• I have looked for existing issues (including closed) about this

Feature Request

Problem with TranscriptionRequestBuilder:

If someone forgets to provide data, calling .build() will trigger panic.

Location: src/transcription.rs:

pub fn build(self) -> TranscriptionRequest {
    if self.data.is_empty() {
        panic!("Data cannot be empty!")
    }
    // ...
}

Problem with VectorSearchRequestBuilder:

Location: src/vector_store/request.rs:

Builder returns a runtime Result if query is missing forcing user to handle misconfiguration error.

pub fn build(self) -> Result<VectorSearchRequest<F>, VectorStoreError> {
    let Some(query) = self.query else {
        return Err(VectorStoreError::BuilderError("`query` is a required...".into()));
    };
    // ...
}

Both of these problems can be mitigated at compile-time similar to AgentBuilder and ClientBuilder by using Typestate pattern.

Motivation

1. Eliminate runtime panic in TranscriptionRequestBuilder
2. Improved DX when building vector search requests

Proposal

• Define universal state markers: Missing (default) and Provided for all builders.
• Initialize with Missing state
• Implement state transitions to Provided within .data() and .load_file() and similar methods
• Implement terminal methods (.build() and .send()) only for Provided state

Alternatives

This might require introduction of additional generics, but is still arguably better and follows existing approach in other builders