fix(recommendation): drop user_id from Rediscover daily hash to preserve sqlc type inference

CI on 8b586c2e caught it: the $1::text cast in the md5 ORDER BY made
sqlc infer the parameter as plain string instead of pgtype.UUID,
generating Column1 string instead of UserID pgtype.UUID on the
ListRediscover*ForUserParams structs. go vet flagged both call
sites in internal/recommendation/home.go where the Go code passes
UserID by name.

Fix: hash on album_id (or artist_id) + current_date only. The
eligibility filter already differs per user (different liked sets),
so the daily-rotation goal is preserved; we just lose per-user salt
in the within-day ordering of overlapping items - acceptable.

Applies to both primary queries AND both fallback queries (all four
had the same cast).

internal/db/dbq/recommendation.sql.go

@@ -182,7 +182,7 @@ FROM general_likes_albums gla
 JOIN albums  ON albums.id = gla.album_id
 JOIN artists ON artists.id = albums.artist_id
 WHERE gla.user_id = $1
-ORDER BY md5(albums.id::text || $1::text || current_date::text)
+ORDER BY md5(albums.id::text || current_date::text)
 LIMIT $2
 `
 
@@ -200,7 +200,10 @@ type ListRediscoverAlbumsFallbackForUserRow struct {
 // service uses this to top up the rediscover row when the primary
 // eligibility query returns fewer than the inner limit. Same daily
 // hash ordering as the primary so the fallback rows stay stable
-// through the day instead of reshuffling on every refresh.
+// through the day instead of reshuffling on every refresh. Hash
+// omits user_id so sqlc can keep the user_id parameter UUID-typed
+// (a $1::text cast would force the param to string); eligibility
+// already differs per user, so output sets differ regardless.
 func (q *Queries) ListRediscoverAlbumsFallbackForUser(ctx context.Context, arg ListRediscoverAlbumsFallbackForUserParams) ([]ListRediscoverAlbumsFallbackForUserRow, error) {
 	rows, err := q.db.Query(ctx, listRediscoverAlbumsFallbackForUser, arg.UserID, arg.Limit)
 	if err != nil {
@@ -267,13 +270,13 @@ SELECT albums.id, albums.title, albums.sort_title, albums.artist_id, albums.rele
 FROM eligible e
 JOIN albums  ON albums.id = e.album_id
 JOIN artists ON artists.id = albums.artist_id
-ORDER BY md5(albums.id::text || $1::text || current_date::text)
+ORDER BY md5(albums.id::text || current_date::text)
 LIMIT $2
 `
 
 type ListRediscoverAlbumsForUserParams struct {
-	Column1 string
-	Limit   int32
+	UserID pgtype.UUID
+	Limit  int32
 }
 
 type ListRediscoverAlbumsForUserRow struct {
@@ -294,7 +297,7 @@ type ListRediscoverAlbumsForUserRow struct {
 // Final cap + diversity + cross-section dedup land in the Go layer
 // (internal/recommendation/home.go).
 func (q *Queries) ListRediscoverAlbumsForUser(ctx context.Context, arg ListRediscoverAlbumsForUserParams) ([]ListRediscoverAlbumsForUserRow, error) {
-	rows, err := q.db.Query(ctx, listRediscoverAlbumsForUser, arg.Column1, arg.Limit)
+	rows, err := q.db.Query(ctx, listRediscoverAlbumsForUser, arg.UserID, arg.Limit)
 	if err != nil {
 		return nil, err
 	}
@@ -342,7 +345,7 @@ LEFT JOIN LATERAL (
     FROM albums WHERE artist_id = artists.id
 ) cnt ON true
 WHERE gla.user_id = $1
-ORDER BY md5(artists.id::text || $1::text || current_date::text)
+ORDER BY md5(artists.id::text || current_date::text)
 LIMIT $2
 `
 
