internal/db/dbq/recommendation.sql.go

@@ -1022,20 +1022,66 @@ func (q *Queries) LoadRadioCandidatesV2(ctx context.Context, arg LoadRadioCandid
 }
 
 const suggestArtistsForUser = `-- name: SuggestArtistsForUser :many
-WITH seeds AS (
+-- Per-user artist suggestions ranked by taste signal x similarity, projected
+-- through artist_similarity_unmatched (out-of-library candidates only).
+--
+-- Seeds are TIERED (rule #131) so the surface never empties:
+--   tier 1 - taste_profile_artists.weight: engagement-graded, time-decayed and
+--            SIGNED by internal/taste, so an artist the user has drifted away
+--            from stops contributing instead of accumulating forever.
+--   tier 2 - likes + completed plays, used ONLY when the profile has no rows
+--            (new account, or before the first daily recompute).
+--
+-- The signal is log-damped: contribution is signal x similarity, and the old
+-- undamped sum let one heavily-played artist's neighbours take every slot --
+-- entrenching harder the MORE the user listened (issue #2367 mechanism 2).
+--
+-- Candidates already in the library, or already requested and not terminal,
+-- are excluded. $1=user_id, $2=half_life_days (tier 2 decay), $3=limit.
+WITH artist_plays AS (
+    -- Completed plays only. The previous seed query counted every play_event,
+    -- so skipping an artist repeatedly INCREASED its signal and pushed more of
+    -- its neighbours at the user (issue #2367 mechanism 3).
+    SELECT t.artist_id, count(*)::bigint AS play_count
+    FROM play_events pe
+    JOIN tracks t ON t.id = pe.track_id
+    WHERE pe.user_id = $1 AND pe.was_skipped = false
+    GROUP BY t.artist_id
+),
+profile_seeds AS (
+    SELECT tpa.artist_id, tpa.weight AS raw_signal
+    FROM taste_profile_artists tpa
+    WHERE tpa.user_id = $1 AND tpa.weight > 0
+),
+fallback_seeds AS (
     SELECT a.id AS artist_id,
            5.0 * (CASE WHEN gla.artist_id IS NOT NULL THEN 1 ELSE 0 END)
            + COALESCE(SUM(EXP(- EXTRACT(epoch FROM now() - pe.started_at) / ($2::float8 * 86400.0))), 0)
-           AS signal,
-           (gla.artist_id IS NOT NULL) AS is_liked,
-           COUNT(pe.id)::bigint AS play_count
+           AS raw_signal
     FROM artists a
     LEFT JOIN general_likes_artists gla ON gla.artist_id = a.id AND gla.user_id = $1
     LEFT JOIN tracks t ON t.artist_id = a.id
-    LEFT JOIN play_events pe ON pe.track_id = t.id AND pe.user_id = $1
-    WHERE gla.artist_id IS NOT NULL OR pe.id IS NOT NULL
+    LEFT JOIN play_events pe
+           ON pe.track_id = t.id AND pe.user_id = $1 AND pe.was_skipped = false
+    WHERE (gla.artist_id IS NOT NULL OR pe.id IS NOT NULL)
+      AND NOT EXISTS (SELECT 1 FROM profile_seeds)
     GROUP BY a.id, gla.artist_id
 ),
+seeds AS (
+    SELECT s.artist_id,
+           ln(1.0 + s.raw_signal) AS signal,
+           (gla.artist_id IS NOT NULL) AS is_liked,
+           COALESCE(ap.play_count, 0)::bigint AS play_count
+    FROM (
+        SELECT artist_id, raw_signal FROM profile_seeds
+        UNION ALL
+        SELECT artist_id, raw_signal FROM fallback_seeds
+    ) s
+    LEFT JOIN general_likes_artists gla
+           ON gla.artist_id = s.artist_id AND gla.user_id = $1
+    LEFT JOIN artist_plays ap ON ap.artist_id = s.artist_id
+    WHERE s.raw_signal > 0
+),
 contributions AS (
     SELECT u.candidate_mbid,
            u.candidate_name,

internal/db/queries/recommendation.sql

@@ -258,27 +258,66 @@ ORDER BY started_at DESC
 LIMIT 1;
 
