Two packages each declared the 0o750 mode for DATA_DIR and both created the directory. internal/datadir now exports DirPerm as the single definition, and internal/database uses it in both places it creates the directory. The value is unchanged, so existing deployments see no permission change. datadir owns it because guarding and creating DATA_DIR is that package's whole purpose and it imports nothing that would form a cycle.
Model: opus-4-8 (implementation and review); fable-5-1 (merge)