Members list API should include role

[mmanciop]

Context

The GET /api/members endpoint returns MemberDefinition objects that include kind, metadata (with dash0.com/id), and spec (with display fields like email, firstName, lastName).

However, the response does not include the member's role (e.g., admin, basic_member).

Request

Include the member's role in the MemberDefinition response, either as a field in MemberSpec or as a label in MemberLabels.

This would allow the CLI (dash0 members list) and other consumers to display the role alongside name, email, and ID.

Current state

• InviteMemberRequest accepts a role field when inviting members.
• MemberDefinition does not return the role.