feat: add custom theme support with color picker UI

- Add Custom variant to Theme enum and CustomThemeColors struct in Rust config
- Add custom_theme_colors field to HikariConfig for storing user-defined colors
- Create color picker UI in ConfigSidebar with 8 customizable color variables
- Implement live preview when editing custom theme colors
- Apply custom colors on app startup when custom theme is selected
- Use dark theme as base, override with user's custom CSS variables

src-tauri/src/config.rs

@@ -92,6 +92,10 @@ pub struct HikariConfig {
 
     #[serde(default)]
     pub profile_bio: Option<String>,
+
+    // Custom theme colors
+    #[serde(default)]
+    pub custom_theme_colors: CustomThemeColors,
 }
 
 impl Default for HikariConfig {
@@ -118,6 +122,7 @@ impl Default for HikariConfig {
             profile_name: None,
             profile_avatar_path: None,
             profile_bio: None,
+            custom_theme_colors: CustomThemeColors::default(),
         }
     }
 }
@@ -150,6 +155,27 @@ pub enum Theme {
     Light,
     #[serde(rename = "high-contrast")]
     HighContrast,
+    Custom,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
+pub struct CustomThemeColors {
+    #[serde(default)]
+    pub bg_primary: Option<String>,
+    #[serde(default)]
+    pub bg_secondary: Option<String>,
+    #[serde(default)]
+    pub bg_terminal: Option<String>,
+    #[serde(default)]
+    pub accent_primary: Option<String>,
+    #[serde(default)]
+    pub accent_secondary: Option<String>,
+    #[serde(default)]
+    pub text_primary: Option<String>,
+    #[serde(default)]
+    pub text_secondary: Option<String>,
+    #[serde(default)]
+    pub border_color: Option<String>,
 }
 
 #[cfg(test)]
@@ -178,6 +204,7 @@ mod tests {
         assert!(config.profile_name.is_none());
         assert!(config.profile_avatar_path.is_none());
         assert!(config.profile_bio.is_none());
+        assert_eq!(config.custom_theme_colors, CustomThemeColors::default());
     }
 
     #[test]
@@ -204,6 +231,7 @@ mod tests {
             profile_name: Some("Test User".to_string()),
             profile_avatar_path: None,
             profile_bio: Some("A test bio".to_string()),
+            custom_theme_colors: CustomThemeColors::default(),
         };
 
         let json = serde_json::to_string(&config).unwrap();
@@ -232,5 +260,8 @@ mod tests {
             serde_json::to_string(&high_contrast).unwrap(),
             "\"high-contrast\""
         );
+
+        let custom = Theme::Custom;
+        assert_eq!(serde_json::to_string(&custom).unwrap(), "\"custom\"");
     }
 }

src/lib/components/ConfigSidebar.svelte

@@ -3,7 +3,9 @@
     configStore,
     type HikariConfig,
     type Theme,
+    type CustomThemeColors,
     applyFontSize,
+    applyCustomThemeColors,
     MIN_FONT_SIZE,
     MAX_FONT_SIZE,
     DEFAULT_FONT_SIZE,
@@ -33,8 +35,20 @@
     profile_name: null,
     profile_avatar_path: null,
     profile_bio: null,
+    custom_theme_colors: {
+      bg_primary: null,
+      bg_secondary: null,
+      bg_terminal: null,
+      accent_primary: null,
+      accent_secondary: null,
+      text_primary: null,
+      text_secondary: null,
+      border_color: null,
+    },
   });
 
+  let showCustomThemeEditor = $state(false);
+
   let isOpen = $state(false);
   let isSaving = $state(false);
   let saveError: string | null = $state(null);
@@ -91,9 +105,33 @@
 
   async function handleThemeChange(theme: Theme) {
     config.theme = theme;
-    await configStore.setTheme(theme);
+    showCustomThemeEditor = theme === "custom";
+    await configStore.setTheme(theme, config.custom_theme_colors);
   }
 
