Error: Permission denied @ apply2files - /usr/local/Cellar/

Goal: Allow Homebrew to write to /usr/local/Cellar without encountering the 'Permission denied @ apply2files' error while preserving system integrity and avoiding architecture‑specific conflicts.

Constraints: Changing ownership with sudo chown can sidestep system protections and may interfere with other software that expects the original permissions; moving Homebrew to the Apple Silicon‑specific /opt/homebrew prefix avoids the error but requires reinstalling existing formulas and may lead to duplicate installations if both Intel and Apple Silicon bins are kept; retaining the /usr/local prefix on Intel Macs raises uncertainty about future migration to Apple Silicon and potential permission regressions.

Is it safer to adjust ownership of /usr/local/Cellar or to migrate Homebrew to /opt/homebrew on Intel Macs? What are the long‑term implications for future Apple Silicon migration if the Intel prefix is retained? How can users verify that permission adjustments do not violate system integrity protections or cause conflicts with other software?