codex-ollama-protocol-bridge

Codex-Ollama Protocol Bridge

Lightweight protocol translation proxy enabling local Ollama models to use Codex CLI tools.

The Problem

Codex CLI v0.130.0+ supports local models via --oss --local-provider ollama. However, Ollama's /v1/responses endpoint (used by Codex) does not properly handle tool-calling with local models — all tool calls fail with unsupported call errors.

The same models produce correct tool_calls through Ollama's /v1/chat/completions endpoint. This bridge performs the protocol translation.

Codex → /v1/responses → [Bridge :11434] → /v1/chat/completions → Ollama :11433
                        ← SSE events ←                    ← JSON response ←

Quick Start

# 1. Start Ollama on port 11433
OLLAMA_HOST="127.0.0.1:11433" ollama serve

# 2. Start the bridge
python3 proxy.py

# 3. Use Codex with any local model
codex --oss --local-provider ollama -m qwen3:14b

Installation

# Clone or copy proxy.py
cp proxy.py /usr/local/bin/codex-bridge
chmod +x /usr/local/bin/codex-bridge

# Deploy as macOS daemon (auto-start on boot)
cp com.x.codex-bridge.plist ~/Library/LaunchAgents/
launchctl load -w ~/Library/LaunchAgents/com.x.codex-bridge.plist

# Or use the control script
./codex-bridge-ctl.sh start

Usage

python3 proxy.py [--listen-port 11434] [--ollama-url http://localhost:11433]
                 [--debug] [--quiet] [--version]

How It Works

Three Core Transformations

1. Request Format Translation — /v1/responses → /v1/chat/completions

   • input → messages[]
   • instructions → system message with tool-use directives
   • stream: true → stream: false (synthesize SSE ourselves)

2. Tool Schema Simplification — Reduce 4,100 tokens → ~800 tokens

   • Strip Codex's internal tools to essential parameters only
   • Codex fills in defaults for omitted params
   • 5× reduction dramatically improves local model accuracy

3. SSE Event Synthesis — Non-streaming JSON → SSE event stream

   • response.created → in_progress → output_item.added → ... → completed
   • Proper output_index for multi-output responses
   • Usage field normalization (prompt_tokens → input_tokens)

Supported Tools

Model Compatibility

Codex Aliases

Add to ~/.zshrc:

# Flagship: qwen3:14b with tool calling
alias cx14='codex --oss --local-provider ollama -m qwen3:14b'
alias cx14e='codex exec --skip-git-repo-check --oss --local-provider ollama -m qwen3:14b'

# Lightweight: huihui4-8b-a4b MoE
alias cxhu='codex --oss --local-provider ollama -m huihui4-8b-a4b:latest'

# Health check
alias codex-health='bash ~/ai-assets/commands/codex-health.sh'

Project Structure

codex-proxy/
├── proxy.py                     # Protocol bridge (807 lines, v1.1.0)
├── README.md                    # This file
├── LICENSE                      # MIT
├── codex-bridge-ctl.sh          # Service control script
├── com.x.codex-bridge.plist     # macOS launchd config
└── paper/
    ├── technical-report.md      # Full technical report (English)
    ├── technical-report-zh.md   # Full technical report (Chinese)
    ├── paper.tex                # LaTeX preprint (arXiv-ready)
    ├── paper.pdf                # Compiled PDF
    └── arxiv-submit.zip         # arXiv submission package

Paper

See paper/technical-report.md for the full academic paper, or paper/technical-report-zh.md for the Chinese version.

@misc{xuanyuan2026ptb,
  title={Lightweight Protocol-Translation Bridges for Heterogeneous
         LLM Tool-Calling APIs},
  author={xuanyuan},
  year={2026},
  note={Technical Report. Code: /Users/x/ai-assets/codex-proxy}
}

Development

Running Tests

Manual end-to-end test:

# Terminal 1: Start Ollama
OLLAMA_HOST="127.0.0.1:11433" ollama serve

# Terminal 2: Start bridge with debug logging
python3 proxy.py --debug

# Terminal 3: Test with Codex
codex exec --skip-git-repo-check --ephemeral --oss \
  --local-provider ollama -m huihui4-8b-a4b:latest \
  "list files in /tmp"

Debugging

# Check bridge health
curl http://127.0.0.1:11434/__health

# Test /v1/responses translation directly
curl -X POST http://127.0.0.1:11434/v1/responses \
  -H "Content-Type: application/json" \
  -d '{"model":"huihui4-8b-a4b:latest","input":"ls /tmp","stream":false,...}'

# View logs
codex-bridge-ctl.sh logs

License

MIT — see LICENSE file.

Related Work

• LiteLLM — Universal LLM proxy
• vLLM — OpenAI-compatible server
• Ollama — Local LLM inference
• Codex CLI — OpenAI coding agent

Citation

If you use this work, please cite:

@misc{xuanyuan2026ptb,
  title={Lightweight Protocol-Translation Bridges for Heterogeneous
         LLM Tool-Calling APIs: A Case Study on Codex-Ollama Interoperation},
  author={xuanyuan},
  year={2026},
  note={Technical Report v1.0}
}