Create and manage sandboxed JavaScript tools for DeepSeek Harness with a Monaco editor and model-driven tool lifecycle.

DeepSeek Harness plugin: per-edit approval with a red/green line diff before write/edit/str_replace_editor — approve once or reject (Claude Code behavior).

DSH web plugin: Office file previewers (.docx/.xlsx/.pptx) for the better-sidebar editor. Registers the docx/xlsx/pptx file viewers through ctx.betterSidebar.registerFileViewer, keeping the heavy Office render libraries (docx-preview / Univer / SheetJS /