[Docs] Clarify permission limitations of "User Light" accounts changing Space member permissions back to "Manage" #1243

Summary

The documentation does not clearly explain that User Light accounts cannot change another member's Space permission back to Manage, even if the acting User Light account itself currently holds Manage permission on that Space. This leads to a confusing and potentially unrecoverable permission lockout scenario that should be explicitly documented.

Additionally, the error message shown when this fails is not helpful and should be improved (or at minimum, documented so users can self-diagnose).

Scenario / Steps to Reproduce

1. User A (Admin) creates a Space.
2. User A adds User B and User C and sets both to Manage permission (so they can add/manage other members).
3. User A leaves the Space.
4. User B accidentally changes their own permission from Manage to Can view.
5. User C (still has Manage permission) tries to set User B's permission back to Manage.

Actual Behavior

User C is not able to restore User B's permission to Manage, because User C is a User Light account, and this account type lacks the capability to assign the Manage permission to other members — even though User C's own Space permission is currently Manage.

Since User A has left the Space, there is no remaining full User/Admin account in the Space, resulting in a lockout: no one can restore Manage permission to anyone.

Unhelpful error message

When User C attempts the role change, the UI only shows something like:

X-Permission ... please contact admin

This error message:

• Does not explain what permission is missing or why the action failed.
• Does not explain that the cause is the account type (User Light) rather than a lack of Space-level permission.
• Tells the user to "contact admin" — but in this scenario, there is no admin left in the Space to contact, which is itself confusing and unhelpful. It's also not clear whether this means "contact your instance Admin" vs. "contact the Space's Manage-level member."

Expected Behavior / Documentation Gap

This may be intended behavior (a limitation of the User Light account type), but it is currently not documented that:

• User Light accounts cannot grant the Manage permission to other members, regardless of their own current Space permission level.
• This limitation can result in a permanent lockout if no full User/Admin account remains in the Space.
• The resulting error message (X-Permission, "please contact admin") is generic/unclear and does not point users toward the actual cause or a solution.

Suggested Documentation Changes

1. Add a clear note in the Space permissions documentation and the User Light account documentation:

   "User Light accounts cannot assign the Manage permission to other Space members, even if they themselves currently have Manage permission."

2. Add a best-practice warning recommending at least one full User/Admin account remain a member of the Space to avoid this lockout scenario.

3. Document whether there is any recovery path (e.g., Admin override, support/CLI tooling) for restoring Manage permission in a Space with only User Light members left.

4. Document the known error message (X-Permission / "please contact admin") in a troubleshooting section, explaining:

   • What it actually means (acting account is User Light and lacks capability to grant Manage permission).
   • Who "admin" refers to in this context (instance Admin, not just a Space member with Manage permission).
   • What steps to take to resolve it (e.g., ask an instance Admin to rejoin the Space and fix permissions).

Suggested Product/Error-Message Improvement (optional, for consideration beyond docs)

While this issue is primarily about documentation, it's worth flagging to the product/engineering team that the error message itself should ideally be improved to be actionable, e.g.:

"Your account type (User Light) cannot grant Manage permission to other members. Please ask an instance Admin to make this change."

This would reduce the need for users to consult documentation at all. If an error-message fix is out of scope for this docs issue, consider filing a separate product/UX issue and cross-linking it here.

Additional Context

This distinction between User Light and full User/Admin accounts isn't obvious in the UI — both appear simply as having "Manage" permission on the Space — making this an easy trap to fall into. Combined with a vague error message, affected users currently have no clear way to understand what happened or how to fix it without filing a support ticket.