#26762 — Cerebras zai-glm-4.7 fails on follow-up turn with reasoning_content

[ElioNeto]

Description

Using cerebras/zai-glm-4.7 on newer OpenCode versions, multi-turn runs that include reasoning and tool calls can fail on a follow-up assistant turn with:

messages.2.assistant.reasoning_content: property 'messages.2.assistant.reasoning_content' is unsupported

I can reproduce this on opencode 1.14.41.

The same prompt worked for me on opencode 1.1.4, and it also works on a local patched build from current dev, so this looks like a regression in how prior assistant reasoning is replayed for Cerebras models.

Plugins

None

OpenCode version

1.14.41

Steps to reproduce

1. Configure a Cerebras provider and use cerebras/zai-glm-4.7

2. Run from a clean directory, for example mkdir inferencex && cd inferencex

3. Run this prompt:

   build an frontend for inferencex performance benchmark

4. Let the run continue into tool use and the next assistant turn

5. Observe the error:

   messages.2.assistant.reasoning_content: property 'messages.2.assistant.reasoning_content' is unsupported

Screenshot and/or share link

Operating System

macOS

Terminal

iTerm2

[ElioNeto]

Resolved via delivery-loop pipeline.

Fix: Added Cerebras-specific normalization in normalizeMessages() that converts reasoning parts to text parts before sending requests to the Cerebras API. The Cerebras API does not support reasoning_content in request messages (unlike OpenAI/DeepSeek) and was rejecting follow-up turns with: 'reasoning_content' is unsupported.

The fix converts non-empty reasoning content to text parts so the model retains context without sending the unsupported field. Empty reasoning parts are filtered out.

Commit: 1ec1cda