LTI Advantage Mapping

Intent

Define how LTI 1.3/LTI Advantage interactions map to internal identity, membership, offering, and grading semantics.

Scope

Initial mapping coverage:

• OIDC launch identity resolution
• Roles claim to membership role mapping
• Context claim to offering/container mapping
• Assignment and grade service linkage
• Competency alignment context propagation for standards projections

Core Mapping Matrix

LTI concept	Internal concept	Notes
sub + platform issuer	identity_binding -> person	External identity binding with validity and provenance
roles claim	offering_membership.membership_role	Role normalization table required
context claim	offering (or learning_container)	Context boundaries map to delivery unit
resource link	learning_unit or assessment_definition	Depends on launch target semantics
NRPS roster	membership import/update flow	Feeds organization and offering memberships
AGS line items/results	assessment score publication	Requires attempt/score provenance
line item metadata/extensions	competency alignment references	Optional bridge from assignment context to competency nodes

Role Normalization

LTI roles should normalize into internal role vocabulary:

• Learner-like roles -> learner
• Instructor-like roles -> teacher
• Teaching assistant roles -> assistant
• Observer/mentor roles -> observer or mentor

All normalized mappings must preserve original role claims for audit.

Launch Flow Notes

1. Resolve platform issuer and client registration
2. Validate OIDC token and nonce
3. Resolve or create identity_binding
4. Resolve canonical person identity
5. Resolve offering context
6. Create/update membership with temporal semantics
7. Emit audit and activity events

Grade Flow Notes

When publishing grades via AGS:

• Grade result should reference internal assessment attempt and score version
• Publication state should be explicit (queued, published, failed)
• Retries must be idempotent per line item and attempt outcome

Security and Traceability Requirements

• Store token provenance metadata required for audit
• Keep mapping between external context IDs and internal offering IDs
• Record claim snapshots for debugging and conformance validation

Open Decisions

1. Multi-platform identity merge policy for the same human person
2. Conflict policy when LTI role claim disagrees with local authorization grants
3. Synchronization timing strategy for NRPS imports (on launch vs scheduled)