Safety

Four rails, every surface.

rail	where	what
clamp	Robot.act	every real write bounded by the row's max_step; the receipt says clamped=True
consent	tools/, CLI, dashboard	mode="sim" and dry_run=True by default; real motion needs confirm=True; strands HITL wraps hardware motion
e-stop	Mesh.estop	emergency_stop(reason) publishes to every peer and latches a lockout; resume(code) requires STRANDS_MESH_OVERRIDE_CODE
audit	mesh.audit	append-only JSONL, signed sequence chain, verify detects a removed or altered record

from strands_robots import Robot
from strands_robots.mesh import Mesh

with Robot("so101", mode="sim") as arm, Mesh(arm, "arm-a") as mesh:
    mesh.estop.emergency_stop("operator: person in the cell")   # every peer latches; act() refuses ESTOP_LATCHED
    mesh.estop.resume("...")                                    # refused unless the code matches STRANDS_MESH_OVERRIDE_CODE

Also true everywhere: is_connected() asks the wire and is never cached; close() turns torque off and releases the port on every exit path; one writer per arm (Robot holds a Lease, a second owner gets LeaseHeldError naming the holder); every refusal names the bad value, the cause and the remedy.