Whether to merge into a writable conf.json at activation instead of linking it from the Nix store.
Plex mpv shim writes this file when it loads settings and whenever a setting is changed from its menu or a Plex remote. With a linked file those writes fail, and the generated player identity (client_uuid) is not kept across restarts.
When enabled, declared settings override existing values and other keys are preserved, including settings later removed from . Changed settings trigger a restart when automatic systemd service switching is enabled. If systemd.user.startServices is false or "suggest", restart the shim manually to load changed settings. A running shim can still write its old values back between the merge and restart; stop it before switching and start it afterward to avoid this window.
Disabling this option later leaves the writable conf.json in place. If settings are nonempty, move or remove it before switching, or Home Manager reports a file collision.