EXPAND ONLY, per the migration order (expand, migrate, verify, contract). No
Postgres implementation, no behaviour change.
internal/catalog now exposes:
type Store interface {
Item / ItemFor / Files / FilesFor / FileByID / FirstFile / FileCount
}
type SQL struct{ db *sql.DB }; func New(db *sql.DB) *SQL
The seven bodies are the old functions moved verbatim. ItemFor still returns the
same ErrNotFound for absent and forbidden, so the security property is
unchanged. A compile-time `var _ Store = (*SQL)(nil)` keeps the implementation
honest.
Deliberately NOT moved: browse lists, home shelves and subsonic album queries.
Those are each package's own presentation concern, and pulling all of them into
the seam is exactly the 186-statement rewrite the seam exists to avoid. The
package doc says so.
Proven substitutable, not just declared: store_test.go implements a fake Store
in memory with no database at all and drives a caller through the interface. A
seam nobody can substitute proves nothing.
The agent's own risk note was right and I acted on it: the seam only pays off
once something actually threads it, and initially nothing did. So internal/
playback — the smallest consumer — now takes a catalog.Store instead of *sql.DB
and is wired with catalog.New(db) at the composition point. It has no database
reference left outside a comment. The remaining consumers (media, jellyfin,
subsonic, metadata) still call the package-level wrappers; threading them is
mechanical, and I would rather do it deliberately than in one sweep.
Verified: gofmt clean, build exit 0, vet exit 0, 25 packages pass, arch rules
pass. End to end against a running server: /playback/resolve still returns
vcodec:hevc for html5 and engine mpv when mpv is offered, an unknown item 404s,
/home and Jellyfin /Items still answer.
Known gap, unchanged by this commit: internal/arch does not enforce "new code
must not take *sql.DB", so the seam can erode by drift. That rule would be the
natural next step if this is to hold.