Coarse-grained reconfigurable architectures (CGRAs) promise high energy efficiency but remain vulnerable to transient upsets and aging-induced defects. We introduce a compiler-transparent reliability framework that provides online error detection and fast in-field recovery without requiring remapping or software checkpoints. The proposed approach distinguishes transient from permanent faults at runtime and enables rapid handover to healthy resources with low performance overhead. Experimental results demonstrate competitive fault coverage, bounded recovery latency, and negligible impact on steady-state throughput. In addition, a mean time to failure (MTTF) improvement of more than 2.5 is achieved over the baseline without fault tolerance.