The Discover request surface was the one recommendation surface still on its
M5c implementation from early May. #796's taste profile, #1488's taste_unheard
bucket and #1490's folksonomy enrichment all modernized in-library surfaces;
this one was never in scope for any of them, so it still projected raw likes +
plays through artist_similarity_unmatched.
Two defects fall out of that signal, `5*liked + Σexp(-age/halflife)` summed
over every play of the artist.
It is unbounded, and contribution is signal × similarity — so a handful of
heavily-played artists monopolize all twelve slots, and their share GROWS the
more the user listens. The surface entrenched harder the better it knew you,
which is exactly backwards and matches the reported "goes stale once it has a
strong signal of your taste".
It also counted every play_event with no was_skipped filter, so skipping an
artist repeatedly INCREASED its signal and pushed more of its neighbours at the
user. ListMostPlayedTracksForUser and the taste engine both filter skips; this
query was the odd one out.
Seeds now come from taste_profile_artists.weight, which the taste engine has
already engagement-graded, time-decayed and signed — an artist the user drifted
away from stops contributing instead of accumulating forever, and can even
contribute negatively. Tiered per rule #131 rather than hard-switched: tier 1 is
the profile, tier 2 is likes + completed plays for a user who has no profile
rows yet (new account, or before the first daily recompute), so the surface
never empties. The old unfiltered-play signal is gone, not kept behind a toggle.
The signal is also log-damped, so one artist cannot take every slot even when
its weight dwarfs the rest.
$2 stays wired to the tier-2 decay: it is genuinely still used there, and
dropping the parameter would have changed the generated signature.
sqlc's image is not on this workstation and the change preserves the query
signature exactly — same three params, same seven columns — so only the
embedded SQL const moves. Both copies are edited and verified byte-identical
rather than pulling a container onto the operator's machine; a malformed query
fails the integration lane loudly, which is the real check either way.
Four integration tests cover what changed: a taste weight alone seeds with no
like or play; tier 2 does not run alongside tier 1; a non-positive weight never
seeds (guarded by a second positive row, so an empty tier 1 can't make it pass
for the wrong reason); and skip-only history seeds nothing.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Add per-user artist-suggestion service ranking out-of-library MBIDs by
signal x similarity. Single-CTE SQL collects user likes (5x weight) and
recency-decayed plays, joins against artist_similarity_unmatched, and
filters in-library candidates plus non-terminal lidarr_requests. The
service resolves top-3 attribution seeds to artist names in a batched
GetArtistsByIDs call so the UI can render "because you liked X" reasons.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusenandClaude Opus 5