arXiv:2610.41032v1 Announce Type: cross Abstract: The interoperability between permissioned and public blockchains is hampered by asymmetric privacy, trust, and governance assumptions. We propose a coordination architecture that decouples cross-domain trust management and privacy enforcement from underlying blockchain protocols, requiring no protocol-level modifications. The framework integrates cryptographic unlinkability mechanisms with incentive-compatible relay selection, combining stake-weighted participation and temporally accumulated reputation to align economic commitment with sustained correctness. We formalize the adversarial model and derive security and privacy properties for cross-domain coordination, demonstrating robustness against Sybil infiltration, collusion, and strategic stake concentration. Simulation-based analysis characterizes key design trade-offs between quorum thresholds, reputation memory, and anonymity parameters, indicating that privacy-preserving coordination can be achieved without degrading responsiveness or incentive stability when parameters are properly tuned.