Azure provider crashes with TypeError on non-OpenAI models (Claude, etc.)

[androolloyd]

Bug

Using any non-OpenAI model under the azure provider (e.g. azure/claude-opus-4-6) crashes with:

TypeError: sdk.responses is not a function. (In 'sdk.responses(modelID)', 'sdk.responses' is undefined)

Root Cause

Azure Claude models in the models.dev catalog use npm: "@ai-sdk/anthropic" with endpoint https://${AZURE_RESOURCE_NAME}.services.ai.azure.com/anthropic/v1. The azure and azure-cognitive-services custom loaders unconditionally call sdk.responses(modelID), which only exists on @ai-sdk/azure and @ai-sdk/openai SDKs.

When the SDK is @ai-sdk/anthropic (has .chat() but no .responses()) or @ai-sdk/openai-compatible (has only .languageModel()), the call crashes.

Affected Models

Any Azure model with a model-level provider.npm override that isn't @ai-sdk/azure:

• azure/claude-opus-4-6 → @ai-sdk/anthropic
• azure/claude-opus-4-5 → @ai-sdk/anthropic
• azure/claude-sonnet-4-5 → @ai-sdk/anthropic
• azure/claude-haiku-4-5 → @ai-sdk/anthropic
• azure/claude-opus-4-1 → @ai-sdk/anthropic

Fix

Guard sdk.responses with existence checks, falling back through sdk.chat → sdk.languageModel:

if (sdk.responses) return sdk.responses(modelID)
if (sdk.chat) return sdk.chat(modelID)
return sdk.languageModel(modelID)

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• TypeError: sdk.responses is not a function when switching models #16049: Same TypeError: sdk.responses is not a function error in the azure/openai loaders, same root cause (unconditional sdk.responses() call), and same proposed fix pattern.

[androolloyd]

Duplicate of #16049. Fix in #16048.