A Tale of Two Particles
Agentic systems have exactly two fundamental particles: text the model reads, and code it can ask to run. One is stochastic, the other deterministic. Almost every confusion about prompts, tools, skills, and agents starts when you lose track of which is which.
The patterns built on top of these two primitives — filtering, skills, progressive disclosure — are all in service of one problem: keeping the stochastic half on the rails as the system grows. This is the problem domain of context engineering. This is the discrete measurement of agent trajectory.
