Another way to fix this kind of issues would be to fallback on the Software Heritage which archives the whole GitHub.
This is something Nix and Guix are trying to achieve: by default, they fetch source code from the original endpoint, but if it doesn't respond anymore, they would query the Software Heritage archive [1].
Because go mod doesn't use SHA, it makes things a bit more complicated but Nix/Guix encountered the same issue and there are some mechanisms to workaround this issue.
This is something Nix and Guix are trying to achieve: by default, they fetch source code from the original endpoint, but if it doesn't respond anymore, they would query the Software Heritage archive [1].
Because go mod doesn't use SHA, it makes things a bit more complicated but Nix/Guix encountered the same issue and there are some mechanisms to workaround this issue.
[1] https://www.softwareheritage.org/2025/05/21/software-heritag...