Overly structured, workflow-based systems that work with today's models will become bottlenecks tomorrow. Engineers must be prepared to shed abstractions and rebuild simpler, more general systems to capture the gains from exponentially improving models.

AI development history shows that complex, hard-coded approaches to intelligence are often superseded by more general, simpler methods that scale more effectively. This "bitter lesson" warns against building brittle solutions that will become obsolete as core models improve.

The "bitter lesson" of AI applies to product development: complex scaffolding built around model limitations (like early vector stores or agent frameworks) will inevitably become obsolete as the models themselves get smarter and absorb those functions. Don't over-engineer solutions that a future model will solve natively.

The focus in AI has shifted from crafting the perfect prompt (prompt engineering) to providing the right information (context engineering), and now to building the entire operational environment—tooling, systems, and access—that enables a model to perform complex tasks. This new paradigm is called harness engineering.

While intricate software "scaffolding" can boost an AI agent's performance, progress is overwhelmingly driven by the core model. A new model generation typically achieves the same capabilities with simple prompts that previously required complex engineering.

Building on AI requires creating custom infrastructure to fill performance gaps. As underlying models improve, founders must be prepared to delete this now-redundant code and upgrade their product vision to tackle the next set of challenges at the new frontier. This cycle of building and deleting is key to staying innovative.

The underlying infrastructure for AI agents ('harnesses') becomes obsolete roughly every six months due to rapid advances in AI models. At Notion, this means completely rewriting the harness multiple times a year, demanding a culture comfortable with constantly rebuilding core systems and discarding previous assumptions.

Many early AI product features, like Claude Code's initial "to-do list," are crutches built to compensate for model weaknesses. As underlying models become more capable, they perform these functions naturally, allowing teams to remove the crutch features and simplify the product.

To fully leverage rapidly improving AI models, companies cannot just plug in new APIs. Notion's co-founder reveals they completely rebuild their AI system architecture every six months, designing it around the specific capabilities of the latest models to avoid being stuck with suboptimal implementations.