minstrel/internal/db/migrations/0035_taste_profile.up.sql

-- 0035_taste_profile.up.sql — per-user taste profile.
--
-- A persistent, decaying model of each user's taste, rebuilt daily from
-- graded play engagement (completion + skip position) plus explicit
-- likes. Two facet tables: weighted artists and weighted genre tags.
-- Weight is a signed float — positive = drawn to, negative = (passively)
-- avoided; magnitude reflects decayed engagement. Candidate sourcing and
-- scoring read them.
--
-- CASCADE on user/artist deletes keeps them clean. Indexed by
-- (user_id, weight DESC) to serve "top taste artists/tags" reads cheaply.

CREATE TABLE taste_profile_artists (
    user_id    uuid             NOT NULL REFERENCES users(id)   ON DELETE CASCADE,
    artist_id  uuid             NOT NULL REFERENCES artists(id) ON DELETE CASCADE,
    weight     double precision NOT NULL,
    updated_at timestamptz      NOT NULL DEFAULT now(),
    PRIMARY KEY (user_id, artist_id)
);

CREATE INDEX taste_profile_artists_user_weight_idx
    ON taste_profile_artists (user_id, weight DESC);

CREATE TABLE taste_profile_tags (
    user_id    uuid             NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    tag        text             NOT NULL,
    weight     double precision NOT NULL,
    updated_at timestamptz      NOT NULL DEFAULT now(),
    PRIMARY KEY (user_id, tag)
);

CREATE INDEX taste_profile_tags_user_weight_idx
    ON taste_profile_tags (user_id, weight DESC);