Plot2D storyboard

Use the Plot2D tutorial for the deterministic calibration fixture. Repeat with a representative measured or computed scalar map for scientific signoff. These are required stories, not completed results.

ID	Action	Required evidence
P2D-01	Hover low/high row and column bins	Physical bin centers and original float64 values match the input; row zero is at the bottom.
P2D-02	Wheel zoom in/out, drag, then Reset View	Scientific pixels and axis limits change together; reset restores the full grid; source values stay unchanged.
P2D-03	Change Color on one of two plots	Map and colorbar change together, numerical limits stay fixed, and the other plot stays unchanged.
P2D-04	Move the tutorial angle slider; replace values with set_data	Reading line moves without resending data; replacement map updates without changing viewport or color limits.
P2D-05	Use narrow/wide layouts, light/dark notebook themes	Labels, menus and axes remain readable; max_width is respected; no clipped controls.
P2D-06	Save PNG, export a Matplotlib figure	Both exports show the current axes, values, viewport, color limits and reading line.
P2D-07	Save notebook after interaction, close and reopen	Test default static preview and opt-in save_state=True separately. Default snapshot omits data_bytes; opt-in preserves float64 arrays. Saved view restores without a kernel where supported; payload size and fallback freshness are stated.
P2D-08	Rapidly replace maps/colormaps while hovering; close during rendering	Hover corresponds to the visible map; stale asynchronous work cannot paint later; resources are released without errors.

Record browser/adapter, map shape and dtype, screenshots before/after, console errors, first-paint time and gesture-to-paint latency. Python state tests and cell execution alone are not browser signoff.