Quick answer: Godot 4 TileSet source edits not persisting after a quick editor exit? Editor caches changes; force save before close.
Edit a tile's collision shape; close editor without saving; reopen; shape is gone.
Save explicitly
Ctrl+S after tile edits. Editor's autosave doesn't cover all paths.
Or watch for dirty flag
Editor shows '*' in title when dirty. Don't close without seeing it disappear.
Enable autosave
Editor Settings > Editor > Autosave Interval. Sets a regular save cadence; surface for quick edits.
“Editor dirty state isn't always visible. Manual save is the discipline.”
Treat Ctrl+S as muscle memory. The editor's autosave is imperfect; your discipline isn't.