web: 2.0.0 is a broad visual regression across the UI (heavier, noisier) vs 0.43.1, not a single component

Summary

2.0.0's web UI is a broad visual regression, not a single component. The UI as a whole reads heavier, noisier and less scannable than 0.43.1 (the previous release): the same session content occupies more space, and the added ornament competes with the content itself. Opening the same conversation in both versions makes the difference obvious at a glance.

What we could narrow down

The base design system is unchanged — these are byte-identical between 0.43.1 and 2.0.0:

• colors (--color-bg, --color-text, --color-accent, …)
• spacing (--space-*), radii (--radius-*), hairline (--p-hairline)
• typography (--font-ui, --font-ui-latin, --leading-normal/prose/relaxed)
• chat rhythm (--chat-turn-gap: 16px, --chat-block-gap: 10px)

So this is not a theme or density-token change; it comes from the component-level restyles that shipped in 2.0.0:

• web: Revamp the right sidebar as a multi-tab panel.
• web: Unify right-side panel headers and give the OpenIn menu a file mode
• web: Render the rich composer placeholder outside the editor
• web: Fix the command tool row rendering noticeably taller than other tool rows.
• web: Fix the slash-command and @-mention panels failing to open on mobile — both panels and the + menu are now grab-handle bottom sheets on small screens.
• web: Add a flat/by-workspace tab to the mobile session list.
• (0.43.0, immediately before) web: restructure the Settings pages

The CSS bundle also grew from 570 KB (index-dAouBbjn.css) to 604 KB (index-BxYISzcB.css), with roughly 200 additional custom properties — a good part of that is new surfaces such as the browser-control UI, but the styling layer as a whole was reworked.

Concrete example — transcript tool rows

Same conversation, transcript tool-call group and thinking row:

0.43.1

• the tool-call group is one flat collapsible line, e.g. ✓ Ran 2 commands;
• each command is a plain single-line entry, small check mark on the right;
• the thinking row is plain text with a duration, no icon.

2.0.0

• every row gains a leading icon glyph and the command text is wrapped in a bordered box;
• the group header gains both a chevron and a colored status dot;
• the thinking row gains its own icon.

The same content then takes noticeably more vertical space and the chrome competes with the command text, making the transcript harder to scan — the opposite of what the "noticeably taller" fix intended.

Ask

Please treat this as a visual regression rather than intended polish; the 0.43.1 treatment was cleaner and denser. Concretely:

• restore the flat, one-line treatment for transcript tool rows (no per-row icon, no box around the command text, no colored status dot);
• reconsider the decorative additions on the panel headers and the composer;
• if the added chrome is intentional, offer a compact/density option so users can keep 0.43.1-like density.

cc @liruifengv (web)

Compare the same conversation in 0.43.1 and 2.0.0, then inspect the component-level restyles for transcript tool rows, panel headers, the composer, mobile sheets, and the session list. Use the listed visual differences as the review checklist; done means the UI returns to a cleaner, denser treatment or provides an explicit compact option.