From 6d835a00fb7080704abaa5541ddb325cf3f7e331 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 22 May 2026 15:37:01 -0400
Subject: [PATCH] fix. almost there

---
 .../svelte/src/internal/client/reactivity/sources.js     | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index 47ed57ce18..ae53fc17ce 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -28,7 +28,8 @@ import {
 	WAS_MARKED,
 	CONNECTED,
 	STATE_EAGER_EFFECT,
-	REACTION_IS_UPDATING
+	REACTION_IS_UPDATING,
+	REACTION_RAN
 } from '#client/constants';
 import * as e from '../errors.js';
 import { legacy_mode_flag, tracing_mode_flag } from '../../flags/index.js';
@@ -361,7 +362,11 @@ export function mark_reactions(batch, signal, wv, updated_during_traversal) {
 
 				if ((flags & WAS_MARKED) === 0) {
 					// Only connected deriveds can be reliably unmarked right away
-					if (flags & CONNECTED) {
+					if (
+						flags & CONNECTED &&
+						active_reaction !== null &&
+						(active_reaction.f & REACTION_RAN) !== 0
+					) {
 						reaction.f |= WAS_MARKED;
 					}