A track, or its fixes in the time window, can now be sheared: hold one end, drag the other, and every fix in between moves in proportion to its time from the end you held. A straight leg stays a straight leg, with a new course and speed, and the map tells you both as you drag. Stretch does the same with the speed alone. Each release is one step, and the keyboard and two small forms do it too.
Analysts can now add lines, areas, circles, ellipses, labels, markers and notes to a plot through a form, style them, give them a time, change and delete them. Each is one step in the plot's history, so Ctrl+Z takes it back. Notes are listed in a new Timeline, and legacy plots bring their circles, ellipses and styling with them.
Annotations can now be drawn straight onto the map: a line, an area, a circle, an ellipse, a label or a marker, with the range, bearing and size shown as you draw. Select one and handles appear, to drag a corner, move a circle or turn an ellipse. Each finished annotation is one step in the plot's history, and so is each change, so Ctrl+Z takes it back. Everything can also be done from the keyboard.
A plot is now one file an analyst can pass to a colleague, and its whole history goes with it. The colleague can undo a step the sender made, go back to any step, and see who did what, with nothing else beside the file.
Debrief now has a time controller. The analyst sets one time window for the whole plot, plays through it at a chosen speed, and hands the plot file to a colleague, who opens it on the same window.
Debrief v4 measures ranges and bearings along the true shape of the Earth. Legacy Debrief did not, so some figures will change slightly.
Phase 1's job is to prove the architecture by walking one path all the way through. You open a catalogue, see a plot on a map, select tracks, run a Python tool, and see its result on the map. That now works in VS Code.
Phase 2 is about trust. An analyst should be able to try something, take it back, have Debrief die mid-save, or share a plot with a colleague who changes it at the same time, and never lose work or have it overwritten without being told.
You no longer need to install anything to try Debrief v4. The blog now has demos you can play with: the real map, tool forms and Python tools, running in your browser.