Routed Model

⚠️ This plugin is currently non-functional. It depends on an OpenCode API that is not yet available. Track progress at opencode issue #26091. Once that issue is resolved this plugin will work as described below.

An OpenCode plugin that displays which model was selected by a LiteLLM auto router when using dynamic model routing (complexity router, semantic router, etc.).

The Problem

When using a LiteLLM auto router (such as the complexity router), requests are dynamically routed to different models based on the input. For example, a simple question might be sent to a cheap model like gpt-4o-mini, while a complex coding task is routed to claude-sonnet-4. OpenCode only sees the router alias (e.g. my-auto-router) and has no visibility into which underlying model actually served the request.

This plugin surfaces that information directly in the OpenCode TUI as a toast notification after each response.

How It Works

1. When you send a message through OpenCode, the request goes to the LiteLLM proxy with your router's model_name alias.
2. The LiteLLM complexity router scores the request across multiple dimensions (token count, code presence, reasoning markers, technical terms, etc.) and selects the appropriate tier model.
3. LiteLLM makes the actual LLM call and returns the response. The response includes the actual model that served the request in the model field.
4. This plugin listens for assistant message events in OpenCode and displays the model name from the response as a toast notification.

Prerequisites

• OpenCode installed and configured
• A LiteLLM proxy running with an auto router configured
• OpenCode connected to the LiteLLM proxy as a custom provider

LiteLLM Complexity Router Setup

If you haven't set up the complexity router yet, here's a quick overview. Add this to your LiteLLM config.yaml:

model_list:
  # Target models for each tier
  - model_name: gpt-4o-mini
    litellm_params:
      model: gpt-4o-mini

  - model_name: gpt-4o
    litellm_params:
      model: gpt-4o

  - model_name: claude-sonnet
    litellm_params:
      model: claude-sonnet-4-20250514

  - model_name: o1-preview
    litellm_params:
      model: o1-preview

  # Complexity router
  - model_name: smart-router
    litellm_params:
      model: auto_router/complexity_router
      complexity_router_config:
        tiers:
          SIMPLE: gpt-4o-mini
          MEDIUM: gpt-4o
          COMPLEX: claude-sonnet
          REASONING: o1-preview
      complexity_router_default_model: gpt-4o

See the LiteLLM auto routing docs for full details.

OpenCode Provider Configuration

Connect OpenCode to your LiteLLM proxy as a custom provider in your opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "provider": {
    "litellm": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "LiteLLM Proxy",
      "options": {
        "baseURL": "http://localhost:4000/v1",
        "apiKey": "your-litellm-api-key"
      },
      "models": {
        "smart-router": {
          "name": "Smart Router (Auto)"
        }
      }
    }
  }
}

Important: The model ID in OpenCode (smart-router above) must match the model_name you configured in LiteLLM, not the raw auto_router/complexity_router value.

Installation

The package is published on npm: opencode-routed-model

You do not need to run npm install manually. OpenCode automatically installs npm plugins using Bun at startup, cached globally in ~/.cache/opencode/node_modules/.

There are two ways to install this plugin.

Option 1: npm plugin (recommended)

Add the plugin to your config file. To apply it to all projects, add it to your global config:

Global (all projects) — ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-routed-model"]
}

To apply it to a single project only, add it to the opencode.json in your project folder instead.

Option 2: Local file

Copy the plugin file directly into your OpenCode plugins directory.

Per project:

mkdir -p .opencode/plugins
curl -o .opencode/plugins/show-routed-model.ts \
  https://raw.githubusercontent.com/jtbnz/opencode-routed-model/main/src/index.ts

Global (all projects):

mkdir -p ~/.config/opencode/plugins
curl -o ~/.config/opencode/plugins/show-routed-model.ts \
  https://raw.githubusercontent.com/jtbnz/opencode-routed-model/main/src/index.ts

Usage

Once installed, restart OpenCode. The plugin activates automatically -- no configuration needed.

After each assistant response, you will see a toast notification in the bottom of the TUI showing which model was used:

Model used: gpt-4o-mini

or

Model used: claude-sonnet-4-20250514

This tells you exactly which model the LiteLLM complexity router chose for that particular request.

How the Complexity Router Selects Models

The LiteLLM complexity router scores each request across seven dimensions:

Dimension	What It Detects	Effect
Token Count	Short or long prompts	Short = simpler, long = more complex
Code Presence	Keywords like function, class, api	Increases complexity
Reasoning Markers	Phrases like "step by step", "think through"	Triggers REASONING tier
Technical Terms	Words like architecture, distributed	Increases complexity
Simple Indicators	Phrases like "what is", "define", "hello"	Decreases complexity
Multi-Step Patterns	Patterns like "first...then", numbered steps	Increases complexity
Question Complexity	Multiple question marks	Increases complexity

The weighted score maps to a tier: SIMPLE, MEDIUM, COMPLEX, or REASONING. Each tier routes to a different model.

Special rule: If 2 or more reasoning markers are detected, the request automatically routes to the REASONING tier regardless of the overall score.

Tier Model Requirements

All models referenced in the tiers config must:

1. Exist as separate model_name entries in your LiteLLM proxy's model list.
2. Support tool/function calling if you are using OpenCode (OpenCode relies on tools for file operations, search, etc.). Models without tool support will fail on simple tasks.

Troubleshooting

Toast shows the router alias instead of the actual model

If you see the alias (e.g. smart-router) instead of the actual model name (e.g. gpt-4o-mini), the AI SDK may not be passing through the response model field. In this case, the actual model can be found:

• In the LiteLLM dashboard under Logs
• In the x-litellm-model-id response header
• By enabling verbose logging: set LITELLM_LOG=DEBUG on your proxy

No toast appears

• Ensure the plugin file is in the correct directory (.opencode/plugins/ or ~/.config/opencode/plugins/)
• Restart OpenCode after adding the plugin
• Check that the file exports the plugin correctly

"Unmapped LLM provider" error

You are likely sending the raw model name (auto_router/complexity_router) instead of the model alias (smart-router). Update your OpenCode model config to use the model_name from your LiteLLM proxy.

Simple queries fail to use tools

Your SIMPLE tier model may not support function/tool calling. Replace it with a model that does (e.g. gpt-4o-mini, claude-haiku, gemini-flash).

Cost Tracking

Because the complexity router dynamically selects different models with different costs, OpenCode cannot accurately track per-request costs. For cost visibility:

• Use the LiteLLM dashboard spend tracking, which knows the actual model per request.
• The x-litellm-response-cost response header contains the cost for each request.
• Query the /spend/logs API for detailed breakdowns by team, key, or model.

Publishing to npm

This package is published at npmjs.com/package/opencode-routed-model.

To publish an update:

1. Make your changes in src/index.ts
2. Bump the version in package.json (follow semver: patch for bug fixes, minor for new features)
3. Run:

npm publish

The prepublishOnly script automatically compiles TypeScript to dist/ before publishing. You do not need to run the build step manually.

You must be logged in to npm (npm login) and have publish access to the package.

License

MIT