APPENDIX A: GLOSSARY OF TERMS AND ACRONYMS

TERMS BEGINNING WITH D Dashboard: a single screen that shows the key numbers about a system's health at a glance. Data exfiltration: the secret theft of private information by sending it out of a protected system. Data minimization: collecting only the data you need. Data protection: the rules and practices that keep personal and sensitive information safe and properly used. Data residency: a requirement that data stay in a particular place. Database: an organized collection of searchable information. Dataset: an organized collection of examples used for testing or learning. Dead end: an approach that was tried and failed. Deadlock: a stuck situation in which two or more agents each wait for the other, so nothing moves forward. Debugging: the work of finding and fixing the cause of a mistake in software. Deep learning: machine learning using neural networks with many layers. Deep-research agent: an agent that investigates a broad question over many steps. Default deny: forbidding anything not explicitly permitted. Defense in depth: protecting a system with several independent safeguards stacked together, so one failure does not cause disaster. Deny-list: a list naming tools or actions that are forbidden, with everything else allowed. Dependency: a piece of outside software that your own software needs in order to work. Deployment: the act of putting software into real use where actual users can reach it. Deprecation: the planned retirement of an old feature, announced ahead of time so users can move to a newer one. Design-decision document: a short record of why a choice was made. Deterministic code: code that gives the same output for the same input. Deterministic control: control in which the steps always happen in the same fixed order decided by code, not by the model. Development Operations (DevOps): the practice of building, releasing, and running ordinary software smoothly and reliably. DevOps: the short form of Development Operations (DevOps). Diff: the list of exact lines added and removed by a change. Direct injection: a prompt injection in which the attacker types the harmful instruction straight into the agent's input. Directed graph: nodes connected by one-way edges. Dispatch: the step in which the harness sends a requested tool call to the right piece of code to carry it out. Distractor: content that resembles the answer but is not the answer. Domain: a particular field of work. Draft versus send: separating creation of a message from dispatching it. Drift: a slow change in a system's behavior over time that nobody planned. Drift monitoring: watching for slow, unplanned changes in behavior so they can be caught early. Dual-agent separation: a safety design using two agents, one that handles untrusted material and one that holds the power to act. Durable storage: storage that survives restarts.