Add Content#empty? to fix Anthropic NoMethodError

lib/ruby_llm/content.rb

@@ -26,6 +26,10 @@ def format
       end
     end
 
+    def empty?
+      @text.to_s.strip.empty? && @attachments.empty?
+    end
+
     # For Rails serialization
     def to_h
       { text: @text, attachments: @attachments.map(&:to_h) }

spec/ruby_llm/content_spec.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe RubyLLM::Content do
+  describe '#empty?' do
+    it 'is true when text is empty and there are no attachments' do
+      expect(described_class.new('')).to be_empty
+    end
+
+    it 'is true when text is whitespace-only and there are no attachments' do
+      expect(described_class.new("   \n\t")).to be_empty
+    end
+
+    it 'is false when text has content' do
+      expect(described_class.new('hello')).not_to be_empty
+    end
+
+    it 'is false when attachments are present without text' do
+      content = described_class.new(nil, 'spec/fixtures/ruby.txt')
+      expect(content).not_to be_empty
+    end
+
+    it 'is false when both text and attachments are present' do
+      content = described_class.new('hello', 'spec/fixtures/ruby.txt')
+      expect(content).not_to be_empty
+    end
+  end
+end