Options hiding inside JSON now fail loudly

README.md

@@ -107,7 +107,7 @@ in Errgonomic::Option::None
 end
 ```
 
-An unhandled Option refuses to leak into your output: `to_s` and `to_json` raise `Errgonomic::SerializeError`, so you handle the inner value deliberately rather than shipping `#<Errgonomic::Option::Some...>` to a user.
+An unhandled Option refuses to leak into your output: `to_s`, `to_json`, and `as_json` raise `Errgonomic::SerializeError`, so you handle the inner value deliberately rather than shipping `#<Errgonomic::Option::Some...>` to a user. The refusal covers `as_json` because Hash and Array serialization recurses through that method, and an Option nested in a payload would otherwise serialize as `{"value": ...}`.
 
 `unwrap!` and `expect!` are for tests and consoles, not application code: they raise on `None`, which is exactly the ambiguous failure the type exists to prevent. Application code should always have a combinator or pattern match that handles the `None` branch explicitly; if none fits, that is a gap worth an issue rather than a reason to unwrap.
 
@@ -148,7 +148,7 @@ in Errgonomic::Result::Err, Exception => e
 end
 ```
 
-Like Options, unwrapped Results refuse `to_s` and `to_json`. And `Object#result?` / `Object#assert_result!` help enforce at runtime that a value is a Result.
+Like Options, unwrapped Results refuse `to_s`, `to_json`, and `as_json`. And `Object#result?` / `Object#assert_result!` help enforce at runtime that a value is a Result.
 
 ### Optional collections
 

lib/errgonomic/option.rb

@@ -556,6 +556,15 @@ def to_json(*_args)
         raise Errgonomic::SerializeError, 'cannot serialize an unwrapped Option'
       end
 
+      # ActiveSupport's Hash#as_json and Array#as_json recurse through their
+      # members with as_json rather than to_json, so an Option nested in a
+      # payload reaches Object#as_json and serializes as its instance
+      # variables. Refuse there too, and the guard holds wherever an Option
+      # travels.
+      def as_json(*_args)
+        raise Errgonomic::SerializeError, 'cannot serialize an unwrapped Option'
+      end
+
       # pp uses its own object dump unless told otherwise; keep it consistent
       # with inspect.
       def pretty_print(pp)

lib/errgonomic/result.rb

@@ -369,6 +369,15 @@ def to_json(*_args)
         raise Errgonomic::SerializeError, 'cannot serialize an unwrapped Result'
       end
 
+      # ActiveSupport's Hash#as_json and Array#as_json recurse through their
+      # members with as_json rather than to_json, so a Result nested in a
+      # payload reaches Object#as_json and serializes as its instance
+      # variables. Refuse there too, and the guard holds wherever a Result
+      # travels.
+      def as_json(*_args)
+        raise Errgonomic::SerializeError, 'cannot serialize an unwrapped Result'
+      end
+
       # pp uses its own object dump unless told otherwise; keep it consistent
       # with inspect.
       def pretty_print(pp)

test/rails_test.rb

@@ -168,6 +168,18 @@ def test_where_with_an_array_of_options
     refute_includes relation.to_sql, 'NULL'
   end
 
+  # Hash and Array serialization recurses with as_json, never to_json, so
+  # the refusal has to sit on as_json to survive nesting.
+  def test_nested_options_and_results_refuse_to_serialize
+    assert_raises(Errgonomic::SerializeError) { Some(5).as_json }
+    assert_raises(Errgonomic::SerializeError) { { a: Some(5) }.to_json }
+    assert_raises(Errgonomic::SerializeError) { { a: None() }.to_json }
+    assert_raises(Errgonomic::SerializeError) { [Some(5)].to_json }
+    assert_raises(Errgonomic::SerializeError) { Ok(5).as_json }
+    assert_raises(Errgonomic::SerializeError) { { a: Err(5) }.to_json }
+    assert_raises(Errgonomic::SerializeError) { [Ok(5)].to_json }
+  end
+
   def test_delegate_optional
     author = Author.create!(name: 'Cixin Liu')
     book = author.books.create!(title: 'Death\'s End')