feat(07-01): extend ThemeContext to support three named themes with THEME_META export

- Expand Theme type to catppuccin-mocha | tokyo-night | catppuccin-latte
- Export THEME_META with label, dark boolean, bg hex, primary hex per theme
- applyTheme toggles .dark and .theme-tokyo-night classes correctly
- toggleTheme cycles all three themes (Mocha -> Tokyo Night -> Latte -> Mocha)
- readStoredTheme falls back to catppuccin-mocha for old localStorage values
- Fix Layout.tsx: replace theme === 'dark' comparison with THEME_META[theme].dark
- Fix MarkdownBody.tsx: replace theme === 'dark' comparisons with THEME_META[theme].dark

ui/src/components/Layout.tsx

@@ -20,7 +20,7 @@ import { useDialog } from "../context/DialogContext";
 import { usePanel } from "../context/PanelContext";
 import { useCompany } from "../context/CompanyContext";
 import { useSidebar } from "../context/SidebarContext";
-import { useTheme } from "../context/ThemeContext";
+import { useTheme, THEME_META } from "../context/ThemeContext";
 import { useKeyboardShortcuts } from "../hooks/useKeyboardShortcuts";
 import { useCompanyPageMemory } from "../hooks/useCompanyPageMemory";
 import { healthApi } from "../api/health";
@@ -67,7 +67,7 @@ export function Layout() {
   const lastMainScrollTop = useRef(0);
   const [mobileNavVisible, setMobileNavVisible] = useState(true);
   const [instanceSettingsTarget, setInstanceSettingsTarget] = useState<string>(() => readRememberedInstanceSettingsPath());
-  const nextTheme = theme === "dark" ? "light" : "dark";
+  const isDarkTheme = THEME_META[theme].dark;
   const matchedCompany = useMemo(() => {
     if (!companyPrefix) return null;
     const requestedPrefix = companyPrefix.toUpperCase();
@@ -331,10 +331,10 @@ export function Layout() {
                   size="icon-sm"
                   className="text-muted-foreground shrink-0"
                   onClick={toggleTheme}
-                  aria-label={`Switch to ${nextTheme} mode`}
-                  title={`Switch to ${nextTheme} mode`}
+                  aria-label="Cycle theme"
+                  title="Cycle theme"
                 >
-                  {theme === "dark" ? <Sun className="h-4 w-4" /> : <Moon className="h-4 w-4" />}
+                  {isDarkTheme ? <Sun className="h-4 w-4" /> : <Moon className="h-4 w-4" />}
                 </Button>
               </div>
             </div>
@@ -389,10 +389,10 @@ export function Layout() {
                   size="icon-sm"
                   className="text-muted-foreground shrink-0"
                   onClick={toggleTheme}
-                  aria-label={`Switch to ${nextTheme} mode`}
-                  title={`Switch to ${nextTheme} mode`}
+                  aria-label="Cycle theme"
+                  title="Cycle theme"
                 >
-                  {theme === "dark" ? <Sun className="h-4 w-4" /> : <Moon className="h-4 w-4" />}
+                  {isDarkTheme ? <Sun className="h-4 w-4" /> : <Moon className="h-4 w-4" />}
                 </Button>
               </div>
             </div>

ui/src/components/MarkdownBody.tsx

@@ -2,7 +2,7 @@ import { isValidElement, useEffect, useId, useState, type ReactNode } from "reac
 import Markdown, { type Components } from "react-markdown";
 import remarkGfm from "remark-gfm";
 import { cn } from "../lib/utils";
-import { useTheme } from "../context/ThemeContext";
+import { useTheme, THEME_META } from "../context/ThemeContext";
 import { mentionChipInlineStyle, parseMentionChipHref } from "../lib/mention-chips";
 
 interface MarkdownBodyProps {
@@ -97,7 +97,7 @@ export function MarkdownBody({ children, className, resolveImageSrc }: MarkdownB
     pre: ({ node: _node, children: preChildren, ...preProps }) => {
       const mermaidSource = extractMermaidSource(preChildren);
       if (mermaidSource) {
-        return <MermaidDiagramBlock source={mermaidSource} darkMode={theme === "dark"} />;
+        return <MermaidDiagramBlock source={mermaidSource} darkMode={THEME_META[theme].dark} />;
       }
       return <pre {...preProps}>{preChildren}</pre>;
     },
@@ -140,7 +140,7 @@ export function MarkdownBody({ children, className, resolveImageSrc }: MarkdownB
     <div
       className={cn(
         "paperclip-markdown prose prose-sm max-w-none break-words overflow-hidden",
-        theme === "dark" && "prose-invert",
+        THEME_META[theme].dark && "prose-invert",
         className,
       )}
     >

ui/src/context/ThemeContext.tsx

@@ -8,7 +8,16 @@ import {
   type ReactNode,
 } from "react";
 
