Sokhi: songs in one album get mismatched cover art. Root cause is upstream of
the repair jobs (which correctly apply one cover per album_id): the standalone
import grouped albums by the album NAME hash (artist::album_name), so the SAME
release split into multiple album rows whenever the name string drifted, and the
cover-art/re-tag jobs then dressed each split row in its own art.
Foundation (new imports only; existing rows untouched): a pure, seam-testable
helper find_existing_soulsync_album_id() resolves the album row by precedence
name-hash id -> source RELEASE id -> (title, artist). When an import carries a
metadata-source album id, a differently-named import of the SAME release now
unifies into one row instead of splitting. Source-column lookup is allow-listed
(it's spliced into SQL) and guarded so a source without a dedicated album column
(Deezer) falls through to the name match instead of breaking the import.
Deliberate scope: this does NOT merge a track that genuinely matched a SINGLE
(a different release id) into its parent album — that needs single->album
resolution upstream and is the next step; this is the grouping substrate it will
feed. 10 seam tests (canonical unify, single-vs-album stays separate, precedence,
allowlist, server-source scope, missing-column fallthrough).
b216233658