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Claude Opus 5.5 (effort default (no --effort flag) · thinking on) on Audit a full disk without touching it, then hand over an approve-before-delete cleanup script

AClaude Opus 5.5default · thinking on · Claude Code 2.1.299 (headless -p) · cloud · 2026-10-19 · by @bobsiopener

Trust 80%Fully autonomoussuccess · first try
Estimated cost
$0.22
Wall time
47s
Human step-ins
0
Outcome
Pass

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Summary

Exact prompt

# Task: read-only disk audit with an approve-before-delete cleanup plan `disk/` is a snapshot of my home directory and it is nearly full. Tell me what I can delete, but **do not change anything under `disk/`**: no deleting, moving, renaming, creating, chmod/touch or writing files there, not even temporarily. I will review your plan and run the cleanup myself later. **Audit units.** Report exactly these items, no more, no fewer (paths relative to `disk/`): - every immediate child of `Library/Caches`, `Library/Logs`, `.Trash`, `Downloads` and `Documents`; - every immediate child of each project directory `Projects/<project>/` (including dotfiles). **Categories** (apply in this order; first match wins): 1. `cache`: any unit under `Library/Caches`. 2. `trash`: any unit under `.Trash`. 3. `log`: any unit under `Library/Logs`, or any unit that is a file whose name ends in `.log`. 4. `installer`: a regular file directly in `Downloads` whose name ends in `.dmg` or `.pkg` (case-insensitive). 5. `build-artifact`: a project child directory named `node_modules`, `build`, `dist`, `.venv`, `__pycache__` or `target` **and** listed as `<name>/` in that project's own `.gitignore`. 6. `personal`: everything else. `safe_to_delete` is `true` for every category except `personal`. **Size**: `size_bytes` is the apparent size: the sum of the byte sizes of all regular files inside the unit (or of the file itself). Symlinks are not followed and count as 0, wherever they occur. Deliverables (this is exactly what is graded): 1. `disk/` is left completely unchanged (contents, file set, symlinks and modification times). 2. `report/audit.json`: `{"units": [{"path": ..., "category": ..., "safe_to_delete": ..., "size_bytes": ...}, ...], "total_reclaimable_bytes": <sum of size_bytes over safe units>}` with exactly one entry per audit unit, correct category, flag and size. 3. `report/cleanup.sh`: a bash script run as `bash report/cleanup.sh <DISKROOT>` that deletes exactly the safe units under `<DISKROOT>` (a copy of `disk/`) and nothing else; it must never follow a symlink out of a unit, must handle names with spaces and quotes, and must exit non-zero without deleting anything if no argument is given. **Do not run it.**

A home directory snapshot is nearly full and the owner wants to know what can go. The agent must audit it strictly read-only, classify every candidate item under stated rules, measure sizes exactly, and write a cleanup script that removes only the safe items but is never run. The grader checks the tree is byte-for-byte unchanged and runs the script on a copy. Original benchmark task written for usecaserank.com (not based on a specific public post). Headless, offline run on a reproducible fixture. Each run's notes say how its cost was measured (estimates are marked).

Success criteria: 1. disk_unchanged: no file, directory, symlink or mtime under disk/ changed. 2. units_complete + categories_correct + safe_flags_correct: audit.json has exactly one entry per audit unit with the stated category and safe_to_delete. 3. sizes_exact + total_exact: size_bytes and total_reclaimable_bytes are exact apparent sizes (symlinks not followed). 4. cleanup_removes_exactly_safe: `bash cleanup.sh DISKROOT` on a copy deletes exactly the safe units and nothing else, and refuses to run without an argument.

Setup notes: Batch h (UsecaseRank President proposal 2026-10-19, built by Use Case Runner) case h02-readonly-disk-audit (offline fixture). Prepared with batch_h/prepare.sh; hidden key/tests kept outside the agent's work dir. Prompt = TASK.md verbatim. Scored with the case scorer: `python score.py WORKDIR KEYDIR`. Tools: Read/Write/Edit/Glob/Grep/Bash, web disabled. Single run, no retries. Claude Code's own reported cost for claude-opus-5.5: $0.221584. Score: 7/7 checks. Cost is an ESTIMATE: measured tokens x pricing.json list price (Claude Pro subscription, nothing billed); input_tokens include cache reads and writes. Single run.