 -- name: SuggestArtistsForUser :many
--- M5c: per-user artist suggestions ranked by signal x similarity. The
--- seeds CTE collects the user's likes (x5) plus recency-decayed plays
--- (exp(-age_days / $2)). The contributions CTE joins those seeds against
--- artist_similarity_unmatched and filters out candidates already in
--- library or already in a non-terminal lidarr_request. The outer SELECT
--- aggregates per candidate, returning the top-3 contributing seeds for
--- attribution. $1=user_id, $2=half_life_days, $3=limit.
-WITH seeds AS (
+-- Per-user artist suggestions ranked by taste signal x similarity, projected
+-- through artist_similarity_unmatched (out-of-library candidates only).
+--
+-- Seeds are TIERED (rule #131) so the surface never empties:
+--   tier 1 - taste_profile_artists.weight: engagement-graded, time-decayed and
+--            SIGNED by internal/taste, so an artist the user has drifted away
+--            from stops contributing instead of accumulating forever.
+--   tier 2 - likes + completed plays, used ONLY when the profile has no rows
+--            (new account, or before the first daily recompute).
+--
+-- The signal is log-damped: contribution is signal x similarity, and the old
+-- undamped sum let one heavily-played artist's neighbours take every slot --
+-- entrenching harder the MORE the user listened (issue #2367 mechanism 2).
+--
+-- Candidates already in the library, or already requested and not terminal,
+-- are excluded. $1=user_id, $2=half_life_days (tier 2 decay), $3=limit.
+WITH artist_plays AS (
+    -- Completed plays only. The previous seed query counted every play_event,
+    -- so skipping an artist repeatedly INCREASED its signal and pushed more of
+    -- its neighbours at the user (issue #2367 mechanism 3).
+    SELECT t.artist_id, count(*)::bigint AS play_count
+    FROM play_events pe
+    JOIN tracks t ON t.id = pe.track_id
+    WHERE pe.user_id = $1 AND pe.was_skipped = false
+    GROUP BY t.artist_id
+),
+profile_seeds AS (
+    SELECT tpa.artist_id, tpa.weight AS raw_signal
+    FROM taste_profile_artists tpa
+    WHERE tpa.user_id = $1 AND tpa.weight > 0
+),
+fallback_seeds AS (
     SELECT a.id AS artist_id,
            5.0 * (CASE WHEN gla.artist_id IS NOT NULL THEN 1 ELSE 0 END)
            + COALESCE(SUM(EXP(- EXTRACT(epoch FROM now() - pe.started_at) / ($2::float8 * 86400.0))), 0)
-           AS signal,
-           (gla.artist_id IS NOT NULL) AS is_liked,
-           COUNT(pe.id)::bigint AS play_count
+           AS raw_signal
     FROM artists a
     LEFT JOIN general_likes_artists gla ON gla.artist_id = a.id AND gla.user_id = $1
     LEFT JOIN tracks t ON t.artist_id = a.id
-    LEFT JOIN play_events pe ON pe.track_id = t.id AND pe.user_id = $1
-    WHERE gla.artist_id IS NOT NULL OR pe.id IS NOT NULL
+    LEFT JOIN play_events pe
+           ON pe.track_id = t.id AND pe.user_id = $1 AND pe.was_skipped = false
+    WHERE (gla.artist_id IS NOT NULL OR pe.id IS NOT NULL)
+      AND NOT EXISTS (SELECT 1 FROM profile_seeds)
     GROUP BY a.id, gla.artist_id
 ),
+seeds AS (
+    SELECT s.artist_id,
+           ln(1.0 + s.raw_signal) AS signal,
+           (gla.artist_id IS NOT NULL) AS is_liked,
+           COALESCE(ap.play_count, 0)::bigint AS play_count
+    FROM (
+        SELECT artist_id, raw_signal FROM profile_seeds
+        UNION ALL
+        SELECT artist_id, raw_signal FROM fallback_seeds
+    ) s
+    LEFT JOIN general_likes_artists gla
+           ON gla.artist_id = s.artist_id AND gla.user_id = $1
+    LEFT JOIN artist_plays ap ON ap.artist_id = s.artist_id
+    WHERE s.raw_signal > 0
+),
 contributions AS (
     SELECT u.candidate_mbid,
            u.candidate_name,

