[Bug]: CSF-Factories: Does not infer types from global decorators

[IanVS]

Describe the bug

I'm experimenting with the new typesafe csf-factories, and noticed that the parameters of custom decorators specified in preview.ts are not inferred. I can still use module augmentation to add them, as before, but I believe one of the goals of the RFC is to avoid the need for that.

Reproduction link

https://stackblitz.com/edit/github-bkfc7ul3?file=src%2Fstories%2FPage.stories.ts&view=editor

Reproduction steps

In the reproduction, I've created a custom decorator (a common one, for react-router), but the types for parameters.routing are not known by preview.meta.

System

N/A

Additional context

No response

[dosubot]

You're correct—typesafe csf-factories in Storybook don't currently infer types for custom parameters defined in global decorators (like those in preview.ts). This means TypeScript won't automatically know about custom fields such as parameters.routing, and manual module augmentation is still required to get type safety for these parameters.

The RFC for typesafe csf-factories does aim to reduce the need for manual augmentation, but the current implementation hasn't bridged the gap yet. The main challenge is that TypeScript can't automatically merge custom parameter types from global decorators into the story meta typings. So, for now, module augmentation remains the recommended approach for custom parameters in global decorators, even with the new CSF factories API improvements (source).

If you want to keep type safety for custom parameters, you'll need to continue using module augmentation until Storybook provides a way to infer these types automatically. This limitation is known and aligns with the current state of the RFC and implementation (source).

To reply, just mention @dosu.

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