Glossary¶
The words these docs use with a fixed meaning: action, backend, checkpoint, embodiment, envelope, extra, gate, grader, lane, policy, provider, refusal, rollout, rung, sketch, transport.
action · One step of robot command: a dict of joint or motor targets, or a list of them (a chunk) when the policy emits several per inference. Also the action field an agent tool call carries, naming which of the tool's verbs to run.
backend · Where a robot object runs: a simulator (MuJoCo, Newton, Isaac) or a hardware driver (lerobot or native). The interface is the same; the backend is what mode= and backend= or driver= select. Simulation and hardware.
checkpoint · The weights of a trained model, on the Hub or on disk, named by pretrained_name_or_path. A checkpoint plus an embodiment plus a processor is a policy.
embodiment · The declared map between a policy's tensor slots and units and a robot's keys and units. One robot can have a sim embodiment and a real one. Embodiments.
envelope · The dict every robot action returns: status and a content list of text, json and image blocks. What the agent reads and what you print.
e-stop · The command that latches every robot on a mesh or in a dashboard into a stopped state until an operator resumes it with proof. Three ways to raise it, two ways to resume; Fleet.
extra · An optional dependency group: pip install "strands-robots[sim-mujoco]". A feature whose extra is missing refuses by naming the extra.
fence · A code block on these pages. Bare python fences run against the commit in CI; python title="sketch" fences open a serial port or need hardware and are verified statically.
gate · gate_motion: the check every command that can move a physical robot passes, in a fixed order, ending in an operator interrupt or a refusal. Agents and robots.
grader · A test under tests/test_docs_*.py that reads the docs and the code together and fails when they disagree: a fence without output, a page over its word cap, a claim the code does not keep.
interrupt · The Strands mechanism that pauses an agent turn to ask a person. The gate raises one named <tool>-command-approval; y resumes and dispatches, anything else declines.
mesh · The Zenoh network robots and dashboards join to see each other, exchange commands and share one e-stop; postures from mTLS to local development. Mesh.
policy · The runtime object that maps an observation and an instruction to actions. Learned (a checkpoint), planned (a motion planner) or scripted (mock). Policies.
provider · A named way of building a policy or a trainer: lerobot_local, remote, wbc, mock. create_policy(provider, ...).
refusal · An error envelope that names what was wrong and what would have been accepted. The docs treat a refusal as an answer; refusal codes.
rollout · One run of a policy on a robot for a duration or a number of steps: run_policy, execute, start_task.
rung · A stage of the ladder: See it, Run it, Talk to it, Real arm, Teach it, Fleet.
sketch · See fence.
transport · What carries a native driver's bytes to the motors: a serial port, a TCP socket, DDS, ROS 2. Named on every hardware robot page.
twin · A MuJoCo model of a physical arm stepped by the same driver, transport="twin", so a command can be rehearsed before the arm moves.