The loop is small. The infrastructure around it is what keeps it stable as features grow.
The same loop, made concrete: a single user turn flows through the agent to a tool and back.
More expensive models bring gains far smaller than expected. Verification, boundaries, feedback, and fallbacks matter more than model capability.
Long context windows do not fix weak context design. Context Rot sets in around 300–400K tokens regardless of the model.
Tools should match Agent goals. Memory belongs on disk, outside the context window.
Four kinds of memory
Comments should outnumber code lines. The reader sees logic, not a language tutorial.