feat: add Runway Characters avatar plugin

Add livekit-plugins-runway for Runway Characters avatar integration.
The LiveKit agent owns the conversational AI stack (STT, LLM, TTS);
Runway provides the visual layer — audio in, avatar video out.

Author: robinandeer

examples/avatar_agents/runway/README.md

@@ -0,0 +1,27 @@
+# LiveKit Runway Avatar Agent
+
+This example demonstrates how to create an animated avatar using [Runway Characters](https://dev.runwayml.com/).
+
+## Usage
+
+* Update the environment:
+
+```bash
+# Runway Config
+export RUNWAYML_API_SECRET="..."
+export RUNWAY_AVATAR_PRESET_ID="..."  # or RUNWAY_AVATAR_ID for a custom avatar
+
+# Google config (or other models, tts, stt)
+export GOOGLE_API_KEY="..."
+
+# LiveKit config
+export LIVEKIT_API_KEY="..."
+export LIVEKIT_API_SECRET="..."
+export LIVEKIT_URL="..."
+```
+
+* Start the agent worker:
+
+```bash
+python examples/avatar_agents/runway/agent_worker.py dev
+```

examples/avatar_agents/runway/agent_worker.py

@@ -0,0 +1,38 @@
+import logging
+import os
+
+from dotenv import load_dotenv
+
+from livekit.agents import Agent, AgentServer, AgentSession, JobContext, cli
+from livekit.plugins import google, runway
+
+logger = logging.getLogger("runway-avatar-example")
+logger.setLevel(logging.INFO)
+
+load_dotenv()
+
+server = AgentServer()
+
+
+@server.rtc_session()
+async def entrypoint(ctx: JobContext):
+    session = AgentSession(
+        llm=google.realtime.RealtimeModel(voice="kore"),
+        resume_false_interruption=False,
+    )
+
+    avatar_id = os.getenv("RUNWAY_AVATAR_ID")
+    preset_id = os.getenv("RUNWAY_AVATAR_PRESET_ID")
+    runway_avatar = runway.AvatarSession(avatar_id=avatar_id, preset_id=preset_id)
+    await runway_avatar.start(session, room=ctx.room)
+
+    await session.start(
+        agent=Agent(instructions="Talk to me!"),
+        room=ctx.room,
+    )
+
+    session.generate_reply(instructions="say hello to the user")
+
+
+if __name__ == "__main__":
+    cli.run_app(server)

examples/avatar_agents/runway/requirements.txt

@@ -0,0 +1,2 @@
+livekit-plugins-runway
+livekit-plugins-google

livekit-plugins/livekit-plugins-runway/README.md

@@ -0,0 +1,62 @@
+# livekit-plugins-runway
+
+[LiveKit Agents](https://docs.livekit.io/agents/) plugin for [Runway Characters](https://dev.runwayml.com/) avatar integration.
+
+Your LiveKit agent owns the full conversational AI pipeline (STT, LLM, TTS). Runway provides the visual layer — audio in, avatar video out.
+
+## Installation
+
+```bash
+pip install livekit-plugins-runway
+```
+
+## Usage
+
+```python
+from livekit.agents import AgentSession, Agent, RoomOutputOptions
+from livekit.plugins import runway
+
+async def entrypoint(ctx):
+    session = AgentSession()
+
+    avatar = runway.AvatarSession(
+        avatar_id="your-custom-avatar-id",
+        # api_key defaults to RUNWAYML_API_SECRET env var
+    )
+    await avatar.start(session, room=ctx.room)
+
+    await session.start(
+        agent=Agent(instructions="Talk to me!"),
+        room=ctx.room,
+        room_output_options=RoomOutputOptions(audio_enabled=False),
+    )
+```
+
+### Using a preset avatar
+
+```python
+avatar = runway.AvatarSession(
+    preset_id="runway-preset-slug",
+)
+```
+
+### With a session duration limit
+
+```python
+avatar = runway.AvatarSession(
+    avatar_id="your-custom-avatar-id",
+    max_duration=300,
+)
+```
+
+## Configuration
+
+| Parameter | Env var | Description |
+|-----------|---------|-------------|
+| `api_key` | `RUNWAYML_API_SECRET` | Runway API key |
+| `api_url` | `RUNWAYML_BASE_URL` | API base URL (default: `https://api.dev.runwayml.com`) |
+| `avatar_id` | — | Custom avatar ID (mutually exclusive with `preset_id`) |
+| `preset_id` | — | Preset avatar slug (mutually exclusive with `avatar_id`) |
+| `max_duration` | — | Maximum session duration in seconds |
+
+LiveKit credentials (`LIVEKIT_URL`, `LIVEKIT_API_KEY`, `LIVEKIT_API_SECRET`) are read from environment variables or can be passed to `avatar.start()`.

