tl;dr: Claude Code's session logs contain "thinking blocks" that are encrypted with a 600-character signature only Anthropic can decrypt, meaning users can't access their agent's actual reasoning locally. The API only returns a summary of the reasoning—not the raw thinking that drove the model's actions—and full thinking output requires an enterprise agreement. This matters for anyone relying on Claude Code for audit trails, since the available logs are a lossy summary rather than the true reasoning chain.