一句话：揭示并发程序故障交互依赖调度，导致仅靠调度相关掩盖消除失败的“幻影修复”，使基于测试的修复判据不可靠。
现代自动化软件工程（ASE）技术（测试、定位、修复）通常假定故障交互是稳定的、输入驱动的语义效应。该假设在顺序程序中基本成立，因为执行顺序固定；但在并发程序中线程交错会重塑可观察行为，从而失效。作者证明并发故障交互本质上是调度依赖的：相同输入在不同调度下可诱导不同的交互类。为刻画该效应，提出并发故障交互（CFI），通过调度索引映射 Mσ 将经典交互关系提升到调度空间 Σ，由此暴露“交互歧义”——故障间因果关系（如掩盖、协同）随调度流形变化。该歧义导致“幻影修复”：补丁通过调度相关的掩盖消除观测失败，而非真正语义修正，使标准基于测试的修复判据在并发场景下根本不可靠。最后提出交互不变性问题（IIP），通过从 NFA 语言包含问题的归约猜想其 PSPACE 难解性，并讨论其对调度感知与组合式程序合成的广泛影响。
Modern automated software engineering (ASE) techniques for testing, localization, and repair often treat fault interactions as stable, input-driven semantic effects. This assumption is largely adequate in sequential settings, where execution order is fixed, but breaks down in concurrent programs where thread interleavings reshape observable behavior. We show that concurrent fault interaction is fundamentally schedule-dependent: identical inputs can induce different interaction classes under different schedules. To capture this effect, we introduce Concurrent Fault Interaction (CFI), which lifts classical interaction relations to the schedule space Σ via a schedule-indexed map Mσ. This perspective exposes interaction ambiguity, where causal relationships between faults, such as masking or synergy, vary across the scheduling manifold. We show that this ambiguity gives rise to phantom fixes: patches that eliminate observed failures through schedule-dependent masking rather than genuine semantic correction, thereby rendering standard test-based repair oracles fundamentally unsound in concurrent settings. Finally, we introduce the Interaction Invariance Problem (IIP), conjecture its PSPACE-hardness via a reduction from NFA language inclusion, and outline its broader implications for schedule-aware and compositional program synthesis.