AGML-229: emit tool call and output events

[KevinWu06]

Summary

Previously, the show tool calls toggle was not working for the LLM and NLU agents for both text and voice features. In the call history, the toggle would not show the tool call logs.

This fix ensures that the tool calls are emitted to the message queue to be picked up and added to the call transcript.

https://linear.app/arklex/issue/AGML-229/agents-fix-tool-call-toggle-for-pipecat-chat-and-voice-transcripts

Description

The previous problem with the NLU agent (voice) was that the tool calls weren't appearing in the call transcript, while regular user/bot messages were. This was because, even though there were listeners to add tool calls to the transcript, the tool calls weren't even being emitted to the message queue. This change ensures that the tool calls are emitted such that the tool calls can populate the call transcipt.

Tests

• Pre-commit code format check: Run pip install pre-commit and pre-commit install before committing changes
• Attach one of run-coverage-tests label, run-diff-coverage-tests label, or run-integration-tests label (to skip test coverage) and ensure the check passes.
• Test case 1: Conversation with LLM agent. Used tool calls, and ended conversation. In chat history, the toggle worked to show/unshow tool call logs.
• Test case 2: Text and Voice conversation with NLU agent. Used tool calls, and ended conversation. In chat history, the toggle worked as expected.

Reviewers

@arklexai/agent-leads

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Note

Medium Risk
Touches core execution flow by adding new message-queue events for every tool invocation, which could affect downstream stream/transcript consumers if they assume a different event cadence or payload shape.

Overview
Ensures tool invocations executed via Executor.step() publish structured EventType.TOOL_CALL and EventType.TOOL_CALL_OUTPUT messages to orch_state.message_queue (including tool name, extracted slot arguments, and a best-effort output string).

This makes tool calls show up in streamed call transcripts for NLU/LLM agent flows when the "show tool calls" toggle is enabled.

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