feat: add per-mode theme overrides

[aneym]

Summary

[theme.custom] applies one set of overrides in both modes, so with auto_switch a value tuned for the dark theme washes out when the light theme activates. #837 proposed per-mode blocks and @ogulcancelik approved a PR there.

This adds [theme.custom.light] and [theme.custom.dark]. Resolution order: theme defaults, then [theme.custom], then the block matching the resolved appearance. Configs that do not use the new blocks resolve exactly as they do today.

[theme]
auto_switch = true

[theme.custom]
accent = "#fe640b"

[theme.custom.light]
text = "#2e3145"
subtext0 = "#494c66"

Both panes are the same seeded layout rendered with catppuccin-latte active; the only difference is the [theme.custom.light] block.

Refs #837. #2032 asks for the same capability from a full-theme-pair angle; this shape covers it through [theme.custom.light]/[theme.custom.dark] alone.

Test plan

• Rebased onto current master (ffc4e263).
• Focused theme tests: 4 passed, covering parsing both blocks, shared-vs-mode precedence, active light/dark resolution, manual-mode fallback, and sidebar_bg/new sidebar row color tokens.
• Full nextest run: 3,329 passed, 3 failed. The failures are unrelated PTY/process timing tests (live_handoff x2 and api_ping pane-info); rerunning the CI suite with exactly those three excluded passed all 3,329 remaining Rust tests plus fmt, clippy, UI architecture, integration assets, and plugin marketplace checks.
• just windows-lint: passed.
• Maintenance script suite: 98 passed, including config-reference parity, docs translation parity, and Windows ConPTY packaging.

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📒 Files selected for processing (3)

• docs/next/CHANGELOG.md
• docs/next/website/src/content/docs/ja/configuration.mdx
• docs/next/website/src/content/docs/zh-cn/configuration.mdx

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---

📝 Walkthrough

Walkthrough

The theme configuration now supports light- and dark-appearance custom color overrides. Automatic theme switching applies active mode overrides after shared custom and legacy accent colors. Tests and documentation cover the new behavior.

Changes

Theme appearance overrides

Layer / File(s)	Summary
Theme configuration contract src/config/theme.rs, src/config.rs	CustomThemeColors defines optional light and dark ModeThemeColors tables. Deserialization tests cover their color values. The type is publicly re-exported.
Mode-aware palette resolution src/app/state.rs, src/app/mod.rs	Automatic theme selection passes active mode overrides to palette resolution. Palette::with_mode_overrides applies token values after shared custom and legacy accent colors. Tests verify precedence and fallback behavior.
Configuration documentation and examples docs/next/website/src/content/docs/configuration.mdx, docs/next/website/src/data/config-reference.json, docs/next/website/src/content/docs/ja/configuration.mdx, docs/next/website/src/content/docs/zh-cn/configuration.mdx, src/main.rs, docs/next/CHANGELOG.md	Documentation, reference data, changelog, and default examples describe light and dark appearance-specific color settings.

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

Merge Risk: ⚪ Minimal · up to b7b3d

This adds optional light- and dark-mode theme overrides while preserving existing behavior for configurations that do not use them; no actionable merge-blocking risk remains beyond normal checks and review.

Sequence Diagram(s)

sequenceDiagram
  participant HostAppearance
  participant resolve_effective_theme
  participant resolve_palette_for_theme_name
  participant Palette
  HostAppearance->>resolve_effective_theme: select light or dark appearance
  resolve_effective_theme->>resolve_palette_for_theme_name: pass active mode overrides
  resolve_palette_for_theme_name->>Palette: apply shared custom colors
  Palette->>Palette: apply active mode-specific colors

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 57.14% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 2 files. (3 skipped: 3 unsupported.)	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly explains the per-mode theme overrides, resolution order, compatibility behavior, tests, and validation results.
Title check	✅ Passed	The title clearly and concisely identifies the main change: adding per-mode theme overrides.
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.

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• Create PR with unit tests

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[kangal-bot]

Hi @aneym, thanks for your interest in contributing!

Herdr automatically admits focused bug fixes from contributors who are not maintainers when the title uses fix: ... or fix(scope): ... and the patch changes no more than 20 files and 1,000 total added or deleted lines.

