Implement progressive query admission, session boundaries and event-driven Studio observations

src/query/schema.ts

@@ -11,6 +11,8 @@ import {
   GraphQLList,
   GraphQLNonNull,
   GraphQLSchema,
+  GraphQLDirective,
+  DirectiveLocation,
   specifiedDirectives,
   visit,
   type GraphQLOutputType,
@@ -294,7 +296,14 @@ export function querySchema(
     return result;
   };
   const schema = new GraphQLSchema({
-    directives: specifiedDirectives,
+    directives: [
+      ...specifiedDirectives,
+      new GraphQLDirective({
+        name: "boundary",
+        locations: [DirectiveLocation.FRAGMENT_SPREAD],
+        args: { name: { type: new GraphQLNonNull(GraphQLString) } },
+      }),
+    ],
     // Nominal projections can mention an interface not reached by a relation.
     types: (() => {
       const requested = new Set<string>();