ADR 0214 / to-be 43: a node seat whose holder keeps nightly restore points of what every module on
the machine declares. A contribution of kind backup may name its module's own directories, filled
per module when placed. The catalogue check refuses a store provider that contributes no backup;
parsing does not, so the providers already running stay readable.
Each contribution grain was a manifest field and a renderer of its own; a module now contributes
to any seat with a kind that seat receives, the holder places it with
${contribution:<seat>:<kind>}, and the contribution depends on the seat. node-hotkeys is the
first new seat to receive (triggers); the display session receives window-manager config.
jschoubben
jochen