bvandeusenandClaude Opus 5.5
fcf5b7e5a8
The same rewrite as d191a282, for four packages whose comments carried the
most history: tuning stories, quotes from the operator, single-install
measurements in library_scale.go, and 'used to' accounts of bugs. The
constraint each story protected stays as a present-tense reason (why tier 3
is reduced not removed, why the randomised arms take an order seed, why the
seed artist is eligible in Songs-like). Comments naming system_cron.go and
config.RecommendationConfig, neither of which holds what they claimed, now
name the scheduler and internal/recsettings.
Checked: non-comment tokens identical to HEAD; gofmt clean.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
76 lines
2.8 KiB
Go
76 lines
2.8 KiB
Go
package recommendation
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import (
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"context"
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"github.com/jackc/pgx/v5/pgtype"
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"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
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)
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// contextAffinityShrinkage is the pseudo-count that pulls a low-play artist's
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// cell-share toward the user's baseline, so an artist with one or two plays
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// can't swing its affinity to ±1 on noise. At k plays the estimate sits
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// halfway between the raw cell-share and the baseline.
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const contextAffinityShrinkage = 5.0
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// ContextAffinity is the read-side map of per-artist time-of-day/weekday
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// affinity for the CURRENT context: artist_id → score in [-1, +1].
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// Absent artists (no play history) score 0, so cold-start candidates stay
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// neutral. The zero value is a valid all-neutral affinity.
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type ContextAffinity struct {
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byArtist map[pgtype.UUID]float64
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}
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// Affinity returns the artist's current-context affinity, or 0 if unknown.
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func (c ContextAffinity) Affinity(artistID pgtype.UUID) float64 {
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return c.byArtist[artistID]
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}
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// LoadContextAffinity computes each artist's affinity for the user's CURRENT
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// context cell — daypart × weekday, narrowed by deviceClass when non-empty
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// (radio passes the current device, the daily mixes pass "" for a
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// device-agnostic cell). For every artist with completed plays in the window it
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// compares the share of that artist's plays that fall in the current cell
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// against the user's overall baseline share, shrinking sparse artists toward
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// the baseline. Returns an empty (all-neutral) affinity when the user has no
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// plays.
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func LoadContextAffinity(
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ctx context.Context, q *dbq.Queries, userID pgtype.UUID, deviceClass string,
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) (ContextAffinity, error) {
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rows, err := q.ListArtistContextPlayCountsForUser(ctx, dbq.ListArtistContextPlayCountsForUserParams{
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ID: userID,
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Column2: deviceClass,
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})
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if err != nil {
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return ContextAffinity{}, err
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}
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var totalPlays, cellPlays int64
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for _, r := range rows {
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totalPlays += r.TotalPlays
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cellPlays += r.CellPlays
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}
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out := ContextAffinity{byArtist: make(map[pgtype.UUID]float64, len(rows))}
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if totalPlays == 0 {
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return out, nil
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}
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baseline := float64(cellPlays) / float64(totalPlays)
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for _, r := range rows {
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out.byArtist[r.ArtistID] = contextAffinity(
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float64(r.CellPlays), float64(r.TotalPlays), baseline, contextAffinityShrinkage)
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}
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return out, nil
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}
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// contextAffinity returns an artist's shrunk cell-share minus the user's
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// baseline share, clamped to [-1, 1]. The shrinkage pseudo-count k pulls
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// low-play artists toward the baseline (→ 0 affinity) so noise can't dominate;
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// a heavily-played artist keeps close to its raw over/under-representation.
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func contextAffinity(cellPlays, totalPlays, baseline, k float64) float64 {
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if totalPlays == 0 {
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return 0
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}
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shrunk := (cellPlays + baseline*k) / (totalPlays + k)
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return clampUnit(shrunk - baseline)
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}
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