fix(typegen): dont treat all document type refs as references (#7366)

It's possible to reference a document the same way as an object is
referenced. However, they will not get the builtin attributes that are
available on a document stored in Content Lake. The Studio treats it as
a "normal" object. Since we are making some assumption around document
we are inlining the whole object whenever this happens, it's an edge
case and not a recommended pattern as it is mixing concerns.

packages/@sanity/schema/src/sanity/extractSchema.ts

@@ -67,6 +67,7 @@ export function extractSchema(
   extractOptions: ExtractSchemaOptions = {},
 ): SchemaType {
   const inlineFields = new Set<SanitySchemaType>()
+  const documentTypes = new Map<string, DocumentSchemaType>()
   const schema: SchemaType = []
 
   // get a list of all the types in the schema, sorted by their dependencies. This ensures that when we check for inline/reference types, we have already processed the type
@@ -83,6 +84,9 @@ export function extractSchema(
     if (base.type === 'type') {
       inlineFields.add(schemaType)
     }
+    if (base.type === 'document') {
+      documentTypes.set(typeName, base)
+    }
 
     schema.push(base)
   })
@@ -147,10 +151,6 @@ export function extractSchema(
   }
 
   function convertSchemaType(schemaType: SanitySchemaType): TypeNode {
-    if (lastType(schemaType)?.name === 'document') {
-      return createReferenceTypeNode(schemaType.name)
-    }
-
     // if we have already seen the base type, we can just reference it
     if (inlineFields.has(schemaType.type!)) {
       return {type: 'inline', name: schemaType.type!.name} satisfies InlineTypeNode
@@ -192,6 +192,14 @@ export function extractSchema(
       return createObject(schemaType)
     }
 
+    if (lastType(schemaType)?.name === 'document') {
+      const doc = documentTypes.get(schemaType.name)
+      if (doc === undefined) {
+        return {type: 'unknown'} satisfies UnknownTypeNode
+      }
+      return {type: 'object', attributes: doc?.attributes} satisfies ObjectTypeNode
+    }
+
     throw new Error(`Type "${schemaType.name}" not found`)
   }