diff --git a/src/main/ThemeRegistry.bootstrap.js b/src/main/ThemeRegistry.bootstrap.js
new file mode 100644
index 0000000..88a75ac
--- /dev/null
+++ b/src/main/ThemeRegistry.bootstrap.js
@@ -0,0 +1,79 @@
+/**
+ * Editor Theme Registry bootstrap — registers all shipped themes at startup.
+ *
+ * Importing this module has the side effect of populating the registry.
+ * `src/main.js` requires this once during startup. Test files require it
+ * after `ThemeRegistry.clear()` to assert the snapshot.
+ *
+ * Theme ids are kebab-case. Categories: 'light' | 'dark' | 'high-contrast'
+ * | 'seasonal'. `isDark` is independent of category — see spec note on
+ * winter-is-coming-light (light-category, dark-not-required) and the future
+ * seasonal-with-dark possibility.
+ *
+ * @module ThemeRegistry.bootstrap
+ */
+
+const ThemeRegistry = require('./ThemeRegistry');
+
+const THEMES = [
+  // ---- 25 existing menu themes (refactor — no behavioural change) ──
+  // Light
+  { id: 'atomonelight', label: 'Atom One Light (Default)', category: 'light', isDark: false },
+  { id: 'github', label: 'GitHub Light', category: 'light', isDark: false },
+  { id: 'light', label: 'Light', category: 'light', isDark: false },
+  { id: 'solarized', label: 'Solarized Light', category: 'light', isDark: false },
+  { id: 'gruvbox-light', label: 'Gruvbox Light', category: 'light', isDark: false },
+  { id: 'ayu-light', label: 'Ayu Light', category: 'light', isDark: false },
+  { id: 'sepia', label: 'Sepia', category: 'light', isDark: false },
+  { id: 'paper', label: 'Paper', category: 'light', isDark: false },
+  { id: 'rosepine-dawn', label: 'Rose Pine Dawn', category: 'light', isDark: false },
+  { id: 'concrete-light', label: 'Concrete Light', category: 'light', isDark: false },
+  // Dark
+  { id: 'dark', label: 'Dark', category: 'dark', isDark: true },
+  { id: 'onedark', label: 'One Dark', category: 'dark', isDark: true },
+  { id: 'dracula', label: 'Dracula', category: 'dark', isDark: true },
+  { id: 'nord', label: 'Nord', category: 'dark', isDark: true },
+  { id: 'monokai', label: 'Monokai', category: 'dark', isDark: true },
+  { id: 'material', label: 'Material', category: 'dark', isDark: true },
+  { id: 'gruvbox-dark', label: 'Gruvbox Dark', category: 'dark', isDark: true },
+  { id: 'tokyonight', label: 'Tokyo Night', category: 'dark', isDark: true },
+  { id: 'palenight', label: 'Palenight', category: 'dark', isDark: true },
+  { id: 'ayu-dark', label: 'Ayu Dark', category: 'dark', isDark: true },
+  { id: 'ayu-mirage', label: 'Ayu Mirage', category: 'dark', isDark: true },
+  { id: 'oceanic-next', label: 'Oceanic Next', category: 'dark', isDark: true },
+  { id: 'cobalt2', label: 'Cobalt2', category: 'dark', isDark: true },
+  { id: 'concrete-dark', label: 'Concrete Dark', category: 'dark', isDark: true },
+  { id: 'concrete-warm', label: 'Concrete Warm', category: 'dark', isDark: true },
+  // ---- 12 new themes ──
+  // Catppuccin (4)
+  { id: 'catppuccin-latte', label: 'Catppuccin Latte', category: 'light', isDark: false },
+  { id: 'catppuccin-frappe', label: 'Catppuccin Frappé', category: 'dark', isDark: true },
+  { id: 'catppuccin-macchiato', label: 'Catppuccin Macchiato', category: 'dark', isDark: true },
+  { id: 'catppuccin-mocha', label: 'Catppuccin Mocha', category: 'dark', isDark: true },
+  // One Light + Tokyo Night Storm
+  { id: 'one-light', label: 'One Light', category: 'light', isDark: false },
+  { id: 'tokyo-night-storm', label: 'Tokyo Night Storm', category: 'dark', isDark: true },
+  // Synthwave / Outrun
+  { id: 'synthwave-84', label: "Synthwave '84", category: 'dark', isDark: true },
+  { id: 'outrun', label: 'Outrun', category: 'dark', isDark: true },
+  // Winter is Coming (light + dark)
+  {
+    id: 'winter-is-coming-light',
+    label: 'Winter is Coming (Light)',
+    category: 'light',
+    isDark: false,
+  },
+  { id: 'winter-is-coming-dark', label: 'Winter is Coming (Dark)', category: 'dark', isDark: true },
+  // Solarized HC + Spring seasonal
+  {
+    id: 'solarized-dark-hc',
+    label: 'Solarized Dark (High Contrast)',
+    category: 'high-contrast',
+    isDark: true,
+  },
+  { id: 'spring-light', label: 'Spring Light', category: 'seasonal', isDark: false },
+];
+
+for (const t of THEMES) ThemeRegistry.register(t);
+
+module.exports = { THEMES };
diff --git a/tests/main/theme-registry-bootstrap.test.js b/tests/main/theme-registry-bootstrap.test.js
new file mode 100644
index 0000000..7f0fea6
--- /dev/null
+++ b/tests/main/theme-registry-bootstrap.test.js
@@ -0,0 +1,99 @@
+/**
+ * @jest-environment node
+ *
+ * Bootstrap snapshot — at startup, ThemeRegistry.list() returns exactly 37
+ * themes (25 existing menu themes + 12 new) in the expected order.