@@ -359,7 +362,8 @@ type ListRediscoverArtistsFallbackForUserRow struct {
 
 // Daily-stable random sample of liked artists, paired with the Go
 // top-up logic in HomeData when the primary eligibility query returns
-// fewer than the inner limit. Daily hash ordering matches the primary.
+// fewer than the inner limit. Daily hash ordering matches the primary
+// (omitting user_id from the hash for the same sqlc-typing reason).
 func (q *Queries) ListRediscoverArtistsFallbackForUser(ctx context.Context, arg ListRediscoverArtistsFallbackForUserParams) ([]ListRediscoverArtistsFallbackForUserRow, error) {
 	rows, err := q.db.Query(ctx, listRediscoverArtistsFallbackForUser, arg.UserID, arg.Limit)
 	if err != nil {
@@ -434,13 +438,13 @@ LEFT JOIN LATERAL (
     SELECT count(*) AS album_count
     FROM albums WHERE artist_id = artists.id
 ) cnt ON true
-ORDER BY md5(artists.id::text || $1::text || current_date::text)
+ORDER BY md5(artists.id::text || current_date::text)
 LIMIT $2
 `
 
 type ListRediscoverArtistsForUserParams struct {
-	Column1 string
-	Limit   int32
+	UserID pgtype.UUID
+	Limit  int32
 }
 
 type ListRediscoverArtistsForUserRow struct {
@@ -462,7 +466,7 @@ type ListRediscoverArtistsForUserRow struct {
 // hashes). cover_album_id derived from a representative album (most
 // recently created album with cover_art_path set).
 func (q *Queries) ListRediscoverArtistsForUser(ctx context.Context, arg ListRediscoverArtistsForUserParams) ([]ListRediscoverArtistsForUserRow, error) {
-	rows, err := q.db.Query(ctx, listRediscoverArtistsForUser, arg.Column1, arg.Limit)
+	rows, err := q.db.Query(ctx, listRediscoverArtistsForUser, arg.UserID, arg.Limit)
 	if err != nil {
 		return nil, err
 	}

internal/db/queries/recommendation.sql

@@ -313,7 +313,7 @@ SELECT sqlc.embed(albums), artists.name AS artist_name
 FROM eligible e
 JOIN albums  ON albums.id = e.album_id
 JOIN artists ON artists.id = albums.artist_id
-ORDER BY md5(albums.id::text || $1::text || current_date::text)
+ORDER BY md5(albums.id::text || current_date::text)
 LIMIT $2;
 
 -- name: ListRediscoverAlbumsFallbackForUser :many
@@ -321,13 +321,16 @@ LIMIT $2;
 -- service uses this to top up the rediscover row when the primary
 -- eligibility query returns fewer than the inner limit. Same daily
 -- hash ordering as the primary so the fallback rows stay stable
--- through the day instead of reshuffling on every refresh.
+-- through the day instead of reshuffling on every refresh. Hash
+-- omits user_id so sqlc can keep the user_id parameter UUID-typed
+-- (a $1::text cast would force the param to string); eligibility
+-- already differs per user, so output sets differ regardless.
 SELECT sqlc.embed(albums), artists.name AS artist_name
 FROM general_likes_albums gla
 JOIN albums  ON albums.id = gla.album_id
 JOIN artists ON artists.id = albums.artist_id
 WHERE gla.user_id = $1
-ORDER BY md5(albums.id::text || $1::text || current_date::text)
+ORDER BY md5(albums.id::text || current_date::text)
 LIMIT $2;
 
 -- name: ListRediscoverArtistsForUser :many
@@ -381,13 +384,14 @@ LEFT JOIN LATERAL (
     SELECT count(*) AS album_count
     FROM albums WHERE artist_id = artists.id
 ) cnt ON true
-ORDER BY md5(artists.id::text || $1::text || current_date::text)
+ORDER BY md5(artists.id::text || current_date::text)
 LIMIT $2;
 
 -- name: ListRediscoverArtistsFallbackForUser :many
 -- Daily-stable random sample of liked artists, paired with the Go
 -- top-up logic in HomeData when the primary eligibility query returns
--- fewer than the inner limit. Daily hash ordering matches the primary.
+-- fewer than the inner limit. Daily hash ordering matches the primary
+-- (omitting user_id from the hash for the same sqlc-typing reason).
 SELECT sqlc.embed(artists),
        cov.id AS cover_album_id,
        cnt.album_count::bigint AS album_count
@@ -403,5 +407,5 @@ LEFT JOIN LATERAL (
     FROM albums WHERE artist_id = artists.id
 ) cnt ON true
 WHERE gla.user_id = $1
-ORDER BY md5(artists.id::text || $1::text || current_date::text)
+ORDER BY md5(artists.id::text || current_date::text)
 LIMIT $2;