Editor interactions

• Drag selection: press the primary pointer in a cell and drag across the grid. Pointer capture continues the gesture outside the initial cell. At the scrollport edge, the view auto-scrolls. Releasing commits the current selection; cancellation or loss of capture stops the gesture.
• Shift-click: extend from the original anchor to another cell; repeated extensions retain that anchor, including when extending in reverse. Arrow keys move focus; Shift-arrows extend/contract the selection. Keyboard movement is bounded to the rendered window, skips hidden/filtered entries, and steps past a merged region as a unit.
• Resize: drag a column or row boundary from its header or anywhere along a cell edge. A six-unit hit area on either side of the boundary gives a stable target; hovering or dragging highlights the whole boundary across the viewport. At intersections the nearest edge wins, with columns winning exact ties. Merged cells expose only their perimeter. The drag is a temporary preview until release, creating a single undoable command. Escape or pointer cancellation restores the original size. Handles are keyboard-focusable: directional arrows change size by 10 units, Shift-arrows by one, and Home resets to the sheet default. Double-click also resets; it is not auto-fit.
• Merge: select a rectangle and choose Merge cells in SelectionToolbar. The top-left cell is the only content owner. A nonempty covered cell causes a useful error instead of data loss. Unmerge cells removes intersecting merges without losing the anchor. Both commands participate in undo/redo and snapshot serialization.

The model and core own all document/selection semantics. React owns pointer capture, DOM hit testing, animation-frame auto-scroll, keyboard events and temporary resize feedback. Spreadsheet is the default composition; these behaviors are also available through SheetGrid and the separate SelectionToolbar.

The full grid shows at most 100 visible rows and 26 visible columns, retaining leading frozen dimensions when given a later window. This is bounded rendering, not full virtualization. Large frozen regions can occupy the entire rendered window.

Style .nori-resize-handle, .nori-selection-toolbar, .nori-view-status, and the existing grid classes. The full resize guide uses --nori-resize-border. Selection colors can be set with --nori-selection-fill and --nori-selection-border. Frozen headers/cells use --nori-header-background and --nori-cell-background when the document has not supplied a background.

Editing and read-only views

Double-click a cell, or press Enter/F2 on a focused cell, to edit its value or formula inline. Enter or moving focus commits through workbook commands; Escape discards the draft. There is no modal overlay.

Use <Spreadsheet workbook={workbook} readOnly /> or <WorkbookProvider workbook={workbook} readOnly> for composed views. SheetGrid, FormulaBar, and SelectionToolbar also accept readOnly. A provider's read-only setting cannot be overridden by its children. Selection, navigation and sheet tabs remain available; editors, resize gestures and merge actions cannot change the document. Switching to read-only cancels an unfinished inline edit or resize.

useWorkbookReadOnly() lets host-owned controls disable undo/redo or other mutation actions. This is a view policy: the host can still update the headless workbook programmatically. The separate SpreadsheetPreview always remains read-only.