Teaching the Boundary: Context Synthesis, Context Ignorance, and Refusal
The instruction hierarchy describes a behavior a model should learn, but a description alone does not make that behavior dependable. This chapter focuses on the paper’s training method: how synthetic examples teach a model to incorporate compatible lower-level constraints, ignore hostile content, and refuse when safe continuation is impossible. Understanding these two complementary methods also explains why the study separates open-domain assistants from closed-domain tasks and why some attack types are deliberately withheld from training.
Context synthesis preserves compatible requests
The first training problem is easy to state and easy to mishandle: how can a model learn that lower-priority instructions are sometimes valid? If every example pairs a user or tool message with a refusal, the model may learn the wrong lesson. It may become resistant to attacks by becoming resistant to users.
The paper addresses this problem with a method it calls context synthesis. It begins with a compositional request—one containing several compatible requirements. “Write a twenty-line poem in Spanish” combines a task, a language, and a length. A generator decomposes the request into smaller pieces: write a poem, use Spanish, and use twenty lines. Those pieces are then placed at different levels of the instruction hierarchy. The model is trained to produce the same ground-truth response it would have produced if the complete request had been supplied as a high-priority instruction.
The causal idea is important. The method does not teach that a user message can overrule a system message. It teaches that a user-level detail can still constrain the answer when it does not conflict with the system’s purpose. Privilege determines who wins if there is a conflict; it does not determine whether compatible information can be used at all.
Suppose a system message defines an assistant as a car-sales helper. A user asks for the best family car in a given price range and asks for the answer in Spanish. The role and the language request can coexist. The higher-level instruction establishes the domain and boundaries; the lower-level instruction fills in a preference or output constraint. Context synthesis creates training situations in which those pieces are separated but the target remains the complete, useful answer.
This is synthetic data generation: examples are constructed rather than collected as a record of naturally occurring conversations. The paper combines it with context distillation, a broader pattern in which a model is prompted with the desired context or rule and the resulting behavior is used as a training target for a model that will later operate without that extra support. The method can therefore teach a relationship that is difficult to specify with a single verbal reminder.
The relationship has two failure directions. If the lower-level pieces are placed without regard to the higher-level purpose, the training data could reward unauthorized overrides. If the data treats every lower-level instruction as hostile, it could create over-refusal. The paper explicitly describes the need to balance prompt-injection resistance against the damage caused by refusing aligned requests. Context synthesis addresses the second risk by making compatibility part of the target behavior.