diff --git a/engine/app/controllers/coplan/application_controller.rb b/engine/app/controllers/coplan/application_controller.rb
index 343413e..50f73b3 100644
--- a/engine/app/controllers/coplan/application_controller.rb
+++ b/engine/app/controllers/coplan/application_controller.rb
@@ -45,11 +45,14 @@ def signed_in?
     end
 
     def authenticate_coplan_user!
+      if request.get? && agent_request?
+        render plain: agent_redirect_instructions, content_type: "text/markdown", status: :unauthorized
+        return
+      end
+
       @current_coplan_user = CoPlan::Authentication.user_from_request(request)
       unless @current_coplan_user
-        if agent_request?
-          render plain: agent_redirect_instructions, content_type: "text/markdown", status: :unauthorized
-        elsif CoPlan.configuration.sign_in_path
+        if CoPlan.configuration.sign_in_path
           redirect_to CoPlan.configuration.sign_in_path, alert: "Please sign in."
         else
           head :unauthorized
diff --git a/spec/requests/browse_spec.rb b/spec/requests/browse_spec.rb
index 928d4f3..bf3b706 100644
--- a/spec/requests/browse_spec.rb
+++ b/spec/requests/browse_spec.rb
@@ -63,6 +63,18 @@ def revise(plan, content, actor: author)
       expect(response).to have_http_status(:ok)
       expect(versioned.slug).to eq("pricing-v1-2")
     end
+
+    it "directs an authenticated non-browser client to the API instructions" do
+      get "/hampton/liveorder/q3/cart-roadmap", headers: {
+        "Accept" => "text/markdown",
+        "User-Agent" => "curl/8.11.0"
+      }
+
+      expect(response).to have_http_status(:unauthorized)
+      expect(response.media_type).to eq("text/markdown")
+      expect(response.body).to include("# CoPlan API")
+      expect(response.body).to include("/agent-instructions")
+    end
   end
 
   describe "the owner's own library" do