This article synthesizes contemporary approaches to fault tolerance in embedded and safety-critical processors, proposes an integrative conceptual framework that unifies soft-error mitigation, lock-step replication, hybrid error-detection architectures, and redundancy-aware scheduling, and evaluates trade-offs that shape practical deployment in harsh and regulated environments. Methods: Building strictly on the provided references, the study performs an exhaustive theoretical integration of published methods—error detection and mitigation at the microarchitectural, core, and system levels—translating empirical insights into a cohesive methodology for designing resilient multi-core and lock-step systems without relying on new experimental data. Results: The synthesis demonstrates how transient-fault recovery techniques (including simultaneous multithreading and core replication) can be combined with trace-interface-based detection, PTM-informed hybrid detectors, and embedded debug features to produce scalable resilience with optimized cost, power, and latency. It also characterizes the contexts—radiation-prone aerospace, automotive zonal controllers, and industrial electronics—where each approach yields maximal benefit. Conclusions: Integrating low-cost hardware redundancy with software-aware detection and recovery strategies yields the best balance between safety integrity, resource overhead, and system performance. The paper identifies precise design patterns, potential pitfalls, and research directions that arise when adopting Triple Core Lock-Step and hybrid PTM detection schemes on modern ARM-class processors targeted for ASIL D and ultra-reliable applications.