Assisted-by: Claude Opus 4.6 via pi

diff --git a/Rakefile b/Rakefile
index b0ec822..494ec76 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,15 @@
 require "minitest/test_task"
 
 Minitest::TestTask.create
+
+directory ".direnv"
+
+desc "Create bundler binstubs (runs when Gemfile.lock changes)"
+file ".direnv/.bundled" => ["Gemfile.lock"] do
+  sh "bundle binstubs --all"
+  touch ".direnv/.bundled"
+end
+
+task binstubs: ".direnv/.bundled"
+
+task default: %i[ test binstubs ]