MCP update_dashboard tool cannot set dashboard owners

[guilleov]

Summary

The MCP update_dashboard tool can edit a dashboard's title, description, slug, published flag, tags, CSS, layout and json_metadata, but it has no way to set the dashboard's owners, and no other MCP tool sets owners either.

Why this matters

A dashboard created through the MCP (generate_dashboard) is owned only by the MCP agent's user. Since an unpublished dashboard is visible only to its owners, the human who drove the agent cannot see or manage their own newly created dashboard, and no MCP client can transfer ownership to them. Today the only workarounds are the Superset UI or direct metadata-DB access.

Proposed change

Add an optional owners field (full-replacement list of user IDs) to the existing update_dashboard tool, mirroring the REST dashboard owners semantics:

• unknown user IDs are rejected up front with a clear OwnersNotFound error,
• an empty list clears owners,
• omitting the field leaves owners unchanged.

Editorship remains enforced via raise_for_editorship, so only current owners or an Admin can change owners (same guarantee as the REST PUT).

Additional context

Small, self-contained enhancement to an existing tool (not a new tool / not SIP-scope). PR to follow and will link back here.

[guilleov]

PR opened: #42002 (adds an owners field to the update_dashboard MCP tool as proposed above).