[Feature request] metadata and add tagging via topics

[ptulpen]

Hello,
I saw that there is the possibility to get the tags and metadata automaticaly scanned in the database
I tried this now with this method: http://wiki.ros.org/rosbag/Cookbook#Add_metadata_to_a_bag

rostopic echo -b 2022-04-06-17-09-38.bag -p /metadata/
%time,field.data
143901999998,vehicle: myvec
143901999998,name: John Doe
143901999998,mytag: whatever

But in the bagsever no medata or tags appear
Also it is not quite clear to me: can I update the metadata like in the api (vehicle, description, latitude, logitude ..) or does metadata in this case mean it gets to be any tag ?
if it means metadata: how do I need to name the keys?

[ptulpen]

The adding of tags worked after I deleted the database and created everything new (not sure what happened there)

[ptulpen]

What still could help: can the description and location also be passed via topics ? (similar to the VEHICLE_NAME)