RFC: [JS] Genkit Client

[Ehesp]

This is an RFC for the Genkit JS Client.

See https://github.com/Ehesp/genkit/blob/js-genkit-client/docs/js-genkit-client-rfc.md for more details.

[gemini-code-assist]

Summary of Changes

Hello @Ehesp, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This RFC proposes a comprehensive and modern JavaScript/TypeScript client SDK for Genkit. It aims to significantly enhance the developer experience by providing a client factory for centralized configuration, end-to-end type safety for flows, robust built-in retry mechanisms, and framework-specific integrations for React and Vue. The design addresses current limitations by reducing boilerplate, improving resilience, and offering a flexible chat primitive, making it easier to consume Genkit flows in client-side applications.

Highlights

• Client Factory: Introduced a createGenkitClient factory for shared configuration, including base URL, headers, retry logic, and custom fetch implementation.
• Type Inference: Proposed end-to-end type safety by inferring input, output, and stream types directly from server-defined flows using TypeScript.
• Retry and Resilience: Designed built-in retry mechanisms with configurable backoff strategies, jitter, and retryable HTTP status codes.
• Framework Integration: Introduced React hooks (useFlow, useChat) and Vue composables for managing flow invocations and chat UIs with reactive state.
• Chat Primitives: Detailed a useChat hook that supports both client-managed and server-managed conversation history via a flexible adapter pattern.
• Error Handling: Defined a GenkitClientError class to provide structured error details from server responses.
• Modular Package Structure: Outlined a modular package structure with a browser-safe, framework-agnostic core and separate React/Vue adapters.

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Changelog

• docs/js-genkit-client-rfc.md
  • Added a new Request for Comments (RFC) document detailing the proposed Genkit Client SDK.

Activity

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[gemini-code-assist]

Code Review

The RFC for the Genkit JS Client is comprehensive and well-thought-out. It effectively addresses the limitations of the current minimal client by proposing a factory pattern, robust type inference, and framework-specific integrations. The inclusion of both client-managed and server-managed chat history approaches via a flexible adapter pattern is a highlight. My feedback focuses on ensuring resource efficiency for long-running chat sessions and clarifying lifecycle management in the React hooks.

[gemini-code-assist]

To ensure consistency with the Vue implementation (line 660), the React useFlow hook should explicitly manage the AbortController lifecycle. It is important that any in-flight requests are automatically aborted when the component unmounts to prevent memory leaks and unnecessary server-side execution.

[gemini-code-assist]

For 'Approach A' (Client-Managed History), sending the full message array on every request can become problematic as conversations grow. This could eventually hit HTTP payload limits or exceed the model's context window. Consider adding a recommendation or a built-in option for a sliding window or message truncation strategy within the ChatAdapter or hook configuration.

[gemini-code-assist]

The 'Lightweight flow contract type' is a very important consideration for large-scale applications. Importing the full Action type (and its zod dependencies) from the server can sometimes lead to circular dependencies or bloated type-checking times in complex monorepos. Prioritizing a dependency-agnostic contract definition would improve the scalability of this approach.