+  function handleCustomColorChange(key: keyof CustomThemeColors, value: string) {
+    config.custom_theme_colors = {
+      ...config.custom_theme_colors,
+      [key]: value || null,
+    };
+    // Live preview
+    if (config.theme === "custom") {
+      applyCustomThemeColors(config.custom_theme_colors);
+    }
+  }
+
+  // Default dark theme colors for color picker defaults
+  const defaultDarkColors: Required<Record<keyof CustomThemeColors, string>> = {
+    bg_primary: "#1a1a2e",
+    bg_secondary: "#16213e",
+    bg_terminal: "#0f0f1a",
+    accent_primary: "#e94560",
+    accent_secondary: "#ff6b9d",
+    text_primary: "#ffffff",
+    text_secondary: "#a0a0a0",
+    border_color: "#2a2a4a",
+  };
+
   function toggleTool(tool: string) {
     if (config.auto_granted_tools.includes(tool)) {
       config.auto_granted_tools = config.auto_granted_tools.filter((t) => t !== tool);
@@ -421,10 +459,10 @@
       <!-- Theme Selection -->
       <div class="mb-4">
         <label class="block text-sm text-[var(--text-secondary)] mb-2">Theme</label>
-        <div class="flex gap-2">
+        <div class="flex flex-wrap gap-2">
           <button
             onclick={() => handleThemeChange("dark")}
-            class="flex-1 px-3 py-2 rounded-lg border transition-colors {config.theme === 'dark'
+            class="flex-1 min-w-[70px] px-3 py-2 rounded-lg border transition-colors {config.theme === 'dark'
               ? 'bg-[var(--accent-primary)] border-[var(--accent-primary)] text-white'
               : 'bg-[var(--bg-primary)] border-[var(--border-color)] text-[var(--text-secondary)] hover:border-[var(--accent-primary)]'}"
           >
@@ -432,7 +470,7 @@
           </button>
           <button
             onclick={() => handleThemeChange("light")}
-            class="flex-1 px-3 py-2 rounded-lg border transition-colors {config.theme === 'light'
+            class="flex-1 min-w-[70px] px-3 py-2 rounded-lg border transition-colors {config.theme === 'light'
               ? 'bg-[var(--accent-primary)] border-[var(--accent-primary)] text-white'
               : 'bg-[var(--bg-primary)] border-[var(--border-color)] text-[var(--text-secondary)] hover:border-[var(--accent-primary)]'}"
           >
@@ -440,17 +478,150 @@
           </button>
           <button
             onclick={() => handleThemeChange("high-contrast")}
-            class="flex-1 px-3 py-2 rounded-lg border transition-colors {config.theme ===
+            class="flex-1 min-w-[70px] px-3 py-2 rounded-lg border transition-colors {config.theme ===
             'high-contrast'
               ? 'bg-[var(--accent-primary)] border-[var(--accent-primary)] text-white'
               : 'bg-[var(--bg-primary)] border-[var(--border-color)] text-[var(--text-secondary)] hover:border-[var(--accent-primary)]'}"
             title="High contrast mode for improved accessibility"
           >
-            High Contrast
+            Contrast
+          </button>
+          <button
+            onclick={() => handleThemeChange("custom")}
+            class="flex-1 min-w-[70px] px-3 py-2 rounded-lg border transition-colors {config.theme === 'custom'
+              ? 'bg-[var(--accent-primary)] border-[var(--accent-primary)] text-white'
+              : 'bg-[var(--bg-primary)] border-[var(--border-color)] text-[var(--text-secondary)] hover:border-[var(--accent-primary)]'}"
+            title="Create your own custom theme"
+          >
+            Custom
           </button>
         </div>
       </div>
 
