When using the qwen3.5-122b-a10b model (via nvidia provider), the following error is returned: System message must be at the beginning

[fanyapeng]

Description

Environment

• OpenCode Version: 1.2.21
• Operating System: Windows
• Provider: nvidia
• Model: qwen/qwen3.5-122b-a10b

Steps to Reproduce

1. Configure opencode.json to use nvidia provider with qwen3.5-122b-a10b model
2. Start opencode and try to interact with the model
3. Error occurs: System message must be at the beginning

Workarounds Attempted
Added the following configuration in opencode.json:
{
"nvidia": {
"models": {
"qwen/qwen3.5-122b-a10b": {
"chat_template_kwargs": {
"enable_system_prompt": true
}
}
}
}
}
But the problem persists.

Expected Behavior
The model should be able to receive and process system prompts normally without returning an error.

Additional Information

• Error occurs every time (100% reproducibility)
• Other models (e.g., glm-4.7, doubao-seed-2.0-code) work fine with this provider
• Have not tried direct curl calls to nvidia API yet

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response

[github-actions]

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

• Duplicate System Message Sent #1301: Duplicate System Message Sent — OpenCode sends multiple system messages; certain models (like the NVIDIA-hosted Qwen model) reject requests where the system message is not at the very beginning or is duplicated.
• Ministral 3 support: error "Only user, assistant and tool roles are supported, got system" #5034: Ministral 3 support — same root cause, a different model rejecting system messages that are not at the beginning of the conversation.

If your issue is the same underlying problem, consider adding a comment or reaction there rather than opening a new report.

[paulgear]

This is a dup of #5034 (and possibly a recurrence of #1301), and I've produced a PR #15018 to fix it. Please add your upvote so it can get merged.