Changelog

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Voice agent endpoints and Cartesia agents

• Voice agent endpoints. You can now list, retrieve, and delete your stored voice agents: GET /v1/voice_agents, GET /v1/voice_agents/{agent_id}, and DELETE /v1/voice_agents/{agent_id}.
• Cartesia voice agents. A voice agent can now be backed by a Cartesia-hosted agent, using the new cartesia_agent type. In LITE Mode, pass cartesia_agent_config on POST /v1/sessions/token with your agent_id and the secret_id of a stored CARTESIA_API_KEY.

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Cartesia TTS support

• Cartesia is now available as a voice provider. The voice_settings object on avatar_persona accepts a new CartesiaVoiceSettings variant (discriminated by provider: "cartesia"), with speed (0.6–1.5, default 1.0) and model.
• New CartesiaModelEnum: sonic-3.5 (default), sonic-3, sonic-2, sonic-turbo.
• SecretTypeEnum — Added CARTESIA_API_KEY and FISH_API_KEY for bring-your-own-key configuration via POST /v1/secrets.
• GET /v1/sessions — Session list entries (ListSessionEntrySchema, ListHistoricEntrySchema) now include api_key_id, identifying the API key that created the session.

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VP8 video encoding deprecated

• VideoEncodingEnum — The VP8 value is deprecated and will be removed in a future release. Use H264 (the default). Sessions that still request VP8 continue to work for now, but should migrate to H264. Affects the encoding field of video_settings on session token requests.

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Introducing Voice Agents

• Two agent types. A liveavatar_agent runs LiveAvatar’s managed FULL Mode pipeline (composed from a voice and a context). An elevenlabs_agent is backed by an ElevenLabs-hosted agent and produces a LITE Mode session — even when referenced from a FULL Mode token request.
• POST /v1/sessions/token (FULL Mode) — New optional voice_agent object referencing a stored voice agent by id. Mutually exclusive with avatar_persona.
• Per-session overrides for a liveavatar_agent: language and dynamic_variables, layered over the agent’s stored config for that session only. Both are rejected with a 400 for an elevenlabs_agent. dynamic_variables is mutually exclusive with the top-level field, capped at 50 entries (keys ≤ 64 chars, string values ≤ 1000 chars).
• POST /v2/embeddings — New optional voice_agent_id to resolve voice and context from a stored voice agent. Mutually exclusive with voice_id / context_id.
• New schema: VoiceAgentRef.

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Attach memory when creating a session token

• POST /v1/sessions/token — FULL Mode tokens now accept an optional memory object. Provide prev_session_id to seed or reuse memory from a prior session, session_memory_id to attach an existing memory, or both (they must resolve to the same memory). Sessions started without it are unaffected.

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Session Memory endpoints

• POST /v1/memory — Create a memory from a completed session. Accepts memory_type (session) and session_id.
• GET /v1/memory — List memories with type, page, and page_size query parameters. Each item returns a memory_content_preview.
• GET /v1/memory/{memory_id} — Fetch a single memory, including its rolled-up memory_content and the per-session session_episodes that compose it.
• DELETE /v1/memory/{memory_id} — Delete a memory and its episodes.
• New schemas: MemoryResponse, MemoryWithEpisodesResponse, MemoryListItemResponse, MemoryEpisodeSchema (each episode carries a session_id, sequence_num, and summary), and MemoryTypeEnum (currently session).

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ElevenLabs Japanese text normalization

• ElevenLabsVoiceSettings — New optional apply_language_text_normalization boolean (default false). Enables ElevenLabs language-specific text normalization to improve pronunciation. Currently only Japanese (ja) is supported; valid only when the session language is set to ja. Adds latency, so it is opt-in.

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Delete Session Events endpoint

• DELETE /v1/sessions/{session_id}/events — New endpoint to hard-delete all events for a given session. Accepts session_id path parameter; authenticated via API key or bearer token.

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JavaScript SDK v0.0.18 — ElevenLabs Agent improvements

• @heygen/liveavatar-web-sdk v0.0.18 — Includes a set of ElevenLabs Agent connector improvements, notably bidirectional passthrough of raw ElevenLabs Conversational AI events. Frontends can now both receive every ElevenLabs server event (via elevenlabs_agent_event) and send raw ElevenLabs client events (via elevenlabs_agent_command) without per-feature plumbing.