+      <!-- Custom Theme Editor -->
+      {#if config.theme === "custom" || showCustomThemeEditor}
+        <div class="mb-4 p-3 bg-[var(--bg-primary)] rounded-lg border border-[var(--border-color)]">
+          <h4 class="text-sm font-medium text-[var(--text-primary)] mb-3">Custom Theme Colors</h4>
+          <div class="grid grid-cols-2 gap-3">
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Background</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.bg_primary || defaultDarkColors.bg_primary}
+                  oninput={(e) => handleCustomColorChange("bg_primary", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.bg_primary || defaultDarkColors.bg_primary}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Secondary BG</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.bg_secondary || defaultDarkColors.bg_secondary}
+                  oninput={(e) => handleCustomColorChange("bg_secondary", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.bg_secondary || defaultDarkColors.bg_secondary}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Terminal BG</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.bg_terminal || defaultDarkColors.bg_terminal}
+                  oninput={(e) => handleCustomColorChange("bg_terminal", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.bg_terminal || defaultDarkColors.bg_terminal}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Border</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.border_color || defaultDarkColors.border_color}
+                  oninput={(e) => handleCustomColorChange("border_color", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.border_color || defaultDarkColors.border_color}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Accent Primary</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.accent_primary || defaultDarkColors.accent_primary}
+                  oninput={(e) => handleCustomColorChange("accent_primary", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.accent_primary || defaultDarkColors.accent_primary}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Accent Secondary</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.accent_secondary || defaultDarkColors.accent_secondary}
+                  oninput={(e) => handleCustomColorChange("accent_secondary", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.accent_secondary || defaultDarkColors.accent_secondary}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Text Primary</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.text_primary || defaultDarkColors.text_primary}
+                  oninput={(e) => handleCustomColorChange("text_primary", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.text_primary || defaultDarkColors.text_primary}
+                </span>
+              </div>
+            </div>
+            <div class="color-input-group">
+              <label class="text-xs text-[var(--text-secondary)]">Text Secondary</label>
+              <div class="flex gap-2 items-center">
+                <input
+                  type="color"
+                  value={config.custom_theme_colors.text_secondary || defaultDarkColors.text_secondary}
+                  oninput={(e) => handleCustomColorChange("text_secondary", e.currentTarget.value)}
+                  class="color-picker"
+                />
+                <span class="text-xs text-[var(--text-tertiary)] font-mono">
+                  {config.custom_theme_colors.text_secondary || defaultDarkColors.text_secondary}
+                </span>
+              </div>
+            </div>
+          </div>
+          <p class="text-xs text-[var(--text-tertiary)] mt-3">
+            Changes preview live. Click Save Settings to persist.
+          </p>
+        </div>
+      {/if}
+
       <!-- Font Size -->
       <div class="mb-4">
         <label for="font-size" class="block text-sm text-[var(--text-secondary)] mb-2">
@@ -664,4 +835,39 @@
     background: var(--text-tertiary);
     cursor: not-allowed;
   }
+
+  /* Color picker styling */
+  .color-input-group {
+    display: flex;
+    flex-direction: column;
+    gap: 0.25rem;
+  }
+
+  .color-picker {
+    width: 32px;
+    height: 32px;
+    padding: 0;
+    border: 2px solid var(--border-color);
+    border-radius: 6px;
+    cursor: pointer;
+    background: transparent;
+  }
+
+  .color-picker::-webkit-color-swatch-wrapper {
+    padding: 2px;
+  }
+
+  .color-picker::-webkit-color-swatch {
+    border-radius: 4px;
+    border: none;
+  }
+
+  .color-picker::-moz-color-swatch {
+    border-radius: 4px;
+    border: none;
+  }
+
+  .color-picker:hover {
+    border-color: var(--accent-primary);
+  }
 </style>

src/lib/components/StatusBar.svelte

@@ -63,6 +63,16 @@
     profile_name: null,
     profile_avatar_path: null,
     profile_bio: null,
+    custom_theme_colors: {
+      bg_primary: null,
+      bg_secondary: null,
+      bg_terminal: null,
+      accent_primary: null,
+      accent_secondary: null,
+      text_primary: null,
+      text_secondary: null,
+      border_color: null,
+    },
   });
 
   let streamerModeActive = $state(false);

src/lib/stores/config.ts

@@ -1,7 +1,18 @@
 import { writable, derived } from "svelte/store";
 import { invoke } from "@tauri-apps/api/core";
 
-export type Theme = "dark" | "light" | "high-contrast";
+export type Theme = "dark" | "light" | "high-contrast" | "custom";
+
+export interface CustomThemeColors {
+  bg_primary: string | null;
+  bg_secondary: string | null;
+  bg_terminal: string | null;
+  accent_primary: string | null;
+  accent_secondary: string | null;
+  text_primary: string | null;
+  text_secondary: string | null;
+  border_color: string | null;
+}
 
 export interface HikariConfig {
   model: string | null;
@@ -25,6 +36,7 @@ export interface HikariConfig {
   profile_name: string | null;
   profile_avatar_path: string | null;
   profile_bio: string | null;
+  custom_theme_colors: CustomThemeColors;
 }
 
