Bad Request: Invalid signature in thinking block when calling jiekou/claude-opus-4.6

[Hayden727]

Description

When invoking the model jiekou/claude-opus-4.6 using opencode version 1.2.13, I receive a 400 Bad Request error with the following details:

Bad Request: InvokeModelWithResponseStream: operation error Bedrock Runtime: InvokeModelWithResponseStream, https response error StatusCode: 400, RequestID: 9f83dbec-9a43-41a3-bd42-12f1368c3089, ValidationException: ***.***.content.0: Invalid `signature` in `thinking` block (request id: 20260225141044173361254Wx47AhVR) (request id: 2026022522103175849703kDgdrQvD) (request id: 20260225141030873658306m3CrpPJJ) (request id: 20260225221029913578496LJYoYIWP) trace_id: 075eefa35d1757e5153230a63c46a7a4

The error indicates that the signature field inside a thinking block is invalid. It appears that the request might contain a thinking block structure that is not properly formed or is not supported by the model.

Plugins

oh-my-opencode

OpenCode version

1.2.13

Steps to reproduce

1. Use opencode version 1.2.13 with oh-my-opencode.
2. Configure the model endpoint for jiekou/claude-opus-4.6.
3. Send a request (presumably with a thinking block in the messages or response format) to the model via the OpenAI-compatible API.
4. Observe the error response.

Screenshot and/or share link

Operating System

Ubuntu24.04 in Docker

Terminal

zsh

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Error: Invalid signature in thinking block #6418: Same error "Invalid signature in thinking block" (closed)
• Invalid signature in thinking block when switching Claude models (Copilot provider) #11546: Same error "Invalid signature in thinking block" when switching Claude models (closed)
• claude-opus-4-6系列模型调用失败 #14920: Open issue about claude-opus-4.6 series failing with a related signature/thinking block error via OpenAI-compatible API