feat: embedding model middleware

[0xlakshan]

Background

There is currently no middleware for embedding models, which would be useful for e.g. setting defaults (see #7947 ).

Summary

This PR adds a middleware wrapEmbeddingModel, making it easier to customize and extend embedding model behavior from unified central space.

This also adds support for defaultEmbeddingSettingsMiddleware middleware, letting users manage things like dimensions and provider options from single central place.

Example

// configure embedding model with settings
const centralSpace = customProvider({
  textEmbeddingModels: {
    'my-embedding-model': wrapEmbeddingModel({
      model: google.textEmbedding('gemini-embedding-001'),
      middleware: defaultEmbeddingSettingsMiddleware({
        settings: {
          providerOptions: {
            google: {
              outputDimensionality: 256,
              taskType: 'CLASSIFICATION',
            },
          },
        },
      }),
    }),
  },
});

// usage with embedMany
const embedManyResponse = await embedMany({
  model: centralSpace.textEmbeddingModel('powerful-embedding-model'),
  values: [
    'sunny day at the beach',
    'rainy afternoon in the city',
    'snowy night in the mountains',
  ],
});
console.log(embedManyResponse.embeddings);

// usage with embed
const response = await embed({
  model: centralSpace.textEmbeddingModel('powerful-embedding-model'),
  value: 'rainy afternoon in the city',
});
console.log(response.embedding);

Manual Verification

• run examples/ai-core/src/middleware/embedding/google-default-settings.ts

Checklist

• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• Formatting issues have been fixed (run pnpm prettier-fix in the project root)
• I have reviewed this pull request (self-review)

Related Issues

Fixes #7947

[0xlakshan]

Hi @gr2m @lgrammel , could you take a quick look at this PR when you get a chance? I’d really appreciate any feedback you have. Thanks :)

[zirkelc]

Is there a a reason it is implement for EmbeddingModelV3 and not the current EmbeddingModelV2?

[0xlakshan]

Hi @zirkelc, you might want to update the ai sdk package, as the EmbeddingModelV2 has been replaced with EmbeddingModelV3. (3 weeks ago)

Related PR - 0c4822d

[0xlakshan]

Hi @lgrammel do i need to make this middleware support for EmbeddingModelV2 as well for backward compatibility.

[lgrammel]

Thanks @0xlakshan I'll take it from here and will make a few changes. V2 support is not desired since it would mean changing the provider package for v2.