alibaba-cn reasoning models (kimi-k2.5, qwen-plus, qwen3, etc.) do not output thinking content

[AdJIa]

Bug Description

When using reasoning models on the alibaba-cn provider (DashScope), no reasoning/thinking content is produced despite models having capabilities.reasoning: true.

This affects all reasoning-capable models on alibaba-cn, not just kimi-k2.5:

• alibaba-cn/kimi-k2.5
• alibaba-cn/qwen-plus, alibaba-cn/qwen-turbo, alibaba-cn/qwen-flash
• alibaba-cn/qwen3-* (8b, 14b, 32b, 235b)
• alibaba-cn/qwq-plus, alibaba-cn/qwq-32b
• alibaba-cn/deepseek-r1*
• alibaba-cn/qvq-max
• etc.

The only exception is alibaba-cn/kimi-k2-thinking, which returns reasoning_content by default.

Root Cause

DashScope's OpenAI-compatible API requires enable_thinking: true in the request body to activate reasoning output. Without this parameter, reasoning_content is either absent or an empty string.

In packages/opencode/src/provider/transform.ts, the options() function handles thinking in two places, but neither covers the alibaba-cn (DashScope) case:

1. Line 607-611: Sets chat_template_args.enable_thinking only for providerID === "opencode" with kimi-k2-thinking
2. Line 634-643: Sets thinking.type: "enabled" only for @ai-sdk/anthropic SDK

The alibaba-cn provider uses @ai-sdk/openai-compatible — neither condition matches.

Reproduction

# No reasoning output (reasoning tokens = 0)
opencode run -m alibaba-cn/kimi-k2.5 --format json --thinking "test"
opencode run -m alibaba-cn/qwen-plus --format json --thinking "test"

# Direct API calls confirm enable_thinking is required:
# Without: no reasoning_content
curl $DASHSCOPE_API -d '{"model":"qwen-plus","messages":[...]}'
# With: reasoning_content present
curl $DASHSCOPE_API -d '{"model":"qwen-plus","messages":[...],"enable_thinking":true}'

Workaround

Add to opencode.json (per model):

{
  "provider": {
    "alibaba-cn": {
      "models": {
        "kimi-k2.5": { "options": { "enable_thinking": true } },
        "qwen-plus": { "options": { "enable_thinking": true } }
      }
    }
  }
}

Environment

• OpenCode version: v1.1.53
• Provider: alibaba-cn (DashScope)
• API: https://dashscope.aliyuncs.com/compatible-mode/v1
• SDK: @ai-sdk/openai-compatible

[github-actions]

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

• Kimi K2.5 can't enable thinking (reasoning_content missing #12090: Kimi K2.5 can't enable thinking (reasoning_content missing) - also reported as OpenAI-compatible provider issue
• No variants (high , low etc..) for the Kimi K2.5 model #12088: No variants (high, low etc..) for the Kimi K2.5 model - related issue with variants not showing
• FIX KIMI K2.5 from "Kimi For Coding" provider NOT having reasoning enabled. #12183: FIX KIMI K2.5 from "Kimi For Coding" provider NOT having reasoning enabled - same symptom across different providers

All these issues relate to Kimi K2.5 reasoning/thinking not working properly. Your detailed analysis about the DashScope API requiring enable_thinking: true parameter is valuable and may help resolve these related issues as well.

Feel free to ignore if these don't address your specific case.