The Submission object

{
  "id": "sub_01HX9N5AB3...",
  "object": "submission",
  "assignment_id": "asg_01HX9...",
  "student_id": "usr_01HX9...",
  "content": { "text": "Lorentz invariance means that the laws of physics..." },
  "files": [
    { "id": "fil_01HX9...", "name": "essay.pdf", "size": 124300, "url": "https://..." }
  ],
  "grade_ai": 8.5,
  "grade_manual": null,
  "final_grade": null,
  "grading_rationale": "## Clarity (4/4)\nThe student opens with...",
  "grading_breakdown": [
    { "criterion": "clarity",  "score": 4, "max": 4 },
    { "criterion": "accuracy", "score": 3, "max": 4 },
    { "criterion": "sources",  "score": 1.5, "max": 2 }
  ],
  "grader_comments": null,
  "human_review_status": "pending",
  "ai_status": "ready",
  "evaluated_at": "2026-05-10T12:34:56Z",
  "uploaded_at": "2026-05-10T12:30:00Z"
}