Standardizing Homebrew’s prefix across macOS architectures and Linux CI

In current Homebrew releases, the installation prefix is architecture- and platform-dependent: Intel macOS commonly uses /usr/local, Apple Silicon uses /opt/homebrew, and Linux uses /home/linuxbrew/.linuxbrew. A local setup can therefore appear healthy while CI resolves a different prefix, architecture-specific bottles, or dependency set.

The unresolved change is whether CI should standardize on the same prefix and Homebrew release as development, or deliberately maintain separate, pinned environments. Prefix selection alone does not establish reproducibility; formula metadata, update timing, and the runner’s CPU architecture also affect what is installed. The comparison should use a documented Homebrew release and verify the effective prefix, Homebrew version, and architecture on each runner.

Which prefix should be the CI baseline when development may use both Intel and Apple Silicon?

Should the baseline be pinned per architecture, and what compatibility checks are needed before switching an existing pipeline from /usr/local to /opt/homebrew?