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1080p avatars, ElevenLabs voice override & expanded Gemini voices

• 1080p avatars — Added support for 1080p avatars on the new payment plan. AvatarSchema exposes an is_1080p boolean to identify them.
• Session token improvements — Hardened JWT payload to strip sensitive fields from the token, also reducing payload size. Sandbox Mode keeps fields visible for testing.
• ElevenLabs voice override — ElevenLabsAgentConfigSchema accepts an optional voice_id that is forwarded as conversation_config_override.tts.voice_id to the ElevenLabs Agent WebSocket, overriding the agent’s default voice for the session.
• Expanded Gemini Realtime voices — GeminiVoiceEnum adds Achernar, Achird, Algenib, Algieba, Alnilam, Autonoe, Callirrhoe, Despina, Enceladus, Erinome, Gacrux, Iapetus, Laomedeia, Pulcherrima, Rasalgethi, Sadachbia, Sadaltager, Schedar, Sulafat, Umbriel, Vindemiatrix, and Zubenelgenubi.

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Gemini Realtime, Vertical Embeds & Dynamic Variables

• Gemini Realtime agent — LITE sessions can now be configured with gemini_realtime_config, running on Gemini Live API with configurable model, voice, and temperature. Supported voices include Aoede, Charon, Fenrir, Kore, Leda, Orus, Puck, and Zephyr. Requires a new GEMINI_API_KEY secret type.
• Embed orientation — /v2/embeddings now accepts an orientation field (horizontal for 16:9 or vertical for 9:16). The response also returns the new embed_id field.
• Session dynamic variables — Session creation now accepts a dynamic_variables object for filling ${var} placeholders in the context’s opening text and prompt (max 50 entries).
• New session filters — GET /v1/sessions now supports embed_id and context_id query parameters.
• New AGENT_HANG_UP session end reason — Added to SessionEndReasonEnum to indicate the agent itself terminated the call. Currently only emitted by the ElevenLabs agent.

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ElevenLabs Events, Embed Transcripts & SDK Update

• ElevenLabs agent events — underlying ElevenLabs server events are now forwarded via the elevenlabs_agent_event event type, giving you access to raw ElevenLabs Conversational AI events
• Transcript on embed — Transcripts are now available directly on embed sessions
• JavaScript SDK updated — Updated the @heygen/liveavatar-web-sdk package with new event types and improvements

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Auth Simplification & Session Filtering

• Authentication — Cleaned up documentation for which endpoints require which auth specifications
• New avatar_id filter on /v1/sessions — List sessions can now be filtered by an optional avatar_id query parameter

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Embeds, Image Avatars & More

• New /v2/embeddings endpoint with sandbox support — Embeds can now be created with Sandbox Mode available
• Built Image Avatar pipeline — Create a fully animated avatar from just a photo using the new validate and submit endpoints

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Improvements

• Update avatar endpoint — You can now change an avatar’s default voice
• Avatar and voice deletion untangled — Deleting a voice no longer affects its associated avatar, and vice versa
• ElevenLabs agent dynamic variables — Configure dynamic variables for ElevenLabs-powered agents that get replaced at session start
• Source events fixed in FULL Mode — avatar.say and avatar.repeat events now correctly return source_event_id

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ElevenLabs Scribe, Embed Improvements

• Added support for ElevenLabs Scribe, expanding ASR capabilities
• Embed Improvements
  • Default language selection, letting users set the language for their embed experience
  • Time limits, giving creators control over session duration

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Voice Settings & Fish Audio

• Added additional voice settings for more granular control over avatar speech
• Added access to Fish Audio as a TTS provider
• New [GET] /v1/languages endpoint to clarify which languages are currently supported

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ElevenLabs Integration

• The v1/secrets endpoint now accepts ElevenLabs API keys
• FULL Mode sessions can now start with your own ElevenLabs keys and voices
• Added integration with ElevenLabs Agent functionality

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LLM Plugin & Session Controls

• Introduced LLM Plugin for custom LLM configurations
• Added customizable session duration controls
• Transcription chunk events are now emitted in real time
• New endpoint to track user credit balances

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Session Configuration & LITE Mode

• New session configuration options for video codec selection (H.264 / VP8)
• Added video quality control settings
• Added voice customization options
• CUSTOM Mode has been renamed to LITE Mode (backward-compatible)
• Bug fix: resolved opening line speech issues

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Push-to-Talk

• Released Push-to-Talk functionality for avatar sessions
• Added accompanying documentation and integration guides

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Sandbox Mode & FULL Mode Improvements

• Introduced Sandbox Mode for testing without credit charges
• Made context optional in FULL Mode configurations, reducing required setup

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Custom Mode & Session List Updates

• Custom Mode now exposes LiveKit Agent token for developers to integrate their own agents
• Session List endpoint updated to use query parameters

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Transcription Endpoint

• New [GET] /v1/sessions/{session_id}/transcript endpoint
• Enables developers to retrieve transcriptions between users and avatars in FULL Mode sessions

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Sessions List Endpoint

• New [GET] /v1/sessions endpoint
• Allows listing of both active and previously active sessions