2026 July Complete Guide: Installing and Using Codex with GPT-5.6 in China

As AI programming enters the "agent era", Codex has evolved beyond a mere code completion tool to become an AI assistant that understands entire projects, modifies code, and autonomously executes tasks. With the release of GPT-5.6, Codex has made a critical leap—shifting from "writing code" to "handling engineering tasks". This guide will take you from zero to one in mastering how to install Codex in China, integrate GPT-5.6 Sol, Terra, and Luna, use cc-switch for stable access, and leverage Codex's core features for practical development.

Codex is an AI programming model and toolset provided by OpenAI, built on the GPT-5 series. It can understand natural language to generate, modify, and execute code. Beyond code generation, it offers project-level code comprehension, automatic code modification and refactoring, shell command execution, bug fixing, and automated task orchestration. In simple terms, Codex combines an AI programming model (GPT-5.x), a local execution agent, and a development toolchain. It is commonly used in forms like CLI (command line, most powerful), IDE plugins (Cursor/VS Code), desktop apps, and cloud-based modes.

GPT-5.6 is the most powerful general-purpose model in the Codex ecosystem, ideal for complex engineering tasks. Its core advantages include stronger code understanding, support for complex project reasoning, a larger context window (suitable for large codebases), and enhanced automation. For daily development, GPT-5.4 is recommended, while GPT-5.6-Sol is the go-to choice for complex tasks.

Using Codex in China boils down to three key steps: installing Codex, configuring the API key, and setting up a proxy (the most critical step). The stability of your access depends heavily on proper proxy configuration.

For CLI installation: First, ensure you have Node.js ≥22 and npm ≥10. Install Codex via npm with the command npm install -g @openai/codex; for China users, it's better to use the npmmirror registry: npm install -g @openai/codex --registry=https://registry.npmmirror.com. Verify the installation with codex --version. You can log in via ChatGPT (run codex and authorize in the browser) or API key (export OPENAI_API_KEY="sk-xxx" then run codex). To use GPT-5.6-sol, either specify it with codex --model gpt-5.6-sol or write it into the configuration file as model = "gpt-5.6-sol".

For stable access in China, using cc-switch is highly recommended. cc-switch is an AI interface management tool that handles API key management, base URL forwarding (proxy), multi-model switching, and local unified entry—essentially an AI gateway plus configuration manager. To install it: download the AppImage from its GitHub release (v3.17.0 for Linux x86_64), make it executable, and run it. Configure the proxy with your base URL, API key, and model (gpt-5.6-sol). Export these settings to Codex by setting OPENAI_API_KEY="sk-xxx" and OPENAI_BASE_URL="https://your-proxy-url/v1" environment variables, or write them into the configuration file. Verify by running codex and asking it to write a "hello world" program.

Core usage of Codex: Navigate to your project directory and run codex. Common commands include analyzing project structure, fixing bugs, refactoring modules, and generating features (like a Go user login system). Auto modes are available: Suggest (provides recommendations), Auto Edit (automatically modifies code), and Full Auto (completes tasks end-to-end).

Codex integrates with IDEs like VS Code, Cursor, and Windsurf. Install the Codex plugin, log in, and select GPT-5.6-sol to enjoy real-time code generation, project context understanding, and on-the-fly code modification.

The biggest value of Codex lies in its automation capabilities—not just writing code, but completing entire development tasks. For example, if you ask it to create a Golang payment system, Codex will automatically set up the project structure, write code, install dependencies, and run tests.

A practical development flow with Codex includes: initializing a Go microservice project with Redis and MySQL; developing user systems and login interfaces; debugging to fix all errors; and optimizing performance. The end result? A single person using Codex can function like an entire development team.

Common issues: Connection failures often stem from network problems or missing proxy configuration—use cc-switch to resolve this. For quota issues, mix GPT-5.4 and GPT-5.6, and control the context window size. For Linux systems without a GUI, use the CLI directly.

Codex and GPT-5.6 are transforming software development: from writing code to describing requirements, from being a tool to an execution agent, and from manual development to automation. The future of development will see humans focusing on thinking, while AI handles implementation.

Sources

• Tencent Cloud Developer Article: https://cloud.tencent.com/developer/article/2708873