Fulcrum vs vellumwidget

vellumwidget compiles a vellum scene or a vellumplot plot into a self-contained client-side htmlwidget with hover, select, brush, lasso, pan/zoom and export, and no server round-trip. The two-way Shiny story is complete: interactions surface as reactive inputs keyed by output id, and vellumwidget_proxy() drives an already-rendered widget from the server without re-rendering it. The last two releases are fidelity work rather than new surface, calibrating hit-testing from the rendered positions of marks and rendering the raster base image at 2x for HiDPI screens.

The direction is declarative. 0.7.0 removed the interaction-intent arguments from as_widget() outright, dropping the signature from roughly 36 arguments to 24 and moving highlight, filter and cross-filter into vellumplot's spec via select_point(), condition() and filter_by(). Each release since has enacted more of that compiled spec on the frozen scene, from conditional encodings to single-view filters to cross-view cross-filtering, leaving the widget as an interpreter of the plot rather than a configuration surface of its own. The bug fixes track the same theme the engine's do: measured geometry and rendered geometry must not drift.

The notes name the remaining hold-outs explicitly, saying hover_mode, crosshair, legend_click, select_mode and the tooltip-appearance arguments remain only until their spec equivalents land, so the next releases most likely move those into vellumplot and shrink as_widget() further. The scale binds flagged as following the filter work are the other stated next step.