Claude Code provider not displaying reasoning/thinking content for Claude 3.5 Sonnet 4.0

[hannesrudolph]

App Version

3.19.1+ (current)

API Provider

Claude Code

Model Used

Claude 3.5 Sonnet 4.0

🔁 Steps to Reproduce

1. Configure Roo Code to use Claude Code provider
2. Set model to Claude 3.5 Sonnet 4.0 (which supports reasoning/thinking)
3. Send a request that should trigger reasoning (e.g., complex problem-solving task)
4. Observe the chat response

💥 Outcome Summary

Expected: Reasoning/thinking process should be displayed in collapsible reasoning blocks in the chat, similar to other providers

Actual: No reasoning/thinking content is displayed in the chat, even though the model supports it and other providers (like AWS Bedrock) show reasoning properly

Technical Analysis

Based on code investigation, the issue appears to be in the Claude Code provider integration:

Backend reasoning processing is implemented:

• claude-code.ts:93-104 correctly processes "thinking" and "redacted_thinking" content types
• Transforms them to "reasoning" stream chunks that should display in UI

Frontend reasoning display exists:

• ChatRow.tsx:900-908 has proper case handling for "reasoning" message types
• ReasoningBlock.tsx component exists for displaying reasoning content

Recent related work:

• PR fix: Add AWS Bedrock Extended Thinking support for Claude models (#4343, #4201) #4447 added reasoning support for AWS Bedrock provider
• Other providers show reasoning correctly

Possible Root Causes

1. Claude Code CLI integration issue: The external Claude CLI might not be returning thinking blocks in the expected format
2. Model configuration: Claude 3.5 Sonnet 4.0 might need specific parameters to enable reasoning output through Claude Code CLI
3. Stream processing bug: Reasoning content might be getting lost in the stream processing pipeline
4. Version mismatch: Claude Code CLI version might not support reasoning output

Expected Behavior

Reasoning/thinking content should display in collapsible blocks similar to other providers, allowing users to see the model's thought process.

📄 Relevant Logs or Errors (Optional)

No specific errors displayed - reasoning content simply doesn't appear in the chat interface.

[dosubot]

This is a known issue that was fixed in Roo Code v3.21.5. The release notes confirm that earlier versions (including 3.19.1) had a bug where reasoning blocks from the Claude Code provider were not displayed correctly due to JSON parsing issues. Upgrading to v3.21.5 or later will resolve this and show reasoning/thinking content as collapsible blocks in the chat, as expected docs.

No extra configuration or CLI flags are needed for reasoning output with the Claude Code provider—just ensure your Claude CLI is installed and authenticated docs.

If you still don’t see reasoning after upgrading, try running a prompt directly with the Claude CLI to confirm that it emits reasoning/thinking content for your model and prompt. If the CLI output includes reasoning but Roo Code does not display it, please share the CLI output and Roo Code logs for further troubleshooting.

To reply, just mention @dosu.

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[hannesrudolph]

One thing is that sometimes the reasoning blocks do display, I'm not sure what is different on those instances.

[hannesrudolph]

PR #5113 has been created to address this issue: #5113

The fix includes:

1. Stream parsing improvements (already merged) to consistently display reasoning/thinking content
2. Disabling the reasoning budget UI controls for Claude Code provider since the CLI doesn't support these parameters