diff --git a/enterprise/app/services/captain/contact_memories/prompt_injection_service.rb b/enterprise/app/services/captain/contact_memories/prompt_injection_service.rb
new file mode 100644
index 000000000..0d48ae0a8
--- /dev/null
+++ b/enterprise/app/services/captain/contact_memories/prompt_injection_service.rb
@@ -0,0 +1,21 @@
+class Captain::ContactMemories::PromptInjectionService
+  def initialize(memories:)
+    @memories = memories
+  end
+
+  def call
+    return '' if @memories.blank?
+
+    lines = @memories.map do |memory|
+      %(  <#{memory.memory_type} confidence="#{format('%.2f', memory.confidence)}">#{escape(memory.content)}</#{memory.memory_type}>)
+    end
+
+    "<memoria_cliente>\n#{lines.join("\n")}\n</memoria_cliente>"
+  end
+
+  private
+
+  def escape(text)
+    text.to_s.gsub('&', '&amp;').gsub('<', '&lt;').gsub('>', '&gt;')
+  end
+end
diff --git a/spec/enterprise/services/captain/contact_memories/prompt_injection_service_spec.rb b/spec/enterprise/services/captain/contact_memories/prompt_injection_service_spec.rb
new file mode 100644
index 000000000..b5e607f3c
--- /dev/null
+++ b/spec/enterprise/services/captain/contact_memories/prompt_injection_service_spec.rb
@@ -0,0 +1,30 @@
+require 'rails_helper'
+
+RSpec.describe Captain::ContactMemories::PromptInjectionService do
+  describe '#call' do
+    it 'returns empty string when memories empty' do
+      result = described_class.new(memories: []).call
+      expect(result).to eq('')
+    end
+
+    it 'formats memories as XML block' do
+      memories = [
+        build_stubbed(:captain_contact_memory, memory_type: 'preferencia', content: 'Prefere Stilo', confidence: 0.92),
+        build_stubbed(:captain_contact_memory, memory_type: 'data_comemorativa', content: 'Aniversário 14/02', confidence: 0.88)
+      ]
+
+      result = described_class.new(memories: memories).call
+
+      expect(result).to include('<memoria_cliente>')
+      expect(result).to include('<preferencia confidence="0.92">Prefere Stilo</preferencia>')
+      expect(result).to include('<data_comemorativa confidence="0.88">Aniversário 14/02</data_comemorativa>')
+      expect(result).to include('</memoria_cliente>')
+    end
+
+    it 'escapes XML-unsafe chars in content' do
+      memories = [build_stubbed(:captain_contact_memory, content: 'texto com <tag> & ampersand')]
+      result = described_class.new(memories: memories).call
+      expect(result).to include('texto com &lt;tag&gt; &amp; ampersand')
+    end
+  end
+end