From 02a7dfab163b0e5a5dd4e8a04e683526bd10d73f Mon Sep 17 00:00:00 2001
From: Linus Rath <139418639+rathlinus@users.noreply.github.com>
Date: Wed, 14 Oct 2026 03:24:00 +0200
Subject: [PATCH] feat: tell plugins when the colour scheme or theme changes

---
 lib/__tests__/plugin-hook-catalog.test.ts |  4 +--
 lib/__tests__/theme-store-hooks.test.ts   | 30 +++++++++++++++++++++++
 stores/theme-store.ts                     | 12 ++++++++-
 3 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 lib/__tests__/theme-store-hooks.test.ts

diff --git a/lib/__tests__/plugin-hook-catalog.test.ts b/lib/__tests__/plugin-hook-catalog.test.ts
index 5b5d56cac..f27f7c0b3 100644
--- a/lib/__tests__/plugin-hook-catalog.test.ts
+++ b/lib/__tests__/plugin-hook-catalog.test.ts
@@ -37,7 +37,7 @@ const sources = ['app', 'components', 'hooks', 'lib', 'stores'].flatMap((d) => s
 
 /** A call site that fires the hook: `xHooks.onFoo.emit(` and friends. */
 function isFired(hookName: string, groupName: string): boolean {
-  const re = new RegExp(`\\b${groupName}\\.${hookName}\\.(emit|emitSync|emitTo|intercept|interceptOutcome|transform|takeOver)\\b`);
+  const re = new RegExp(`\\b${groupName}\\.${hookName}\\s*\\.(emit|emitSync|emitTo|intercept|interceptOutcome|transform|takeOver)\\b`);
   return re.test(sources);
 }
 
@@ -47,7 +47,7 @@ function isFired(hookName: string, groupName: string): boolean {
 const NOT_YET_WIRED = new Set<HookGroup>([
   'mail-list', 'mail-read', 'mail-compose', 'mail-send', 'mail-organize', 'mail-mailboxes', 'mail-search',
   'mail-sync', 'calendar', 'contacts', 'tasks', 'files', 'settings', 'identities',
-  'filters', 'vacation', 'templates', 'auth', 'security', 'theme', 'notifications', 'ui', 'keyboard',
+  'filters', 'vacation', 'templates', 'auth', 'security', 'notifications', 'ui', 'keyboard',
 ]);
 
 describe('hook catalogue', () => {
diff --git a/lib/__tests__/theme-store-hooks.test.ts b/lib/__tests__/theme-store-hooks.test.ts
new file mode 100644
index 000000000..803bf84b8
--- /dev/null
+++ b/lib/__tests__/theme-store-hooks.test.ts
@@ -0,0 +1,30 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { clearAllHooks, themeHooks } from '@/lib/plugin-hooks';
+import { useThemeStore } from '@/stores/theme-store';
+
+beforeEach(() => {
+  clearAllHooks();
+  useThemeStore.setState({ theme: 'light', resolvedTheme: 'light', activeThemeId: null });
+});
+
+describe('theme hooks', () => {
+  it('tells plugins when the colour scheme changes', () => {
+    const fn = vi.fn();
+    themeHooks.onThemeChange.register('t', fn);
+
+    useThemeStore.getState().setTheme('dark');
+
+    expect(fn).toHaveBeenCalledWith({ theme: 'dark', resolved: 'dark' });
+  });
+
+  it('tells plugins when another theme is activated, and not when nothing changed', () => {
+    const fn = vi.fn();
+    themeHooks.onCustomThemeChange.register('t', fn);
+
+    useThemeStore.setState({ activeThemeId: 'ocean' });
+    useThemeStore.setState({ activeThemeId: 'ocean' });
+
+    expect(fn).toHaveBeenCalledTimes(1);
+    expect(fn).toHaveBeenCalledWith({ themeId: 'ocean' });
+  });
+});
diff --git a/stores/theme-store.ts b/stores/theme-store.ts
index d06df2822..5e31ac3fa 100644
--- a/stores/theme-store.ts
+++ b/stores/theme-store.ts
@@ -644,4 +644,14 @@ async function downloadThemeAsset(theme: ServerThemeInfo, kind: 'css' | 'skin'):
     console.warn(`[theme-store] Failed to download ${kind} for theme "${theme.id}"`);
     return null;
   }
-}
\ No newline at end of file
+}
+// Plugins hear about every change of scheme or theme, whichever path made it
+// (settings, the system switching to dark, a forced admin theme).
+useThemeStore.subscribe((state, prev) => {
+  if (state.theme !== prev.theme || state.resolvedTheme !== prev.resolvedTheme) {
+    void themeHooks.onThemeChange.emit({ theme: state.theme, resolved: state.resolvedTheme });
+  }
+  if (state.activeThemeId !== prev.activeThemeId) {
+    void themeHooks.onCustomThemeChange.emit({ themeId: state.activeThemeId });
+  }
+});