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| 1 | + |
| 2 | +# LiveKit Agent Workflows |
| 3 | + |
| 4 | +## Agent Architecture Overview |
| 5 | + |
| 6 | +LiveKit Agents implement conversational AI workflows through a structured pipeline: |
| 7 | +- **Speech-to-Text (STT)**: Convert audio input to text |
| 8 | +- **Large Language Model (LLM)**: Process conversation and generate responses |
| 9 | +- **Text-to-Speech (TTS)**: Convert text responses to audio |
| 10 | +- **Turn Detection**: Determine when user has finished speaking |
| 11 | +- **Voice Activity Detection (VAD)**: Detect speech presence |
| 12 | + |
| 13 | +## Agent Implementation Patterns |
| 14 | + |
| 15 | +### Core Agent Class |
| 16 | +```python |
| 17 | +from livekit.agents import Agent, RunContext, function_tool |
| 18 | + |
| 19 | +class ConversationalAgent(Agent): |
| 20 | + def __init__(self): |
| 21 | + super().__init__() |
| 22 | + # Define agent behavior through instructions |
| 23 | + self.instructions = """ |
| 24 | + System prompt defining: |
| 25 | + - Agent personality and role |
| 26 | + - Available capabilities |
| 27 | + - Communication style |
| 28 | + - Behavioral boundaries |
| 29 | + """ |
| 30 | + |
| 31 | + @function_tool |
| 32 | + async def custom_capability(self, context: RunContext, parameter: str): |
| 33 | + """Function tools extend agent capabilities beyond conversation. |
| 34 | + |
| 35 | + Args: |
| 36 | + parameter: Clear description for LLM understanding |
| 37 | + """ |
| 38 | + # Implementation logic |
| 39 | + return "Tool result" |
| 40 | +``` |
| 41 | + |
| 42 | +### Agent Lifecycle & Context |
| 43 | + |
| 44 | +#### RunContext Usage |
| 45 | +- **Session Access**: `context.room` for room information |
| 46 | +- **State Management**: Track conversation state across turns |
| 47 | +- **Event Handling**: Respond to room events and participant actions |
| 48 | +- **Resource Management**: Handle cleanup and resource disposal |
| 49 | + |
| 50 | +#### Conversation Flow |
| 51 | +1. **Audio Reception**: Agent receives participant audio stream |
| 52 | +2. **Speech Processing**: STT converts audio to text transcript |
| 53 | +3. **LLM Processing**: Language model generates response using instructions and tools |
| 54 | +4. **Audio Generation**: TTS converts response to audio |
| 55 | +5. **Turn Management**: System detects conversation turns and manages interruptions |
| 56 | + |
| 57 | +## Pipeline Configuration Patterns |
| 58 | + |
| 59 | +### Session Setup |
| 60 | +```python |
| 61 | +async def entrypoint(ctx: JobContext): |
| 62 | + await ctx.connect(auto_subscribe=AutoSubscribe.AUDIO_ONLY) |
| 63 | + |
| 64 | + # Configure the conversational AI pipeline |
| 65 | + session = AgentSession( |
| 66 | + stt=provider.STT(), # Speech recognition |
| 67 | + llm=provider.LLM(), # Language understanding/generation |
| 68 | + tts=provider.TTS(), # Speech synthesis |
| 69 | + turn_detector=provider.TD(), # End-of-turn detection |
| 70 | + vad=provider.VAD() # Voice activity detection |
| 71 | + ) |
| 72 | + |
| 73 | + # Start the agent workflow |
| 74 | + session.start(YourAgent()) |
| 75 | +``` |
| 76 | + |
| 77 | +### Pipeline Variations |
| 78 | + |
| 79 | +#### Traditional Multi-Provider Pipeline |
| 80 | +- Separate providers for each component (STT, LLM, TTS) |
| 81 | +- Maximum flexibility in provider selection |
| 82 | +- Optimized for specific use cases (latency, quality, cost) |
| 83 | + |
| 84 | +#### Unified Provider Pipeline (e.g., OpenAI Realtime) |
| 85 | +- Single provider handles entire conversation flow |
| 86 | +- Reduced latency through integrated processing |
| 87 | +- Built-in voice activity detection and turn management |
| 88 | + |
| 89 | +## Function Tool Patterns |
| 90 | + |
| 91 | +### Tool Design Principles |
| 92 | +- **Clear Documentation**: LLM uses docstrings to understand tool purpose |
