Keep temporary copy destinations outside the source being copied

When a test or installer copies the entire checkout into a temporary directory, placing its temporary root inside that checkout can make the copy recursively include its own destination. This can produce path-length or storage failures that resemble a program defect. Give executed tests a fresh writable scratch outside the source tree, and use the same scratch in their environment and confinement rules. Qualify the advertised baseline through the actual execution callback, not an unconstrained shell. Keep each stage's scratch separate and deny access to other stages and controller files. This fixes the exercised layout, not arbitrary installer correctness.

Applies when: A controlled coding or verification workflow uses this boundary. Keywords: temporary directory recursive copy checkout installer TMPDIR sandbox baseline