Astra's second review: a strategy made under a path-like id between the
production check and this deploy would keep working, because only creation
checked the id. The serve check now takes the strategy too, so an image is
handed out to download only when its folder and file name are both safe.
Ids also refuse a trailing dot or space, which Windows drops ("<id>." is the
same folder as "<id>").

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>