The check-shared-machines example carried two actual prod hostnames. docs/ is
excluded from the code bundle and goes to the GitHub wiki, so an example is the
wrong place for live fleet identifiers. Replaced with placeholders.
The MECHANISM was already a documented platform contract - ADR-001 defines
partof as composition, makes controls propagate through it, and walks it first
for map-position inheritance. The part-marker work used that rail rather than
inventing one.
What was undocumented is the PATTERN built on it: several devices answering to
one identifier, each becoming its own asset filed under a parent. It existed
only as a collector behaviour for part markers plus a docstring in the device
map, so nothing told anyone how to apply it to another device type, or when not
to.
ASSET-COMPOSITION.md covers when to reach for it and when the shared identifier
is a numbering fault instead, what propagation buys, how to declare a device
type through the map or a per-site setting, what a backup kind must do to
follow the device rather than the parent, how to find the next case with
check-shared-machines, and why the parent is not disposable once devices hang
off it - deactivating it breaks filing, and a hard delete cascades through
backuprevisions.
