OpenRouter qwen/qwen3.6-plus-preview:free returns duplicate tool calls — every bash command executes twice

[agent01001]

Description

When using the qwen/qwen3.6-plus-preview:free model via OpenRouter, every single bash tool call in the API response is duplicated. The same tool call with identical arguments appears twice, causing OpenCode to execute every command twice.

Session log analysis confirms 100% duplication rate — every bash command evaluated twice at the exact same timestamp:

• date: 2x
• echo ---: 2x
• cal: 2x
• which chrome-devtools: 2x
• chrome-devtools click: 2x

The same model family via OpenCode's direct endpoint (qwen3.6-plus-free) does NOT duplicate — only the OpenRouter-hosted preview variant exhibits this.

Impact: Toggle elements (clicks, checkboxes) fire twice — first click opens, second immediately closes. Every bash command runs twice, doubling side effects.

openrouter-session-duplicate-tool-calls.log

Plugins

chrome-devtools-mcp

OpenCode version

1.3.13

Steps to reproduce

1. Configure OpenCode to use qwen/qwen3.6-plus-preview:free via OpenRouter
2. Start a session and ask the model to run any bash command (e.g., date)
3. Check session logs at ~/.local/share/opencode/log/
4. Observe every bash command evaluated twice at the same timestamp

Screenshot and/or share link

No response

Operating System

Linux

Terminal

bash

[Integer-Conversion-Error]

Also seeing this myself. Duplicate tool calls, duplicating messages (sending them and then still seeing them as pending, then it sends again once the first one has gone, sending the message twice)

[avgurtiza]

Same here. It's calling my migrations twice, and trying to create databases manually in an attempt to fix it. DB client complains that the database exists and fails.

I had it spawn subagents for three tasks, it created 6 doing the same thing.

[remcoboerma]

Also in 1.15.11