Leaked source code of Macintosh System Software 7.1 (m68k + some PPC architecture). Dates back to early 2010's.
GitHub - laniku/sys71src: Apple Macintosh System Software 7.1 source leak (m68k + basic PPC)
Apple Macintosh System Software 7.1 source leak (m68k + basic PPC) - laniku/sys71src
github.com
Interesting find - though some said it's been out there for a while and is incomplete - it's new to me and thought I'd share the URL. Would be very interesting to have build/patched version of 7.1 with some fixes baked in.