Contributors who are not maintainers may submit only focused bug fixes. If this pull request fixes a bug, rename it to use a conventional fix: ... or fix(scope): ... title, then tag a maintainer to review and reopen it.

Feature requests, behavior changes, and other proposals belong in GitHub Discussions and require maintainer approval before a pull request.

If this gate classified the pull request incorrectly, reply and tag a maintainer listed in .github/MAINTAINERS. A verified maintainer can reopen it; reopening by anyone else will be closed again automatically.

Patch size: 7 changed files, 391 changed lines.

See https://github.com/herdrdev/herdr/blob/master/CONTRIBUTING.md for the contribution policy.

[greptile-apps]

Greptile Summary

Adds light- and dark-specific custom theme overrides that are layered over shared overrides when automatic theme switching is active.

• Extends theme configuration parsing and reference documentation with theme.custom.light and theme.custom.dark.
• Applies the override block matching the resolved host appearance after the base theme and shared custom colors.
• Preserves manual theme behavior by leaving mode-specific blocks inactive when auto_switch is disabled.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
src/app/mod.rs	Resolves and applies the active appearance-specific override after shared theme colors while preserving manual-mode behavior.
src/app/state.rs	Adds palette support for applying every mode-specific color token.
src/config/theme.rs	Adds deserializable light and dark override blocks and parsing coverage.
src/config.rs	Re-exports the new mode-specific theme color model.
src/main.rs	Documents the new override blocks in the generated default configuration.
docs/next/website/src/data/config-reference.json	Adds reference entries for all supported light- and dark-specific color tokens.

_{Reviews (13): Last reviewed commit: "docs: complete per-mode theme documentat..." | Re-trigger Greptile}

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⚠️ Outside diff range comments (1)

src/config/theme.rs (1)

126-146: 🗄️ Data Integrity & Integration | 🟠 Major | ⚡ Quick win

Add sidebar_bg to mode-specific overrides.

ModeThemeColors omits sidebar_bg, although CustomThemeColors and Palette support it. A user cannot set a light-only or dark-only sidebar background.

Add sidebar_bg to ModeThemeColors. Apply it in Palette::with_mode_overrides. Add parsing and palette-resolution coverage.

Proposed fix

--- a/src/config/theme.rs
+++ b/src/config/theme.rs
 pub struct ModeThemeColors {
     pub accent: Option<String>,
     pub panel_bg: Option<String>,
+    pub sidebar_bg: Option<String>,
     pub surface0: Option<String>,

--- a/src/app/state.rs
+++ b/src/app/state.rs
         if let Some(c) = &custom.panel_bg {
             self.panel_bg = parse_color(c);
         }
+        if let Some(c) = &custom.sidebar_bg {
+            self.sidebar_bg = parse_color(c);
+        }

Based on supplied downstream context, src/app/state.rs:641-692 has the same omission.

---

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Configuration used: Organization UI

Review profile: CHILL

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Run ID: 1cefb19c-6dd0-416f-9a93-164b72966a75

📥 Commits

Reviewing files that changed from the base of the PR and between 66ee3b8 and d1a4e65.

📒 Files selected for processing (7)

• docs/next/website/src/content/docs/configuration.mdx
• docs/next/website/src/data/config-reference.json
• src/app/mod.rs
• src/app/state.rs
• src/config.rs
• src/config/theme.rs
• src/main.rs

🚧 Files skipped from review as they are similar to previous changes (6)

• docs/next/website/src/content/docs/configuration.mdx
• docs/next/website/src/data/config-reference.json
• src/main.rs
• src/app/state.rs
• src/app/mod.rs
• src/config.rs

[aneym]

Added sidebar_bg to the per-mode overrides in baff68f: field on ModeThemeColors, applied in with_mode_overrides, covered in the parse and palette-resolution tests, and documented under theme.custom.light/theme.custom.dark in the config reference.

[aneym]

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[ogulcancelik]

Reviewed the implementation, precedence, manual-mode behavior, config coverage, and documentation. Rebased onto current master; local and CI checks pass, and both review bots are clear.

[ogulcancelik]

@aneym sorry for taking so long, ty!