The #319 retirement's constructive half, slice 1: a new top-level
`exec <target>` executes a campaign document (file, register-then-run, or
64-hex content id — byte-behaviour of the retired `campaign run`, which no
longer parses) or a fully-bound signal blueprint (synthetic single run,
record line byte-identical to `aura run`'s, root-name gate migrated).
Flag discipline is per-leg: --parallel-instruments on campaign targets,
--tap on blueprint targets (refused on campaign targets with prose).
File routing peeks the document's top-level "kind" key: is_blueprint_file
alone cannot tell two .json classes apart.
--override (the #246 residue) and the measurement leg follow in later
slices; run/sweep/walkforward/mc/generalize stay alive until the removal
slice.
refs #319
claude
78b80ec0fd