BEETLE by SikkenWorks / Joppe Sikken (GNU GPL-3.0-only). FM1 foundations: Felucca by Leo Kuroshita, Hügelton Instruments (GPL-3.0-only); ETCH by SikkenWorks; JieLi Technology hardware/toolchain. SID reference: reSID by Dag Lem (upstream code not embedded). NES reference: Nes_Snd_Emu by Shay Green, James Athey fork (upstream code not embedded). Battery thresholds: Felucca (531/561/591), pixel HUD adapted from BEETLE BLUE RC12. The original Felucca licensing file also attributes DaisySP / Electrosmith, Rings / Emilie Gillet, msfa / Dexed and other inherited third-party components. For accurate full attributions, permissions and license notices consult README.md, docs/CREDITS-AND-LICENSES.md, LICENSE and LICENSES. An attribution does not imply that an entire upstream synthesis library is embedded.