Release v0.20.0 · vercel-labs/json-render

Named slots for React: Components can declare named slots such as header and footer, while children remains the default slot. Slots are preserved through validation, streaming, nested conversion, code export, playground views, and Devtools navigation (#320). Built from the original contribution by @wotnak in #105
Nested repeats: repeat.statePath now accepts item-relative paths such as { "$item": "employees" }, enabling nested data rendering across React, React Native, React Email, React PDF, Image, Ink, Solid, Svelte, and Vue (#319). Built from the original contribution by @tmchow in #256
Harness chat example: Added a complete Next.js example using the AI SDK 7 harness adapter, agent delegation, sandbox transport, and json-render components (#302)

Chained action params: Named onSuccess and onError actions now receive their configured params across core and all renderer bridges (#307)
Consistent optional visibility: Element visible fields now remain optional across Zod 4 versions, while prompts explicitly require children arrays for every element (#299)
Spec validation and autofix: Dangling child references are pruned, malformed visibility conditions are reported, and repeated items can be filtered safely (#300)

Release toolchain hardening: The workspace now requires Node.js 24 and pnpm 11, enforces package engine checks, and applies a minimum package release age (#293)

Custom renderer bridges that implement the core executeAction callback must now accept an ActionBinding instead of a bare action name. This exposes chained action params to custom integrations at compile time (#307)

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