+ */
+
+const EXPECTED_IDS = [
+  // Existing — light
+  'atomonelight',
+  'github',
+  'light',
+  'solarized',
+  'gruvbox-light',
+  'ayu-light',
+  'sepia',
+  'paper',
+  'rosepine-dawn',
+  'concrete-light',
+  // Existing — dark
+  'dark',
+  'onedark',
+  'dracula',
+  'nord',
+  'monokai',
+  'material',
+  'gruvbox-dark',
+  'tokyonight',
+  'palenight',
+  'ayu-dark',
+  'ayu-mirage',
+  'oceanic-next',
+  'cobalt2',
+  'concrete-dark',
+  'concrete-warm',
+  // New — Catppuccin
+  'catppuccin-latte',
+  'catppuccin-frappe',
+  'catppuccin-macchiato',
+  'catppuccin-mocha',
+  // New — One Light + Tokyo Night Storm
+  'one-light',
+  'tokyo-night-storm',
+  // New — Synthwave / Outrun
+  'synthwave-84',
+  'outrun',
+  // New — Winter is Coming
+  'winter-is-coming-light',
+  'winter-is-coming-dark',
+  // New — Solarized HC + Spring seasonal
+  'solarized-dark-hc',
+  'spring-light',
+];
+
+describe('ThemeRegistry.bootstrap', () => {
+  beforeEach(() => {
+    // Reset module registry so both ThemeRegistry and bootstrap re-load fresh.
+    // Otherwise Jest's module cache returns the already-evaluated bootstrap
+    // (whose registration loop has already run once), leaving list() empty
+    // across subsequent tests.
+    jest.resetModules();
+  });
+
+  test('registers exactly 37 themes in the expected order', () => {
+    const ThemeRegistry = require('../../src/main/ThemeRegistry');
+    ThemeRegistry.clear();
+    require('../../src/main/ThemeRegistry.bootstrap');
+    expect(ThemeRegistry.list().map((t) => t.id)).toEqual(EXPECTED_IDS);
+  });
+
+  test('every theme has a valid shape', () => {
+    const ThemeRegistry = require('../../src/main/ThemeRegistry');
+    ThemeRegistry.clear();
+    require('../../src/main/ThemeRegistry.bootstrap');
+    for (const t of ThemeRegistry.list()) {
+      expect(typeof t.id).toBe('string');
+      expect(typeof t.label).toBe('string');
+      expect(['light', 'dark', 'high-contrast', 'seasonal']).toContain(t.category);
+      expect(typeof t.isDark).toBe('boolean');
+    }
+  });
+
+  test('expected category counts', () => {
+    const ThemeRegistry = require('../../src/main/ThemeRegistry');
+    ThemeRegistry.clear();
+    require('../../src/main/ThemeRegistry.bootstrap');
+    const counts = ThemeRegistry.list().reduce((acc, t) => {
+      acc[t.category] = (acc[t.category] || 0) + 1;
+      return acc;
+    }, {});
+    // 10 existing light + one-light + winter-is-coming-light + catppuccin-latte = 13 light (spring-light is category=seasonal)
+    expect(counts.light).toBe(13);
+    // 15 existing dark + 3 catppuccin dark + tokyo-night-storm + synthwave-84 + outrun + winter-is-coming-dark = 22 dark
+    expect(counts.dark).toBe(22);
+    expect(counts['high-contrast']).toBe(1);
+    // 1: spring-light (the only seasonal theme in v1)
+    expect(counts.seasonal).toBe(1);
+  });
+});