  Joint measurements of two-Pauli observables are a powerful tool for both the
control and protection of quantum information. By following a simple recipe for
measurement choices, single- and two- qubit rotations using two-Pauli parity
and single qubit measurements are guaranteed to be unitary whilst requiring
only a single ancilla qubit. This language for measurement based quantum
computing is shown to be directly applicable to encoded double quantum dot
singlet-triplet spin qubits, by measuring spin-parity between dots from
neighboring qubits. Along with exchange interaction, a complete, leakage free,
measurement based gate set can be shown, up to a known Pauli correction. Both
theoretically exact spin-parity measurements and experimentally demonstrated
asymmetric spin-parity measurements are shown to be viable for achieving the
proposed measurement based scheme, provided some extra leakage mitigating
measurement steps. This new method of spin qubit control offers a leakage
suppressed, low resource overhead implementation of a measurement-based control
that is viable on current spin qubit processor devices.
