fix(theme): keep default active rows subtle and add navigate cursor color

[ogulcancelik]

Summary

Follow-up to #2794 (refs #2792). That fix made active Space/Agent rows visible on themes where they blended into a matching terminal background, but it did so by brightening the active-row highlight on every built-in theme, noticeably changing how existing themes look.

This PR narrows the change to the philosophy: don't alter defaults that weren't broken, fix the ones that were, and give the Navigate cursor its own color so the two highlights can't be confused.

• Restore the pre-fix: keep active sidebar rows visible #2794 active-row appearance for themes whose highlight was already visible (catppuccin, catppuccin-latte, tokyo-night-day, gruvbox-light, solarized-light, kanagawa-lotus, rose-pine, vesper). The desktop characterization frame digest returns to its pre-fix: keep active sidebar rows visible #2794 value, confirming the default theme renders identically to current stable.
• Keep dedicated, subtler active_row_bg values for themes where the old highlight was invisible or ambiguous against a matching terminal background (tokyo-night, dracula, nord, gruvbox, one-dark, one-light, solarized, kanagawa, rose-pine-dawn).
• Add a per-theme selection_bg for the Navigate-mode cursor row (expanded workspace cards and collapsed sidebar rows). Most themes use an accent-tinted background so the cursor is distinct by hue from the passive active highlight.
• Expose theme.custom.selection_bg as an override, documented in the config reference and en/ja/zh configuration pages.

Testing

• just check (fmt, cargo nextest, maintenance scripts) green after rebasing onto master.
• New palette test asserts every built-in selection color stays distinct from both the matching terminal background (>=1.05:1) and the active-row color; active-row visibility floor adjusted to the new subtle values.
• Custom theme override test covers selection_bg.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: e0f6dcdc-411c-49d7-bf4c-345a23715b27

📥 Commits

Reviewing files that changed from the base of the PR and between 15539d3 and 60dadce.

📒 Files selected for processing (10)

• docs/next/CHANGELOG.md
• docs/next/website/src/content/docs/configuration.mdx
• docs/next/website/src/content/docs/ja/configuration.mdx
• docs/next/website/src/content/docs/zh-cn/configuration.mdx
• docs/next/website/src/data/config-reference.json
• src/app/state.rs
• src/config/theme.rs
• src/main.rs
• src/ui/sidebar.rs
• src/ui/tab_surface.rs

---

📝 Walkthrough

Walkthrough

The PR adds Palette::selection_bg for Navigate-mode sidebar selections. Built-in themes define the color, custom themes can override it, sidebar rendering uses it, and configuration documentation describes the new option.

Changes

Navigate Selection Background

Layer / File(s)	Summary
Palette and theme configuration src/app/state.rs, src/config/theme.rs	The palette defines separate selection and active-row colors. Custom themes support selection_bg. Tests validate parsing, contrast, and color distinction.
Sidebar selection rendering src/ui/sidebar.rs, src/ui/tab_surface.rs	Collapsed and expanded selected workspace rows use palette.selection_bg. Rendering expectations and the desktop frame digest are updated.
Configuration documentation and defaults src/main.rs, docs/next/website/src/content/docs/..., docs/next/website/src/data/config-reference.json, docs/next/CHANGELOG.md	Default comments, configuration references, localized documentation, and the changelog describe theme.custom.selection_bg.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 60dad

This change narrows active-row styling to affected themes and adds a distinct, configurable Navigate cursor color; no actionable merge-blocking risk remains after normal checks and review.

Sequence Diagram(s)

sequenceDiagram
  participant CustomThemeColors
  participant PaletteWithOverrides
  participant Sidebar
  NavigateMode->>CustomThemeColors: configure selection_bg
  CustomThemeColors->>PaletteWithOverrides: provide optional color
  PaletteWithOverrides->>Sidebar: expose Palette::selection_bg
  NavigateMode->>Sidebar: select workspace row
  Sidebar-->>NavigateMode: render row with selection_bg

Loading

Possibly related PRs

• herdrdev/herdr#2382: Both PRs modify sidebar row highlighting in src/ui/sidebar.rs.
• herdrdev/herdr#2794: Both PRs modify Palette, custom theme colors, and sidebar row background handling.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main changes to active-row defaults and Navigate cursor colors.
Description check	✅ Passed	The description directly explains the theme highlighting changes, configuration support, documentation, and tests.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue/2792-nav-cursor-color

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}