internal/recommendation/suggestions.go

@@ -1,7 +1,14 @@
-// suggestions.go is the M5c per-user artist-suggestion service. Reads
-// the user's likes + plays, projects them through artist_similarity_unmatched
-// via a single CTE, returns top-N candidates with top-3 attribution seeds
-// resolved to artist names.
+// suggestions.go is the per-user artist-suggestion service behind the
+// Discover request surface. Seeds from the taste profile (falling back to
+// likes + completed plays for a user who has none yet), projects those seeds
+// through artist_similarity_unmatched via a single CTE, and returns top-N
+// out-of-library candidates with top-3 attribution seeds resolved to names.
+//
+// Originally M5c, which seeded from raw likes + plays. That signal grew
+// without bound and counted skips as engagement, so a few heavily-played
+// artists monopolized every slot and the surface entrenched harder the more
+// the user listened. Reworked to seed from the taste profile in issue #2367;
+// see internal/db/queries/recommendation.sql for the tiering.
 package recommendation
 
 import (
@@ -32,8 +39,12 @@ type SeedContribution struct {
 }
 
 // SuggestArtists returns top-N artist suggestions for the user. limit is
-// capped at 50 (default 12 when out of range); halfLifeDays is the
-// recency-decay half-life for plays (default 30, operator-tunable).
+// capped at 50 (default 12 when out of range).
+//
+// halfLifeDays (default 30) is the recency-decay half-life for the TIER-2
+// seed path only — the likes + completed-plays fallback used while the user
+// has no taste-profile rows yet. Once the profile is populated it seeds
+// instead, carrying its own decay, so this knob stops applying.
 func SuggestArtists(ctx context.Context, pool *pgxpool.Pool, userID pgtype.UUID, halfLifeDays float64, limit int) ([]ArtistSuggestion, error) {
 	if limit <= 0 || limit > 50 {
 		limit = 12

