fix

packages/svelte/src/internal/client/dom/blocks/boundary.js

@@ -107,17 +107,16 @@ export class Boundary {
 			if (hydrating && pending) {
 				this.#pending_effect = branch(() => pending(this.#anchor));
 
-				// ...now what? we need to start rendering `boundary_fn` offscreen,
-				// and either insert the resulting fragment (if nothing suspends)
-				// or keep the pending effect alive until it unsuspends.
-				// not exactly sure how to do that.
-
 				// future work: when we have some form of async SSR, we will
 				// need to use hydration boundary comments to report whether
 				// the pending or main block was rendered for a given
 				// boundary, and hydrate accordingly
 				queueMicrotask(() => {
-					// destroy_effect(/** @type {Effect} */ (this.#pending_effect));
+					if (this.#pending_count === 0) {
+						pause_effect(/** @type {Effect} */ (this.#pending_effect), () => {
+							this.#pending_effect = null;
+						});
+					}
 
 					this.#main_effect = this.#run(() => {
 						return branch(() => this.#children(this.#anchor));