livekit-plugins/livekit-plugins-runway/livekit/plugins/runway/__init__.py

@@ -0,0 +1,36 @@
+# Copyright 2025 LiveKit, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Runway Characters avatar plugin for LiveKit Agents"""
+
+from .avatar import AvatarSession, RunwayException
+from .version import __version__
+
+__all__ = [
+    "RunwayException",
+    "AvatarSession",
+    "__version__",
+]
+
+from livekit.agents import Plugin
+
+from .log import logger
+
+
+class RunwayPlugin(Plugin):
+    def __init__(self) -> None:
+        super().__init__(__name__, __version__, __package__, logger)
+
+
+Plugin.register_plugin(RunwayPlugin())

livekit-plugins/livekit-plugins-runway/livekit/plugins/runway/avatar.py

@@ -0,0 +1,181 @@
+from __future__ import annotations
+
+import asyncio
+import os
+
+import aiohttp
+
+from livekit import api, rtc
+from livekit.agents import (
+    DEFAULT_API_CONNECT_OPTIONS,
+    NOT_GIVEN,
+    AgentSession,
+    APIConnectionError,
+    APIConnectOptions,
+    APIStatusError,
+    NotGivenOr,
+    get_job_context,
+    utils,
+)
+from livekit.agents.voice.avatar import DataStreamAudioOutput
+from livekit.agents.voice.room_io import ATTRIBUTE_PUBLISH_ON_BEHALF
+
+from .log import logger
+
+DEFAULT_API_URL = "https://api.dev.runwayml.com"
+API_VERSION = "2024-11-06"
+SAMPLE_RATE = 16000
+_AVATAR_AGENT_IDENTITY = "runway-avatar-agent"
+_AVATAR_AGENT_NAME = "runway-avatar-agent"
+
+
+class RunwayException(Exception):
+    """Exception for Runway errors"""
+
+
+class AvatarSession:
+    """A Runway Characters avatar session.
+
+    Creates a realtime session backed by Runway's avatar inference pipeline.
+    The customer's LiveKit agent owns the conversational AI stack (STT, LLM, TTS);
+    Runway provides the visual layer — audio in, avatar video out.
+    """
+
+    def __init__(
+        self,
+        *,
+        avatar_id: NotGivenOr[str | None] = NOT_GIVEN,
+        preset_id: NotGivenOr[str | None] = NOT_GIVEN,
+        max_duration: NotGivenOr[int] = NOT_GIVEN,
+        api_url: NotGivenOr[str] = NOT_GIVEN,
+        api_key: NotGivenOr[str] = NOT_GIVEN,
+        avatar_participant_identity: NotGivenOr[str] = NOT_GIVEN,
+        avatar_participant_name: NotGivenOr[str] = NOT_GIVEN,
+        conn_options: APIConnectOptions = DEFAULT_API_CONNECT_OPTIONS,
+    ) -> None:
+        if not avatar_id and not preset_id:
+            raise RunwayException("Either avatar_id or preset_id must be provided")
+        if avatar_id and preset_id:
+            raise RunwayException("Provide avatar_id or preset_id, not both")
+
+        self._avatar_id = avatar_id
+        self._preset_id = preset_id
+        self._max_duration = max_duration
+
+        self._api_url = api_url or os.getenv("RUNWAYML_BASE_URL", DEFAULT_API_URL)
+        self._api_key = api_key or os.getenv("RUNWAYML_API_SECRET")
+        if self._api_key is None:
+            raise RunwayException(
+                "api_key must be set either by passing it to AvatarSession or "
+                "by setting the RUNWAYML_API_SECRET environment variable"
+            )
+
+        self._avatar_participant_identity = avatar_participant_identity or _AVATAR_AGENT_IDENTITY
+        self._avatar_participant_name = avatar_participant_name or _AVATAR_AGENT_NAME
+        self._http_session: aiohttp.ClientSession | None = None
+        self._conn_options = conn_options
+
+    def _ensure_http_session(self) -> aiohttp.ClientSession:
+        if self._http_session is None:
+            self._http_session = utils.http_context.http_session()
+        return self._http_session
+
+    async def start(
+        self,
+        agent_session: AgentSession,
+        room: rtc.Room,
+        *,
+        livekit_url: NotGivenOr[str] = NOT_GIVEN,
+        livekit_api_key: NotGivenOr[str] = NOT_GIVEN,
+        livekit_api_secret: NotGivenOr[str] = NOT_GIVEN,
+    ) -> None:
+        livekit_url = livekit_url or (os.getenv("LIVEKIT_URL") or NOT_GIVEN)
