Transfer-based anti-money laundering (AML) systems monitor token flows through transaction-graph abstractions, implicitly assuming that economically meaningful value migration is sufficiently encoded in transfer-layer connectivity. In this paper, we demonstrate that this assumption, the bedrock of current industrial forensics, fundamentally collapses in composable smart-contract ecosystems. We formalize two structural mechanisms that undermine the completeness of transfer-layer attribution. First, we introduce Principal-Execution-Beneficiary (PEB) separation, where intent originators, transaction executors (e.g., MEV searchers), and ultimate beneficiaries are functionally decoupled. Second, we formalize state-mediated value migration, where economic coupling is enforced through invariant-driven contract state transitions (e.g., AMM reserve rebalancing) rather than explicit transfer continuity. Through a real-world case study of role-separated limit order execution and a constructive cross-pool arbitrage model, we prove that these mechanisms render transfer-layer observation neither attribution-complete nor causally closed. We further argue that simply expanding transfer-layer tracing capabilities fails to resolve the underlying attribution ambiguity inherent in structurally decoupled execution. Under modular composition and open participation markets, these mechanisms are structurally generative, implying that heuristic-based flow tracing has reached a formal observational boundary. We advocate for a paradigm shift toward AML based on execution semantics, focusing on the restitution of economic causality from atomic execution logic and state invariants rather than static graph connectivity.

翻译：基于转账的反洗钱系统通过交易图抽象监控代币流动，其隐含假设是经济上有意义的价值迁移充分编码于转账层连接中。本文证明，这一构成当前工业取证基石的假设，在可组合的智能合约生态系统中根本性失效。我们形式化了两种破坏转账层归因完整性的结构机制。首先，引入主体验益分离机制，其中意图发起者、交易执行者（如MEV搜索者）和最终受益人功能解耦。其次，形式化状态中介价值迁移机制，其中经济耦合通过不变量驱动的合约状态转换（如AMM储备重新平衡）而非显式转账连续性实现。通过角色分离限价单执行的实际案例研究和构建性跨池套利模型，我们证明这些机制使转账层观测既非归因完备也非因果封闭。我们进一步论证，单纯扩展转账层追踪能力无法解决结构解耦执行中固有的归因模糊性。在模块化组合与开放参与市场条件下，这些机制具有结构生成性，这意味着基于启发式的流动追踪已达形式化观测边界。我们倡导向基于执行语义的反洗钱范式转变，聚焦于从原子执行逻辑与状态不变量中重建经济因果性，而非静态图连接关系。