OpenRouter models with mandatory reasoning reject requests with `reasoning:{enabled:false}`

[fegloff]

Problem

Models like stepfun/step-3.5-flash:free on OpenRouter require reasoning to always be enabled. When Claude Code sends a non-thinking request (background tasks, subagents), it includes thinking:{type:"disabled"} in the Anthropic format.

The openrouter transformer converts this to reasoning:{enabled:false}, which these models reject with:

API Error: 400 {"error":{"message":"Error from provider(openrouter,stepfun/step-3.5-flash:free: 400): {"error":{"message":"Reasoning is mandatory for this endpoint and
cannot be disabled.","code":400,"metadata":{"provider_name":null}}}Error: Error from provider(openrouter,stepfun/step-3.5-flash:free: 400):
{"error":{"message":"Reasoning is mandatory for this endpoint and cannot be disabled.","code":400,"metadata":{"provider_name":null}}}\n at qn
(/Users/userName/.nvm/versions/node/v23.11.1/lib/node_modules/@musistudio/claude-code-router/dist/cli.js:582:7451)\n at fD
(/Users/userName/.nvm/versions/node/v23.11.1/lib/node_modules/@musistudio/claude-code-router/dist/cli.js:582:11338)\n at process.processTicksAndRejections
(node:internal/process/task_queues:105:5)\n at async cN
(/Users/userName/.nvm/versions/node/v23.11.1/lib/node_modules/@musistudio/claude-code-router/dist/cli.js:582:8659)","type":"api_error","code":"provider_response_error"}}

Root Cause

In dist/cli.js, the openrouter transformer's transformRequestIn:

// Current (broken for mandatory-reasoning models)
e.thinking && (r.reasoning = {effort: EN(e.thinking.budget_tokens), enabled: e.thinking.type === "enabled"})
When thinking.type === "disabled", this sends reasoning:{enabled:false} — which mandatory-reasoning models reject.

Fix
Only forward the reasoning parameter when thinking is explicitly enabled. When disabled, omit it entirely so the model uses its default:


// Fixed
e.thinking && e.thinking.type === "enabled" && (r.reasoning = {effort: EN(e.thinking.budget_tokens), enabled: true})
Steps to Reproduce
Set stepfun/step-3.5-flash:free as the router model for any route
Trigger a background/subagent task (e.g. Task tool in Claude Code)
Observe 400 error from OpenRouter
Environment
CCR version: 2.0.0
Model: stepfun/step-3.5-flash:free via OpenRouter

[sambitos23]

Thank you, its works

[phoehnel]

As a workaround, you can enforce thinking in claude by setting:
export CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING=1

[sambitos23]

@phoehnel where I need to add this?
in dist/cli.js or any other place

[estelarsorteo-hash]

@phoehnel where I need to add this? in dist/cli.js or any other place

hey just copy and paste that command in your linux command line then hit enter, before running the claude command

[lyqluis]

this may help: add an option to openrouter transformer

  "models": [ ... ],
  "transformer": {
    "use": [
      [
        "openrouter",
        { "reasoning": { "enabled": true } }
      ]
    ]
  }