A material may be private: only its author and the users it is shared
with see it. Every student read (list, detail, course detail and
counters, the checklist linked material, the token twins) goes through
one visibility fragment. Existing materials stay public with no author.
GET/PUT /_bm/api/v1/materials/{id}/access let the author, a material
manager, toggle the flag and pick the users; the first change of an
author-less material makes the caller its author.
Per-user checklists with items that may link a course, reading, deadline,
material or own presentation deck. An item with a reading shares the
reading's read mark. Student API routes with token twins, MCP tools,
migrations, tests and README.
