Every image records the identity of its build inputs. forgefirm-manifest.bbclass
gives a component recipe a per-file source fingerprint (git ls-tree blob ids,
submodules recursed; file:// sources hashed with git hash-object); the kernel
and glowforge.ko publish theirs through do_deploy because kernel-module-split
leaves the module recipe's main package empty. forgefirm-image-manifest.bbclass
assembles the entries with the platform identity - machine, modules directory,
device tree hashes, layer content hashes (meta-forgefirm and the meta-openglow
layers by content, the kas-managed layers by revision) - into
/etc/forgefirm-manifest.json and deploys a copy next to the image. Layer
revisions and dirty flags stay outside the identity, so a rebuild from an
unchanged tree keeps its content hash and the release and dev images of one
build share it. The acceptance tool and the release gate read this file.