Mirrors the Chart.js adapter's { maidr, layerDatasetIndices } contract: the
schema plus the bookkeeping needed to route navigation back into the host
library. maidr.onNavigate is deliberately not set — wiring it is the
binder's job, and leaving extraction pure is what makes it testable.
The result of extracting a set of worksheets.
Mirrors the Chart.js adapter's
{ maidr, layerDatasetIndices }contract: the schema plus the bookkeeping needed to route navigation back into the host library.maidr.onNavigateis deliberately not set — wiring it is the binder's job, and leaving extraction pure is what makes it testable.