refactor(question): effectify QuestionService (#17432)

packages/opencode/src/util/schema.ts

@@ -15,3 +15,40 @@ export const withStatics =
   <S extends object, M extends Record<string, unknown>>(methods: (schema: S) => M) =>
   (schema: S): S & M =>
     Object.assign(schema, methods(schema))
+
+declare const NewtypeBrand: unique symbol
+type NewtypeBrand<Tag extends string> = { readonly [NewtypeBrand]: Tag }
+
+/**
+ * Nominal wrapper for scalar types. The class itself is a valid schema —
+ * pass it directly to `Schema.decode`, `Schema.decodeEffect`, etc.
+ *
+ * @example
+ *   class QuestionID extends Newtype<QuestionID>()("QuestionID", Schema.String) {
+ *     static make(id: string): QuestionID {
+ *       return this.makeUnsafe(id)
+ *     }
+ *   }
+ *
+ *   Schema.decodeEffect(QuestionID)(input)
+ */
+export function Newtype<Self>() {
+  return <const Tag extends string, S extends Schema.Top>(tag: Tag, schema: S) => {
+    type Branded = NewtypeBrand<Tag>
+
+    abstract class Base {
+      declare readonly [NewtypeBrand]: Tag
+
+      static makeUnsafe(value: Schema.Schema.Type<S>): Self {
+        return value as unknown as Self
+      }
+    }
+
+    Object.setPrototypeOf(Base, schema)
+
+    return Base as unknown as
+      & (abstract new (_: never) => Branded)
+      & { readonly makeUnsafe: (value: Schema.Schema.Type<S>) => Self }
+      & Omit<Schema.Opaque<Self, S, {}>, "makeUnsafe">
+  }
+}