[Feature Request]: Add adjustable conversation pane width (percentage) in Desktop GUI

[lidao2026-Coding]

Is your feature request related to a problem?

Yes. The Desktop GUI conversation pane has a fixed width that is too narrow — on wide Windows monitors (1440p/4K) the chat column occupies only a small portion of the screen center while both sides are large empty spaces. This wastes screen real estate and makes long conversations harder to read.

Describe the solution you'd like

Add a conversation pane width setting (in percentage), e.g. 40%–90%, adjustable in Settings, and/or a drag-to-resize handle between the conversation pane and the side panels. The choice should persist across sessions.

• Settings → Appearance: "Conversation pane width: 60% (slider)"
• Optional: a draggable splitter for quick manual adjustment, with the percentage synced back to settings

Describe alternatives you've considered

• Auto-expand the chat pane to fill the window when side panels are collapsed.
• A fixed "wide mode" toggle.

Additional context

• Platform: Windows 11, 2560×1440 display.
• Version: DeepCode Desktop 0.1.0 (v2.0.0 runtime).
• This is purely a UI/layout improvement; no backend changes needed (frontend: desktop/src/**).

[Zongwei9888]

Thanks — implemented in #161. Settings → Appearance → Conversation width, adjustable from 40% to 100%.

Your diagnosis was right: the column was pinned to a fixed maximum. It turned out the same constant was hardcoded in three separate places (the conversation, the composer and the goal rail), so they all share one value now. At 100% the original width is restored, so nothing changes unless you move the slider.

The drag-to-resize handle you mentioned as an alternative isn't built yet — the slider seemed like the smaller step and should cover the main problem. If the handle would help in daily use, let us know and we'll look at adding it.