Fix: Extra inputs are not permitted, field: 'messages[2].provider_specific_fields

[Sameerlite]

Relevant issues

Fireworks doesn't like messages[2].provider_specific_fields in its request and throws an error. This Pr removes this field. The transform response doesn't add any provider_specific_fields in the response, so this means that some other LLMs provider_specific_fields from history had gotten added

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• I have Added testing in the tests/litellm/ directory, Adding at least 1 test is a hard requirement - see details
• My PR passes all unit tests on make test-unit
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CI (LiteLLM team)

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• 45-49 passing tests: acceptable but needs attention
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Type

🆕 New Feature
🐛 Bug Fix
🧹 Refactoring
📖 Documentation
🚄 Infrastructure
✅ Test

Changes

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Feb 3, 2026 10:55am

[greptile-apps]

Greptile Overview

Greptile Summary

Fixed FireworksAI API compatibility by removing provider_specific_fields from messages before sending requests. This field caused API errors with the message "Extra inputs are not permitted, field: 'messages[n].provider_specific_fields'".

Changes:

• Added field removal in _transform_messages_helper (transformation.py:239-242) after existing cache_control filtering
• Uses safe message.pop("provider_specific_fields", None) with type check to prevent KeyError
• Follows established pattern similar to cache_control filtering on line 238
• Added comprehensive test coverage with 3 test cases (with field, without field, mixed)

Impact:

• Prevents API errors when provider_specific_fields is present in messages
• No breaking changes - only removes unsupported field before API call
• Maintains all other message properties intact

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Score reflects a well-implemented bug fix with proper testing. The change is minimal, follows established patterns in the codebase, includes comprehensive test coverage, and has no breaking changes or performance implications
• No files require special attention

Important Files Changed

Filename	Overview
litellm/llms/fireworks_ai/chat/transformation.py	Added provider_specific_fields filtering to prevent FireworksAI API errors - clean implementation
tests/test_litellm/llms/fireworks_ai/chat/test_fireworks_ai_chat_transformation.py	Added comprehensive test coverage for provider_specific_fields removal functionality

Sequence Diagram

sequenceDiagram
    participant Client
    participant LiteLLM
    participant FireworksAIConfig
    participant FireworksAI API

    Client->>LiteLLM: chat completion request with messages
    LiteLLM->>FireworksAIConfig: transform_request(messages)
    FireworksAIConfig->>FireworksAIConfig: _transform_messages_helper(messages)
    
    Note over FireworksAIConfig: Loop through each message
    FireworksAIConfig->>FireworksAIConfig: filter_value_from_dict(message, "cache_control")
    FireworksAIConfig->>FireworksAIConfig: Check if "provider_specific_fields" exists
    
    alt provider_specific_fields exists
        FireworksAIConfig->>FireworksAIConfig: message.pop("provider_specific_fields", None)
        Note over FireworksAIConfig: Removes field to prevent API error
    end
    
    FireworksAIConfig-->>LiteLLM: cleaned messages
    LiteLLM->>FireworksAI API: API request (without provider_specific_fields)
    FireworksAI API-->>LiteLLM: successful response
    LiteLLM-->>Client: completion response

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[greptile-apps]

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