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400 thinking is enabled but reasoning_content is missing #97

@naejin

Description

@naejin

Describe the bug
The attempt_completion tool fails with a 400 error stating thinking is enabled but reasoning_content is missing in assistant tool call message at index 2. This occurs when an agent completes a task and tries to submit the result via attempt_completion. The error is reproducible across multiple retry attempts and appears to be a platform-level issue rather than a user-code issue. The underlying task work (file changes, commits) succeeds, but the final handoff via attempt_completion is blocked.

To Reproduce
Steps to reproduce the behavior:

  1. Complete a task that requires file edits and a final attempt_completion call
  2. Call attempt_completion with a valid result string
  3. Observe the tool returns Verification Subagent Failed: 400 thinking is enabled but reasoning_content is missing in assistant tool call message at index 2
  4. Retry the same attempt_completion call — the error persists

Expected behavior
attempt_completion should accept the result and complete the task handoff successfully, or provide a meaningful error related to the task content rather than an internal platform thinking/reasoning_content mismatch.

Screenshots
N/A — error is returned as a tool result message.

Surface and Version:

  • IDE: VSCode with Dirac extension
  • Dirac extension version: 0.3.29
  • LLM API provider: Moonshot, api.moonthot.ai
  • Model: kimi-k2.6

Additional context

  • The error appears to originate from a verification subagent that inspects the assistant's tool call message.
  • The thinking is enabled part suggests the subagent expects a reasoning_content field in the assistant message when that mode is active, but the field is absent.
  • The error index (at index 2) may refer to the third message in the conversation context passed to the verification subagent.
  • This blocks task completion even though all actual work (file writes, git commits) was completed successfully.

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