echo

A pass-through op — echoes its argument bytes unchanged.

The canonical trivial op for warp tests that need an op but don't care what it computes. Unlike MultiNodeWarpSim.trackedEchoRegistry's per-sim tracked echo (which closes over the sim's execution log), this one is stateless and statically declared, so it is @WarpOp-auto-registered: install it with opRegistryOf(WarpOps) — the generated registrar for this package — instead of a hand-written registry.register(OpId("echo"), ...) line.