Truncate base64 data URIs in inspect/to_html output

Long base64-encoded images made console and HTML output unreadable.
Now displays: "data:image/png;base64,iVBORw0K... (12345 chars)"

- Add AI.truncate_data_uris helper to recursively truncate in nested structures
- Apply truncation in Chat#inspectable_attributes and Message#inspect
- Add specs for truncation behavior

Author: raghubetina

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.5.3] - 2026-02-03
+
+### Added
+
+- **Truncate base64 data URIs in output**: Long base64-encoded images in messages are now truncated in `inspect` and `to_html` output for readability. Displays as `"data:image/png;base64,iVBORw0K... (12345 chars)"`.
+
 ## [0.5.2] - 2026-02-03
 
 ### Fixed

ai-chat.gemspec

@@ -2,7 +2,7 @@
 
 Gem::Specification.new do |spec|
   spec.name = "ai-chat"
-  spec.version = "0.5.2"
+  spec.version = "0.5.3"
   spec.authors = ["Raghu Betina", "Jelani Woods"]
   spec.email = ["raghu@firstdraft.com", "jelani@firstdraft.com"]
   spec.homepage = "https://github.com/firstdraft/ai-chat"

lib/ai-chat.rb

@@ -13,6 +13,31 @@ def self.wrap_html(content)
   def self.amazing_print(object, **options)
     AmazingPrint::Inspector.new(**options).awesome(object)
   end
+
+  # Recursively truncate base64 data URIs in nested structures for cleaner output
+  def self.truncate_data_uris(obj)
+    case obj
+    when Hash
+      obj.transform_values { |v| truncate_data_uris(v) }
+    when Array
+      obj.map { |v| truncate_data_uris(v) }
+    when String
+      truncate_data_uri(obj)
+    else
+      obj
+    end
+  end
+
+  def self.truncate_data_uri(str)
+    return str unless str.is_a?(String) && str.start_with?("data:") && str.include?(";base64,")
+
+    match = str.match(/\A(data:[^;]+;base64,)(.+)\z/)
+    return str unless match
+
+    prefix = match[1]
+    data = match[2]
+    "#{prefix}#{data[0, 20]}... (#{data.length} chars)"
+  end
 end
 
 require_relative "ai/message"

lib/ai/chat.rb

@@ -208,8 +208,8 @@ def inspectable_attributes
       attrs << [:@conversation_id, @conversation_id]
       attrs << [:@last_response_id, @last_response_id] if @last_response_id
 
-      # 3. Messages (the main content, without response details)
-      display_messages = @messages.map { |msg| msg.except(:response) }
+      # 3. Messages (the main content, without response details, with truncated data URIs)
+      display_messages = @messages.map { |msg| AI.truncate_data_uris(msg.except(:response)) }
       attrs << [:@messages, display_messages]
 
       # 4. Optional features (only if enabled/changed from default)

lib/ai/message.rb

@@ -3,7 +3,7 @@
 module AI
   class Message < Hash
     def inspect
-      AI.amazing_print(self, plain: !$stdout.tty?, index: false)
+      AI.amazing_print(display_hash, plain: !$stdout.tty?, index: false)
     end
 
     def pretty_inspect
@@ -17,7 +17,13 @@ def pretty_print(q)
     end
 
     def to_html
-      AI.wrap_html(AI.amazing_print(self, html: true, index: false))
+      AI.wrap_html(AI.amazing_print(display_hash, html: true, index: false))
+    end
+
+    private
+
+    def display_hash
+      AI.truncate_data_uris(to_h)
     end
   end
 end

spec/unit/chat_spec.rb

@@ -168,6 +168,42 @@
       expect(attr_names).to include(:@web_search)
       expect(attr_names).to include(:@schema)
     end
+
+    it "truncates base64 data URIs in message content" do
+      base64_image = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk"
+      chat.add([
+        {type: "input_text", text: "What is this?"},
+        {type: "input_image", image_url: base64_image}
+      ], role: "user")
+
+      attrs = chat.inspectable_attributes
+      messages_attr = attrs.find { |name, _| name == :@messages }
+      display_messages = messages_attr[1]
+      image_content = display_messages[0][:content][1]
+
+      expect(image_content[:image_url]).to eq("data:image/png;base64,iVBORw0KGgoAAAANSUhE... (60 chars)")
+    end
+
+    it "does not truncate regular strings" do
+      chat.add("Hello, this is a normal message", role: "user")
+
+      attrs = chat.inspectable_attributes
+      messages_attr = attrs.find { |name, _| name == :@messages }
+      display_messages = messages_attr[1]
+
+      expect(display_messages[0][:content]).to eq("Hello, this is a normal message")
+    end
+
+    it "does not truncate non-base64 data URIs" do
+      data_uri = "data:text/plain,Hello%20World"
+      chat.add([{type: "input_text", text: data_uri}], role: "user")
+
+      attrs = chat.inspectable_attributes
+      messages_attr = attrs.find { |name, _| name == :@messages }
+      display_messages = messages_attr[1]
+
+      expect(display_messages[0][:content][0][:text]).to eq(data_uri)
+    end
   end
 
   describe "#inspect" do

spec/unit/message_spec.rb

@@ -36,6 +36,19 @@
 
       expect(message.inspect).not_to eq({role: "user", content: "Hello"}.inspect)
     end
+
+    it "truncates base64 data URIs in content" do
+      base64_image = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk"
+      message = AI::Message[
+        role: "user",
+        content: [
+          {type: "input_text", text: "What is this?"},
+          {type: "input_image", image_url: base64_image}
+        ]
+      ]
+
+      expect(message.inspect).to include("data:image/png;base64,iVBORw0KGgoAAAANSUhE... (60 chars)")
+    end
   end
 
   describe "#pretty_inspect" do