fix: populate tool_calls in conversation history for streamEvents - #98

Problem

When using streamEvents() with memory enabled, getConversationHistory() returns AIMessage objects with an empty tool_calls array, even when the agent used tools during execution (fixes #8).

The issue is in how conversation history is saved at the end of streamEvents():

// Before — tool calls are discarded
this.addToHistory(new AIMessage(finalResponse))

The AIMessage receives only the text response. Tool call data is available throughout execution but never propagated to the history entry.

Fix

Track tool calls from on_tool_start events as the agent runs. These events are emitted by LangChain for every tool invocation and provide the tool name, input args, and run ID in a provider-agnostic way (works with ChatBedrockConverse, ChatOpenAI, ChatAnthropic, etc.).

When saving to history, pass the accumulated tool calls to the AIMessage constructor:

// After — tool calls are preserved
this.addToHistory(new AIMessage({
  content: finalResponse,
  tool_calls: capturedToolCalls.length > 0 ? capturedToolCalls : undefined,
}))

Changes

• : 18 lines changed
  • Add array before the event loop
  • Capture events to accumulate tool call data
  • Pass to when saving final response to history