Setup generation, ownership and errors

Setup validates every declaration and destination before writing. If any declaration is invalid, none of the declared output files changes.

After a successful preflight, setup atomically replaces every generated layer, target, design and chartpack that it declares. There is no overwrite prompt or flag. Maintained and undeclared files are untouched.

File	Owner	Replaced by setup?
setup.yaml	Experiment author	No
setup.py	Standard entry point	No
Declared generated layer	Setup	Yes
Declared target	Setup	Yes
Declared design	Setup	Yes
Declared chartpack	Setup	Yes
Maintained layer	Person or run script	No
run_*.py	Experiment author	No

Run scripts consume the generated or maintained artefacts directly. They keep working after setup.yaml and setup.py are removed.

Common setup errors include unknown fields, duplicate keys, unsafe output filenames, selectors that match nothing, invalid projection years, duplicate destinations, missing maintained files and design IDs that do not name a declared layer.

To take manual ownership of a generated file, stop rerunning the declaration that creates it or remove that declaration. Editing a generated file and then running setup again loses the manual change.