diff --git a/README.md b/README.md
index 53c0fed..75b1813 100644
--- a/README.md
+++ b/README.md
@@ -500,7 +500,15 @@ Layout:
   `/atom.xml`. After a deploy, `web/scripts/publish.sh` writes one
   `site.standard.document` record per post (config in `web/sequoia.json`)
   and writes each record's at:// URI back into the post's frontmatter,
-  which renders as a `rel="site.standard.document"` link tag. Tests:
+  which renders as a `rel="site.standard.document"` link tag. `/architecture`
+  is the audit page: the extension's contexts, the calls each one makes, and
+  what is stored where, around a diagram whose source is
+  `web/src/diagrams/architecture.mmd`. The site's CSP has no `unsafe-inline`,
+  so Mermaid cannot run in the browser; `npm --prefix web run diagram` renders
+  it to `architecture.svg` in a local Chrome and strips the CSS the CSP would
+  drop, leaving the page's own `.diagram` rules in `global.css` to supply the
+  colors and the light/dark theme. Editing either the `.mmd` or the render
+  script re-renders the SVG in place, like the brand assets below. Tests:
   `npm --prefix web test`.
 - `infra/` — OpenTofu for the frontpage and metadata hosting
 - `brand/` — canonical logo SVGs (`mark.svg`, `sticker.svg`, plus
diff --git a/TODO.md b/TODO.md
index 0bc29b1..7b58644 100644
--- a/TODO.md
+++ b/TODO.md
@@ -160,6 +160,12 @@ behaviour is a takedown risk, not a paperwork one. The privacy policy itself
 now describes the per-site check and the ecosystem lookups; this is the other
 copy of those claims, and the two should not drift apart.
 
+There is now a third copy: `/architecture` names each caller, each host and
+each stored item, and is the version a reviewer can check against the source.
+It is the most specific of the three, so it is the one that goes stale first —
+when a network call is added or removed, `web/src/diagrams/architecture.mmd`
+and the tables in `web/src/pages/architecture.astro` need the same edit.
+
 ## Decide what to do about the 843 kB popup chunk
 
 `dist/chunks/oauth-*.js` is 843 kB (169 kB gzipped) against a 34 kB popup,