From 1ef297f25de64f220bce8ff020f38d399b69a647 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Tue, 23 Sep 2025 23:47:50 +0200
Subject: [PATCH] fix: ensure tick resolves within a macrotask (#16825)

Race them against each other - in almost all cases requestAnimationFrame will fire first, but e.g. in case the window is not focused or a view transition happens, requestAnimationFrame will be delayed and setTimeout helps us resolve fast enough in that case

Fixes #16429
Fixes https://github.com/sveltejs/kit/issues/14220
---
 .changeset/wise-bottles-explode.md             | 5 +++++
 packages/svelte/src/internal/client/runtime.js | 8 +++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/wise-bottles-explode.md

diff --git a/.changeset/wise-bottles-explode.md b/.changeset/wise-bottles-explode.md
new file mode 100644
index 0000000000..d3b2931272
--- /dev/null
+++ b/.changeset/wise-bottles-explode.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure tick resolves within a macrotask
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 22a1890e0f..b8f5f5ffc9 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -500,7 +500,13 @@ export function update_effect(effect) {
  */
 export async function tick() {
 	if (async_mode_flag) {
-		return new Promise((f) => requestAnimationFrame(() => f()));
+		return new Promise((f) => {
+			// Race them against each other - in almost all cases requestAnimationFrame will fire first,
+			// but e.g. in case the window is not focused or a view transition happens, requestAnimationFrame
+			// will be delayed and setTimeout helps us resolve fast enough in that case
+			requestAnimationFrame(() => f());
+			setTimeout(() => f());
+		});
 	}
 
 	await Promise.resolve();