Report progress with curl
Set $SPACE_UUID in your shell first, or
create a space
and come back through the Connect menu to get it filled in.
Create a task, keep its uuid.
Report progress. Every write replaces the whole state — send all of it each time.
Finish it. This is what sends the notification.
The whole API as OpenAPI 3.1, if you would rather generate a client than write one. Same document at /openapi.yml.