A comprehension check is a lightweight verification that the person responsible for a change genuinely understands it. Rather than asking "did the tests pass," it asks "can you explain what this does, why it is written this way, and how it might break" — tied to the specific diff in front of the engineer.
Its purpose is to catch understanding debt at the moment it would otherwise form. When an AI tool generates code, the check turns the end of that session into a brief learning moment: the engineer confirms their mental model against the actual change, and any gap becomes visible while it is still cheap to close. Because each check is anchored to real code the engineer just shipped, it measures comprehension against evidence instead of self-report.
Done well, comprehension checks are fast and formative, not a gate that punishes. Their aggregate output feeds an engineer's knowledge map — deepening demonstrated mastery where understanding holds up, and flagging concepts the team is routing around. This is the primitive that turns everyday AI-assisted shipping into a signal for where learning is needed.