Add extended thinking examples (multi-turn + tool use)

examples/thinking_multi_turn.rb

@@ -0,0 +1,60 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+# typed: strong
+
+require_relative "../lib/anthropic"
+
+# gets API credentials from environment variable `ANTHROPIC_API_KEY`
+anthropic = Anthropic::Client.new
+
+# --- Turn 1: Ask an initial question with extended thinking enabled ---
+puts("--- Turn 1: Initial question ---")
+
+first_response = anthropic.messages.create(
+  model: "claude-sonnet-4-5-20250929",
+  max_tokens: 8000,
+  thinking: {type: :enabled, budget_tokens: 5000},
+  messages: [{role: :user, content: "What are the three largest prime numbers below 1000?"}]
+)
+
+first_response.content.each do |block|
+  case block
+  when Anthropic::ThinkingBlock
+    puts("Thinking: #{block.thinking[0..200]}...")
+  when Anthropic::TextBlock
+    puts("Response: #{block.text}")
+  end
+end
+
+# --- Turn 2: Follow up, carrying forward thinking blocks ---
+#
+# IMPORTANT: When using extended thinking in multi-turn conversations, you must
+# include ALL content blocks from the assistant's previous response — including
+# `thinking` and `redacted_thinking` blocks — in the messages array. The API
+# will reject requests that strip thinking blocks from prior assistant turns.
+#
+# The response's `.content` already contains the correctly typed blocks
+# (ThinkingBlock, RedactedThinkingBlock, TextBlock), so you can pass them
+# directly as the assistant message content.
+puts("\n--- Turn 2: Follow-up question (thinking blocks carried forward) ---")
+
+second_response = anthropic.messages.create(
+  model: "claude-sonnet-4-5-20250929",
+  max_tokens: 8000,
+  thinking: {type: :enabled, budget_tokens: 5000},
+  messages: [
+    {role: :user, content: "What are the three largest prime numbers below 1000?"},
+    # Pass ALL content blocks (thinking + text) from the first response
+    {role: :assistant, content: first_response.content},
+    {role: :user, content: "Now multiply the largest of those primes by 2. Is the result also prime?"}
+  ]
+)
+
+second_response.content.each do |block|
+  case block
+  when Anthropic::ThinkingBlock
+    puts("Thinking: #{block.thinking[0..200]}...")
+  when Anthropic::TextBlock
+    puts("Response: #{block.text}")
+  end
+end

examples/thinking_with_tools.rb

@@ -0,0 +1,103 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+# typed: false
+
+require_relative "../lib/anthropic"
+
+# gets API credentials from environment variable `ANTHROPIC_API_KEY`
+client = Anthropic::Client.new
+
+# Define a simple calculator tool using the SDK's BaseModel pattern.
+class CalculatorInput < Anthropic::BaseModel
+  required :expression, String, doc: "A mathematical expression to evaluate, e.g. '2 + 3 * 4'"
+
+  doc "Evaluate a mathematical expression and return the result"
+end
+
+# --- Step 1: Send a request with both extended thinking and tools ---
+puts("--- Step 1: Sending request with thinking + tools ---")
+
+user_message = {
+  role: "user",
+  content: "I have 147 apples and want to split them evenly among 7 baskets. " \
+           "How many apples go in each basket, and how many are left over?"
+}
+
+response = client.messages.create(
+  model: "claude-sonnet-4-5-20250929",
+  max_tokens: 8000,
+  thinking: {type: :enabled, budget_tokens: 5000},
+  messages: [user_message],
+  tools: [CalculatorInput]
+)
+
+# Display thinking and identify tool use
+response.content.each do |block|
+  case block
+  when Anthropic::ThinkingBlock
+    puts("Thinking: #{block.thinking[0..200]}...")
+  when Anthropic::TextBlock
+    puts("Text: #{block.text}")
+  when Anthropic::Models::ToolUseBlock
+    puts("Tool call: #{block.name}(#{block.input.inspect})")
+  end
+end
+
+# --- Step 2: Handle tool use if requested ---
+if response.stop_reason == :tool_use
+  tool_use = response.content.grep(Anthropic::Models::ToolUseBlock).first
+  raise "Tool use block not found" unless tool_use
+
+  # Simulate executing the calculator tool.
+  # In a real application, you would evaluate the expression or call an external service.
+  puts("\n--- Step 2: Executing tool '#{tool_use.name}' ---")
+  expression = tool_use.input["expression"]
+  puts("Expression: #{expression}")
+
+  # rubocop:disable Security/Eval
+  result = eval(expression).to_s
+  # rubocop:enable Security/Eval
+  puts("Result: #{result}")
+
+  # --- Step 3: Send the tool result back, including all prior content blocks ---
+  #
+  # When combining thinking with tools, the assistant message must include ALL
+  # content blocks from the response (thinking blocks + tool_use blocks).
+  puts("\n--- Step 3: Sending tool result back ---")
+
+  final_response = client.messages.create(
+    model: "claude-sonnet-4-5-20250929",
+    max_tokens: 8000,
+    thinking: {type: :enabled, budget_tokens: 5000},
+    messages: [
+      user_message,
+      # Include the full assistant response (thinking + tool_use blocks)
+      {role: :assistant, content: response.content},
+      # Provide the tool result
+      {
+        role: :user,
+        content: [
+          {
+            type: :tool_result,
+            tool_use_id: tool_use.id,
+            content: [{type: :text, text: result}]
+          }
+        ]
+      }
+    ],
+    tools: [CalculatorInput]
+  )
+
+  puts("\n--- Final response ---")
+  final_response.content.each do |block|
+    case block
+    when Anthropic::ThinkingBlock
+      puts("Thinking: #{block.thinking[0..200]}...")
+    when Anthropic::TextBlock
+      puts("Response: #{block.text}")
+    end
+  end
+else
+  # Model answered directly without using tools
+  puts("\n--- Model responded without tool use ---")
+end