generated-write
An advisory: it explains, and blocks nothing, on a hand edit to a declared output, which the next run overwrites.
What it catches
A hand edit to a declared output, which the next run overwrites.
Seeing it
A verdict names its rule in brackets, which is how you got here:
advise [generated-write]: ...
magus describe rule generated-write prints the same entry at a terminal, and
magus describe rules lists every rule this workspace enforces.