internal/recommendation/suggestions_integration_test.go

@@ -330,3 +330,145 @@ func TestSuggestArtists_EmptyForNewUser(t *testing.T) {
 		t.Errorf("len = %d, want 0 (new user has no signal)", len(out))
 	}
 }
+
+// --- Slice 1 (#2372): taste-profile seeding, tiering, and the skip fix ---
+
+func setTasteWeight(t *testing.T, pool *pgxpool.Pool, userID, artistID pgtype.UUID, weight float64) {
+	t.Helper()
+	if _, err := pool.Exec(context.Background(),
+		`INSERT INTO taste_profile_artists (user_id, artist_id, weight) VALUES ($1, $2, $3)
+		 ON CONFLICT (user_id, artist_id) DO UPDATE SET weight = EXCLUDED.weight`,
+		userID, artistID, weight,
+	); err != nil {
+		t.Fatalf("set taste weight: %v", err)
+	}
+}
+
+func insertSkippedPlayEvent(t *testing.T, pool *pgxpool.Pool, userID, trackID pgtype.UUID, startedAt time.Time) {
+	t.Helper()
+	ctx := context.Background()
+	var sessionID pgtype.UUID
+	if err := pool.QueryRow(ctx,
+		`INSERT INTO play_sessions (user_id, started_at, last_event_at, client_id)
+		 VALUES ($1, $2, $2, 'skip-test') RETURNING id`,
+		userID, startedAt,
+	).Scan(&sessionID); err != nil {
+		t.Fatalf("insert play_session: %v", err)
+	}
+	if _, err := pool.Exec(ctx,
+		`INSERT INTO play_events (user_id, track_id, session_id, started_at, was_skipped)
+		 VALUES ($1, $2, $3, $4, true)`,
+		userID, trackID, sessionID, startedAt,
+	); err != nil {
+		t.Fatalf("insert skipped play_event: %v", err)
+	}
+}
+
+// Tier 1: a taste-profile weight alone seeds a suggestion, with no like and no
+// play on the seed artist. Before #2367 the profile was ignored entirely here.
+func TestSuggestArtists_TasteProfileWeightSeedsTier1(t *testing.T) {
+	pool := newPool(t)
+	user := seedUser(t, pool, "alice")
+	seed := seedArtist(t, pool, "Profile Seed", "")
+
+	setTasteWeight(t, pool, user.ID, seed.ID, 4.0)
+	seedUnmatched(t, pool, seed.ID, "out-mbid", "Outsider", 0.9)
+
+	out, err := SuggestArtists(context.Background(), pool, user.ID, 30, 12)
+	if err != nil {
+		t.Fatalf("SuggestArtists: %v", err)
+	}
+	if len(out) != 1 {
+		t.Fatalf("len = %d, want 1 (taste weight alone should seed)", len(out))
+	}
+	if out[0].MBID != "out-mbid" {
+		t.Errorf("mbid = %q, want out-mbid", out[0].MBID)
+	}
+	if out[0].Score <= 0 {
+		t.Errorf("score = %v, want > 0", out[0].Score)
+	}
+}
+
+// Once the profile has any positive row, tier 2 is not consulted — so an artist
+// the user played but that the taste engine did not keep does NOT seed. That is
+// the point of the rewrite: the taste engine decides what counts as affinity.
+func TestSuggestArtists_TasteProfileSupersedesRawPlays(t *testing.T) {
+	pool := newPool(t)
+	user := seedUser(t, pool, "alice")
+	kept := seedArtist(t, pool, "Kept By Taste", "")
+	dropped := seedArtist(t, pool, "Dropped By Taste", "")
+
+	setTasteWeight(t, pool, user.ID, kept.ID, 3.0)
+
+	// `dropped` has real completed plays but no profile row.
+	album := seedAlbumForArtist(t, pool, dropped.ID, "Album")
+	track := seedTrackOnAlbum(t, pool, album.ID, dropped.ID, "Track")
+	insertPlayEvent(t, pool, user.ID, track.ID, time.Now().Add(-1*time.Hour))
+
+	seedUnmatched(t, pool, kept.ID, "kept-cand", "Kept Candidate", 0.9)
+	seedUnmatched(t, pool, dropped.ID, "dropped-cand", "Dropped Candidate", 0.9)
+
+	out, err := SuggestArtists(context.Background(), pool, user.ID, 30, 12)
+	if err != nil {
+		t.Fatalf("SuggestArtists: %v", err)
+	}
+	if len(out) != 1 {
+		t.Fatalf("len = %d, want 1 (tier 2 must not run alongside tier 1)", len(out))
+	}
+	if out[0].MBID != "kept-cand" {
+		t.Errorf("mbid = %q, want kept-cand", out[0].MBID)
+	}
+}
+
+// A non-positive taste weight is not affinity. Guarded by a second, positive
+// row so tier 1 stays active — otherwise an empty tier 1 would fall through to
+// tier 2 and the assertion would pass for the wrong reason.
+func TestSuggestArtists_NonPositiveTasteWeightDoesNotSeed(t *testing.T) {
+	pool := newPool(t)
+	user := seedUser(t, pool, "alice")
+	positive := seedArtist(t, pool, "Still Liked", "")
+	abandoned := seedArtist(t, pool, "Abandoned", "")
+
+	setTasteWeight(t, pool, user.ID, positive.ID, 2.0)
+	setTasteWeight(t, pool, user.ID, abandoned.ID, -1.5)
+
+	seedUnmatched(t, pool, positive.ID, "pos-cand", "Positive Candidate", 0.9)
+	seedUnmatched(t, pool, abandoned.ID, "neg-cand", "Negative Candidate", 0.9)
+
+	out, err := SuggestArtists(context.Background(), pool, user.ID, 30, 12)
+	if err != nil {
+		t.Fatalf("SuggestArtists: %v", err)
+	}
+	for _, s := range out {
+		if s.MBID == "neg-cand" {
+			t.Fatalf("negative-weight artist seeded a suggestion: %+v", s)
+		}
+	}
+	if len(out) != 1 || out[0].MBID != "pos-cand" {
+		t.Errorf("out = %+v, want only pos-cand", out)
+	}
+}
+
+// Tier 2 counts COMPLETED plays only. Previously every play_event counted, so
+// skipping an artist repeatedly increased its signal and pushed more of its
+// neighbours at the user (#2367 mechanism 3).
+func TestSuggestArtists_SkippedPlaysDoNotSeedTier2(t *testing.T) {
+	pool := newPool(t)
+	user := seedUser(t, pool, "alice")
+	skipped := seedArtist(t, pool, "Only Skipped", "")
+
+	album := seedAlbumForArtist(t, pool, skipped.ID, "Album")
+	track := seedTrackOnAlbum(t, pool, album.ID, skipped.ID, "Track")
+	for i := 0; i < 5; i++ {
+		insertSkippedPlayEvent(t, pool, user.ID, track.ID, time.Now().Add(-time.Duration(i+1)*time.Hour))
+	}
+	seedUnmatched(t, pool, skipped.ID, "skip-cand", "Skip Candidate", 0.9)
+
+	out, err := SuggestArtists(context.Background(), pool, user.ID, 30, 12)
+	if err != nil {
+		t.Fatalf("SuggestArtists: %v", err)
+	}
+	if len(out) != 0 {
+		t.Errorf("len = %d, want 0 (skips are not affinity): %+v", len(out), out)
+	}
+}