Online keys, meaning keys used in an automated fashion, never serve a role that clients end up trusting for the files they install, and where keys are online, exceptional care is taken: they are held in a hardware security module and used only when the artifacts being signed have passed the policy defined for secure build and commit, so that automated signing cannot bless an artifact that failed the pipeline's checks.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.