Delegation

discendo-sdk/delegation allows instructors and administrators to delegate specific, granular permissions to a Teaching Assistant (TA) in a single course section and revoke them at any time.

By default, TAs have baseline permissions (viewing rosters, grading, taking attendance). Delegation allows course instructors to customize TA capabilities—such as granting the ability to post announcements or manage content—without altering global security policies.

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At a Glance

Import	import { DelegationService, ActionNotDelegableError, NotAnActiveTaError } from 'discendo-sdk/delegation'
Repositories	DelegationRepository (in RepositoryContext), plus users, courses, enrollments
Events	delegation.granted, delegation.revoked
Permissions	delegation.grant, delegation.revoke, delegation.view
Enforcement	Always on: Every method requires an { actorId } and a configured policy.

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Data Model (TaGrant)

interface TaGrant {
  id: Id;
  enrollmentId: Id; // Tied to the TA's section enrollment, NOT user ID
  sectionId: Id;
  action: string; // e.g. 'content.manage'
  grantedBy: Id; // Instructor or admin who created the grant
  grantedAt: Timestamp;
  revokedAt?: Timestamp; // Set when revoked (never deleted)
}

Key Behavioral Principles:

1. Grants attach to enrollments, not users: A grant is tied to enrollmentId. If a TA drops and re-enrolls, their new enrollment is a fresh record with zero grants.
2. Permissions never grow downwards: An instructor can only delegate permissions they personally hold in that section. TAs cannot delegate permissions to others.
3. Only designated actions are delegable: An action must declare delegable: true in DEFAULT_RULES.

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Delegable Actions

Delegable Action	Capability Granted to the TA
content.manage	Create, edit, publish, and reorder course content
communication.postAnnouncement	Post section-wide announcements to students
enrollment.enroll	Enroll new students (also requires enrollment.grantRole.student)
enrollment.grantRole.student	Grant the student role
assessment.recordOffline	Record in-class or manual submissions for students
grading.grantExtension	Grant deadline time extensions to students
grading.excuse	Excuse a student from an assignment
scheduling.manageOccurrence	Reschedule or cancel specific class meetings
scheduling.recordAttendance	Take attendance for scheduled meetings
reporting.recordAttendance	Record attendance through the reporting service

Non-delegable actions

Actions like enrollment.bulkEnroll, enrollment.promoteWaitlist, enrollment.reviewRequest, and granting staff roles (instructor, admin) can never be delegated.

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DelegationService

new DelegationService(
  repos: RepositoryContext,
  options: {
    policy: PermissionPolicy
    delegableActions?: string[]
    events?: EventBus
  }
)

grant(sectionId, taUserId, action, actor): Promise<TaGrant>

Grants a privilege to an active TA:

const grant = await delegation.grant(
  "sec-101",
  "u-ta-bob",
  "communication.postAnnouncement",
  { actorId: "u-prof" },
);

• Verifies that the actor has delegation.grant permission in the section.
• Verifies that the target user is currently an active TA in that section (throws NotAnActiveTaError otherwise).
• Verifies that action is delegable (throws ActionNotDelegableError otherwise).
• Idempotent: If an active grant already exists for that action, the existing grant is returned.
• Emits delegation.granted.

revoke(grantId, actor): Promise<TaGrant>

Revokes an existing grant:

await delegation.revoke(grant.id, { actorId: "u-prof" });

• Sets revokedAt: new Date(). The record is preserved for auditing.
• Emits delegation.revoked.

listActiveForTa(sectionId, taUserId, actor): Promise<TaGrant[]>

Lists all active grants held by a TA in a section.

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Errors

Error	Cause
NotAnActiveTaError	Target user is not currently enrolled as an active TA in the section.
ActionNotDelegableError	The requested action cannot be delegated to a TA.
PermissionDeniedError	Actor lacks permission or does not hold the action themselves.

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Known Limitations

• Section scope only: Grants cannot be created account-wide or course-wide; they are strictly section-scoped.
• No expiration timestamps: Grants remain active until explicitly revoked or until the TA's enrollment ends.