& so it begins

apps/main/src/lib/components/nav-main.svelte

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+<script lang="ts">
+    import * as Collapsible from "$lib/components/ui/collapsible/index.js";
+    import * as Sidebar from "$lib/components/ui/sidebar/index.js";
+    import type { AppSidebarItem } from "$lib/core/constants";
+    import ChevronRight from "@lucide/svelte/icons/chevron-right";
+    import Icon from "./atoms/icon.svelte";
+
+    let { items }: { items: AppSidebarItem[] } = $props();
+
+    const sidebar = Sidebar.useSidebar();
+</script>
+
+<Sidebar.Group>
+    <Sidebar.Menu>
+        {#each items as mainItem (mainItem.title)}
+            <Collapsible.Root
+                open={mainItem.isActive}
+                class="group/collapsible"
+            >
+                <Sidebar.MenuItem>
+                    <!-- Split the behavior: main button redirects, chevron expands -->
+                    <div class="flex w-full items-center">
+                        <!-- Main navigation button that redirects -->
+                        <Sidebar.MenuButton class="flex-1 pr-1">
+                            {#snippet child({ props })}
+                                <a href={mainItem.url} {...props}>
+                                    {#if mainItem.icon}
+                                        <mainItem.icon />
+                                    {/if}
+                                    <span>{mainItem.title}</span>
+                                </a>
+                            {/snippet}
+                        </Sidebar.MenuButton>
+
+                        <!-- Chevron button that only toggles the collapsible content -->
+                        {#if mainItem.items && sidebar.open}
+                            <Collapsible.Trigger class="p-2">
+                                {#snippet child({ props })}
+                                    <div
+                                        {...props}
+                                        class="bg-background hover:bg-accent flex cursor-pointer items-center justify-center rounded-sm p-1"
+                                    >
+                                        <Icon
+                                            icon={ChevronRight}
+                                            cls="w-4 h-4 transition-transform duration-200 group-data-[state=open]/collapsible:rotate-90"
+                                        />
+                                        <span class="sr-only"
+                                            >Toggle {mainItem.title} submenu</span
+                                        >
+                                    </div>
+                                {/snippet}
+                            </Collapsible.Trigger>
+                        {/if}
+                    </div>
+
+                    <!-- Collapsible submenu content -->
+                    <Collapsible.Content>
+                        {#if mainItem.items}
+                            <Sidebar.MenuSub>
+                                {#each mainItem.items as subItem (subItem.title)}
+                                    <Sidebar.MenuSubItem>
+                                        <Sidebar.MenuSubButton>
+                                            {#snippet child({ props })}
+                                                <a
+                                                    href={subItem.url}
+                                                    {...props}
+                                                >
+                                                    <span>{subItem.title}</span>
+                                                </a>
+                                            {/snippet}
+                                        </Sidebar.MenuSubButton>
+                                    </Sidebar.MenuSubItem>
+                                {/each}
+                            </Sidebar.MenuSub>
+                        {/if}
+                    </Collapsible.Content>
+                </Sidebar.MenuItem>
+            </Collapsible.Root>
+        {/each}
+    </Sidebar.Menu>
+</Sidebar.Group>