From 26c8914a26d08aa33bc75177f8db36594defb921 Mon Sep 17 00:00:00 2001
From: syuilo <4439005+syuilo@users.noreply.github.com>
Date: Thu, 6 Nov 2025 18:07:03 +0900
Subject: [PATCH] fix(frontend): improve startViewTransition handling

---
 packages/frontend/src/theme.ts | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/packages/frontend/src/theme.ts b/packages/frontend/src/theme.ts
index 4da8c02d33..2fca4e79ae 100644
--- a/packages/frontend/src/theme.ts
+++ b/packages/frontend/src/theme.ts
@@ -146,17 +146,26 @@ export function applyTheme(theme: Theme, persist = true) {
 
 	if (window.document.startViewTransition != null) {
 		window.document.documentElement.classList.add('_themeChanging_');
-		window.document.startViewTransition(async () => {
-			applyThemeInternal(theme, persist);
-			await nextTick();
-		}).finished.then(() => {
+		try {
+			window.document.startViewTransition(async () => {
+				applyThemeInternal(theme, persist);
+				await nextTick();
+			}).finished.then(() => {
+				window.document.documentElement.classList.remove('_themeChanging_');
+				globalEvents.emit('themeChanged');
+			});
+		} catch (err) {
+			// 様々な理由により startViewTransition は失敗することがある
+			// ref. https://github.com/misskey-dev/misskey/issues/16562
+
+			console.error(err);
+
 			window.document.documentElement.classList.remove('_themeChanging_');
-			// 色計算など再度行えるようにクライアント全体に通知
+			applyThemeInternal(theme, persist);
 			globalEvents.emit('themeChanged');
-		});
+		}
 	} else {
 		applyThemeInternal(theme, persist);
-		// 色計算など再度行えるようにクライアント全体に通知
 		globalEvents.emit('themeChanged');
 	}
 }