Manifests: allow custom docs pages (parameters.docs.page) to contribute content to the components manifest

[mohammad-naji7]

Is your feature request related to a problem? Please describe.

The components manifest (manifests/components.json) only includes docs content from attached MDX files. Docs authored as custom React pages via parameters.docs.page — a long-standing, documented Storybook feature —contribute nothing to the manifest.

The practical impact: for design systems that document components this way, the Storybook MCP server (get-documentation) returns only story snippets and props. All the content that actually guides correct usage — usage guidelines, accessibility guidance, do/don'ts, composition rules — is invisible to AI agents, even though it's right there in Storybook.

We understand why: manifest generation is static analysis, and arbitrary React can't be statically extracted. But currently there's also no escape hatch to provide the content ourselves.

Describe the solution you'd like

An official way for a project to supply manifest content for a component's docs, for example:

export default {
  component: Card,
  parameters: {
    docs: {
      page: CardDocs, // custom React docs page (unchanged)
      manifestContent: cardDocsMarkdown, // string, included in the manifest docs entries
    },
  },
};

A statically analyzable string (or a module reference the generator can resolve, similar to how story snippets work) would be enough. The existing docs field on manifest component entries already has the right shape — this would just give non-MDX users a way to populate it.e

Describe alternatives you've considered

• Migrating docs to MDX: works (MDX is picked up automatically), but for us that means rewriting 60+ docs pages and losing TypeScript checking of docs content, plus the manifest would receive raw MDX source including any embedded JSX.
• A workaround we run in production: a vite plugin that runs after storybook build, loads each stories module in an SSR module runner (jsdom globals + stubs for @storybook/addon-docs/blocks etc.), walks the element tree returned by parameters.docs.page, serializes our docs DSL to markdown, and merges it into the manifest at serve time via @storybook/mcp's manifestProvider. It works well (60+ components extracted), but it necessarily depends on internals and per-project shims — exactly the kind of thing an official hook would eliminate. Happy to share the implementation if it's useful as a reference.

Are you able to assist to bring the feature to reality?

no

Additional context

Related: #32673 (extracting metadata from meta.parameters.docs.X) — this request is the docs-page-content case of that idea. Given how quickly the manifests/MCP ecosystem is being adopted for agent workflows, non-MDX docs setups are likely to hit this gap more often.