# Context glossary

These terms explain the product and its conversation flow. Implementation
details belong in [architecture](architecture.md) and the source. Model/provider
names shown in a deployment are configuration examples, not definitions.

| Term | Meaning |
|---|---|
| Speech-to-speech client | The browser interface used to start a voice conversation, display transcripts, and play the assistant's reply |
| Pipeline | The ordered backend path: VAD → STT → LLM → TTS |
| VAD | Voice activity detection; determines when a user speech segment starts and stops |
| STT | Speech to text; transcribes an audio utterance |
| LLM | Language model; generates response text and optional tool calls |
| VLM | Vision-language model; a language model with image support when that capability is configured |
| TTS | Text to speech; synthesizes response audio with the configured voice/model |
| Realtime backend | The service that processes audio and exposes the `/v1/realtime` WebSocket protocol |
| Client server/proxy | The local FastAPI service serving the page and optional HTTP/WebSocket bridges |
| Builder | A person/team credited with creating the interface or deployment, distinct from a model's authors |
| Powered by | Hosting or inference infrastructure credited by the deployment |
| Tool | A callable operation used on demand; distinct from the pipeline stages that process ordinary turns |
| Native tool declaration | A function name, description and JSON Schema sent in `session.tools` |
| Tool executor | Code that receives a tool call, executes it and returns the result to the model |
| Web search | The browser-supported native tool whose request goes through the server's `/api/search` proxy |
| Search proxy | Same-origin server route holding a deployment search key and calling the external provider |
| ApiPilot | The dynamic-tool discovery/execution bridge, with both HTTP endpoints and model-text call markers |
| Call marker | Internal structured text such as `<<<APIPILOT_CALL:...>>>` used by the ApiPilot bridge; separate from native function-call events |
| Tools panel | Controls for available browser tools and search-key configuration |
| Settings | Connection, voice, audio and instruction controls persisted in browser storage |
| Identity block | The header's product/user identity, separate from configuration dialogs |
| About panel | Introduction and project/pipeline credits |
| Caller profile | Information looked up using the page's `phoneNumber`, used for identity display and optionally model context |
| RAG context | Reference material explicitly applied by the operator for the current session |
| Episode context | Content loaded for the page's `episode_id`, treated as the current episode reference |
| Queue | Users waiting for an available compute slot; waiting is not yet an active conversation |
| Ticket | A held queue position returned by the load balancer |
| Position | The displayed place in the queue; distinct from a time estimate |
| Claim | The transition from a waiting ticket to an allocated realtime session and usage reservation |
| At capacity | A full waiting queue that cannot accept another ticket |
| Barge-in | User speech interrupts an active assistant response, coordinating playback clearing and backend cancellation |
| Log-only reasoning | External transcript processing that observes/logs the turn without replacing native speech output |