Glossary

Terms are normative: code, docs, and protocol fields use these words with exactly these meanings. Add here first; then use.

Term	Meaning
Milestone	A product-level promise (M0…M8) with a gate anyone can check; the roadmap’s unit (docs/17, docs/13).
Slice	One reviewable increment inside a milestone: lands on main, reviewed retrospectively in docs/reviews/; split or inserted as planning finds necessary (docs/13).
Agent	The Fjarr process on the robot: libfjarr embedded in the customer’s software, or the fjarr-agent reference daemon.
Capability	A pluggable unit of functionality (camera video, remote desktop, file transfer…). Owns media tracks and/or DataChannel message namespaces. See docs/05.
Capability consumer	Whoever the capability serves: a peer consumer (a dashboard connected P2P) or the backend consumer (observability ingest, OTA orchestration).
Operator host	The machine an operator connects from. A browser for every capability but one; for the network tunnel a native fjarr-connect process, because a browser cannot create a network interface (ADR-0024).
Link	The point-to-point IP path of one fjarr.net session: one operator host, one robot, two tunnel addresses. Never a network — links never join, and nothing routes between them (docs/27).
Tunnel address	The address an end owns on its tunnel interface. The operator’s is fixed; a robot’s is derived from its robot id (docs/27).
Session	One WebRTC peer connection between an agent and one operator client, carrying whatever capabilities were granted. Identified by session_id.
Session grant	The short-lived signed token (JWT) minted by the customer’s backend that authorizes creating a session with specific capabilities. See docs/09.
Signaling	The message exchange (offer/answer/ICE) that establishes sessions, relayed by fjarr-server. Never carries media.
Sidecar	fjarr-server deployed next to the customer’s backend, per ADR-0015.
Fjarr Cloud	The managed, multi-tenant implementation of the same contract as the sidecar.
Envelope	The single tagged-union message format used on control channels; every message has type, event_id, and a payload. See docs/08.
Correlation (event_id)	Requests carry a unique id; responses echo it. Long operations reply accept → feedback* → result, all with the same id.
Track	One WebRTC media stream (e.g. one camera, one monitor). Announced in the track manifest before media flows.
Track manifest	Metadata listing every track in an offer (track_id, label, kind, codec, payload type) so UIs can label streams before frames arrive.
Producer pipeline	The persistent GStreamer pipeline owning capture + encode. Survives peer churn.
Consumer pipeline	The disposable per-session pipeline feeding one webrtcbin.
FrameHub	The fan-out between producer and consumer pipelines: encode once, serve N sessions.
DC	WebRTC DataChannel. Fjarr defines reliability classes per channel (docs/08).
Robot ID	The customer’s canonical identifier for a device. Fjarr never invents its own device identity; it authenticates the customer’s.
Tenant	One customer organization in a multi-tenant fjarr-server/Cloud deployment.
Relay / TURN	Media forwarded through coturn when direct P2P fails. Ephemeral HMAC credentials only (docs/10).
Portal	XDG Desktop Portal — the D-Bus permission layer for Wayland screen capture and input.
EIS / libei	Emulated Input (server/library) — the Wayland-native input injection path.
uinput	Linux kernel interface for creating virtual input devices below the display server.
Backend consumer flows	Robot↔backend traffic that is not P2P: observability ingest, OTA campaign control.
Store-and-forward	The agent’s bounded offline buffer for durable events, replayed on reconnect (whitelisted types only).
Deadman	A safety timeout that stops actuation when control input goes silent. Spec’d and tested, never incidental (docs/15).
ADR	Architecture Decision Record — docs/adr/.