| 93 | +- **Error Handling**: Graceful failure with meaningful user feedback |
| 94 | +- **Async Implementation**: Non-blocking execution for real-time performance |
| 95 | +- **Context Awareness**: Leverage RunContext for session-specific behavior |
| 96 | + |
| 97 | +### Tool Categories |
| 98 | +- **Information Retrieval**: API calls, database queries, web searches |
| 99 | +- **Actions**: External system integration, state changes |
| 100 | +- **Computation**: Data processing, calculations, transformations |
| 101 | +- **Media Processing**: Image analysis, file handling, content generation |
| 102 | + |
| 103 | +## Voice Pipeline Optimization |
| 104 | + |
| 105 | +### Turn Detection Strategies |
| 106 | +- **VAD-Only**: Simple voice activity detection |
| 107 | +- **Semantic Turn Detection**: Context-aware conversation boundaries |
| 108 | +- **Hybrid Approach**: VAD + semantic analysis for optimal user experience |
| 109 | + |
| 110 | +### Latency Optimization |
| 111 | +- **Model Selection**: Balance capability vs. response time |
| 112 | +- **Streaming**: Real-time processing where supported |
| 113 | +- **Caching**: Reduce repeated processing overhead |
| 114 | +- **Connection Management**: Maintain persistent connections |
| 115 | + |
| 116 | +## Error Handling & Resilience |
| 117 | + |
| 118 | +### Common Failure Modes |
| 119 | +- **Provider Outages**: Network issues, service unavailability |
| 120 | +- **Audio Quality**: Poor input affecting transcription accuracy |
| 121 | +- **Tool Failures**: External service errors, timeout conditions |
| 122 | +- **Resource Limits**: Rate limiting, quota exhaustion |
| 123 | + |
| 124 | +### Resilience Patterns |
| 125 | +- **Graceful Degradation**: Reduced functionality during partial failures |
| 126 | +- **Retry Logic**: Intelligent retry with backoff strategies |
| 127 | +- **Fallback Providers**: Alternative services for critical components |
| 128 | +- **User Communication**: Clear error messages and recovery guidance |
| 129 | + |
| 130 | +## Testing Conversational Agents |
| 131 | + |
| 132 | +### LLM-Based Evaluation |
| 133 | +```python |
| 134 | +# Test conversational behavior with semantic evaluation |
| 135 | +async def test_agent_response(): |
| 136 | + async with AgentSession(llm=test_llm) as session: |
| 137 | + await session.start(YourAgent()) |
| 138 | + result = await session.run(user_input="test scenario") |
| 139 | + |
| 140 | + # Evaluate response quality using LLM judgment |
| 141 | + await result.expect.next_event().is_message(role="assistant").judge( |
| 142 | + llm=judge_llm, |
| 143 | + intent="Expected behavior description" |
| 144 | + ) |
| 145 | +``` |
| 146 | + |
| 147 | +### Tool Testing |
| 148 | +```python |
| 149 | +# Mock external dependencies for reliable testing |
| 150 | +with mock_tools(YourAgent, {"external_api": mock_response}): |
| 151 | + # Test tool behavior under controlled conditions |
| 152 | +``` |
| 153 | + |
| 154 | +## Monitoring & Observability |
| 155 | + |
| 156 | +### Built-in Metrics |
| 157 | +- **Performance**: Latency, throughput, error rates |
| 158 | +- **Usage**: Token consumption, API calls, session duration |
| 159 | +- **Quality**: Turn accuracy, interruption handling, user satisfaction |
| 160 | + |
| 161 | +### Custom Metrics Collection |
| 162 | +```python |
| 163 | +@session.on("metrics_collected") |
| 164 | +def handle_metrics(event: MetricsCollectedEvent): |
| 165 | + # Process and forward metrics to monitoring systems |
| 166 | + custom_analytics.track(event.metrics) |
| 167 | +``` |
| 168 | + |
| 169 | +- STT: Audio duration, transcript time, streaming mode |
| 170 | +- LLM: Completion duration, token usage, TTFT |
| 171 | +- TTS: Audio duration, character count, generation time |
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