diff --git a/src/tapir.md b/src/tapir.md
index d044148..9e16321 100644
--- a/src/tapir.md
+++ b/src/tapir.md
@@ -19,6 +19,9 @@ together, e.g. authentication depends on a shared cryptographic transcript
 , and the main [cwtch](./cwtch.md) peer app is based on the authentication
 application.
 
+## Primitives
+
+**TODO**
 
 ## Applications