diff --git a/platform/wiki.mdx b/platform/wiki.mdx
index 838664e..b34f2b7 100644
--- a/platform/wiki.mdx
+++ b/platform/wiki.mdx
@@ -28,7 +28,7 @@ import HostedMcpCard from '/snippets/hosted-mcp-card.mdx';
     Open **Wiki** in the Console and choose a **Repository**.
   </Step>
   <Step title="Pick an article">
-    The **Articles** index lists every page. Use **Search pages** or **Find in the wiki** to jump to a topic.
+    The sidebar starts with **Overview**, then **Subsystems**, the main parts of the code, with each one's areas underneath. **Areas** that aren't part of a subsystem come next, production code first, then tests, vendored code, tooling, and docs. The **Glossary** comes last. Use **Search pages** to jump to a topic. Search covers subsystem pages and the glossary too.
   </Step>
   <Step title="Read">
     Each article has **Key components**, diagrams you can expand, and **Relevant source files**. **On this page** lists its sections, and **Previous page** and **Next page** move through the wiki in order.
@@ -40,6 +40,12 @@ import HostedMcpCard from '/snippets/hosted-mcp-card.mdx';
 
 Turn on **Reading mode** to hide the surrounding Console while you read.
 
+### Diagrams
+
+The **Overview** page has an architecture diagram of the repository. Click a box to open its page. If a diagram is bigger than its frame, drag it to see the rest, or expand it. The zoom and expand buttons sit under the diagram. On a phone, swipe sideways to pan and up or down to scroll the page.
+
+A wiki built before subsystems were added keeps its older sidebar, grouped by folder.
+
 ## Confidence labels
 
 | Label | Means |