The #1249 mechanism (stamp WHY a track is in the snapshot at build
time, freeze it onto the play at ingestion, break it down in metrics)
generalizes from a For You one-off to the standard for every system
mix (#1270):
- Migration 0039 widens both pick_kind CHECKs (drop + re-add in the
same change) to taste/fresh + Discover's dormant/cross_user/random
+ tier1-3 for the rule-#131 eligibility ladders.
- GetForYouPickKindForTrack becomes GetSystemPickKindForTrack
(user, variant, track); ingestion stamps any systemPlaylistSources
play from its own variant's live snapshot, live + offline paths.
- Discover stamps its candidate bucket on discoverTrack before the
interleave, making the 40/30/30 allocation measurable; dedup keeps
the taking bucket's stamp.
- Metrics replace the for_you special-case with one pick-kind
vocabulary — any family with attributed plays gets a breakdown,
future stamping mixes need no metrics change.
- Web: breakdown sub-rows are now toggled per surface (collapsed by
default) so eight stamping mixes don't swamp the card.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TsF3cNoKrqCYsU78cXC8U6
Milestone #127 step 2 (#1249). For You deliberately blends two
populations — a head of top-scored taste picks and a tail sampled from
deeper ranking (the freshness injection) — but the metrics judged it as
one blob, so its skip rate couldn't distinguish "the taste engine is
missing" from "the freshness tax is too high". That number decides the
exploration share before we tune it.
- Migration 0038: nullable pick_kind ('taste'|'fresh') on both
playlist_tracks (stamped at snapshot build) and play_events (frozen at
play-ingestion — the snapshot rebuilds daily, so attribution cannot be
reconstructed at read time).
- Builder: pickHeadAndTail marks head=taste / tail=fresh; the small-pool
fallback is all taste (top-N-by-score IS the taste mechanism). Other
variants persist NULL.
- Ingestion: for_you plays (live + offline replay) look the track up in
the user's current snapshot; not found → unattributed, never guessed.
- Metrics: For You's row gains a breakdown (taste / fresh / earlier
unattributed plays), parent row stays the sum; web card renders the
sub-rows indented with the same baseline deltas + low-data dimming.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TsF3cNoKrqCYsU78cXC8U6
First of three stages for system-playlist sample-history dedup
(Fable #415, server-side rotation per the operator's choice).
Schema (migration 0027):
- play_events.source (nullable text): which surface a play came
from. 'for_you' / 'discover' feed rotation; NULL for library /
user-playlist / radio / Subsonic.
- system_playlist_rotation_state(user_id, playlist_kind,
played_track_ids uuid[], rotation_started_at, updated_at): the
per-(user,kind) set of already-heard tracks this rotation.
Ingest:
- New RecordPlayStartedWithSource on the writer; RecordPlayStarted
is now a thin source="" wrapper so the frozen Subsonic shim is
untouched (no signature ripple).
- When source is a known system kind, the same txn appends the
track to rotation state (AppendRotationPlayed keeps the array a
set via the conflict CASE).
- /api/events play_started accepts an optional "source".
No serve-behavior change yet — Stage 2 makes shuffle prefer the
unplayed tail + resets on exhaustion; Stage 3 wires the clients to
send source and consume the rotation-aware order.
Tests: rotation appends + dedupes for a system source; source-less
play writes no rotation row. (Existing RecordPlayStarted tests are
unchanged — same wrapper signature, identical behavior at source="".)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
ListRecentSessionTracks + UpdatePlayEventVector for the vector capture
path inside RecordPlayStarted. LikeTrack switches to :execrows so the
contextual-likes capture can detect insert vs already-exists. Existing
callers updated to ignore the count for now; later tasks consume it.
Tables and indexes per spec §5. session_vector_at_play ships nullable
so M3 doesn't need a follow-up migration. Table is named play_sessions
to avoid collision with the existing sessions (HTTP auth) table from
migration 0004.
bvandeusen