File kinds

Every file and folder in a scan is put into one of eleven kinds. The breakdown by kind is what the sidebar shows, what the type report is built from, and what the snapshot comparison compares.

The eleven kinds

Kind	What lands in it
game	Game content — detected by the folder, not the extension.
video	.mp4 .mov .mkv .avi .webm .wmv .flv .m4v .mpg .mpeg
audio	.mp3 .flac .wav .aac .ogg .m4a .alac
image	.png .jpg .jpeg .gif .webp .svg .bmp .tiff .heic .raw .psd
archive	.zip .7z .rar .tar .gz .bz2 .xz .zst .iso .dmg .img .vhd .vhdx
document	.pdf .doc .docx .odt .rtf .txt .md .rst .csv .xls .xlsx .ods .ppt .pptx .key .numbers .pages .epub .mobi
code	.py .js .ts .tsx .jsx .go .rs .java .c .cpp .h .cs .rb .php .swift .kt .sh .json .yaml .yml .toml .xml .html .css .sql .db .sqlite
cache	Cache, log and temporary content.
application	.exe .msi .so .dylib .app .deb .rpm .pkg .appimage
system	.dll .sys .drv .efi
other	Everything else — including every file with no extension.

The order they are presented in is fixed: game → video → archive → document → cache → application → audio → image → code → system → other.

How a file is classified

The extension decides, unless a parent folder has already decided.

Rule	Effect
The file has an extension in the table above	That kind.
The file has no extension, or an unknown one	other.

The extension is read straight off the name rather than through pathlib.PurePath, whose parser is pure Python and showed up as a measurable part of the cost of a scan.

Note

.ts is TypeScript here, not an MPEG transport stream. A developer machine holds thousands of small .ts sources; broadcast captures in that format are rare.

How a folder is classified

A folder’s name decides, and the decision is inherited by everything below it.

Folder name matches	Kind
Contains cache anywhere	cache
Has log or logs as a whole word	cache
Has temp or tmp as a whole word	cache
Has game, games, steam, epic, gog, origin, uplay or battle.net as a whole word	game
Has app, apps, application, applications, program, programs, software or bin as a whole word	application
Anything else	other

The matching is deliberately asymmetric:

• cache matches anywhere. Cache, AppCache and cached_content all match.
• log, logs, temp and tmp must be whole words. Matching log anywhere would catch Dialog and Catalogue; matching temp anywhere would catch Template. A word boundary is any of a space, a dot, an underscore or a dash.

Inheritance

Once a folder is classified, its whole subtree inherits that kind. A Cache folder contains caches, whatever the extensions of the files inside it are. A Steam folder is game content, whatever is in it.

The inheritance means the numbers add up: a file is counted in exactly one kind, so the type report’s total equals the size of the scan.

Caution

This is why the kind of a folder is decided by its name, not by what it contains. A folder called logs holding your only copy of something is still reported as cache, and the reclaimable list will offer it. Move it out of the folder, or do not stage it — the cleanup gate always asks before anything is removed.

Where the kinds are used

Place	What it uses the kind for
diskgoup types	The file-type breakdown.
diskgoup reports types	The CSV type report.
diskgoup snapshots compare	Which category grew.
diskgoup search --kind	Filtering the search.
The treemap colours	The colour of a folder.
diskgoup cleanup	The reclaimable list — only cache folders are offered.

Reclaimable kinds

Only cache is reclaimable. The reclaimable list is built from the top-most cache folders — the ones whose parent is not itself a cache folder — so staging one covers its whole subtree and nothing is offered twice.

Every other kind is there to be measured, not deleted.