GitHub is retiring the macos-14 (Sonoma) hosted runner image, and it's doing it the loud way — eight brownout windows through October where jobs targeting macos-14, macos-14-large, or macos-14-xlarge are deliberately failed. The first runs today from 14:00 to 00:00 UTC; the rest are scattered across the month, and on November 2 the image is removed entirely. If your workflows still pin macos-14, move them now. Arm64 jobs can go to macos-15 or macos-latest (now macos-26); Intel builds that need x64 should take macos-15-large to buy one more OS generation. Leave it until a brownout catches you and the failure reads like a flaky runner, not a scheduled one.