zenoh-pico endpoint over serial not visible when router uses exported session config

[Oussama-Dallali99]

I'm debugging a Zenoh setup with the following architecture:

A Zenoh router running on the robot
An MCU connected via serial link using zenoh-pico
A session config exported before launching the robot's navigation stack to add a namespace

Current behavior:

Some key expressions (e.g., tf) appear correctly namespaced, confirming the session config is partially working
Data originating from the firmware does not appear at all and is non-functional
This suggests the zenoh-pico endpoint is either not joining the same Zenoh session or not being correctly bridged through the router

Context:
In this setup, ROS 2 launch-based namespacing is not an option, so I'm relying on exported Zenoh session configuration to introduce namespacing for the robot.
Questions:

Is using an exported Zenoh session configuration the appropriate way to namespace a robot in Zenoh-based systems?
What components need to be configured or verified to ensure all endpoints (including zenoh-pico) participate correctly in the same session?
Are there specific considerations for zenoh-pico endpoints connected via serial that might prevent them from respecting the session namespace?

Any guidance on troubleshooting this setup or alternative approaches would be greatly appreciated.

[JEnoch]

The namespace configuration in Zenoh prepends this namespace to all key expressions declared by the Session. When another Session is configured with the same namespace, it's automatically removed from the key expr and your application communicate with the remote Session as if there is no namespace.
The namespace configuration has no effect on a router which is not declaring any key expressions but only routing them.

So using the Zenoh namespace would work only if all your Sessions are configuring it, including the zenoh-pico applications.
But as zenoh-pico doesn't have a namespace configuration, you need to prepend the namespace yourself in your application.

Also, be aware that the Zenoh namespace doesn't match with the expected position of ROS namespace in the current mapping made by rmw_zenoh and described here:

• https://github.com/ros2/rmw_zenoh/blob/8a0808e586a7b2a4fc50997f2cb25535c926f895/docs/design.md#topic-and-service-name-mapping-to-zenoh-key-expressions
• https://github.com/ros2/rmw_zenoh/blob/8a0808e586a7b2a4fc50997f2cb25535c926f895/docs/design.md#graph-cache

Meaning that a Zenoh namespace is really different than a ROS namespace and cannot be used as an equivalent.