plano/demos/llm_routing/codex_router

Codex Router - Multi-Model Access with Intelligent Routing

Plano extends Codex to access multiple LLM providers through a single interface and route coding requests to the best configured model.

Benefits

• Single Interface: Use Codex while routing through Plano
• Task-Aware Routing: Route requests based on coding task intent
• Provider Flexibility: Mix OpenAI, Anthropic, and local models behind one endpoint
• Routing Transparency: Inspect exactly which model served each request

How It Works

Plano sits between Codex and configured providers:

Your Request -> Codex -> Plano -> Selected Model -> Response

Quick Start

Prerequisites

# Install Codex CLI
npm install -g @openai/codex

# Ensure Docker is running
docker --version

1) Enter this demo directory

cd demos/llm_routing/codex_router

2) Set API keys

export OPENAI_API_KEY="your-openai-key-here"
export ANTHROPIC_API_KEY="your-anthropic-key-here"

3) Start Plano

# Install with uv (recommended)
uv tool install planoai
planoai up

# Or if already installed with uv
uvx planoai up

4) Launch Codex through Plano

planoai cli-agent codex
# Or if installed with uv:
uvx planoai cli-agent codex

The Codex launcher integration configures:

OPENAI_BASE_URL=http://127.0.0.1:12000/v1
OPENAI_API_KEY=test

If arch.codex.default exists in model_aliases, planoai cli-agent codex automatically starts Codex with:

codex -m arch.codex.default

Monitor Routing Decisions

In a second terminal:

sh pretty_model_resolution.sh

This prints MODEL_RESOLUTION lines so you can see request model -> resolved model mappings in real time.

Advanced Usage

Override Codex model for a session

planoai cli-agent codex --settings='{"CODEX_MODEL":"openai/gpt-4.1-2025-04-14"}'

Context window guidance

Codex works best with a large context window. Use models/configuration that support at least 64k context when possible.

Notes

• Plano's default: true model is only used when a client request does not specify a model.
• If Codex sends an explicit model in requests, aliasing/routing rules decide the final upstream model.