feat(db): add artist_similarity_unmatched schema (migration 0012)

internal/db/dbq/models.go

@@ -216,6 +216,15 @@ type ArtistSimilarity struct {
 	FetchedAt pgtype.Timestamptz
 }
 
+type ArtistSimilarityUnmatched struct {
+	SeedArtistID  pgtype.UUID
+	CandidateMbid string
+	CandidateName string
+	Score         float64
+	Source        string
+	FetchedAt     pgtype.Timestamptz
+}
+
 type ContextualLike struct {
 	ID            pgtype.UUID
 	UserID        pgtype.UUID

internal/db/dbq/similarity.sql.go

@@ -172,6 +172,38 @@ func (q *Queries) UpsertArtistSimilarity(ctx context.Context, arg UpsertArtistSi
 	return err
 }
 
+const upsertArtistSimilarityUnmatched = `-- name: UpsertArtistSimilarityUnmatched :exec
+INSERT INTO artist_similarity_unmatched (
+    seed_artist_id, candidate_mbid, candidate_name, score, source
+) VALUES ($1, $2, $3, $4, $5)
+ON CONFLICT (seed_artist_id, candidate_mbid, source) DO UPDATE SET
+    candidate_name = EXCLUDED.candidate_name,
+    score          = EXCLUDED.score,
+    fetched_at     = now()
+`
+
+type UpsertArtistSimilarityUnmatchedParams struct {
+	SeedArtistID  pgtype.UUID
+	CandidateMbid string
+	CandidateName string
+	Score         float64
+	Source        string
+}
+
+// Persists an out-of-library similar-artist MBID. Idempotent on
+// (seed_artist_id, candidate_mbid, source) — re-fetches refresh the
+// name/score and bump fetched_at.
+func (q *Queries) UpsertArtistSimilarityUnmatched(ctx context.Context, arg UpsertArtistSimilarityUnmatchedParams) error {
+	_, err := q.db.Exec(ctx, upsertArtistSimilarityUnmatched,
+		arg.SeedArtistID,
+		arg.CandidateMbid,
+		arg.CandidateName,
+		arg.Score,
+		arg.Source,
+	)
+	return err
+}
+
 const upsertTrackSimilarity = `-- name: UpsertTrackSimilarity :exec
 INSERT INTO track_similarity (track_a_id, track_b_id, score, source, fetched_at)
 VALUES ($1, $2, $3, 'listenbrainz', now())