The current spec build script does not output the latest version of ecma262biblio.json, which would be useful for tooling consumption:

Suggested Change:

--- "build-only": "ecmarkup --no-ecma-262-biblio --verbose spec.html out/index.html --css out/ecmarkup.css --js out/ecmarkup.js", 
+++ "build-only": "ecmarkup --no-ecma-262-biblio --verbose spec.html out/index.html --css out/ecmarkup.css --js out/ecmarkup.js --biblio out/ecma262biblio.json", 

This would allow tools to fetch https://tc39.es/ecma262/ecma262biblio.json to ensure links in proposals are generated against the latest version of the spec.