T4-W05 Attendance Identity Contract¶

Same attendance occurrence¶

Canonical identity:

op.attendance.sheet  := unique(register_id, session_id, attendance_date)  # SQL
operational lookup   := (session_id, attendance_date)                      # soft find
op.attendance.line   := unique(student_id, attendance_id, attendance_date) # SQL

For Core W05 per-lesson Product API:

One sheet per op.session per school-local attendance date.
One line per student per sheet.
Multiple subject/session sheets on the same calendar day are allowed (different session_id).

Duplicate / retry semantics¶

Faculty session-sheet/save and admin sheet/create are upserts:

Existing sheet for session+date is reused.
Existing line for student+sheet is writen; otherwise create.
Rapid retry / double-click must not create a second canonical line (SQL unique + upsert).

Class change¶

Lines remain bound to the sheet’s session/batch at write time. Moving a student to another batch later does not auto-rewrite historical lines; new sessions use the new roster membership check.

Daily / smart / RFID¶

Out of this contract. Daily arrival-departure uses the same op.attendance.line model with attendance_scope=arrival_departure but is not W05 cert SSOT.