RecordPlayStarted and RecordSyntheticCompletedPlay both capture the
session vector inside their existing transactions. Single private
helper queries the prior 5 tracks, builds the vector, UPDATEs the
just-inserted play_event. Tests verify the seed flag boundary and
session-scope isolation.
Owns the auto-close-prior step (caps each user at one open row),
spec §6 skip classification rule on play_ended (AND of completion <
0.5 and duration_played < 30s), and skip_events row writes. Synthetic
completed play wires the Subsonic /rest/scrobble?submission=true path
into the same store as native events.
bvandeusen