Layered Keymap Overrides

Problem

Blender saves the entire keymap as one huge single blob and is hard to maintain for users. When you upgrade, Blender can't tell which entries are your customizations and which are stale defaults, so shortcuts silently break or conflict. Users who've migrated across several major versions accumulate dead entries and have to either manually audit everything or start from scratch.

Proposal

Store user customizations as a seperate file on top of a read-only default keymap, the same way VS Code handles settings with usersettings.json. The override file only records what the user added, remapped, or removed. On upgrade, Blender merges it onto the new defaults and flags any entries that reference renamed or removed operators instead of silently breaking.

Benefits

• Shortcuts survive upgrades without manual intervention.
• Users can see exactly what they've changed at a glance.
• Override files are small, shareable, and easy to version-control.