The scaffold (or scaffolding) is the code layer that wraps a language model and turns it into an agent capable of acting. It is not the model itself, but all the infrastructure surrounding it: it manages the reasoning loop, connects external tools, maintains memory, and translates the model's decisions into concrete actions on the environment.
Its importance lies in the fact that an isolated model only generates text; it is the scaffold that provides operational autonomy. The same model can behave very differently depending on the scaffold orchestrating it. Its common components are:
- Control loop: decides when to continue reasoning or to act.
- Tool interface: allows for executing code, searching, or calling APIs.
- Context management: organizes memory, history, and prompts.
A clear example is a programming agent: the scaffold reads the model, executes the commands it proposes, captures errors, and returns them for iteration. The quality of the scaffold usually determines the final performance as much as the model itself.