OCI: Cohere responseFormat/Pydantic

[gotsysdba]

Relevant issues

Fixes #20582

Pre-Submission checklist

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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)

CI status guideline:

• 50-55 passing tests: main is stable with minor issues.
• 45-49 passing tests: acceptable but needs attention
• <= 40 passing tests: unstable; be careful with your merges and assess the risk.

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Type

🆕 New Feature
✅ Test

Changes

• Add response_format support for OCI chat models. Maps OpenAI's response_format parameter to OCI's responseFormat, with vendor-specific type formatting: generic OCI models expect uppercase values (TEXT, JSON_OBJECT) while Cohere models expect lowercase (text, json_schema). The shorthand type json is mapped to JSON_OBJECT for generic models.
• Handle json_schema structured output. When response_format includes a json_schema payload, the snake_case key is renamed to OCI's camelCase jsonSchema in the outgoing request.
• Add responseFormat field to OCIChatRequestPayload so generic OCI requests can carry the response format through to the API.
• Make token detail fields optional in response models for Gemini support. OCICompletionTokenDetails.acceptedPredictionTokens, OCICompletionTokenDetails.reasoningTokens, and OCIPromptTokensDetails.cachedTokens are now Optional[int] since not all OCI responses include these sub-fields.
• Make CohereMessage.message optional. Assistant messages containing only tool calls may have null content, so the field must allow None.
• Add CohereResponseJSONSchemaFormat type and expand CohereChatRequest.responseFormat union to support json_schema response format alongside the existing text format.

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Feb 7, 2026 8:47pm

[greptile-apps]

Greptile Overview

Greptile Summary

This PR adds response_format support for OCI chat models with proper vendor-specific handling. The implementation correctly maps OpenAI's response_format parameter to OCI's responseFormat, handling both generic OCI models (uppercase types: TEXT, JSON_OBJECT) and Cohere models (lowercase types: text, json_schema). The shorthand json type is properly mapped to JSON_OBJECT for generic models.

Key changes:

• Transforms json_schema (snake_case) to jsonSchema (camelCase) for OCI API compatibility
• Makes token detail fields optional in response models for Gemini support
• Makes CohereMessage.message optional to support assistant messages with only tool calls
• Adds comprehensive test coverage for all scenarios

The implementation follows existing patterns in the codebase and includes proper test coverage.

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The implementation is well-structured with proper vendor-specific handling, comprehensive test coverage for all scenarios, and backward-compatible type changes. The code follows existing patterns in the LiteLLM codebase and correctly transforms parameters between OpenAI and OCI formats.
• No files require special attention

Important Files Changed

Filename	Overview
litellm/llms/oci/chat/transformation.py	Added response_format support with vendor-specific transformations (uppercase for generic OCI, lowercase for Cohere), json_schema to jsonSchema mapping, and proper handling in optional params. Logic is sound.
litellm/types/llms/oci.py	Made token detail fields and CohereMessage.message optional for broader OCI model support. Added CohereResponseJSONSchemaFormat type and expanded response format union. All changes are backward compatible.
tests/test_litellm/llms/oci/chat/test_oci_chat_transformation.py	Added comprehensive tests for response_format transformations (json_object, text, json shorthand) and token details handling. All test cases properly cover the new functionality.
tests/test_litellm/llms/oci/chat/test_oci_cohere_tool_calls.py	Added tests for Cohere-specific json_schema response format handling, lowercase type preservation, and tool-call-only messages with null content. Test coverage is thorough.

Sequence Diagram

sequenceDiagram
    participant Client
    participant OCIChatConfig
    participant _get_optional_params
    participant CohereChatRequest
    participant OCIChatRequestPayload
    participant OCI_API

    Client->>OCIChatConfig: transform_request(model, messages, optional_params)
    OCIChatConfig->>OCIChatConfig: get_vendor_from_model(model)
    
    alt Cohere Model
        OCIChatConfig->>_get_optional_params: vendor=COHERE, optional_params
        _get_optional_params->>_get_optional_params: Map response_format to responseFormat
        alt json_schema format
            _get_optional_params->>_get_optional_params: Pop json_schema, add as jsonSchema
            _get_optional_params->>_get_optional_params: Keep type lowercase (json_schema)
        else text format
            _get_optional_params->>_get_optional_params: Keep type lowercase (text)
        end
        _get_optional_params-->>OCIChatConfig: transformed params
        OCIChatConfig->>OCIChatConfig: adapt_messages_to_cohere_standard(messages)
        OCIChatConfig->>CohereChatRequest: Create with message, chatHistory, responseFormat
        CohereChatRequest-->>OCI_API: Send Cohere request
    else Generic OCI Model
        OCIChatConfig->>_get_optional_params: vendor=GENERIC, optional_params
        _get_optional_params->>_get_optional_params: Map response_format to responseFormat
        alt json_schema format
            _get_optional_params->>_get_optional_params: Pop json_schema, add as jsonSchema
            _get_optional_params->>_get_optional_params: Convert type to uppercase
        else json shorthand
            _get_optional_params->>_get_optional_params: Convert json to JSON_OBJECT
        else other types
            _get_optional_params->>_get_optional_params: Convert type to uppercase
        end
        _get_optional_params-->>OCIChatConfig: transformed params
        OCIChatConfig->>OCIChatRequestPayload: Create with messages, responseFormat
        OCIChatRequestPayload-->>OCI_API: Send generic OCI request
    end
    
    OCI_API-->>OCIChatConfig: Response
    OCIChatConfig->>OCIChatConfig: transform_response()
    OCIChatConfig-->>Client: ModelResponse

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