actor_class followed the constant it cached, not the one the app has

lib/clickwrap/configuration.rb

@@ -307,16 +307,29 @@ def describe_authentication_with=(value)
       @describe_authentication_with = ensure_callable(value, "describe_authentication_with")
     end
 
-    # The constantized actor class, resolved lazily on first use. Lazy on
-    # purpose: the initializer that sets `config.actor_class_name = "User"` runs
-    # before the User model is necessarily loaded.
+    # The constantized actor class, resolved lazily on EVERY use. Lazy on
+    # purpose: the initializer that sets `config.actor_class_name = "User"`
+    # runs before the User model is necessarily loaded.
+    #
+    # Not memoized, deliberately. This used to cache the resolved Class object
+    # and re-resolve only when the class NAME changed — which is never, since
+    # the name is set once in an initializer. In a Rails app with reloading,
+    # the class behind that name is replaced on every code change: Zeitwerk
+    # unloads the old User and defines a new one, same name, different object.
+    # The cache then held a class no living record was an instance of, and
+    # `actor.is_a?(config.actor_class)` failed for a perfectly ordinary User.
+    #
+    # What that looked like from the outside was worse than the bug: the
+    # ConfigurationError names the offending class and the configured class,
+    # and both printed "User". The message read as a contradiction, sent
+    # people to an initializer that was correct, and came back after every
+    # edit — the first signup of a dev session worked and the second did not.
+    #
+    # `constantize` after the first load is a const_get, and this is called
+    # once per capture rather than in a loop, so there was nothing to save.
+    # `parent_controller_class` below has always resolved this way.
     def actor_class
-      name = actor_class_name
-      if @actor_class.nil? || @actor_class_name_at_resolution != name
-        @actor_class = name.constantize
-        @actor_class_name_at_resolution = name
-      end
-      @actor_class
+      actor_class_name.constantize
     end
 
     def parent_controller_class = parent_controller_class_name.constantize

test/configuration_test.rb

@@ -107,6 +107,35 @@ class ConfigurationTest < ActiveSupport::TestCase
     assert_equal User, Clickwrap.config.actor_class
   end
 
+  # A Rails app with reloading replaces the class behind a name on every code
+  # change: Zeitwerk unloads the old constant and defines a new one, same
+  # name, different object. actor_class used to cache the resolved Class and
+  # re-resolve only when the NAME changed — which never happens, because the
+  # name is set once in an initializer — so from the second edit of a dev
+  # session onwards it handed back a class no live record was an instance of.
+  #
+  # The symptom was a ConfigurationError that named the same class twice
+  # ("asked to record User as the actor, but ... the records that can act are
+  # User"), which reads as a contradiction and points at an initializer that
+  # is correct.
+  test "the actor class follows the constant when the app reloads it" do
+    Clickwrap.config.actor_class_name = "ReloadableActor"
+    Object.const_set(:ReloadableActor, Class.new)
+    first = Clickwrap.config.actor_class
+
+    # What a reload does, in one line.
+    Object.send(:remove_const, :ReloadableActor)
+    Object.const_set(:ReloadableActor, Class.new)
+
+    refute_equal first.object_id, Clickwrap.config.actor_class.object_id,
+      "actor_class handed back the class the app had already thrown away"
+    assert_equal ReloadableActor, Clickwrap.config.actor_class
+    assert ReloadableActor.new.is_a?(Clickwrap.config.actor_class),
+      "a freshly reloaded record is not an instance of the cached class"
+  ensure
+    Object.send(:remove_const, :ReloadableActor) if Object.const_defined?(:ReloadableActor)
+  end
+
   test "an unknown document store is refused by name" do
     error = assert_raises(Clickwrap::ConfigurationError) do
       Clickwrap.config.store_document_contents_in = :s3