qwen3-coder fails to call edit tool

[mausch]

Description

When using https://openrouter.ai/qwen/qwen3-coder:free it fails to call the edit tool.

It fails over and over again with:

Error: The edit tool was called with invalid arguments: [
  {
    "expected": "string",
    "code": "invalid_type",
    "path": [
      "oldString"
    ],
    "message": "Invalid input: expected string, received object"
  },
  {
    "expected": "string",
    "code": "invalid_type",
    "path": [
      "newString"
    ],
    "message": "Invalid input: expected string, received object"
  }
].
Please rewrite the input so it satisfies the expected schema.

Plugins

none

OpenCode version

1.1.1

Steps to reproduce

1. Set provider to Openrouter
2. Set model to qwen/qwen3-coder:free
3. Ask it to make any edits

Screenshot and/or share link

Operating System

NixOS

Terminal

xterm

[github-actions]

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

• Tool.edit should recieve json object #6838: Tool.edit should receive json object - Similar issue where LLM passes JSON objects instead of strings to edit tool parameters

The root cause appears to be that some LLM models (like Qwen3-coder) pass JSON objects for oldString and newString when they should pass strings. This is similar to the broader issue documented in #6838 where models struggle with properly stringifying JSON content for the edit tool.

Feel free to ignore if your specific case differs from these existing issues.

[PhantomKnight287]

Facing same on Macos 15.6.1 and Ghostty