grader.probe_runtime

Code injected into the student's kernel after their notebook runs.

This module never runs on the grading host. Its source is appended to the notebook as extra cells (see executor.py), so it must:

• depend only on the standard library plus whatever the student imported,
• never raise into the student's namespace,
• describe objects rather than name them, because students do not use the solution's variable names (design.md §21),
• run the hidden test calls in-kernel so the tests never appear in the notebook the student receives (design.md §22).

Everything it produces is a JSON summary — no pickles leave the container.