Release Notes

from line.events import AgentUpdateCall

# In an agent's process method:
yield AgentUpdateCall(voice_id="5ee9feff-1265-424a-9d7f-8e4d431a12c7")
yield AgentUpdateCall(pronunciation_dict_id="dict-123")

import os
from line import CallRequest
from line.llm_agent import LlmAgent, LlmConfig, end_call
from line.voice_agent_app import AgentEnv, VoiceAgentApp

async def get_agent(env: AgentEnv, call_request: CallRequest):
    return LlmAgent(
        model="anthropic/claude-haiku-4-5-20251001",
        api_key=os.getenv("ANTHROPIC_API_KEY"),
        tools=[end_call],
        config=LlmConfig(
            system_prompt="You are a helpful assistant.",
            introduction="Hello! How can I help you today?",
        ),
    )

app = VoiceAgentApp(get_agent=get_agent)

# OpenAI
LlmAgent(model="gpt-5-nano", api_key=os.getenv("OPENAI_API_KEY"), ...)

# Anthropic
LlmAgent(model="anthropic/claude-haiku-4-5-20251001", api_key=os.getenv("ANTHROPIC_API_KEY"), ...)

# Google Gemini
LlmAgent(model="gemini/gemini-2.5-flash-preview-09-2025", api_key=os.getenv("GEMINI_API_KEY"), ...)

# With fallbacks
LlmAgent(
    model="gpt-5-nano",
    config=LlmConfig(fallbacks=["anthropic/claude-haiku-4-5-20251001", "gemini/gemini-2.5-flash-preview-09-2025"]),
    ...
)

from typing import Annotated
from line.llm_agent import loopback_tool, passthrough_tool, handoff_tool
from line.events import AgentEndCall

@loopback_tool
async def get_weather(ctx, city: Annotated[str, "City name"]) -> str:
    """Get current weather for a city."""
    return f"72°F and sunny in {city}"

@passthrough_tool
async def end_call(ctx):
    """End the call."""
    yield AgentEndCall()

@handoff_tool
async def transfer_to_support(ctx, event):
    """Transfer to support agent."""
    async for output in support_agent.process(ctx.turn_env, event):
        yield output

from typing import Annotated
from line.llm_agent import loopback_tool

@loopback_tool(is_background=True)
async def check_bank_balance(ctx, account_id: Annotated[str, "Account ID"]):
    """Check account balance (may take a few seconds)."""
    yield "Checking your balance..."  # Immediate acknowledgment
    balance = await api.get_balance(account_id)  # Long operation
    yield f"Your balance is ${balance:.2f}"  # Triggers new LLM completion

from line.llm_agent import end_call, send_dtmf, transfer_call, web_search, agent_as_handoff

agent = LlmAgent(
    tools=[
        end_call,                    # End the call
        send_dtmf,                   # Send DTMF tones
        transfer_call,               # Transfer to phone number
        web_search,                  # Real-time web search
        agent_as_handoff(other_agent, name="transfer_to_billing"),
    ],
    ...
)

spanish_agent = LlmAgent(
    model="gpt-5-nano",
    config=LlmConfig(system_prompt="Speak only in Spanish.", ...),
    ...
)

main_agent = LlmAgent(
    tools=[
        agent_as_handoff(
            spanish_agent,
            handoff_message="Transferring to Spanish support...",
            name="transfer_to_spanish",
            description="Transfer when user requests Spanish.",
        ),
    ],
    ...
)

LlmConfig(
    system_prompt="You are a helpful assistant.",
    introduction="Hello! How can I help?",

    # Sampling parameters
    temperature=0.7,
    max_tokens=1024,
    top_p=0.95,

    # Resilience
    num_retries=2,
    fallbacks=["gpt-5-nano"],
    timeout=30.0,

    # Provider-specific options
    extra={"reasoning_effort": "high"},
)

# v0.1.x
from line.voice_agent_app import VoiceAgentApp
from line.voice_agent_system import VoiceAgentSystem
from line.bridge import Bridge
from line.nodes import ReasoningNode
from line.events import (
    AgentSpeechSent,
    UserTranscriptionReceived,
    EndCall,
    TransferCall,
)

# v0.2
from line.voice_agent_app import VoiceAgentApp, AgentEnv
from line.llm_agent import LlmAgent, LlmConfig
from line.llm_agent import end_call, transfer_call, loopback_tool, passthrough_tool
from line.events import (
    AgentSendText,
    AgentEndCall,
    AgentTransferCall,
    UserTurnEnded,
    CallStarted,
)

from typing import Union, Tuple

AgentSpec = Union[Agent, Tuple[Agent, run_filter, cancel_filter]]

from line.events import (
    CallStarted, CallEnded, UserTurnEnded, UserTurnStarted, UserDtmfSent
)

async def get_agent(env: AgentEnv, call_request: CallRequest):
    agent = LlmAgent(...)

    # Include UserDtmfSent in run_filter to process DTMF
    run_filter = [CallStarted, UserTurnEnded, UserDtmfSent, CallEnded]
    cancel_filter = [UserTurnStarted]

    return (agent, run_filter, cancel_filter)

async def get_agent(env: AgentEnv, call_request: CallRequest):
    agent = LlmAgent(...)

    # Empty cancel_filter = agent won't be interrupted
    run_filter = [CallStarted, UserTurnEnded, CallEnded]
    cancel_filter = []

    return (agent, run_filter, cancel_filter)

def my_run_filter(event: InputEvent) -> bool:
    """Only process events during business hours."""
    if isinstance(event, CallStarted):
        return is_business_hours()
    return isinstance(event, (UserTurnEnded, CallEnded))

async def get_agent(env: AgentEnv, call_request: CallRequest):
    agent = LlmAgent(...)
    return (agent, my_run_filter, [UserTurnStarted])

from typing import AsyncIterable
from line.events import (
    InputEvent,
    OutputEvent,
    AgentSendText,
    CallStarted,
    UserTurnEnded,
)

class CustomAgent:
    """Custom agent implementing the Agent protocol."""

    async def process(self, env, event: InputEvent) -> AsyncIterable[OutputEvent]:
        if isinstance(event, CallStarted):
            yield AgentSendText(text="Hello from custom agent!")
        elif isinstance(event, UserTurnEnded):
            # Your custom logic here
            user_message = event.content[0].content
            response = await your_custom_logic(user_message, event.history)
            yield AgentSendText(text=response)

litellm              # Multi-provider LLM support
pydantic             # Type validation for events
phonenumbers >= 9.0  # Phone number validation for transfer_call

exa-py               # Exa web search integration
duckduckgo-search    # Fallback web search