Piece-set licensing

The 39 piece sets under Motif/pieces/ were sourced from lichess-org/lila. Their licensing is heterogeneous, and a chunk of them have terms that conflict with closed-source commercial distribution. This doc is the audit-of-record so future work doesn’t have to re-derive it.

Original source-of-truth: lila/COPYING.md. If something here looks wrong or out-of-date, that file wins.

Summary

Bucket	Count	Apache-2.0 stack compatible?	Closed-source commercial OK?
Permissive (CC0, MIT, Apache 2.0, CC BY 4.0)	7	✅	✅
Share-alike artwork (CC BY-SA 4.0)	1	✅ as-is	✅ (no relicense)
GPL v2/v3 copyleft	4	⚠️ propagates to bundled software	❌
AGPLv3+ (explicit + lila default)	12	⚠️ network-use copyleft	❌
CC BY-NC-SA (non-commercial)	15	❌	❌

Per-set breakdown

Clean for commercial use — 8

Set	License	Source
`celtic`	MIT	Maurizio Monge
`chessnut`	Apache 2.0	Alexis Luengas
`fantasy`	MIT	Maurizio Monge
`firi`	CC BY 4.0	James Faure
`kiwen-suwi`	CC BY 4.0	neverRare
`rhosgfx`	CC0 1.0	RhosGFX
`shapes`	CC BY-SA 4.0	flugsio
`spatial`	MIT	Maurizio Monge

CC BY 4.0 / CC BY-SA 4.0 / MIT / Apache 2.0 all require attribution. CC0 requires nothing. shapes is share-alike — fine to ship as-is, but derivatives must stay CC BY-SA 4.0.

GPL — copyleft propagates to bundled software — 4

Set	License	Author
`cburnett`	GPLv2+	Colin M.L. Burnett
`merida`	GPLv2+	Armando Hernandez Marroquin
`mono`	GPLv2+	Thibault Duplessis + cburnett
`mpchess`	GPLv3+	Maxime Chupin

These can ship in GPL’d applications. They cannot ship inside a closed-source binary; including them forces the whole work under GPL.

AGPLv3+ — explicit attribution in lila COPYING — 3

Set	License	Author
`letter`	AGPLv3+	usolando
`pirouetti`	AGPLv3+	pirouetti
`pixel`	AGPLv3+	therealqtpi

AGPLv3+ — by lila’s catch-all default — 9

Not listed in COPYING.md, so under lila’s stated rule they inherit lila’s AGPLv3+. Some of these may actually have permissive licenses upstream that lila just never tracked. Worth chasing if any of these become load-bearing:

alpha (lichess default set — likely worth tracing)
chess7
companion
governor
kosal
leipzig
reillycraig
riohacha
shahi-ivory-brown

Non-commercial — cannot ship commercially — 15

CC BY-NC-SA 4.0 (or 2.5 for xkcd). Fine for local dev / private use with attribution. Forbidden in any product that has commercial intent — including a free-to-use app monetized via subscriptions, ads, or being sold.

From sadsnake1: cardinal, dubrovny, fresca, gioco, icpieces, maestro, staunty, tatiana.

Others: anarcandy (caderek), caliente (avi), california (Jerry S.), cooke (fejfar), disguised (danegraphics), horsey (cham, michael1241), xkcd (Randall Munroe).

Practical implications

For local dev / the PROMOTE-stack harness: everything is fine, assuming attribution stays intact and the harness stays private.
For Motif published as Apache 2.0: only the 8 commercially-safe sets really belong; the rest force constraints on Motif consumers that an Apache 2.0 library shouldn’t impose.
For closed-source commercial apps built on PROMOTE: only the 8 commercially-safe sets are usable without licensing entanglement.
For GPL’d apps consuming PROMOTE: the 4 GPL sets and the 12 AGPL sets become available too, depending on whether the app is GPL or AGPL.

Things this doc deliberately does not decide

Whether to physically separate clean sets from problematic ones in the directory tree.
Whether to chase upstreams for the 9 “AGPL-by-default” sets to find real permissive origins.
Whether to ship a LICENSES.md per-set attribution file alongside the SVGs (required by MIT / Apache 2.0 / CC BY for redistribution).

Those decisions get made when commercialization gets concrete — they’re easier with this audit in hand than without.

Audit metadata

Source consulted: lila/COPYING.md, retrieved 2026-05-14.
Sets audited: 39 (every directory under Motif/pieces/ as of commit 13989ea).
lila’s set inventory had 40 sets at the time of audit — we don’t carry monarchy.