ChatCLI: Assistant console output lacks preceding newline, breaking external print statements

[MSameerAbbas]

Feature Type

Nice to have

Feature Description

When using the conversation_item_added event in console mode to print custom output (e.g., Rich panels), assistant messages render incorrectly because they lack a preceding newline, while user messages render correctly.

The Problem

In chat_cli.py, _print_audio_mode() continuously overwrites the current line using \r (carriage return) at 16 FPS to display the audio level meter:

# chat_cli.py lines 505-514
def _print_audio_mode(self) -> None:
    # ...
    sys.stdout.write(
        f"\r[Audio] {self._input_device_name[-20:]} [{self._micro_db:6.2f} dBFS] ..."
    )
    sys.stdout.flush()

When the conversation_item_added event fires for assistant messages, any external print() or console.print() call ends up on the same line as the audio meter, breaking the output:

[Audio] rophone (Plantronics [-87.05 dBFS] [------------------------------]╭──────────── Assistant ────────────╮
│ Hello, how can I help you today? │
╰───────────────────────────────────╯

However, user messages render correctly because the DEBUG livekit.agents - received user transcript log is printed first, which includes a newline:

2025-12-12 17:16:43,528 - DEBUG livekit.agents - received user transcript {"user_transcript": "Yes.", "language": "en"}
╭─ User ─╮
│ Yes.   │
╰────────╯

Reproduction

@session.on("conversation_item_added")
def on_conversation_item_added(event: ConversationItemAddedEvent):
    from rich.console import Console
    from rich.panel import Panel
    console = Console()
    role = event.item.role
    console.print(Panel(event.item.text_content or "", title=role.capitalize()))

Run with livekit-agents console in audio mode. Assistant panels will have their top border merged with the audio level line.

Suggested Fix

Before emitting conversation_item_added (or other events where user code might print to stdout), the ChatCLI should:

1. Print a newline to move to a fresh line, OR
2. Clear the current line with \r + spaces + \r, OR
3. Provide a mechanism to pause/resume the audio bar rendering around event emissions

Workarounds / Alternatives

As a workaround, users can manually print a newline before their output:

@session.on("conversation_item_added")
def on_conversation_item_added(event: ConversationItemAddedEvent):
    if event.item.role == "assistant":
        print()  # Force newline before assistant output
    console.print(Panel(...))

However, this is not ideal as it requires users to understand the internal rendering behavior of ChatCLI.

Additional Context

Additional Context

• Affects: livekit-agents console mode (ChatCLI)
• File: livekit/agents/voice/chat_cli.py
• Method: _print_audio_mode() (lines 505-514)
• Event: conversation_item_added emission timing relative to audio bar rendering