The arrow keys moved focus between heatmap days, but only a pointer opened the tooltip, so keyboard users never saw a day's counts. Focusing a cell now shows the same tooltip, set off the cell's corner, and blurring it hides the tooltip.
Verified in the mockup from live site.json at 1280 px, dark and light, with the focus on a mid-grid day and on the last column.
Before / after, Nov 5 focused, dark:
Light:
🤖 Generated with Claude Code