Build Data

Inspect and clean up Xcode DerivedData across enrolled agents.

The Build Data page at /build-data is a fleet-wide view of the disk that Xcode consumes but never reclaims: per-project DerivedData folders, shared Xcode caches, and the iOS Device Support symbols kept for every iOS version that has ever been connected to one of your Macs.

Instead of visiting each machine and deleting folders by hand, you scan every enrolled agent at once, see which folders still belong to a live worktree and which are orphans, and delete across machines in a single action.

How a scan works

Nothing is read from disk until you ask for it, and measuring sizes is far more expensive than listing folders.

1. Refresh lists the folders

   Refresh dispatches a scan job to every eligible agent. Each agent walks its configured DerivedData directories and reports folder names, paths, modification times, and the volume each one lives on. The footer shows Scanned N of M eligible agents while this runs.

2. The server links folders to worktrees

   Each folder’s recorded workspace path is matched against the worktrees known for that agent, choosing the longest matching path. That match is what turns a nameless MyApp-abc123 folder into a row you can act on confidently.

3. Calculate sizes on demand

   Calculate sizes sends a second job that measures disk usage for the selected entries. Until then the Disk usage column is empty — sizing a large DerivedData tree is slow, so it is never done automatically.

4. Select and delete

   Select rows and use Delete selected, or delete a single row from its actions menu. Deletion is dispatched per agent and always requires an explicit confirmation.

Per-agent scan progress is reported individually, so a single unreachable Mac does not block the rest:

Agent status	Meaning
queuing / queued / scanning	The scan job is on its way to the agent, or running
complete	Results were returned and merged into the table
failed / timed out / cancelled	The agent could not finish; the error is shown alongside
offline	The agent was not connected when the scan started
agent update required	That agent’s control agent is too old to support build-data scans
invalid response	The agent replied with something the server could not parse

Derived Data

Column	What it shows
Folder	The DerivedData folder name, plus a status badge when it is not a plain linked project
Worktree path	The worktree this folder belongs to, shown relative to the agent’s base repository directory
Modified	Last modification time — the ordering that matters most when deciding what is safe to remove
Disk usage	Measured size, once you have run Calculate sizes
Agent	The Mac holding the folder
Actions	Lock, unlock, or delete this single entry

Entry statuses

Status	Meaning
(no badge)	The folder maps to a worktree that still exists
Unlinked	No matching worktree — usually a branch that has been deleted. These are the safest deletions and often the largest win
Build starting	A build has just begun writing this folder; leave it alone
Shared cache	An Xcode cache shared across projects rather than belonging to one worktree. Deleting it is safe but slows the next build on that machine

Locking

Lock from cleanup marks an entry as protected. A locked entry is excluded from the automatic reclamation described below, and deleting it by hand requires a second confirmation that lists exactly which folders are protected.

The same protection covers entries with executing work — a build or run currently using that worktree — even when they are not locked.

Overriding the protection prompt deletes DerivedData out from under a running build. The build fails rather than corrupting anything, but it fails.

iOS Device Support

Xcode keeps a folder of symbols and support files for every iOS version it has ever seen on a connected device. These accumulate for years and are commonly the largest single reclaim on a developer Mac.

The card lists them by iOS version, Disk usage, and Agent, and supports the same select-and-delete flow.

Deleting these is low-risk. Xcode recreates the folder for a given iOS version the next time a device running it is connected — you pay one slow reconnect, not a permanent loss.

Automatic cleanup

The Disk Space monitor in the sidebar can reclaim DerivedData on its own when a monitored volume runs low. It is deliberately conservative:

• Only project entries linked to a known worktree are eligible. Unlinked folders, shared caches, and Device Support are never touched automatically.
• Locked entries and worktrees with executing work are excluded, and the check is repeated immediately before deletion in case work started in between.
• Exactly one entry — the oldest by modification time on the low volume — is removed per pass, then the monitor waits for the next disk report to decide whether more is needed.

Two thresholds govern it: a cleanup threshold below which reclamation begins, and a lower pressure threshold used once the volume is in pressure mode. Pressure mode engages automatically when a volume is below the cleanup threshold and nothing safe is left to delete, and can also be set manually per agent.

Everything the monitor removes is recorded in the deletion history with source Automatic, so a folder that vanished overnight is always accounted for.

Deletion history

The Deletion history card lists what was removed from each agent over the last 90 days, with the folder, worktree path, agent, deletion time, and whether the source was User or Automatic. Long histories page with Load more.

Clear history empties the records only. It does not restore anything, and it does not touch files on any agent.

Notes

• Which directories are scanned depends on each agent’s DerivedData location setting, so an agent using a non-default location is scanned there.
• Deletion requires the target agent to be online at the moment the job is created — an offline agent’s entries cannot be removed until it reconnects.
• Sizes are a point-in-time measurement. Rescan before acting on numbers from an earlier session.
• Removing DerivedData never affects source code, worktrees, or Git state. The cost is a slower next build.

Related pages

Worktrees

The worktrees that Derived Data entries are matched against.

Builds

The builds that create these folders in the first place.