Milestone #160 Opt 5. A collaborative candidate arm: tracks by artists
co-played across the instance with the seed's artist.
Minstrel is a single shared-library, multi-user server (no per-user
library ACL — verified: no owner/share/group model), so the "household"
is the whole instance's user set; the rule #47 scoping is satisfied by
the shared-library boundary. Single-user servers produce no edges.
- No migration: source='user_cooccurrence' was pre-whitelisted in the
0009 similarity CHECK from day one.
- internal/db/queries/coplay.sql: Delete + Insert artist co-play edges.
Score = Jaccard of the two artists' distinct-player sets (controls for
globally-popular artists); >= 2 co-players AND Jaccard >= floor kept
(the floor also self-limits hub artists). Completed plays, 365d window.
- internal/coplay: periodic worker (6h) that atomic-replaces the
user_cooccurrence edge set from play_events — pure local SQL, no
external calls. Wired in main.go alongside the similarity worker.
- LoadRadioCandidatesV2: new coplay_artists arm (source='user_cooccurrence',
seed-artist based, 0.5 damp like similar_artists) + $11 limit;
CandidateSourceLimits.UserCoplay (default 20, For-You 40).
- Integration tests: perfect-overlap Jaccard=1.0 edge + single-user
empty-set gate.
Device axis and AcousticBrainz (Opt 4) are separately tracked; this
closes the milestone-#160 sequential options.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
