Who launched

When your element is constructed, api already knows who opened the tool, from where, and into which location. These are plain properties — no calls, no waiting.

The person

api.userobject

The person who launched.

fields

idstring

Their Voshi user ID. Stable across every launch, every course, and every school: the same person is the same id next term and at another institution. Use it to recognize a returning user.

memberstring

Their membership in this course. A person has one id and one member per course they are in. Enrollment-specific state keys on this.

groupsstring[]

Their role groups in this course: student, instructor, assistant, manager, and occasionally mentor (an observer). Usually one.

given_name, family_name, full_name, emailstring | null

Present only for course staff. On a student launch all four are null — students are anonymous to your tool, by design. Never rely on a name being there.

api.groupsstring[]

The same list as api.user.groups, always an array.

api.isStaffboolean

true for an instructor, assistant, or manager launch. Staff can write all four storage scopes and should see your tool's setup and review features.

api.isStudentboolean

true for a student launch that is not also staff. Students can write only their own two storage scopes.

A mentor (an observer, watching a student's progress) is neither: both flags are false. Show a mentor what a student sees, without the student's actions — and never score one.

api.hasGroup(group)boolean

Whether the launched person holds group: api.hasGroup('assistant').

this.$('#setup-button').hidden = !this.api.isStaff
this.$('#submit-button').hidden = !(this.api.isStudent && this.api.canSubmitGrade)

The place

api.locationobject

Which of your locations this launch is for: { id, extid, type, label }. Switch on extid — it is your own identifier, exactly as you declared it. id is Voshi's; type and label are what was recorded when the link was placed.

api.courseobject

The course: { id, name, label }. name is its title ("Intro to Computing"), label its short code ("CS101").

api.contextstring

The course's ID, the same as api.course.id.

api.organizationobject

The school's side: { title, issuer, client, deployment }. title is the institution's name; the other three are Voshi IDs for the LMS installation your tool was launched from. Most tools only ever read title.

api.appstring

Your tool's ID — the one on the Settings tab.

api.launchIdstring

This launch's ID, one per visit. It matches the Launches tab in the dashboard.

Grading

api.canSubmitGradeboolean

Whether this launch has a gradebook column to report to: an assessment location that was placed through the Voshi deep linking dialog. When it is false, say nothing about grades at all. See Grades.

When a launch ends

A launch is one visit, and it does not last forever. It ends 12 hours after the tool's last call to Voshi — every save or read slides the clock forward, so a learner who is working stays launched for as long as they work — and at once when the tool is suspended, archived, or deleted, when the code the course runs is replaced, or when the learner is no longer in the course. After that no call succeeds: each throws a VoshiAuthenticationError.

Your tool does not have to notice. The first call Voshi refuses ends the launch: the frame is sent to a page that tells the learner the session has ended and to reopen the activity from the course, which closes your tool. What matters is that work is saved as the learner goes, not only at the end, so that nothing is lost when that happens.

To handle the end yourself instead — show your own notice, or keep an unsaved answer on screen — listen for the voshi-session-expired event on your element and prevent it. Every later call still fails, so the tool should stop trying to save:

constructor(api) {
    super()
    this.addEventListener('voshi-session-expired', event => {
        event.preventDefault()        // the frame stays on your tool
        this.showRelaunchNotice()
    })
}

The launch data's api.expires and api.idle say when the token would end if nothing else happened; a tool rarely needs them.

The whole launch

api.launch_dataobject

Everything Voshi sent, as received. The properties above cover what a tool needs; this is the escape hatch. Its fields are documented in the Launch Data reference — the same payload an externally hosted tool receives as a signed token. Your tool never needs the api, storage, files, grade, or version entries in it; those are what the client and the page already use on your behalf.

What a launch does not tell you

• Nothing in advance. Voshi does not announce a school, course, or student before they launch. The first launch is the first your tool hears of any of them.
• No LMS internals. Every ID is Voshi's own. There is no LMS user ID, course ID, or link ID in the launch.
• No history. A repeat launch looks like the first one. Recognize a returning learner by api.user.member and resume from what you saved in storage.