From 88576488f0317a1d0bea2929e70de3189d0d6ab6 Mon Sep 17 00:00:00 2001
From: Kenta Ishizaki <kentaishizaki@55728.jp>
Date: Fri, 17 Apr 2026 07:50:53 +0900
Subject: [PATCH] Add Content#empty? to fix Anthropic NoMethodError

Fixes #729

RubyLLM::Content did not implement #empty?, causing NoMethodError
in Anthropic provider code paths that check
`msg.content.nil? || msg.content.empty?` when content is a
Content instance (e.g. messages with ActiveStorage attachments).

Content#empty? now returns true when text is blank (nil, empty,
or whitespace-only) and there are no attachments, consistent with
String#empty? and Array#empty? semantics.
---
 lib/ruby_llm/content.rb       |  4 ++++
 spec/ruby_llm/content_spec.rb | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 spec/ruby_llm/content_spec.rb

diff --git a/lib/ruby_llm/content.rb b/lib/ruby_llm/content.rb
index d4010c4ba..1a9a27742 100644
--- a/lib/ruby_llm/content.rb
+++ b/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) }
diff --git a/spec/ruby_llm/content_spec.rb b/spec/ruby_llm/content_spec.rb
new file mode 100644
index 000000000..70dc44c1a
--- /dev/null
+++ b/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