The class VoyageEmbeddings in the LangChainJS framework is making use of the endpoints at https://api.voyageai.com/v1. This only works for API keys created directly on Voyage AI's website (https://dashboard.voyageai.com/api-keys).

API Keys created on the Atlas UI as described in our official documentation require the API url https://ai.mongodb.com/v1. We need to update the VoyageEmbeddings class in LangChainJS to support both endpoints.

Desired User Experiece

The current way to work with Atlas-created Voyage keys is to manually set the API's url:

const embeddings = new VoyageEmbeddings({
      apiKey: "my-voyage-api-key",
      basePath: "https://ai.mongodb.com/v1",
    });

// This fails because the request calls the wrong domain:
// 'api.voyage.com' instead of 'ai.mongodb.com'
await embeddings.embedQuery("Hello world");

console.log(embeddingModel.apiUrl)
// outputs: 'htps://api.voyageai.com/v1/embeddings'

// Workaround: set apiUrl directly
embeddingModel.apiUrl = "https://ai.mongodb.com/v1/embeddings"; 
await embeddings.embedQuery("Hello world");  // works!

Users should be able to pass the apiUrl param in the constructor:

const embeddings = new VoyageEmbeddings({
      apiKey: "my-voyage-api-key",
      basePath: "https://ai.mongodb.com/v1",
    });

expect(embeddings.apiUrl).toBe("https://ai.mongodb.com/v1/embeddings");

Acceptance Criteria

• A PR has been opened against https://github.com/langchain-ai/langchainjs
• The LangChain team has acknowledge this PR.
• Test that apiUrl is set to the domain passed in the VoyageEmbeddings constructor.
• Nice to have: auto-endpoint detection similar to Python. (Could not find evidence/samples of this in the Python repository).