I am trying to integrate an external app with Canvas via LTI. I was able to quickly use LTI to handle teacher assignment creation and student assignment launches. However, I'm stumped on how a teacher could launch my external app in order to view a particular assignment/student submission. The closest I've come is passing my LTI URL back to the outcomes URL (via 'ltiLaunchUrl') when a student completes an assignment. This prompts the Speed Grader to launch an LTI request to my app when a student session is selected. However, this LTI request does not contain the student id, assignment ID or the 'lis_result_sourcedid', so my app is unable to determine which student is being graded.
Am I just looking in the wrong place? Is there some way to get Canvas to launch my external app so that an educator can review a particular student assignment submission? Any feedback much appreciated!