Reactive variable updated from parent and child component

I have a parent component (List) which displays a list of child components (Block). Nested blocks have a button that allows the user to add/remove them to the selection.The List component also contains a table were are listed all the selected Blocks: the user can unselect a Block there too.

My problem is that when unselected from the table#selection, the isSelected variable is obviously not updated

How can I dynamically update the isSelected variable inside the Block component? Am I handling the logic wrong?

Example reproduced here

List.svelte

<script>    import Block from './Block.svelte';    export let blocks = [];    let selection = {};    let isBlockSelected = (block) => selection.hasOwnProperty(block.id);    function removeFromSelection(blockId) {        const { [blockId]: _, ...rest } = selection;        selection = rest;        // 🛑 TODO make block aware that it has been unselected    }    function addToSelection(block) {        selection = { ...selection, [block.id]: block };    }    function handleToggleSelection(event) {        const { block } = event.detail;        if (!isBlockSelected(block)) {            addToSelection(block);        } else {            removeFromSelection(block.id);        }    }</script><div>    {#each blocks as block (block.id)}<Block {block} on:toggleSelection={handleToggleSelection} isSelected={isBlockSelected(block)}/>    {/each}</div><table id="selection"><tbody>        {#each Object.entries(selection) as [id, meta]}<tr><td><a href="/page/{id}" target="_blank">{meta.title}</a><button class="delete" aria-label="close" on:click={() => removeFromSelection(id)}></button></td></tr>        {/each}</tbody></table>

Block.svelte

<script>    import {createEventDispatcher} from "svelte";    export let block;    export let isSelected = false;    const dispatch = createEventDispatcher();    function toggleSelection(block) {        dispatch('toggleSelection', { block });        isSelected = !isSelected    }</script><div>    {block.title}<button on:click={() => toggleSelection(block)}>        {#if isSelected}            Remove from selection        {:else}            Add to selection        {/if}</button></div>