Pricing
00
In productionbeginnerAI code review

The AI's publisher connects to nothing

Fix the QoS the LLM left off so the sensor publisher matches its subscriber.

Pairs with Prompting an LLM for correct ROS 2 in Use AI efficiently with ROS 2. Read the concept first, then diagnose it here.

Open repair workspace

Operator report

The generated publisher runs, but `ros2 topic info --verbose` shows 0 matched subscriptions on /scan.

Ubuntu 24.04, ROS 2 Jazzy, rclpy/rclcpp, an LLM coding assistant + MCP

01

System boundary

Trace only the relevant path.

3 nodes
  1. 01LLM-generated publisher→
  2. 02QoS profile→
  3. 03sensor subscriberOUT
02

How this lab works

You diagnose it. No command list.

Open the repair workspace and gather your own evidence in a real terminal. No diagnostic commands are handed to you - finding the fault is the exercise. Stuck? Progressive hints unlock inside the workspace.

03

Verification

Pass more than the visible symptom.

4 checks
  • QoS matches the subscriber
  • Data is received
  • Hidden regression behavior
  • Root cause explanation