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name: mac-disk-pressure-recovery description: Diagnose and recover disk space on macOS safely. Use when the Mac reports low storage, disk pressure, ENOSPC/build failures, or the user asks for storage cleanup. Prioritize non-destructive cache cleanup, detect unusual growth in /private/var/folders (especially com.google.Chrome.code_sign_clone), and report before/after capacity with exact paths.

Mac Disk Pressure Recovery

Use this skill to run a fast, safe disk-pressure investigation on macOS and reclaim space with minimal risk.

Trigger Conditions

• User reports "disk is full", "storage pressure", "空き容量がない", "容量逼迫"
• Build/install failures caused by ENOSPC or low free space
• macOS warns about low disk space and the user asks for cleanup

Safety Rules

1. Measure first (df, du) and keep before/after numbers.
2. Delete only re-creatable data by default: caches, temp files, build artifacts.
3. Do not delete user documents, repositories, or app data without explicit user approval.
4. For high-impact cleanup (simulators, SDK components, backups, large apps), propose and ask.
5. If protected paths fail with Operation not permitted, continue with deletable targets and report skipped paths.

Workflow

1. Baseline Capacity

df -h / /System/Volumes/Data

Urgent threshold:

• /System/Volumes/Data free < 15 GiB, or
• capacity > 90%

2. Identify Hotspots Quickly

Run the bundled report script first:

./scripts/disk_hotspots.sh

Or manual probes:

du -h -d 1 "$HOME" | sort -hr | head -n 40
du -h -d 1 "$HOME/Library" | sort -hr | head -n 40
du -h -d 1 /Library | sort -hr | head -n 30
du -h -d 1 /Applications | sort -hr | head -n 30
du -h -d 1 /private | sort -hr | head -n 30

3. Reclaim Safe Space First

Use dry-run first:

./scripts/cleanup-safe-caches.sh

Apply:

./scripts/cleanup-safe-caches.sh --apply

This targets:

• ~/Library/Caches (best effort)
• ~/.npm/_cacache, ~/.npm/_npx
• ~/.gradle/caches, ~/.gradle/wrapper/dists
• ~/Library/Developer/Xcode/DerivedData
• ~/.cache
• Optional tool cleanup when available: brew cleanup -s, pnpm store prune

4. Check Known High-Impact Anomaly

From this incident, a major leak pattern was Chrome code-sign clones under /private/var/folders.

Inspect:

./scripts/cleanup-chrome-code-sign-clone.sh

Apply cleanup:

./scripts/cleanup-chrome-code-sign-clone.sh --apply

Notes:

• Close Chrome first when possible.
• This can reclaim tens of GiB if stale clone folders accumulated.

5. Optional Cleanup Requiring User Confirmation

Only do these after explicit approval:

• /Library/Developer/CoreSimulator pruning/reset
• Android SDK component pruning (ndk, system-images, old platforms)
• Old backup directories (~/backup/*)
• Unused large apps in /Applications

6. Verify and Report

df -h /System/Volumes/Data

Always report:

1. Before/after free space with exact numbers.
2. Paths cleaned and estimated reclaimed size.
3. Remaining large directories and next optional actions.

⚠️ よくある落とし穴

• Chrome code-sign clone の肥大化を見逃す: /private/var/folders 配下の com.google.Chrome.code_sign_clone が数十GiB に膨れることがある。cleanup-chrome-code-sign-clone.sh で定期的にチェックすること
• ユーザーデータの誤削除: Safety Rules に従い、キャッシュ・テンプファイル・ビルドアーティファクトのみ削除する。リポジトリ、ドキュメント、アプリデータは明示的な承認なしに削除しない
• Operation not permitted で作業を止める: SIP（System Integrity Protection）で保護されたパスは削除できない。エラーが出ても削除可能なターゲットで作業を続行し、スキップしたパスを報告すること
• before/after の記録忘れ: 作業前に df -h でベースラインを取り、作業後にも必ず実行する。数値なしでは成果が分からない

Bundled References

• references/case-chrome-code-sign-clone.md: concrete case notes from this incident.