Add agent information to UserAgent

lib/stripe/api_requestor.rb

@@ -928,6 +928,9 @@ def self.maybe_gc_connection_managers
       user_agent = "Stripe/#{api_mode} RubyBindings/#{Stripe::VERSION}"
       user_agent += " " + format_app_info(Stripe.app_info) unless Stripe.app_info.nil?
 
+      ai_agent = SystemProfiler.detect_ai_agent
+      user_agent += " AIAgent/#{ai_agent}" unless ai_agent.empty?
+
       headers = {
         "User-Agent" => user_agent,
         "Authorization" => "Bearer #{req_opts[:api_key]}",
@@ -1089,6 +1092,23 @@ def self.uname_from_system_ver
         "uname lookup failed"
       end
 
+      AI_AGENTS = [
+        ["ANTIGRAVITY_CLI_ALIAS", "antigravity"],
+        ["CLAUDECODE", "claude_code"],
+        ["CLINE_ACTIVE", "cline"],
+        ["CODEX_SANDBOX", "codex_cli"],
+        ["CURSOR_AGENT", "cursor"],
+        ["GEMINI_CLI", "gemini_cli"],
+        ["OPENCODE", "open_code"],
+      ].freeze
+
+      def self.detect_ai_agent(env = ENV)
+        AI_AGENTS.each do |env_var, agent_name|
+          return agent_name if env[env_var] && !env[env_var].empty?
+        end
+        ""
+      end
+
       def initialize
         @uname = self.class.uname
       end
@@ -1097,7 +1117,7 @@ def user_agent
         lang_version = "#{RUBY_VERSION} p#{RUBY_PATCHLEVEL} " \
                        "(#{RUBY_RELEASE_DATE})"
 
-        {
+        ua = {
           application: Stripe.app_info,
           bindings_version: Stripe::VERSION,
           lang: "ruby",
@@ -1108,6 +1128,11 @@ def user_agent
           uname: @uname,
           hostname: Socket.gethostname,
         }.delete_if { |_k, v| v.nil? }
+
+        ai_agent = self.class.detect_ai_agent
+        ua[:ai_agent] = ai_agent unless ai_agent.empty?
+
+        ua
       end
     end
 

test/stripe/api_requestor_test.rb

@@ -797,6 +797,9 @@ class RequestorTest < Test::Unit::TestCase
         context "app_info" do
           should "send app_info if set" do
             old = Stripe.app_info
+
+            APIRequestor::SystemProfiler.stubs(:detect_ai_agent).returns("")
+
             Stripe.set_app_info(
               "MyAwesomePlugin",
               partner_id: "partner_1234",
@@ -832,6 +835,26 @@ class RequestorTest < Test::Unit::TestCase
           end
         end
 
+        context "ai_agent" do
+          should "include AI agent in request headers" do
+            APIRequestor::SystemProfiler.stubs(:detect_ai_agent).returns("cursor")
+
+            stub_request(:post, "#{Stripe::DEFAULT_API_BASE}/v1/account")
+              .with do |req|
+                assert_match(/AIAgent\/cursor$/, req.headers["User-Agent"])
+
+                data = JSON.parse(req.headers["X-Stripe-Client-User-Agent"])
+                assert_equal "cursor", data["ai_agent"]
+
+                true
+              end.to_return(body: JSON.generate(object: "account"))
+
+            client = APIRequestor.new("sk_test_123")
+            client.send(request_method, :post, "/v1/account", :api,
+                        &@read_body_chunk_block)
+          end
+        end
+
         context "error handling" do
           should "handle error response with empty body" do
             stub_request(:post, "#{Stripe::DEFAULT_API_BASE}/v1/charges")
@@ -1734,5 +1757,23 @@ class SystemProfilerTest < Test::Unit::TestCase
         _ = APIRequestor::SystemProfiler.uname_from_system_ver
       end
     end
+
+    context ".detect_ai_agent" do
+      should "detect agent when env var is set" do
+        assert_equal "claude_code", APIRequestor::SystemProfiler.detect_ai_agent({"CLAUDECODE" => "1"})
+      end
+
+      should "return empty string when no agent env vars are set" do
+        assert_equal "", APIRequestor::SystemProfiler.detect_ai_agent({})
+      end
+
+      should "return first matching agent when multiple env vars are set" do
+        assert_equal "cursor", APIRequestor::SystemProfiler.detect_ai_agent({"CURSOR_AGENT" => "1", "OPENCODE" => "1"})
+      end
+
+      should "ignore empty string env vars" do
+        assert_equal "", APIRequestor::SystemProfiler.detect_ai_agent({"CLAUDECODE" => ""})
+      end
+    end
   end
 end