Range selection engine

The range engine handles anchor/focus/range and hot paths for bulk operations.

1) Core concepts

• Anchor — starting cell.
• Focus — current active cell.
• Range — rectangle between anchor and focus.

2) Basic operations

// pseudo‑operations at orchestration level
orchestration.selection.setAnchor({ rowIndex: 0, colKey: "service" })
orchestration.selection.setFocus({ rowIndex: 5, colKey: "owner" })
const range = orchestration.selection.getRange()

3) What the UI adapter must do

• Ensure a single active focus.
• Support shift‑selection to build a range.
• Preserve anchor/focus on scroll.

4) Diagnostics

• Validate rowIndex/colKey against the current model.
• Use runtime events to inspect transitions.