Deco Async Section Rendering — Framework Architecture

Internal documentation for the async section rendering system in @decocms/start.

When to Use This Skill

• Debugging why a section is or isn't being deferred
• Understanding the full request flow from CMS resolution to on-scroll loading
• Extending the async rendering system (new cache tiers, new deferral strategies)
• Fixing issues with deferred section data resolution
• Understanding how bot detection and SEO safety work
• Working on @decocms/start framework code

Problem Solved

TanStack Start serializes all loaderData as JSON in a <script> tag for client-side hydration. When a CMS page has 20+ sections with commerce data, the HTML payload becomes enormous (8+ MB on some pages). The root cause: resolveDecoPage fully resolves ALL sections, and TanStack Start embeds everything.