Scratch hygiene

Temporary work is not a delivery. Every scratch item has a lifetime, and a task is not finished while its byproducts are still on disk.

Where scratch goes

Scratch lives under the operating system's temp directory, in one folder per task (%LOCALAPPDATA%\Temp\<task> on Windows, $TMPDIR/<task> elsewhere) - never inside the repository, the workspace root, or the user profile root.
Name the folder after the task so a later sweep can tell whose it is and whether anything still needs it.
A script that turned out reusable is no longer scratch: move it into the project's tools/ or the skill's scripts/, delete the temp copy, and say where it went.
Review payloads, extracted archives and copied checkouts belong in the temp folder of the task that needed them, not in the project tree.