Disk Usage

Survey this machine's disk usage and report where the space went.

Scope: $ARGUMENTS — when empty, survey every mounted filesystem.

This command is read-only. Do not delete, move, compress, or modify anything. Do not halt a virtual machine or WSL guest under any circumstance. Produce an analysis the user can act on, and end by offering the disk-reclaim skill.

Establish the layer structure

Read references/virtual-disks.md first.

Run df -h and identify every distinct filesystem with its used and available space. Determine which of them is the binding constraint — the one closest to full — because that governs which findings matter.

When a filesystem is a virtual disk, find its backing file on the host and compare that file's allocated size against the used space reported inside the guest. The gap is balloon: space recoverable by compaction alone, without deleting anything. Report it as a distinct figure.

Check whether the guest issues TRIM, so the report can explain whether balloon will keep re-accumulating.

Measure

Survey each filesystem separately. Prefer dust with an explicit depth and minimum size, falling back to du when unavailable.

Set the minimum size relative to the filesystem rather than using a fixed value, so a small disk still produces findings and a large one is not drowned in them. Around one percent of total capacity works.

Resolve symlinks before recording a size. Configuration directories managed by a dotfiles repository routinely appear under two paths, and counting both inflates the total while implying a duplicate that does not exist.

Classify

Assign every candidate to a tier from references/candidate-catalog.md. Classify at the level where content is homogeneous — a protected history root frequently contains regenerable build artifacts, and those are separable.

For anything holding agent transcripts or session data, read references/agent-history.md. Identify each tool's discovery glob, whether it maintains a state database, and whether it supports compressing its own history natively. Report what is protected and why; propose nothing destructive here.

For candidates that look like duplicates, run the path-set comparison in references/redundancy-proofs.md and record the outcome as redundant, mergeable, conflicted, or unique. A directory named like a backup is not a backup until the proof says so — and a diff reporting no differing files proves nothing on its own.

For directories of upstream clones kept for reading, read references/study-repos.md. Report huge clones, clones that are not shallow, and build artifacts as three separate groups, and check each clone for unpushed work before calling it a conversion candidate.

Output

Follow references/output-contract.md.

Lead with the binding constraint in one line. An inventory of large directories does not answer "where did my space go" when the real limit is a different layer the user has not looked at.

Portability notes

• $ARGUMENTS — the text the user passed when invoking this skill. If your host does not substitute it, read it as the user's request in the current turn, and ask when there is none.
• Bundled files — every relative path in this skill points at a file shipped inside this skill directory. Read them from here, not from the host's plugin tree.