Early-Stage Characterization of Two-Qubit Gate Incoherent Error at Scale

High-fidelity two-qubit gates are essential for quantum error correction and scalable quantum algorithms. Flux pulse-activated CZ gates are a leading approach for scalable quantum computing, enabling fast gates with demonstrated high-fidelity performance. Activating strong coupling between qubits may amplify flux sensitivity and hybridization effects, leading to a complex trade space between gate speed, incoherent error, and higher-order dynamics like leakage. Here, we introduce a method for device-wide characterization of qubit coherence under flux modulation directly in terms of effective coupling strength on a symmetric tunable coupler scheme. This technique provides a scalable diagnostic for early prediction of coherence-limited gate performance prior to full two-qubit calibration. This method decouples intrinsic design behavior from device-specific parameters, enabling fair comparison across chips and fabrication runs for optimal chip selection and coherence monitoring over time.