macOS Dev Disk Space Sweep

Use this skill for space investigations on local or SSH-accessible macOS developer machines. Start read-only, rank candidates, and ask before deleting anything.

Safety Rules

• Do not delete on the first pass unless the user explicitly approves exact paths or categories.
• Treat CI runner workspaces as hot unless the user confirms the runner is paused or the target is disposable.
• Preserve Metal toolchains and current simulator runtimes unless the user says otherwise.
• For simulator cleanup, distinguish unavailable devices/runtimes from active named devices used for app testing.
• Verify ownership before attempting to remove another user's files.
• If a command requires sudo or another account, report the exact permission blocker and the handoff command instead of retrying noisily.

Read-Only Sweep

Start with filesystem pressure:

df -h / /System/Volumes/Data 2>/dev/null || df -h /

Scan common developer storage sinks:

du -sh \
  "$HOME/Library/Developer/Xcode/DerivedData" \
  "$HOME/Library/Developer/CoreSimulator" \
  "$HOME/Library/Developer/Xcode/iOS DeviceSupport" \
  "$HOME/Library/Developer/Xcode/UserData/Previews" \
  "$HOME/Library/Caches" \
  "$HOME/.cache" \
  "$HOME/.npm" \
  "$HOME/Library/Containers/com.docker.docker" \
  "$HOME/.codex" \
  "$HOME/.claude/projects" \
  "$HOME/.claude/file-history" \
  "$HOME/Downloads" \
  "$HOME/Developer" \
  "$HOME/workspace" 2>/dev/null | sort -hr

Drill into the largest buckets only:

du -sh "$TARGET"/* 2>/dev/null | sort -hr | head -30

Useful targeted checks:

xcrun simctl list devices unavailable 2>/dev/null
xcrun simctl runtime list 2>/dev/null
brew cleanup -n 2>/dev/null
docker system df 2>/dev/null
du -sh "$HOME/.codex"/* 2>/dev/null | sort -hr
du -sh "$HOME/.claude/projects" "$HOME/.claude/file-history" 2>/dev/null   # report-only

Agent Storage (Codex and Claude Code)

• ~/.claude/projects and ~/.claude/file-history are report-only. They hold Claude Code session history and memory. Report their size; never propose them as deletion targets or give a cleanup command for them.
• ~/.codex locations (sessions, worktrees) can grow large. Old worktrees may hold uncommitted work, so check git status in each first, and propose archiving sessions to a location the user chooses rather than rm.

Ranking Cleanup Candidates

Group findings by confidence:

• Usually safe after confirmation: Xcode DerivedData, module caches, old build folders, Homebrew cleanup, package manager caches, stale agent worktrees with no uncommitted work, old Downloads.
• Needs app/tool context: CoreSimulator devices, iOS DeviceSupport, Docker Desktop data, Hugging Face/Whisper model caches.
• Avoid by default: Claude Code history (~/.claude/projects, ~/.claude/file-history; report-only), active runner workspaces, current simulator devices, current Metal toolchains, repo checkouts with uncommitted work.

Report Format

Return a compact table or bullets:

• path/category
• size
• why it is likely safe or risky
• exact cleanup command, marked read-only estimate or requires approval
• expected reclaim if known

When deleting after approval:

1. Re-list the exact target.
2. Confirm ownership/permissions.
3. Run the narrow cleanup.
4. Re-check df -h.
5. Report before/after free space and any failures.

Common Large Sinks

• On iOS development Macs the biggest are usually Xcode DerivedData, CoreSimulator devices and runtimes, ~/.cache/huggingface, Docker Desktop storage, and agent sessions and worktrees (~/.codex/sessions, ~/.codex/worktrees).
• On runner hosts, old simulator runtimes can be removed with xcrun simctl runtime delete, but runner workspaces may be actively used.
• Permission-denied cascades usually mean the target belongs to another user; stop and verify with ls -ldeO or stat.