Export submissions via the Canvas GraphQL API

Verified steps

1. Authenticate identically to the REST API using a Bearer token in the Authorization header; the GraphQL endpoint is at /api/graphql on your Canvas instance (e.g., https://yourschool.instructure.com/api/graphql).
2. Query the course by its Canvas ID or by sis_course_id using the course(id:) field, then traverse assignmentsConnection to list assignments and their submissionsConnection to retrieve submission data.
3. Request pagination cursors in your query using the standard GraphQL Relay pagination pattern (first, after arguments on *Connection fields); the default page size is 20 and the maximum is 100 — use pageInfo { hasNextPage endCursor } to drive iteration.
4. In the submission objects, request fields such as submittedAt, score, grade, state, userId, and attachmentsConnection for file submissions; note that anonymous grading assignments return null for user-identifying fields while anonymization is active.
5. For large exports, use the REST API's GET /api/v1/courses/:course_id/students/submissions?student_ids[]=all endpoint as an alternative when GraphQL complexity limits are a concern; Canvas caps GraphQL query complexity at 375,000.
6. Parse and store the results; cursors are opaque strings and must be passed verbatim in the after argument — do not attempt to decode or construct them.