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.
A module that needs code after waking wrote into the service manager's sleep units; it now
contributes shell code for a named moment, which derives a dependency on node-power.
Seed the eleven node seats with the verbs they start with. A provision may
have the machine's reach: a requirement for it resolves only to a provider
in the node's own set, is never pulled in, and is refused naming who could.
A shell contribution's for gains xinitrc and xresources, placed only by the
holder of node-display-server.
A module contributes environment variables, PATH entries and shell code in named slots;
the holder of the matching seat places them with ${environment:posix|systemd} and
${shell:<shell>:<slot>}. Rendered in module order with a naming line per contribution,
PATH entries added only when missing, machine facts resolved first. A variable two
modules set, or a placeholder outside its seat's holder, is refused at parse (the
catalogue check) and at composition. Filled after every other placeholder pass, so no
scanner ever reads a shell's own ${...}.
jschoubben
jochen