feat(dsl): add VCR infrastructure for DSL functional tests

test/dsl/functional/roast_dsl_examples_test.rb

@@ -338,6 +338,39 @@ class RoastDSLExamplesTest < FunctionalTest
         assert_empty stderr
       end
 
+      test "VCR infrastructure works for DSL chat workflows" do
+        workflow_code = <<~RUBY
+          # typed: false
+          # frozen_string_literal: true
+
+          #: self as Roast::DSL::Workflow
+
+          config do
+            chat(:test) do
+              model("gpt-4o")
+              assume_model_exists!
+            end
+          end
+
+          execute do
+            chat(:test) { "What is the deepest lake?" }
+          end
+        RUBY
+
+        VCR.use_cassette("dsl_vcr_test") do
+          stdout, stderr = in_sandbox :vcr_test do
+            File.write("dsl/vcr_test.rb", workflow_code)
+            result = Roast::DSL::Workflow.from_file("dsl/vcr_test.rb", EMPTY_PARAMS)
+            File.delete("dsl/vcr_test.rb")
+            result
+          end
+
+          assert_empty stderr
+          assert_predicate stdout, :present?
+          assert_match(/deepest/i, stdout)
+        end
+      end
+
       test "simple_repeat.rb workflow runs successfully" do
         stdout, stderr = in_sandbox :simple_repeat do
           Roast::DSL::Workflow.from_file("dsl/simple_repeat.rb", EMPTY_PARAMS)

test/dsl/support/functional_test.rb

@@ -4,12 +4,27 @@ module DSL
   class FunctionalTest < ActiveSupport::TestCase
     setup do
       Roast::Helpers::Logger.reset
+
+      # Configure environment variables for VCR testing (same pattern as YAML tests)
+      # DSL chat cogs respect OPENAI_API_BASE environment variable
+      unless ENV["RECORD_VCR"]
+        ENV["OPENAI_API_KEY"] = "dummy-key"
+        ENV["GOOGLE_API_KEY"] = "dummy-key"
+        ENV["OPENAI_API_BASE"] = "http://mytestingproxy.local/v1"
+      end
     end
 
     # Set up a temporary sandbox directory with all the examples
     # Parameter workflow_id is an arbitrary namespace/subdirectory within the sandbox
     # Returns an array of strings [stdio_output, stderr_output]
     def in_sandbox(workflow_id, &block)
+      _run_in_sandbox(workflow_id, &block)
+    end
+
+    private
+
+    # Internal helper that sets up sandbox environment
+    def _run_in_sandbox(workflow_id, &block)
       root_project_path = Dir.pwd
       examples_source_path = File.join(root_project_path, "dsl")