Chrome and partners release Modern Web Guidance 1.0 to steer coding agents toward native browser APIs

Chrome, in collaboration with Firefox, MDN, and Edge, has released version 1.0 of Modern Web Guidance, a set of over 200 open-source implementation guides for coding agents. The guides cover native browser features such as CSS highlights, dialog backdrops, and field-sizing, which agents often overlook in favor of older JavaScript patterns. The project is packaged as an agent skill and a search CLI designed to keep context usage small, and it includes a legacy-scan tool that flags outdated code patterns. According to the developers, internal evaluations showed agents passing 92% of about 1,700 assertions with the guidance, compared with 55% without it.