#32647 Sidebar: a slight gap beside each row and rounder row corners, as ChatGPT's

Leo, 2026-11-02, comparing ChatGPT's selected sidebar row (inset from the sidebar's edge, soft corners) with ours (running right up to the divider, tighter corners):

"CHATGPT HAS A SLIGHT GAP"
"WE DON'T"
"JUST ADD A SLIGHT GAP (PADDING) AND SMOOTH OUT A BIT MORE OF OUR CORNERS ON THE SIDEBAR WORKSPACES"

What changes

• Gap. A row's fill now stops the leading inset short of the sidebar's trailing edge (SidebarStyle.rowEdgeGap) and of the curved main-pane card (rowToPaneGap): 6 pt compact, 8 pt comfortable, the same as its left side. It was 1.5 pt / 2.5 pt. ChatGPT keeps 8 pt (16 px at 2x) between its 30 pt row and the divider; ours scales that to the 24 pt compact row and matches the left inset exactly.
• Corners. Every row fill's corner (SidebarDensityTokens.rowCornerRadius: workspace rows, pinned rows, group headers, the lift card) is the item corner plus space1: 8 pt compact, 9 pt comfortable, continuous curve as before (was 6 / 7). ChatGPT's measures about 9 to 10 pt on its 30 pt row.
• Unchanged: row height, icons, text, colours, glass, and the trailing marks, which stay on the grid's 24 pt column (trailingCenter reads sidebarTrailCenter - rowEdgeGap, so the column does not move). The Chrome group line's inside inset keeps its measured 4 pt (it now reads the item corner directly).

Spec: leo-workspace design/sidebar.md and design/grid.md §5.4 updated with the gap and radius; owner note in plans/cmux-next/sidebar-owner.md.

Tests updated to the new geometry: SidebarRowGutterTests (fill ends the inset from the edge), SidebarGridAlignmentTests (edge gap per density), SidebarGroupLineLayoutTests (inside inset from the item corner).

Risk: low; token values only, contained to the sidebar row fill. Lands as a leo-named fix.

Changelog

• Changed: sidebar rows keep a small gap from the sidebar's edge on both sides and have softer, rounder corners.

Observed / Not run

• Measured ChatGPT's gap and corner from the design references (apps/chatgpt/live/sidebar-machine-details-hover-card.png, sidebar-chat-hover-preview.png).
• Fleet compile check and sidebar suites: see comments.

Agent session: agent session

🤖 Generated with Claude Code

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Summary by cubic

Matches the sidebar's selected row styling to ChatGPT's, so rows sit with an even gap from both sidebar edges and have softer, rounder corners.

• Row fills now stop the leading inset (6 pt compact, 8 comfortable) short of the sidebar's trailing edge and of the curved main-pane card, replacing the previous 1.5/2.5 pt gaps.
• Row fill corners are one space1 rounder (8 pt compact, 9 comfortable), near ChatGPT's measured corner on its taller row.
• The trailing clearance and the slot clamp are both measured from where fills ended before, so the gap moves the fill without shifting the trailing column or the resize-band reach: marks stay on the grid's 24 pt line and footer Search / wide band badges don't move inward.
• Row height, icons, text, colors, glass, and trailing marks are unchanged.
• Tests updated for the new geometry: SidebarRowGutterTests, SidebarGridAlignmentTests, SidebarGroupLineLayoutTests, SidebarNestedGroupAlignmentTests, SidebarRowHoverFollowTests.

Token-only changes, contained to sidebar row fills and slot clamps, so risk is low.