macOS Storage Management

Safely reclaim local Mac storage without mistaking cloud placeholders for resident data, losing File Provider content, or flattening metadata onto an incompatible external filesystem.

Trigger

Load this skill when the user asks to free space on a Mac, move Documents/Desktop/Downloads to an external SSD, archive iCloud/File Provider folders, migrate between APFS and ExFAT, or explain conflicting Finder, du, and df storage figures.

Safety Principles

1. Measure the live Data volume, not only /. On modern macOS, use df -h "$HOME" because /System/Volumes/Data carries user data.
2. Inspect the destination filesystem before choosing a copy method. ExFAT does not preserve native macOS symlinks, ownership, permissions, extended attributes, resource forks, or every filename semantic.
3. Treat File Provider folders specially. A logical file can be dataless with zero allocated blocks. Its apparent size is not reclaimable local space until downloaded.
4. Never delete on a partial copy. Copy/archive, independently verify, re-check source identity/state, then remove only verified source objects.
5. Do not force cloud hydration onto a critically full disk. If placeholders materially exceed free space, move only resident files or free space elsewhere first.
6. Report actual reclaimed capacity. Compare df before/after; do not equate logical file size with local blocks released.

Diagnosing an oversized “System Data” category

Treat the Storage Settings number as a classification clue, not a filesystem path. Before recommending cleanup: