ROS Message Evidence Refresher

This bridge assumes you already know ROS 2 topics and message interfaces from ros2-for-students.

The task here is to read runtime evidence precisely. For a topic, record:

• topic name;
• message type;
• relevant fields and units;
• publisher/subscriber evidence;
• one observed or supplied value;
• timestamp or freshness context when available.

A message type describes a contract. It does not prove a publisher is active. One observed message proves one observation, not continuous health.

Checkpoint

Build a compact message evidence record and state one claim the interface proves, one the runtime observation proves, and one neither proves.