Executor

Zinc advances work by running package software.

Flow

prepare(source, args) -> assembly_fragment
advance(assembly_fragment) -> assembly_fragment

If an advance step cannot move, it returns an error.

zn run loops until the assembly fragment contains final result bytes.

read shape
confirm shape
prepare request
run package software
store result
move head
repeat while more parts remain

Advance either moves the fragment or returns an error. Completion is detected from result bytes.