From e0e48b392a03ee5bc592fd5ec7077788696ed385 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 19 Apr 2025 18:12:05 -0400
Subject: [PATCH] WIP

---
 packages/svelte/src/internal/client/reactivity/effects.js | 4 +++-
 packages/svelte/src/internal/client/render.js             | 2 --
 packages/svelte/src/internal/client/runtime.js            | 7 +++++++
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index d506168e80..aa4d510730 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -41,7 +41,7 @@ import { get_next_sibling } from '../dom/operations.js';
 import { async_derived, derived } from './deriveds.js';
 import { capture } from '../dom/blocks/boundary.js';
 import { component_context, dev_current_component_function } from '../context.js';
-import { active_fork } from './forks.js';
+import { active_fork, Fork } from './forks.js';
 
 /**
  * @param {'$effect' | '$effect.pre' | '$inspect'} rune
@@ -234,6 +234,7 @@ export function inspect_effect(fn) {
  * @returns {() => void}
  */
 export function effect_root(fn) {
+	Fork.ensure();
 	const effect = create_effect(ROOT_EFFECT, fn, true);
 
 	return () => {
@@ -247,6 +248,7 @@ export function effect_root(fn) {
  * @returns {(options?: { outro?: boolean }) => Promise<void>}
  */
 export function component_root(fn) {
+	Fork.ensure();
 	const effect = create_effect(ROOT_EFFECT, fn, true);
 
 	return (options = {}) => {
diff --git a/packages/svelte/src/internal/client/render.js b/packages/svelte/src/internal/client/render.js
index 3479c87a9d..404965d9ab 100644
--- a/packages/svelte/src/internal/client/render.js
+++ b/packages/svelte/src/internal/client/render.js
@@ -206,8 +206,6 @@ function _mount(Component, { target, anchor, props = {}, events, context, intro
 	// @ts-expect-error will be defined because the render effect runs synchronously
 	var component = undefined;
 
-	Fork.ensure();
-
 	var unmount = component_root(() => {
 		var anchor_node = anchor ?? target.appendChild(create_text());
 
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index ecc3450aab..6015c39a74 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -684,6 +684,11 @@ function infinite_loop_guard() {
 function flush_queued_root_effects() {
 	var was_updating_effect = is_updating_effect;
 
+	// TODO it should be impossible to get here without an active fork
+	if (!active_fork && queued_root_effects.length > 0) {
+		console.trace('here');
+	}
+
 	try {
 		var flush_count = 0;
 		is_updating_effect = true;
@@ -901,6 +906,8 @@ function process_effects(root, async_effects, render_effects, effects) {
 export function flushSync(fn) {
 	var result;
 
+	Fork.ensure();
+
 	if (fn) {
 		is_flushing = true;
 		flush_queued_root_effects();