explainlisted

The user asked you to explain something. Produce one self-contained HTML page a technical reader absorbs in a few minutes: - **Why** it exists: the motivation, the decisions, the rejected alternatives. - **How** it works: the architecture, the key mechanisms, the non-obvious parts. ## What the page is for Three ideas decide everything else. **It serves a mission.** The user asked for a reason - to review a change in that area, to debug something, to stop nodding along in a meeting. Infer the reason from how they asked. The mission decides what goes on the page, and what stays off it. Without a mission the page drifts into a generic overview of the subject, which is this skill's main failure mode. **It builds fluency, not retention.** The reader needs to hold the subject now. One read cannot build long-term recall. Do not pad the page with exercises to fake it. **It starts from what the reader knows.** Working memory is small. Anchor each mechanism to something already on the page, or already in the reader's hands: a familiar pattern, the layer above it, the thing it replaced. Then extend by one step. Five unanchored concepts explain nothing. ## Depth ELI5 in tone. Far past ELI5 in substance. Deliberately short of exhaustive. Calibrate to this: the reader can hold the subject, follow a conversation about it, and ask a sharp question. Not this: the reader can implement or maintain it. Give one concrete win the reader gets immediately. They can review a change here, na