 const defaultConfig: HikariConfig = {
@@ -49,6 +61,16 @@ const defaultConfig: HikariConfig = {
   profile_name: null,
   profile_avatar_path: null,
   profile_bio: null,
+  custom_theme_colors: {
+    bg_primary: null,
+    bg_secondary: null,
+    bg_terminal: null,
+    accent_primary: null,
+    accent_secondary: null,
+    text_primary: null,
+    text_secondary: null,
+    border_color: null,
+  },
 };
 
 function createConfigStore() {
@@ -104,9 +126,24 @@ function createConfigStore() {
     closeSidebar: () => isSidebarOpen.set(false),
     toggleSidebar: () => isSidebarOpen.update((open) => !open),
 
-    setTheme: async (theme: Theme) => {
+    setTheme: async (theme: Theme, customColors?: CustomThemeColors) => {
-      await updateConfig({ theme });
+      const updates: Partial<HikariConfig> = { theme };
-      applyTheme(theme);
+      if (customColors) {
+        updates.custom_theme_colors = customColors;
+      }
+      await updateConfig(updates);
+      let currentConfig: HikariConfig = defaultConfig;
+      config.subscribe((c) => (currentConfig = c))();
+      applyTheme(theme, currentConfig.custom_theme_colors);
+    },
+
+    setCustomThemeColors: async (colors: CustomThemeColors) => {
+      await updateConfig({ custom_theme_colors: colors });
+      let currentConfig: HikariConfig = defaultConfig;
+      config.subscribe((c) => (currentConfig = c))();
+      if (currentConfig.theme === "custom") {
+        applyCustomThemeColors(colors);
+      }
     },
 
     setFontSize: async (size: number) => {
@@ -176,12 +213,52 @@ function createConfigStore() {
   };
 }
 
-export function applyTheme(theme: Theme) {
+export function applyTheme(theme: Theme, customColors?: CustomThemeColors) {
   if (typeof document !== "undefined") {
-    document.documentElement.setAttribute("data-theme", theme);
+    // For custom theme, we use dark as the base and override with custom colors
+    document.documentElement.setAttribute("data-theme", theme === "custom" ? "dark" : theme);
+
+    // Clear any previously applied custom colors
+    clearCustomThemeColors();
+
+    // Apply custom colors if theme is custom
+    if (theme === "custom" && customColors) {
+      applyCustomThemeColors(customColors);
+    }
   }
 }
 
+export function applyCustomThemeColors(colors: CustomThemeColors) {
+  if (typeof document === "undefined") return;
+
+  const root = document.documentElement;
+  if (colors.bg_primary) root.style.setProperty("--bg-primary", colors.bg_primary);
+  if (colors.bg_secondary) root.style.setProperty("--bg-secondary", colors.bg_secondary);
+  if (colors.bg_terminal) root.style.setProperty("--bg-terminal", colors.bg_terminal);
+  if (colors.accent_primary) root.style.setProperty("--accent-primary", colors.accent_primary);
+  if (colors.accent_secondary) root.style.setProperty("--accent-secondary", colors.accent_secondary);
+  if (colors.text_primary) root.style.setProperty("--text-primary", colors.text_primary);
+  if (colors.text_secondary) root.style.setProperty("--text-secondary", colors.text_secondary);
+  if (colors.border_color) root.style.setProperty("--border-color", colors.border_color);
+}
+
+export function clearCustomThemeColors() {
+  if (typeof document === "undefined") return;
+
+  const root = document.documentElement;
+  const customProperties = [
+    "--bg-primary",
+    "--bg-secondary",
+    "--bg-terminal",
+    "--accent-primary",
+    "--accent-secondary",
+    "--text-primary",
+    "--text-secondary",
+    "--border-color",
+  ];
+  customProperties.forEach((prop) => root.style.removeProperty(prop));
+}
+
 const MIN_FONT_SIZE = 10;
 const MAX_FONT_SIZE = 24;
 const DEFAULT_FONT_SIZE = 14;

src/routes/+page.svelte

@@ -255,7 +255,7 @@
 
       // Apply saved settings on startup
       const config = configStore.getConfig();
-      applyTheme(config.theme);
+      applyTheme(config.theme, config.custom_theme_colors);
       applyFontSize(config.font_size);
 
       // Apply always-on-top setting