WIP

packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js

@@ -312,9 +312,10 @@ export function EachBlock(node, context) {
 		declarations.push(b.let(node.index, index));
 	}
 
-	const { has_await } = node.metadata.expression;
-	const get_collection = b.thunk(collection, has_await);
-	const thunk = has_await ? b.thunk(b.call('$.get', b.id('$$collection'))) : get_collection;
+	const is_async = node.metadata.expression.is_async();
+
+	const get_collection = b.thunk(collection, node.metadata.expression.has_await);
+	const thunk = is_async ? b.thunk(b.call('$.get', b.id('$$collection'))) : get_collection;
 
 	const render_args = [b.id('$$anchor'), item];
 	if (uses_index || collection_id) render_args.push(index);
@@ -341,12 +342,13 @@ export function EachBlock(node, context) {
 		statements.unshift(b.stmt(b.call('$.validate_each_keys', thunk, key_function)));
 	}
 
-	if (has_await) {
+	if (is_async) {
 		context.state.init.push(
 			b.stmt(
 				b.call(
 					'$.async',
 					context.state.node,
+					node.metadata.expression.blockers(),
 					b.array([get_collection]),
 					b.arrow([context.state.node, b.id('$$collection')], b.block(statements))
 				)

packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js

@@ -37,7 +37,8 @@ export function HtmlTag(node, context) {
 				b.call(
 					'$.async',
 					context.state.node,
-					b.array([b.thunk(expression, true)]),
+					node.metadata.expression.blockers(),
+					b.array([b.thunk(expression, node.metadata.expression.has_await)]),
 					b.arrow([context.state.node, b.id('$$html')], b.block([statement]))
 				)
 			)

packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js

@@ -11,10 +11,10 @@ import { build_expression, add_svelte_meta } from './shared/utils.js';
 export function KeyBlock(node, context) {
 	context.state.template.push_comment();
 
-	const { has_await } = node.metadata.expression;
+	const is_async = node.metadata.expression.is_async();
 
 	const expression = build_expression(context, node.expression, node.metadata.expression);
-	const key = b.thunk(has_await ? b.call('$.get', b.id('$$key')) : expression);
+	const key = b.thunk(is_async ? b.call('$.get', b.id('$$key')) : expression);
 	const body = /** @type {Expression} */ (context.visit(node.fragment));
 
 	let statement = add_svelte_meta(
@@ -23,12 +23,13 @@ export function KeyBlock(node, context) {
 		'key'
 	);
 
-	if (has_await) {
+	if (is_async) {
 		statement = b.stmt(
 			b.call(
 				'$.async',
 				context.state.node,
-				b.array([b.thunk(expression, true)]),
+				node.metadata.expression.blockers(),
+				b.array([b.thunk(expression, node.metadata.expression.has_await)]),
 				b.arrow([context.state.node, b.id('$$key')], b.block([statement]))
 			)
 		);

packages/svelte/src/compiler/phases/3-transform/client/visitors/Program.js

@@ -272,12 +272,25 @@ function transform_body(program, context) {
 					context.visit(b.var(s.node.id, s.node.init))
 				);
 
+				if (visited.declarations.length === 1) {
 					return b.thunk(
 						b.assignment('=', s.node.id, visited.declarations[0].init ?? b.void0),
 						s.has_await
 					);
 				}
 
+				// if we have multiple declarations, it indicates destructuring
+				return b.thunk(
+					b.block([
+						b.var(visited.declarations[0].id, visited.declarations[0].init),
+						...visited.declarations
+							.slice(1)
+							.map((d) => b.stmt(b.assignment('=', d.id, d.init ?? b.void0)))
+					]),
+					s.has_await
+				);
+			}
+
 			if (s.node.type === 'ClassDeclaration') {
 				return b.thunk(
 					b.assignment(

packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js

@@ -93,10 +93,10 @@ export function SvelteElement(node, context) {
 		);
 	}
 
-	const { has_await } = node.metadata.expression;
+	const is_async = node.metadata.expression.is_async();
 
 	const expression = /** @type {Expression} */ (context.visit(node.tag));
-	const get_tag = b.thunk(has_await ? b.call('$.get', b.id('$$tag')) : expression);
+	const get_tag = b.thunk(is_async ? b.call('$.get', b.id('$$tag')) : expression);
 
 	/** @type {Statement[]} */
 	const inner = inner_context.state.init;
@@ -139,13 +139,14 @@ export function SvelteElement(node, context) {
 		)
 	);
 
-	if (has_await) {
+	if (is_async) {
 		context.state.init.push(
 			b.stmt(
 				b.call(
 					'$.async',
 					context.state.node,
-					b.array([b.thunk(expression, true)]),
+					node.metadata.expression.blockers(),
+					b.array([b.thunk(expression, node.metadata.expression.has_await)]),
 					b.arrow([context.state.node, b.id('$$tag')], b.block(statements))
 				)
 			)

packages/svelte/src/internal/client/reactivity/async.js

@@ -56,10 +56,8 @@ export function flatten(blockers, sync, async, fn) {
 
 	var was_hydrating = hydrating;
 
-	Promise.all(blockers).then(() => {
-		restore();
-
-		const result = Promise.all(async.map((expression) => async_derived(expression)))
+	function run() {
+		Promise.all(async.map((expression) => async_derived(expression)))
 			.then((result) => {
 				restore();
 
@@ -82,11 +80,22 @@ export function flatten(blockers, sync, async, fn) {
 			.catch((error) => {
 				invoke_error_boundary(error, parent);
 			});
+	}
 
-		unset_context();
+	if (blockers.length > 0) {
+		Promise.all(blockers).then(() => {
+			restore();
 
-		return result;
+			try {
+				return run();
+			} finally {
+				batch?.deactivate();
+				unset_context();
+			}
 		});
+	} else {
+		run();
+	}
 }
 
 /**
@@ -274,7 +283,8 @@ export async function async_body(anchor, fn) {
 export function run(thunks) {
 	const restore = capture();
 
-	let promise = Promise.resolve();
+	// let promise = Promise.resolve();
+	let promise = new Promise((f) => Batch.enqueue(() => f(undefined)));
 
 	var boundary = get_boundary();
 	var batch = /** @type {Batch} */ (current_batch);

packages/svelte/src/internal/client/reactivity/sources.js

@@ -34,7 +34,7 @@ import * as e from '../errors.js';
 import { legacy_mode_flag, tracing_mode_flag } from '../../flags/index.js';
 import { get_stack, tag_proxy } from '../dev/tracing.js';
 import { component_context, is_runes } from '../context.js';
-import { Batch, eager_block_effects, schedule_effect } from './batch.js';
+import { Batch, current_batch, eager_block_effects, schedule_effect } from './batch.js';
 import { proxy } from '../proxy.js';
 import { execute_derived } from './deriveds.js';