Windows Disk Triage

What it is

18trees-windows-disk-triage is a Windows disk-space triage skill for Claude Code, Codex, and any AI tool that can execute shell commands.

When the C drive fills up there are two familiar paths: ask an AI for a string of Remove-Item -Recurse -Force, or install a one-click cleanup tool. Both leave you in the same place — you do not know what was removed, or whether the same thing will happen again.

This skill takes a third path: a read-only scan, a four-level risk grading, your decision on each item, and only then execution. What it produces is a checklist, not an execute button.

How it is structured

The project has four layers.

Rule sources. skills/windows-disk-triage/ is the single source of truth. SKILL.md holds the triage workflow, the four grading levels, the field notes, and the red lines; references/safe-cleanup-checklist.md is the core asset — 40+ paths grouped by category, each annotated with typical usage, notes, and deletion impact, where the usage figures are empirical ranges rather than statistics.

Packaging and delivery. scripts/build-dist.sh concatenates the rules and the checklist into the single-file dist/windows-disk-triage.md, which has zero external references and can be read directly as a C-drive cleanup reference. Delivery takes three routes: Claude Code through the plugin marketplace, Codex by copying the skill directory, and command-capable tools that have no skill mechanism (Cursor, Windsurf, a custom agent) by handing them the whole single file as instructions. dist/ is a generated artifact; the rules are maintained only in skills/.

Triage runtime. Every scan is read-only, drilling down level by level instead of recursing the entire drive at once. Results are graded into four levels: zero-risk, needs a decision, needs migration or a system operation, and do not touch. For system directories that require administrator rights, the skill hands the commands to the user to run — it never attempts elevation.

Where it lands. The commands act on the C drive of Windows 10 / 11. examples/ holds two samples — the raw read-only scan output and the resulting triage report, which stops at “tell me which items to execute” without deleting a single file.

Design decisions worth noting

Every entry answers “what happens if I delete it”. Deletion impact is mandatory: either “none”, or a concrete cost, or explicitly unverified when it is not known. A new path submitted without one is not merged.

Red lines are listed separately and never touched. Credentials, login state, chat databases, and system directories are hard-coded in the checklist; pagefile.sys is only ever migrated, hiberfil.sys is turned off with powercfg, and WinSxS is only handled with DISM.

No elevation is attempted. Start-Process -Verb RunAs is blocked by security policy, so commands for system directories are handed to the user to run as administrator. The decision about what to delete, and who deletes it, stays with the person.

Migrations are verified before the source goes. A migration must compare the file count and byte count of source and destination, and only a matching result prompts deletion of the source.

The rules live in one place. The single-file version is generated by the script and rebuilt after any rule change; consistency is guaranteed by the script, not by hand-copying.

What problems it solves

• A full C drive no longer starts with installing a cleanup tool: you get a graded checklist first, with the deletion impact written out for every item.
• The checklist works without any AI — the single-file version has zero external references and reads as a reference list on its own.
• High-cost items such as system directories, the hibernation file, and virtual memory have a specific treatment (migration, powercfg /h off, DISM) instead of a plain delete.
• Elevation is explicitly out of scope, so the user always performs the deletion.
• Even inside an AI tool, the skill only scans, grades, and lists; it never makes the deletion decision for the user.