A developer Mac setup that does not fill up every three months

Cleaning a developer Mac every three months is a symptom of a setup problem rather than a discipline problem. Most of the recurring growth has a configuration answer, and the ones that do not are quick to automate.

The four settings worth changing once

1. A shared plugin or package cache for anything that defaults to per project copies, starting with Terraform.
2. Docker's disk on an external drive, which is usually the single largest file on the machine.
3. Model and framework caches pointed elsewhere, via the environment variables in ML framework caches.
4. Simulator runtimes limited to the platforms you actually target.

What belongs where

The split is about write frequency rather than size, which is the point made in what belongs on an external SSD: a folder written to thousands of times per build belongs on the fastest drive you have.

The quarterly command

find ~ -maxdepth 6 -type d \
  \( -name node_modules -o -name target -o -name .next -o -name build \) \
  -mtime +90 2>/dev/null -exec du -sh {} + | sort -h | tail -20

Everything that prints is build output from a project untouched for three months. Removing it costs one rebuild if you return, and this single command is usually worth more than every other item on this page combined.

What to automate rather than remember

• docker builder prune weekly, filtered by age.
• Simulator cleanup after each Xcode upgrade.
• A prune step in CI, per CI runner caches.
• A monthly measurement saved to a file, so growth is visible rather than sudden.

The measurement that tells you it is working

du -sh ~/.[a-z]* 2>/dev/null | sort -h | tail -10 > ~/Desktop/dev-space-$(date +%F).txt

Two of those a month apart show whether the setup is holding. If one folder is growing steadily, it is either missing a shared cache or missing a prune, and the guides for each toolchain cover both.