Set fill color

What it does

Select cells and click the Fill color swatch in the toolbar, then pick a color — the selected cells get that background color. Fill color is presentation, separate from the cell's value: filling =A1+B1 paints the cell background without touching the formula or its computed value. It undoes and redoes like any other edit. Fill color is toolbar-only — Google Sheets has no keyboard shortcut for it, so Studio doesn't either.

Verification

The scenario runner cannot drive a toolbar color swatch (it has no verb for it yet — a known gap tracked as a follow-up), so the manifest scenario above only asserts the driveable invariant (selecting a cell never changes its value/formula). The fill-application path itself is verified two other ways: the operation's unit tests assert fillColorPatch('#fff2cc') === { fill: '#fff2cc' } and the styleContributor wiring, and it is browser-verified — applyFormat({ fill: '#fff2cc' }) paints the selected cell's background cream and undo reverts it. Full runner-driven E2E coverage lands once a toolbar-action verb exists.

Verified behavior

Matches Google Sheets: In Google Sheets, the Fill color control (the paint-bucket swatch in the toolbar) sets the background/fill color of the selected cells to a chosen color. Fill color is a presentation attribute independent of the cell's value or formula: it changes the cell's background, not what it computes to, and it undoes/redoes like any edit. Setting it does not alter the cell's stored value or formula. Google Sheets has no keyboard shortcut for fill color — it is toolbar-only.

Selecting a formula cell leaves its value and formula unchanged (presentation-independence)

Given

• A1 = 5
• A2 = =A1*2

When I click A2

Then

• A2 shows 10
• A2 has formula =A1*2