# V43 Source Edit Undo

This complete package is based on V42 and adds a source-edit undo stack.

## New control

- `Ctrl + Z`: undo the latest source edit.

## What is saved in an undo point

Undo points are created before expensive/source-changing actions:

- normal source brush stroke
- finite-fault stamp patch placement
- advanced node tune changes: move, delete, slip/amplitude, delay, zero-height, copy-template
- source CSV load
- preset load
- clear-all sources

The undo snapshot restores:

- all source nodes
- finite-fault stamp groups and current open/closed group state
- next stamp patch id
- selected node index
- rupture delay cursor

After undo, the simulation is reset and source fields are rebuilt from the restored source list.

## Notes

- This is an undo stack only; redo is not implemented.
- Runtime wave state itself is not restored. It is rebuilt from the restored source state at time 0.
- Selection-only operations, view movement, settings changes, and run/pause are not added as undo points.
