Data source protocol

This document describes the DataGridDataSource contract (advanced entrypoint).

1) Why it exists

• unified pull + push channel
• abort‑first under viewport churn
• partial invalidation without full resets

2) API

DataGridDataSource<T>:

• pull(request) — required demand API
• subscribe(listener) — optional push stream
• invalidate(invalidation) — optional invalidation hook

DataGridDataSourcePullRequest:

• range, priority, reason, signal
• sortModel, filterModel, groupBy, groupExpansion

3) Row model integration

createDataSourceBackedRowModel provides:

• range‑driven demand (setViewportRange)
• abort‑first cancellation
• invalidate range/all
• diagnostics via getBackpressureDiagnostics()