feat(docs-next): dynamically redirect section URLs to first leaf page

packages/stacks-docs-next/_redirects

@@ -2,22 +2,6 @@
 https://alpha.stackoverflow.design/*             https://stackoverflow.design/:splat            301
 https://beta.stackoverflow.design/*              https://stackoverflow.design/:splat            302
 
-# Section index pages → first child (mirrors Navigation.svelte L67)
-/brand/                                         /brand/logo                                     302
-
-/copy/                                          /copy/voice                                     302
-/copy/patterns/                                 /copy/patterns/messages                         302
-
-/system/                                        /system/develop/using-stacks                    302
-/system/develop/                                /system/develop/using-stacks                    302
-/system/accessibility/                          /system/accessibility/intro                     302
-/system/foundation/                             /system/foundation/color-fundamentals           302
-/system/base/                                   /system/base/backgrounds                        302
-/system/forms/                                  /system/forms/checkbox                          302
-/system/components/                             /system/components/activity-indicator           302
-
-/handbook/                                      /handbook/story                                 302
-/resources/                                     /resources/fonts                                302
 
 # Email section → v2 docs
 /email*                                         https://v2.stackoverflow.design/email:splat     302
@@ -65,9 +49,6 @@ https://beta.stackoverflow.design/*              https://stackoverflow.design/:s
 # General catch-all: all remaining /product/* → /system/*
 /product/*                                      /system/:splat                                  302
 
-# Assets
-/assets/img/logo-stacks@2x.png                  /assets/img/logos/so/logo-stacks@2x.png        302
-
 # Legacy /content paths (brand & copywriting, migrated Feb 2026)
 /content                                        /copy                                           302
 /content/guidelines/principles                  /copy                                           302

packages/stacks-docs-next/src/routes/[category]/+page.server.ts

@@ -0,0 +1,9 @@
+import type { PageServerLoad } from "./$types";
+import { error } from "@sveltejs/kit";
+
+export const load: PageServerLoad = async (event) => {
+    const parent = await event.parent();
+    if (!parent.active) {
+        throw error(404, `No content found for /${event.params.category}`);
+    }
+};

packages/stacks-docs-next/src/routes/[category]/[[section]]/[subsection]/+page.server.ts

@@ -1,5 +1,5 @@
 import type { PageServerLoad } from "./$types";
-import { error } from "@sveltejs/kit";
+import { error, redirect } from "@sveltejs/kit";
 import type { Component } from "svelte";
 import { render } from "svelte/server";
 import TurndownService from "turndown";
@@ -10,6 +10,13 @@ const turndownService = new TurndownService({
 
 const mdFiles = import.meta.glob("$docs/**/*.md");
 
+type NavItem = { slug: string; items?: NavItem[] };
+
+function firstLeafSlug(prefix: string, item: NavItem): string {
+    if (!item.items?.length) return `${prefix}/${item.slug}`;
+    return firstLeafSlug(`${prefix}/${item.slug}`, item.items[0]);
+}
+
 export const load: PageServerLoad = async (event) => {
     // SECURITY: Check auth first - don't load any content if unauthorized
     const parent = await event.parent();
@@ -56,5 +63,10 @@ export const load: PageServerLoad = async (event) => {
         };
     }
 
+    // If the active item is a section (has children), redirect to the first leaf page
+    if (parent.active?.items?.length > 0) {
+        throw redirect(302, `/${firstLeafSlug(slug, parent.active.items[0])}`);
+    }
+
     throw error(404, `No content found for ${slug}`);
 };