Claude Sonnet 4.6 with medium thinking gets stuck in reasoning loop on Windows (PowerShell) #27062

Description

Title: Claude Sonnet 4.6 with medium thinking gets stuck in reasoning loop on Windows (PowerShell)

Body:

Description
When using Claude Sonnet 4.6 with medium thinking enabled, the model gets stuck in a loop where it plans and describes file changes entirely within the thinking/reasoning block but never executes the actual tool calls. Sometimes it even writes code inside the thinking trace instead of outputting it.

Environment

• OS: Windows (PowerShell)
• Model: claude-sonnet-4-6
• Thinking: medium
• OpenCode version: [1.14.48]

Steps to reproduce

1. Open a project in OpenCode
2. Select Claude Sonnet 4.6 with medium thinking
3. Ask the model to edit or refactor a file
4. Observe that changes are described in the thinking trace but no tool calls are executed

Expected behavior
Model completes thinking phase then executes tool calls to make the actual file changes.

Actual behavior
Model loops inside the thinking trace, planning changes but never acting on them. In some cases it writes code directly in the thinking block.

Related issues

• Models get stuck in reasoning loop - making changes only in thinking, not actually executing tool calls #15271
• Claude extended thinking + tool use: signature not preserved in message history #6176

Plugins

No response

OpenCode version

1.14.48

Steps to reproduce

Steps to reproduce

1. Open a project in OpenCode
2. Select Claude Sonnet 4.6 with medium thinking
3. Ask the model to edit or refactor a file
4. Observe that changes are described in the thinking trace but no tool calls are executed

Screenshot and/or share link

No response

Operating System

Windows 11

Terminal

Powershell