what — explain the concepts, not the timeline

A session ends. The work is done and the summary is accurate, and you still cannot review the next PR in that area, because eight of the nouns were new. That gap does not close by re-reading the summary. It closes by someone naming the eight nouns and defining them.

Nothing else in the stack does this. Bridge (P1) records what happened. /handoff writes state for the next agent. /comprehend runs a multi-stage teach-to-mastery loop. /what is the fast one: the vocabulary of the last stretch of work, explained once, grounded in where it actually appeared.

The one rule

Concepts, not chronology.

If the answer reads "first I did X, then Y, then Z", it is a session log and it has failed. /what is organised by idea, ranked by what blocks understanding — never by what was hardest to build or said most often.