register
Persist web-service metadata for contentKey in the GPKG gpkg_web_service extension table. Capabilities XML/JSON in WebServiceInfo.metadata survives across launches so the layer can be reconstructed without an online capabilities request.
Infallible contract. Implementations catch and log any storage failures (read-only DB, IDB write rejected, filesystem error, etc.) — they never throw. The layer's in-memory wiring still works even if persistence fails; the user just loses the ability to reopen the layer offline.