The ACP fixture configured read-only as the deployment default for both parent and child. Its delegated write therefore remained denied even with inheritance disabled, so the scenario could not fail on the regression it claimed to protect.
Delete the overlay, scenario registration, sessions, prompt, and 473-line tool-schema sidecar. The Loader-booted headless snapshot remains the real composition guard: only its parent carries read-only while the deployment default is workspace-write, so removing inheritance makes the child write reach disk and fails the test.
Keeping one discriminating snapshot avoids 662 lines of duplicated fixture data and makes the review evidence correspond to the actual security boundary.
Tianyi Cui
a70f1a2b7a