WIP

Author: Rich-Harris

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 = {}) => {

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());
 

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();