+        livekit_api_key = livekit_api_key or (os.getenv("LIVEKIT_API_KEY") or NOT_GIVEN)
+        livekit_api_secret = livekit_api_secret or (os.getenv("LIVEKIT_API_SECRET") or NOT_GIVEN)
+        if not livekit_url or not livekit_api_key or not livekit_api_secret:
+            raise RunwayException(
+                "livekit_url, livekit_api_key, and livekit_api_secret must be set "
+                "by arguments or environment variables"
+            )
+
+        job_ctx = get_job_context()
+        local_participant_identity = job_ctx.local_participant_identity
+
+        livekit_token = (
+            api.AccessToken(api_key=livekit_api_key, api_secret=livekit_api_secret)
+            .with_kind("agent")
+            .with_identity(self._avatar_participant_identity)
+            .with_name(self._avatar_participant_name)
+            .with_grants(api.VideoGrants(room_join=True, room=room.name))
+            .with_attributes({ATTRIBUTE_PUBLISH_ON_BEHALF: local_participant_identity})
+            .to_jwt()
+        )
+
+        logger.debug("starting Runway avatar session")
+        await self._create_session(livekit_url, livekit_token, room.name)
+
+        agent_session.output.audio = DataStreamAudioOutput(
+            room=room,
+            destination_identity=self._avatar_participant_identity,
+            wait_remote_track=rtc.TrackKind.KIND_VIDEO,
+            sample_rate=SAMPLE_RATE,
+        )
+
+    async def _create_session(self, livekit_url: str, livekit_token: str, room_name: str) -> None:
+        assert self._api_key is not None
+        assert isinstance(self._api_url, str)
+
+        if self._avatar_id:
+            avatar = {"type": "custom", "avatarId": self._avatar_id}
+        else:
+            avatar = {"type": "runway-preset", "presetId": self._preset_id}
+
+        body: dict = {
+            "model": "gwm1_avatars",
+            "avatar": avatar,
+            "livekit": {
+                "url": livekit_url,
+                "token": livekit_token,
+                "roomName": room_name,
+            },
+        }
+
+        if self._max_duration:
+            body["maxDuration"] = self._max_duration
+
+        for attempt in range(self._conn_options.max_retry):
+            try:
+                async with self._ensure_http_session().post(
+                    f"{self._api_url}/v1/realtime_sessions",
+                    headers={
+                        "Authorization": f"Bearer {self._api_key}",
+                        "X-Runway-Version": API_VERSION,
+                    },
+                    json=body,
+                    timeout=aiohttp.ClientTimeout(sock_connect=self._conn_options.timeout),
+                ) as response:
+                    if not response.ok:
+                        text = await response.text()
+                        raise APIStatusError(
+                            "Runway API returned an error",
+                            status_code=response.status,
+                            body=text,
+                        )
+                    return
+
+            except Exception as error:
+                if isinstance(error, APIStatusError):
+                    raise
+
+                if isinstance(error, APIConnectionError):
+                    logger.warning(
+                        "failed to call Runway avatar API",
+                        extra={"error": str(error)},
+                    )
+                else:
+                    logger.exception("failed to call Runway avatar API")
+
+                if attempt < self._conn_options.max_retry - 1:
+                    await asyncio.sleep(self._conn_options.retry_interval)
+
+        raise APIConnectionError("Failed to start Runway Avatar Session after all retries")

livekit-plugins/livekit-plugins-runway/livekit/plugins/runway/log.py

@@ -0,0 +1,3 @@
+import logging
+
+logger = logging.getLogger("livekit.plugins.runway")

livekit-plugins/livekit-plugins-runway/livekit/plugins/runway/version.py

@@ -0,0 +1 @@
+__version__ = "0.1.0"