Make the cascade DSL getter return the configured value

CHANGELOG.md

@@ -48,6 +48,7 @@
 * [#2819](https://github.com/ruby-grape/grape/pull/2819): Freeze coercers at construction, synchronize `Grape::Util::Cache` lookups, and assign `Route#regexp_capture_index` eagerly - [@ericproulx](https://github.com/ericproulx).
 * [#2824](https://github.com/ruby-grape/grape/pull/2824): Fix cascaded routes (`X-Cascade: pass`) leaking `route_info` and path captures into the next matched route's `route` and `params` - [@ericproulx](https://github.com/ericproulx).
 * [#2825](https://github.com/ruby-grape/grape/pull/2825): Stop `present` entity autodetection from picking up a top-level `::Entity` constant - [@ericproulx](https://github.com/ericproulx).
+* [#2827](https://github.com/ruby-grape/grape/pull/2827): Make the `cascade` DSL getter return the configured value (`cascade false` read back as `true`) - [@ericproulx](https://github.com/ericproulx).
 * Your contribution here.
 
 ### 3.3.4 (2026-07-25)

UPGRADING.md

@@ -3,6 +3,10 @@ Upgrading Grape
 
 ### Upgrading to >= 4.0.0
 
+#### The `cascade` getter returns the configured value
+
+Calling `cascade` with no argument used to report whether cascading had been *configured at all* (`cascade false` still read back as `true`, contradicting the actual runtime behavior, which was correctly disabled). It now returns the configured value itself — `true`/`false` as set, or `true` when never set. Code that used the getter to detect "was `cascade` called" rather than "does this API cascade" must track that separately.
+
 #### `forward_match` is no longer exposed on routes
 
 `forward_match` is an internal, construction-time detail that decides how a route matches incoming paths (a prefix match for mounted Rack apps, the compiled pattern otherwise). It is now passed to `Grape::Router::Route` as a keyword argument and derived from the mounted app instead of being carried in the route's options.

lib/grape/dsl/routing.rb

@@ -16,7 +16,7 @@ def mounted(&block)
       end
 
       def cascade(value = nil)
-        return inheritable_setting.cascade_defined? ? !inheritable_setting.cascade.nil? : true if value.nil?
+        return inheritable_setting.cascade_defined? ? inheritable_setting.cascade : true if value.nil?
 
         inheritable_setting.cascade = value
       end

spec/grape/api_spec.rb

@@ -4890,12 +4890,33 @@ def uniqe_id_route
   describe '.cascade' do
     subject { api.cascade }
 
-    let(:api) do
-      Class.new(Grape::API) do
-        cascade true
+    context 'when not set' do
+      let(:api) { Class.new(described_class) }
+
+      it { is_expected.to be(true) }
+    end
+
+    context 'when set to true' do
+      let(:api) do
+        Class.new(Grape::API) do
+          cascade true
+        end
       end
+
+      it { is_expected.to be(true) }
     end
 
-    it { is_expected.to be(true) }
+    # Regression: the getter returned whether cascade had been set at all
+    # (!value.nil?), so `cascade false` still read back as true — contradicting
+    # the runtime cascading behavior, which was correctly disabled.
+    context 'when set to false' do
+      let(:api) do
+        Class.new(Grape::API) do
+          cascade false
+        end
+      end
+
+      it { is_expected.to be(false) }
+    end
   end
 end