A stale background render could finish and apply after a newer one had already landed, since results were applied in whatever order they arrived rather than dispatch order. An in-repo render (git status, toolchain-version items) is reliably slower than a plain directory's render, so leaving a repo would often show the old repo's git status and right-prompt items well after cd, clearing only once a later render happened to win the race. Stamp each dispatched render with a generation number and drop any result whose stamp doesn't match the latest dispatch, so a superseded render can no longer overwrite a fresher one.