Introduction: What Are Autonomous Coding Agents?

Autonomous coding agents can:

• Plan multi-step tasks

• Write, execute, and debug code

• Use external tools and simulate environments

• Interact with files, the web, and user prompts

Qwen3-Coder—paired with Cline act mode—offers the most agentic open-source toolkit for building such systems.

This post guides you through building real autonomous developer agents using Qwen3-Coder and Cline, with no proprietary APIs or cloud dependencies.

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1. Tools You'll Use

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2. Setting Up Your Agent

Clone the Qwen Agent Repo:

bash
git clone https://github.com/QwenLM/Qwen-Agent.git
cd Qwen-Agent
pip install -r requirements.txt

Run CLI with Qwen3-Coder:

bash
python cli.py --model Qwen3-Coder-480B-A35B-Instruct

Use vLLM or DeepSpeed-MoE if running on GPU clusters

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3. What Is Cline [act mode]?

Cline is a browser/agent interface where Qwen3-Coder operates in "act" mode — meaning it:

• Thinks and plans tasks

• Writes and executes code blocks (e.g., JS, canvas logic)

• Updates output or canvas in real time

• Adjusts based on user feedback

It’s perfect for building agents that simulate, visualize, and interact with users autonomously.

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4. Prompting Your Agent

Here’s a sample agentic prompt:

“Simulate a solar system with 5 planets orbiting a sun using canvas and JavaScript. Include gravitational pull and mouse to rotate view.”

Qwen3-Coder will:

1. Write HTML + canvas boilerplate

2. Add JS animation loop

3. Integrate orbital physics

4. Suggest enhancements (like speed control)

You can edit and re-prompt in real-time to refine behavior.

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5. Agent Use Cases in Cline

Each project is fully generated and controlled by the agent using a single prompt and minimal edits.

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6. Multi-Step Reasoning Example

Prompt:

“Build a JavaScript app that lets me draw on a canvas, then click a button to download the image as PNG.”

Agent Actions:

1. Plan components: canvas, draw logic, button, export function

2. Generate HTML/JS with canvas.toDataURL()

3. Bind button to download() function

4. Ask for confirmation, then refine

The agent thinks step-by-step, even without explicit instructions.

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7. Using Local Tools and Files

Qwen3-Coder agents can:

• Read file content

• Write Python scripts

• Execute shell commands

• Simulate tool workflows (e.g., ffmpeg, curl, make)

For advanced CLI tasks, combine with tool_api.py to sandbox I/O.

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8. Why Qwen3-Coder Outperforms Others

Qwen3-Coder is purpose-built for building autonomous developer tools — including full-stack workflows.

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Conclusion: Build, Test, Iterate — Agentically

With Qwen3-Coder + Cline:

• Your LLM becomes a developer assistant

• You can deploy full coding workflows with real logic + UI

• Your agents can simulate, plan, and act — all in one interface

It’s agentic development without black boxes or cloud restrictions.

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Resources

• Qwen3-Coder on Hugging Face

• GitHub – Qwen Agent CLI

• Try Cline & Web Dev Mode

• Qwen3 Use Cases & Demos