Abstract
This is a first-person design account of building an in-place AI explainer, using it for months as a browser extension and as a local desktop application, and discovering that its defining feature was not the one it shipped with. A single-shot inline explanation resolves a word but rarely the confusion: the first answer raises the question actually worth asking, and a tool that cannot take that question sends users to a chat window to restate everything — removing the first tab and leaving the second. The paper argues that a follow-up which opens a panel or a separate surface forfeits the entire premise, so the real engineering problem is a conversation that grows without displacing the passage it is about. It makes a coherence argument for going standalone: an explainer that trains the expectation of an answer in place, then vanishes for PDFs, documents and messages, replaces a reliable habit with an unreliable one. It argues that the launcher pattern — the obvious route to system-wide availability — is the wrong interaction model, contrasting the two across five properties. The paper states honestly what is built and what is not, records how retiring the extension silently invalidated a pricing tier that depended on it, and sets out five checkable commitments for a standalone version, including treating the record of what a reader failed to understand as sensitive.