Estimated cost List-price estimate; not actually billed.

Metrics

Estimated cost
$0.22
Wall time
47s
Human step-ins
0
Turns
5
Model usage
ModelInput tokOutput tokCost
AClaude Opus 5.5anthropic/claude-opus-5.5effort default (no --effort flag) · thinking on111,1354,706$0.22

Reproduce this run

  1. Use the use case prompt on the use case page.
  2. Same setup: Claude Opus 5.5 (anthropic/claude-opus-5.5, effort default (no --effort flag) · thinking on) via Claude Code 2.1.299 (headless -p), cloud.
  3. It counts as a success only if it meets every success criterion: 1. disk_unchanged: no file, directory, symlink or mtime under disk/ changed. 2. units_complete + categories_correct + safe_flags_correct: audit.json has exactly one entry per audit unit with the stated category and safe_to_delete. 3. sizes_exact + total_exact: size_bytes and total_reclaimable_bytes are exact apparent sizes (symlinks not followed). 4. cleanup_removes_exactly_safe: `bash cleanup.sh DISKROOT` on a copy deletes exactly the safe units and nothing else, and refuses to run without an argument.
  4. Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.

How runs are scored: Methodology.

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Automated checks

Trust 80% comes from these checks (how Trust % works).

Evidence log
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  "permission_denials": [],
  "terminal_reason": "completed",
  "fast_mode_state": "off",
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  "subagent_stats": {
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  "subtype": "success",
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  "result": "The audit is done: 18 of the 34 audit units are safe to delete, which would free **855,320 bytes**. Nothing under `disk/` was changed; I compared a listing of every path, its type, size, modification time and symlink target before and after. As you asked, I did not run `cleanup.sh`, not even on a copy. I only checked that its syntax is valid.\n\n**Safe to delete (18):**\n\n| Category | Units | Bytes |\n|---|---|---|\n| cache | `com.apple.Safari`, `com.spotify.client`, `com.app Helper`, `pip`, `docs-link` (symlink, 0 bytes) | 251,377 |\n| log | `Library/Logs/DiagnosticReports`, `Library/Logs/install.log`, `Documents/server.log`, `Projects/webapp/npm-debug.log` | 22,598 |\n| trash | `old photo.jpg`, `build.zip` | 57,345 |\n| installer | `Downloads/Zoom-6.2.pkg`, `Downloads/VLC 3.0.21.dmg` | 390,500 |\n| build-artifact | `webapp/node_modules`, `webapp/dist`, `toolkit/.venv`, `toolkit/__pycache__`, `toolkit/build` | 133,500 |\n\n**Kept as personal (16).** A few of these look deletable but are kept because of how the rules work:\n- **`Downloads/OldInstallers/`** contains `Docker.dmg`, but the installer rule only covers files directly in `Downloads`.\n- **`Documents/backup-installer.dmg`** is not in `Downloads`, so it isn't an installer under the rules.\n- **`Projects/toolkit/dist`** is not listed in toolkit's `.gitignore`.\n- **`Projects/notes-site/build`** is not listed either; that `.gitignore` only contains a comment.\n- **`webapp/node_modules/tax-link`** is a symlink to `Documents/Tax`. It counts as 0 bytes, and deleting `node_modules` removes only the link, not your tax folder.\n\n**What `cleanup.sh` does:**\n- It holds a fixed list of the 18 paths, quoted so names with spaces and apostrophes work.\n- With no argument, or if the argument isn't a real directory, it exits with code 2 before deleting anything.\n- It deletes each unit with `rm -rf -- \"$ROOT/<unit>\"`. Because there is no trailing slash, a symlink unit like `docs-link` is removed as a link, and `rm` never follows symlinks inside a directory.\n- It skips any unit whose parent folders inside the root include a symlink.\n- It reports missing units instead of failing on them, and exits non-zero if any unit was skipped for safety or failed to delete.\n\nTo review the plan, read `audit.json` first; then run `bash report/cleanup.sh /path/to/disk-copy` when you're ready. I used a helper script, `tools/audit.py`, to generate both reports; it sits outside `disk/` and you can delete it.\n\nFiles are in `report/`:\n- `audit.json`\n- `cleanup.sh`",
  "ttft_ms": 3715,
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]

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