Originally contributed by @LVT382009 as a skill in PR #12212. Ported to the plugin system so the behaviour runs automatically via post_tool_call and on_session_end hooks — the agent never needs to remember to call a tool.

How it works

Hook	Behaviour
`pre_tool_call`	Snapshot which paths named in the call's arguments do not exist yet, keyed by the owning task/session plus `tool_call_id` (the id alone is not unique: llama.cpp reuses one constant id).
`post_tool_call`	When `write_file` / `terminal` / `patch` creates a file matching `test_`, `tmp_`, or `.test.` inside `HERMES_HOME` — a path named in the call that did not exist before it — track it silently as `test` / `temp` / `cron-output`. Existing files the call edits, runs or lists are never tracked, and neither is any path the call's own snapshot did not cover (e.g. one another plugin's `modify` hook swapped in). Calls without a `tool_call_id` (execute_code RPC) are not tracked.
`on_session_end`	If any test files were auto-tracked during this turn, run `quick` cleanup (no prompts).

Deletion rules (same as the original PR):

Category	Threshold	Confirmation
`test`	every session end	Never
`temp`	>7 days since tracked	Never
`cron-output`	>14 days since tracked	Never
empty dirs under HERMES_HOME	always	Never
`research`	>30 days, beyond 10 newest	Always (deep only)
`chrome-profile`	>14 days since tracked	Always (deep only)
files >500 MB	never auto	Always (deep only)

Slash command

/disk-cleanup status                     # breakdown + top-10 largest
/disk-cleanup dry-run                    # preview without deleting
/disk-cleanup quick                      # run safe cleanup now
/disk-cleanup deep                       # quick + list items needing prompt
/disk-cleanup track <path> <category>    # manual tracking
/disk-cleanup forget <path>              # stop tracking

Safety

is_safe_path() rejects anything outside HERMES_HOME or /tmp/hermes-*
Windows mounts (/mnt/c etc.) are rejected
The state directory $HERMES_HOME/disk-cleanup/ is itself excluded
$HERMES_HOME/logs/, memories/, sessions/, skills/, plugins/, and config files are never tracked
User project trees (workspace/, projects/, plans/, home/, patches/, skins/, themes/, contributors/, profiles/, backups/) and kanban/ (task attachments/workspaces) are never tracked or swept, even for files named test_*/tmp_*
A tracked directory under a protected top level (e.g. cache/, which holds terminal snapshots) is never removed; only its files age out. Stale entries are logged as SKIPPED and dropped
Backup/restore is scoped to tracked.json — the plugin never touches agent logs
Atomic writes: .tmp → backup → rename