---
title: {{title}}
status: needs-review
type: concept
last_reviewed: {{date}}
---

# {{title}}

## In plain terms

{{summary}}

<!-- What this concept is and why it matters across features. A few sentences, no jargon. -->

## Design approach

{{description}}

<!-- The model and why it is shaped this way, at role level. No identifiers or counts — that is
     mechanism and it lives in the code. Would it survive a rename-everything refactor? -->

## Invariants & boundaries

<!-- What must always hold or is forbidden across the features that use this concept.
     Link each to the test that enforces it, or mark it "untested". -->

## Decisions

<!-- Pointers to ADRs (docs/architecture/decisions/). The durable why; reference, never restate. -->

## Key files

- `{{source}}` — {{file_description}}

<!-- One line of narrative ROLE per file. The registry holds the exact list. -->