What we learned building an AI tool loop that edits a native presentation document

Most AI presentation tools generate HTML, images, or one-shot exports. In Deckium, the model and the user edit the same structured presentation document through different interfaces. The agent uses bounded tools for objects, text, geometry, charts, and images. A user can then move, resize, rewrite, or delete anything. The next model turn receives that updated document as context. Implementation lessons: Stable object IDs are essential for preserving conversational references. Narrow tools are easier to validate than unrestricted document patches. Overflow, overlap, and text-density checks let the model review its own output. Human edits are authoritative state, not drift to overwrite. Electron + React, open source under MIT. GitHub: https://github.com/sleipner42/Deckium Demo: https://www.reddit.com/r/SideProject/comments/1vku0jh/i_opensourced_deckium_an_ai_presentation_editor/ Where should the boundary sit between direct agent edits and staged suggestions in a document editor?