feat(rust): add reasoning_content field to ChatMessage types

[AnthonyRonning]

Summary

Add optional reasoning_content field to ChatMessage and ChatMessageDelta structs in the Rust SDK.

Motivation

Models like Kimi K2 (via vLLM/Tinfoil) can expose their reasoning/thinking process through a reasoning_content field in the response. Without this field in the SDK types, the reasoning content is silently dropped during deserialization.

Changes

• Added reasoning_content: Option<String> to ChatMessage (for non-streaming responses)
• Added reasoning_content: Option<String> to ChatMessageDelta (for streaming responses)
• Both fields use #[serde(skip_serializing_if = "Option::is_none")] to avoid serializing when not present

Testing

• cargo check passes

Summary by CodeRabbit

• New Features

  • Chat messages can now include an optional "reasoning content" field.

• Tests

  • Test fixtures updated to include the new optional field where applicable.
  • Added a streaming test that verifies reasoning content can be produced in deltas for the relevant model.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds an optional reasoning_content: Option<String> (with serde(skip_serializing_if = "Option::is_none")) to ChatMessage and ChatMessageDelta in rust/src/types.rs, updates test payloads to include the field (initialized as None), and adds a streaming test asserting reasoning_content appears for the kimi-k2-thinking model.

Changes

Cohort / File(s)	Summary
Type additions rust/src/types.rs	Added reasoning_content: Option<String> to ChatMessage and ChatMessageDelta with serde(skip_serializing_if = "Option::is_none").
Test updates rust/tests/ai_integration.rs, rust/tests/api_keys.rs	Added reasoning_content: None to multiple ChatMessage instances in tests; introduced test_reasoning_content_with_kimi_k2_thinking to assert reasoning_content appears in streaming deltas; minor safe changes to streaming usage checks.

Sequence Diagram(s)

(Skipped — changes are type additions and test updates without a new multi-component control flow requiring visualization.)

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• feat: make ChatMessage content field flexible to support multiple for… #47: Modifies the same message structs (ChatMessage / ChatMessageDelta) — potentially conflicts or overlapping edits to message fields.

Poem

🐰 I nibble code in morning light,

A tiny field tucked out of sight,
Optional whispers, soft and keen,
Reasoning dreams in places unseen,
Hopping on, delighted and bright.

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding a reasoning_content field to ChatMessage types in Rust, matching the core objective of supporting this field in both ChatMessage and ChatMessageDelta structs.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[cloudflare-workers-and-pages]

Deploying opensecret-sdk with    Cloudflare Pages

Latest commit:	5f970f1
Status:	✅  Deploy successful!
Preview URL:	https://45afd2b8.opensecret-sdk.pages.dev
Branch Preview URL:	https://add-reasoning-content.opensecret-sdk.pages.dev

View logs

[greptile-apps]

Greptile Overview

Greptile Summary

Added optional reasoning_content field to both ChatMessage and ChatMessageDelta structs in the Rust SDK to capture reasoning/thinking processes from AI models like Kimi K2. The implementation follows proper Rust/serde patterns with Option<String> type and #[serde(skip_serializing_if = "Option::is_none")] to ensure backward compatibility. All test fixtures have been updated to initialize the field as None.

Key changes:

• ChatMessage and ChatMessageDelta now include reasoning_content: Option<String>
• Test fixtures updated across ai_integration.rs and api_keys.rs
• New test test_reasoning_content_with_kimi_k2_thinking added to verify the feature works with streaming responses

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The changes are well-contained, follow Rust best practices with proper Option types and serde attributes, maintain backward compatibility through skip_serializing_if, and include appropriate test coverage. The implementation is straightforward and doesn't modify any core logic.
• No files require special attention

Important Files Changed

Filename	Overview
rust/src/types.rs	Added reasoning_content field to ChatMessage and ChatMessageDelta structs with proper serde attributes
rust/tests/ai_integration.rs	Updated test fixtures to include reasoning_content: None and added new test for Kimi K2 thinking model
rust/tests/api_keys.rs	Updated test fixture to include reasoning_content: None for API key streaming test

Sequence Diagram

sequenceDiagram
    participant Client as Rust SDK Client
    participant API as OpenSecret API
    participant Model as AI Model (e.g., Kimi K2)
    
    Client->>API: ChatCompletionRequest (with messages)
    API->>Model: Forward request
    
    alt Streaming Response
        loop For each token
            Model-->>API: ChatCompletionChunk with delta
            Note over Model,API: delta.reasoning_content (if available)<br/>delta.content (response text)
            API-->>Client: Encrypted ChatCompletionChunk
            Client->>Client: Deserialize with reasoning_content field
        end
    else Non-Streaming Response
        Model-->>API: ChatCompletionResponse
        Note over Model,API: message.reasoning_content (if available)<br/>message.content (response text)
        API-->>Client: Encrypted ChatCompletionResponse
        Client->>Client: Deserialize with reasoning_content field
    end

Loading