"Provider returned error" hides actual Kimi/Moonshot API errors | Opencode GO | kimi k2.6 #23665

Description

I just purchased the OpenCode Go subscription today and was excited to use Kimi K2.6, but encountered this issue immediately.

When using Kimi K2.6 (or other Moonshot models) with OpenCode Go provider, errors from the upstream API are wrapped by the Vercel AI SDK with a generic "Provider returned error" message, losing the actual error details. Additionally, schemas with $ref cause "conflicting keywords found after $ref expansion" errors for Moonshot/Kimi APIs.

Root Cause:

1. Vercel AI SDK wraps provider errors with "Provider returned error" and stores real error in metadata.raw
2. Moonshot/Kimi APIs reject JSON schemas that have $ref with additional keywords like description after $ref expansion

Plugins

["opencode-ralph-loop"]

OpenCode version

1.4.11

Steps to reproduce

1. Subscribe to OpenCode Go
2. Configure OpenCode to use Kimi K2.6 model (opencode-go/kimi-k2.6)
3. Run a prompt that triggers an API error (e.g., using tool calls)
4. Error shows as generic "Provider returned error" instead of actual reason
5. If using tools, get error: tools.function.parameters is not a valid moonshot flavored json schema, details: <At path 'properties.variantOptions': conflicting keywords found after $ref expansion: description>

Screenshot and/or share link

Operating System

macOS 26.4.1

Terminal

zed ide terminal