Engineer Subhadip Mitra lays out a hierarchical framework for understanding AI model internals, moving from behavioral output analysis through attention mechanisms to full circuit tracing. He connects earlier work on detecting AI sandbagging via linear probes on hidden states to Anthropic’s circuit-tracing techniques, which use sparse autoencoders and attribution graphs to map causal computational pathways inside a model. The piece argues mechanistic interpretability is moving from academic research toward practical production use, particularly for debugging multi-agent systems and building safety interventions at the representation level rather than through output-level constraints alone.