How do you envision this feature/change to look/work like?

Follow up on #310

In a messaging handler, dev export a type like this:

export type RequestBody = {
   a: string
   b: number
}

-> Automatic type inference/linking for the messaging API via the metadata interface ?!

What is the purpose of this change/feature? Why?

Type-safety from the handler export seems like a fun way to provide total type-interface abstraction.

(OPTIONAL) Example implementations

No response

(OPTIONAL) Contact Details

No response

Verify canary release

• I verified that the issue exists in plasmo canary release

Code of Conduct

• I agree to follow this project's Code of Conduct
• I checked the current issues for duplicate problems.