UI/UX improvement: Better color contrast and text readability for long sessions

[bevis-wong]

Problem

The current UI has limited color variety and readability issues that cause eye strain during long usage:

1. The interface is dominated by only blue and bright white colors.
2. The pure white text in the main output panel is too harsh against the black background, which makes it uncomfortable to read for extended periods.
3. All text (including the agent's "thinking" process and the final output to the user) uses the same blue/white scheme, making it hard to visually distinguish different types of content at a glance.

Proposed solution

1. Reduce the brightness of the main output text. The muted gray tone used in the right-side tasks panel provides a good example of a much more comfortable color for long sessions.
2. Assign a distinct color to the agent's "thinking" process text (e.g., a soft dark orange) to clearly differentiate it from the user-facing output text.
3. Add more subtle color variations across the UI to improve visual hierarchy without sacrificing the dark theme aesthetic.

Alternatives considered

• Adjusting my terminal's contrast settings is not a good solution, as it affects all other applications.
• Using a custom terminal theme also changes the look of other tools, so it's not ideal for just DeepSeek-TUI.

Additional context

The color scheme of the tasks panel already shows that softer grays work well with the dark background. Applying similar principles to the main output and adding a different accent color for the thinking process would greatly improve usability and readability.

[Hmbown]

thank you so much - I am trying to figure this out the best way possible and appreciate these ideas

[Hmbown]

This is the main follow-up I’d use for the readability pass after v0.8.17.

v0.8.17 adds /theme and a light/dark theme path, but it does not fully address the contrast hierarchy described here. The next patch should tune the dark palette for long-session reading and make thinking/tool/final-answer text visually distinct without making the screen noisy. This also overlaps with #936, so we should handle them together rather than making separate one-off color tweaks.

[Hmbown]

v0.8.18 includes a first readability pass in draft release PR #1094.

What landed:

• body text is softened from pure white to reduce long-session glare
• reasoning/thinking text uses a warmer accent with light-theme adaptation
• palette audit coverage was added for the new colors

Verification:

• cargo test -p deepseek-tui dark_palette_uses_soft_body_text_and_warm_reasoning --locked -> passed
• cargo test -p deepseek-tui render_thinking --locked -> 5 passed, 0 failed

I am treating this as partial rather than fully closing the issue. The larger tooltip/detail behavior for clipped labels and deeper light-theme polish should stay open for a later, more visual QA-heavy pass.