UC-002 Open a delegated account

Overview	Requirements	Analysis	Design	Implementation	Tests
Use cases	Requirements	Analysis	Design	Implementation	Tests

Use-case information

Field	Value
Actor	Authorised user
Package	Sessions
Goal	Work inside an account the user is delegated, and leave it.
Type	Primary, essential
Level	User goal
Requirement	RF-003, RF-004
Domain entities	Delegation, AuthorisedUser, DelegatedAccount, DelegatedSession, SessionPermission

Context

The authorised user needs to see or do something as another person. The plugin lets them do it through Moodle’s own login-as, but only while the delegation is valid, and it keeps checking.

Preconditions

• The user is signed in, active, and a site administrator or holder of local/delegateaccount:use.
• An active delegation exists from the user to the account.

Postconditions

• Success: the user works as the account; Moodle’s log records every action under both names; the session is marked with its delegation.
• Failure: the user stays in their own account and sees why access was refused.

Main flow

Step	Actor	System
1	Opens Delegated accounts in the user menu.	Lists the accounts the user may open, from their active delegations.
2	Chooses an account.	Re-checks the use right, the delegation, the state of the account and the administrator protection.
3		Starts Moodle’s login-as, marks $SESSION with the delegation id and applies the session permissions.
4	Works in the account.	On each request verifies the delegation and re-applies the permissions.
5	Chooses Return to my account.	Ends the login-as session.

Alternative flows

ID	Starts at step	Condition	Behaviour	Ends
A1	2	The user is not allowed or the delegation does not exist.	Refuses with error_unauthorised.	End
A2	2	The account is deleted, suspended or the guest.	Refuses with error_targetunavailable.	End
A3	2	The account is a site administrator and the protection is on.	Refuses with error_privilegedtarget.	End
A4	4	The delegation is revoked, expires or the account is suspended.	Logs the user out and explains why on the login page.	End

Business rules

ID	Rule
RN-003	Access is checked every time.
RN-004	Administrators are protected by default.
RN-006	A session that stops being valid is ended.

Specification

Behaviour source of truth: specification.puml

Wireframes