-type Theme = "light" | "dark";
+export type Theme = "catppuccin-mocha" | "tokyo-night" | "catppuccin-latte";
+
+export const THEME_META: Record<Theme, { label: string; dark: boolean; bg: string; primary: string }> = {
+  "catppuccin-mocha": { label: "Catppuccin Mocha", dark: true, bg: "#1e1e2e", primary: "#89b4fa" },
+  "tokyo-night":      { label: "Tokyo Night",       dark: true, bg: "#1a1b26", primary: "#7aa2f7" },
+  "catppuccin-latte": { label: "Catppuccin Latte",  dark: false, bg: "#eff1f5", primary: "#1e66f5" },
+};
+
+const VALID_THEMES: Theme[] = ["catppuccin-mocha", "tokyo-night", "catppuccin-latte"];
+const DEFAULT_THEME: Theme = "catppuccin-mocha";
 
 interface ThemeContextValue {
   theme: Theme;
@@ -17,36 +26,47 @@ interface ThemeContextValue {
 }
 
 const THEME_STORAGE_KEY = "paperclip.theme";
-const DARK_THEME_COLOR = "#18181b";
-const LIGHT_THEME_COLOR = "#ffffff";
 const ThemeContext = createContext<ThemeContextValue | undefined>(undefined);
 
-function resolveThemeFromDocument(): Theme {
-  if (typeof document === "undefined") return "dark";
-  return document.documentElement.classList.contains("dark") ? "dark" : "light";
+function isValidTheme(value: string | null): value is Theme {
+  return value !== null && VALID_THEMES.includes(value as Theme);
+}
+
+function readStoredTheme(): Theme {
+  if (typeof document === "undefined") return DEFAULT_THEME;
+  try {
+    const stored = localStorage.getItem(THEME_STORAGE_KEY);
+    return isValidTheme(stored) ? stored : DEFAULT_THEME;
+  } catch {
+    return DEFAULT_THEME;
+  }
 }
 
 function applyTheme(theme: Theme) {
   if (typeof document === "undefined") return;
-  const isDark = theme === "dark";
+  const meta = THEME_META[theme];
   const root = document.documentElement;
-  root.classList.toggle("dark", isDark);
-  root.style.colorScheme = isDark ? "dark" : "light";
+  root.classList.toggle("dark", meta.dark);
+  root.classList.toggle("theme-tokyo-night", theme === "tokyo-night");
+  root.style.colorScheme = meta.dark ? "dark" : "light";
   const themeColorMeta = document.querySelector('meta[name="theme-color"]');
   if (themeColorMeta instanceof HTMLMetaElement) {
-    themeColorMeta.setAttribute("content", isDark ? DARK_THEME_COLOR : LIGHT_THEME_COLOR);
+    themeColorMeta.setAttribute("content", meta.bg);
   }
 }
 
 export function ThemeProvider({ children }: { children: ReactNode }) {
-  const [theme, setThemeState] = useState<Theme>(() => resolveThemeFromDocument());
+  const [theme, setThemeState] = useState<Theme>(() => readStoredTheme());
 
   const setTheme = useCallback((nextTheme: Theme) => {
     setThemeState(nextTheme);
   }, []);
 
   const toggleTheme = useCallback(() => {
-    setThemeState((current) => (current === "dark" ? "light" : "dark"));
+    setThemeState((current) => {
+      const idx = VALID_THEMES.indexOf(current);
+      return VALID_THEMES[(idx + 1) % VALID_THEMES.length];
+    });
   }, []);
 
   useEffect(() => {
@@ -54,7 +74,7 @@ export function ThemeProvider({ children }: { children: ReactNode }) {
     try {
       localStorage.setItem(THEME_STORAGE_KEY, theme);
     } catch {
-      // Ignore local storage write failures in restricted environments.
+      // Ignore localStorage write failures in restricted environments.
     }
   }, [theme]);