CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Pipecat is an open-source Python framework for building real-time voice and multimodal conversational AI agents. It orchestrates audio/video, AI services, transports, and conversation pipelines using a frame-based architecture.

Common Commands

# Setup development environment
uv sync --group dev --all-extras --no-extra gstreamer --no-extra krisp

# Install pre-commit hooks
uv run pre-commit install

# Run all tests
uv run pytest

# Run a single test file
uv run pytest tests/test_name.py

# Run a specific test
uv run pytest tests/test_name.py::test_function_name

# Preview changelog
towncrier build --draft --version Unreleased

# Update dependencies (after editing pyproject.toml)
uv lock && uv sync

Architecture

Frame-Based Pipeline Processing

All data flows as Frame objects through a pipeline of FrameProcessors:

Transport Input → Pipeline Source → [Processor1] → [Processor2] → ... → Pipeline Sink → Transport Output

Key components:

Frames (src/pipecat/frames/frames.py): Data units (audio, text, video) and control signals. Flow DOWNSTREAM (input→output) or UPSTREAM (acknowledgments/errors).
FrameProcessor (src/pipecat/processors/frame_processor.py): Base processing unit. Each processor receives frames, processes them, and pushes results downstream.
Pipeline (src/pipecat/pipeline/pipeline.py): Chains processors together.
ParallelPipeline (src/pipecat/pipeline/parallel_pipeline.py): Runs multiple pipelines in parallel.
Transports (src/pipecat/transports/): External I/O layer (Daily WebRTC, LiveKit WebRTC, WebSocket, Local). Abstract interface via BaseTransport.
Services (src/pipecat/services/): 60+ AI provider integrations (STT, TTS, LLM, etc.). Extend base classes: AIService, LLMService, STTService, TTSService, VisionService.
Serializers (src/pipecat/serializers/): Convert frames to/from wire formats for WebSocket transports. FrameSerializer base class defines serialize() and deserialize(). Telephony serializers (Twilio, Plivo, Vonage, Telnyx, Exotel, Genesys) handle provider-specific protocols and audio encoding (e.g., μ-law).
RTVI (src/pipecat/processors/frameworks/rtvi.py): Real-Time Voice Interface protocol bridging clients and the pipeline. RTVIProcessor handles incoming client messages (text input, audio, function call results). RTVIObserver converts pipeline frames to outgoing messages: user/bot speaking events, transcriptions, LLM/TTS lifecycle, function calls, metrics, and audio levels.

Important Patterns

Context Aggregation: LLMContext accumulates messages for LLM calls; UserResponse aggregates user input
Turn Management: Turn management is done through LLMUserAggregator and LLMAssistantAggregator, created with LLMContextAggregatorPair
User turn strategies: Detection of when the user starts and stops speaking is done via user turn start/stop strategies. They push UserStartedSpeakingFrame and UserStoppedSpeakingFrame respectively.
Interruptions: Interruptions are usually triggered by a user turn start strategy (e.g. VADUserTurnStartStrategy) but they can be triggered by other processors as well, in which case the user turn start strategies don't need to.
Uninterruptible Frames: These are frames that will not be removed from internal queues even if there's an interruption. For example, EndFrame and StopFrame.
Events: Most classes in Pipecat have BaseObject as the very base class. BaseObject has support for events. Events can run in the background in an async task (default) or synchronously (sync=True) if we want immediate action. Synchronous event handlers need to exectue fast.

Key Directories

Directory	Purpose
`src/pipecat/frames/`	Frame definitions (100+ types)
`src/pipecat/processors/`	FrameProcessor base + aggregators, filters, audio
`src/pipecat/pipeline/`	Pipeline orchestration
`src/pipecat/services/`	AI service integrations (60+ providers)
`src/pipecat/transports/`	Transport layer (Daily, LiveKit, WebSocket, Local)
`src/pipecat/serializers/`	Frame serialization for WebSocket protocols
`src/pipecat/audio/`	VAD, filters, mixers, turn detection, DTMF
`src/pipecat/turns/`	User turn management

Code Style

Docstrings: Google-style. Classes describe purpose; __init__ has Args: section; dataclasses use Parameters: section.
Linting: Ruff (line length 100). Pre-commit hooks enforce formatting.
Type hints: Required for complex async code.

Docstring Example

class MyService(LLMService):
    """Description of what the service does.

    More detailed description.

    Event handlers available:

    - on_connected: Called when we are connected

    Example::

        @service.event_handler("on_connected")
        async def on_connected(service, frame):
            ...
    """

    def __init__(self, param1: str, **kwargs):
        """Initialize the service.

        Args:
            param1: Description of param1.
            **kwargs: Additional arguments passed to parent.
        """
        super().__init__(**kwargs)

Changelog

Every user-facing PR needs a changelog fragment in changelog/:

changelog/<PR_number>.<type>.md

Types: added, changed, deprecated, removed, fixed, security, other

Content format (include the -):

- Added support for new feature X.

Skip changelog for: documentation-only, internal refactoring, test-only, CI changes.

Service Implementation

When adding a new service:

Extend the appropriate base class (STTService, TTSService, LLMService, etc.)
Implement required abstract methods
Handle necessary frames
By default, all frames should be pushed in the direction they came
Push ErrorFrame on failures
Add metrics tracking via MetricsData if relevant
Follow the pattern of existing services in src/pipecat/services/

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