })
+
+  test('a small release of sidecars only is marked for the sidecar fold', async ({ assert }) => {
+    await storeIn(GROUP, 1_000_000, [
+      ...upload(1_000_000, 'Murdoch Mysteries S8D1.nzb', 1, '[00/80]', '2026-10-05T10:00:00Z'),
+      ...upload(1_000_010, 'Some.Tool.v1.zip', 1, '[01/01]', '2026-10-05T10:00:00Z'),
+      ...upload(1_000_020, 'Some.Show.S01E01.part01.rar', 2, '[02/30]', '2026-10-05T10:00:00Z'),
+    ])
+    const flags = new Map((await db.from('releases').select('name', 'sidecar_only')).map((r) => [r.name, r.sidecar_only]))
+    assert.isTrue(flags.get('Murdoch Mysteries S8D1'))
+    assert.isFalse(flags.get('Some.Tool.v1'))
+    // Over 1 MB: not looked at.
+    assert.isNull(flags.get('Some.Show.S01E01'))
+  })
 })