Command Center: can't scroll past the prompt input in tiled views (2x2/3x2/3x3)

Summary

In the Command Center in PostHog Code, when a prompt is long in a tiled view (2x2, 3x2, or 3x3), scrolling is trapped inside the text input field. You can't scroll the surrounding tile, so you can't reach:

• the execute button below the prompt
• the suggestions rendered underneath
• the branch/repo selector above the prompt

The only workarounds today are using the magnification/zoom-out tool or switching to a 1x1 or 1x2 layout.

Steps to reproduce

1. Open the Command Center and switch to a tiled layout (2x2, 3x2, or 3x3).
2. In a tile, type/paste a long prompt that overflows the input.
3. Try to scroll within the tile to reach the execute button, suggestions, or the branch/repo selector.

Expected: the tile content can be reached (the tile scrolls, or controls stay visible).
Actual: only the text inside the editor scrolls; the execute button, suggestions, and branch/repo selector are clipped and unreachable.

Root cause (initial investigation)

The scroll is trapped inside the Tiptap editor div; nothing in the surrounding tile provides a scroll region:

• GridCell is overflow-hidden with no scroll — packages/ui/src/features/command-center/components/CommandCenterGrid.tsx:117
• TaskInput uses h-full with no overflow scroll; controls live in an absolutely-positioned, center-aligned box (branch/repo selector at bottom-full, suggestions at top-full), so they overflow the tile rather than scroll into view — packages/ui/src/features/task-detail/components/TaskInput.tsx:748, :773, :1031
• SessionView's input wrapper is a plain <Box className="relative"> with no scroll — packages/ui/src/features/sessions/components/SessionView.tsx:586
• overflow-y-auto is applied only to the editor text area itself (with a max-h cap) — packages/ui/src/features/message-editor/components/PromptInput.tsx:358

Screenshot

Screenshot from the original report to be attached.

Reported in Slack: https://posthog.slack.com/archives/C0ACRAMJUAG/p1782753764134549

Start with the tiled layout in packages/ui/src/features/command-center/components/CommandCenterGrid.tsx:117, then trace the input wrappers at TaskInput.tsx:748, :773, :1031, SessionView.tsx:586, and PromptInput.tsx:358. Reproduce a long prompt in a 2x2, 3x2, or 3x3 tile and inspect how overflow is handled. Done means the branch/repo selector, execute button, and suggestions are reachable without zooming out or changing layout.