The biggest problem with spec-driven development is that your product evolves dynamically. Today's requirements logic and next month's, next quarter's, and next year's are completely different.

For example, today's interface design doesn't need caching, and array fields are faked with comma-separated text—this is to go live quickly. Next quarter, due to security and performance concerns, you'll need to change it back.

Every requirement change is the result of countless parameter combinations. How do you completely record all the out-of-band context in documentation? How do you cover all variables comprehensively? Unless you have a brain-computer interface constantly reading your memory to feed the agent.

If you could be so meticulous that you only need documentation to act as a clairvoyant or God who has already cleaned up every mess, then you've already solved software engineering's ultimate problem: there is no silver bullet.