diff --git a/crates/ailang-core/tests/design_schema_drift.rs b/crates/ailang-core/tests/design_schema_drift.rs
index 498e724..699c4a6 100644
--- a/crates/ailang-core/tests/design_schema_drift.rs
+++ b/crates/ailang-core/tests/design_schema_drift.rs
@@ -288,8 +288,8 @@ fn design_md_anchors_every_def_kind() {
         (r#""kind": "fn""#, Def::Fn(fn_def)),
         (r#""kind": "const""#, Def::Const(const_def)),
         (r#""kind": "type""#, Def::Type(type_def)),
-        (r#""kind": "ClassDef""#, Def::Class(class_def)),
-        (r#""kind": "InstanceDef""#, Def::Instance(instance_def)),
+        (r#""kind": "class""#, Def::Class(class_def)),
+        (r#""kind": "instance""#, Def::Instance(instance_def)),
     ];
 
     for (anchor, def) in exemplars {
diff --git a/docs/DESIGN.md b/docs/DESIGN.md
index 4c5d4c5..d54c5d3 100644
--- a/docs/DESIGN.md
+++ b/docs/DESIGN.md
@@ -1382,7 +1382,7 @@ Three additive schema extensions; no existing module becomes invalid.
 **`ClassDef`** — top-level definition kind, declares a class:
 
 ```
-{ "kind": "ClassDef",
+{ "kind": "class",
   "name": "Show",
   "param": "a",
   "superclass": null,
@@ -1403,7 +1403,7 @@ sites) or an AST body (method is optional with the body as fallback).
 **`InstanceDef`** — top-level definition kind, declares an instance:
 
 ```
-{ "kind": "InstanceDef",
+{ "kind": "instance",
   "class": "Show",
   "type": "Int",
   "methods": [