A userscript (that I can use with TamperMonkey, etc. on Firefox) to:
- when I open a link to bookshop.org, suggest waterstones + anna's archive links for that isbn if they exist and flag if they don't exist
- when I open a link in amazon, suggest waterstones + anna's archive links for that isbn if they exist and flag if they don't exist
- when I open a link in waterstones, suggest anna's archive link for that isbn if it exists and flag if it doesn't exist
somewhere in the corner of the page.