.ontos Protocol VS Code Extension
Node-first VS Code support for .ontos files.

Install
Install .ontos Protocol from Open VSX, Cursor, VSCodium, or Visual Studio
Marketplace after publication. Maintainers can build and install the release
VSIX locally:
npm run release:vscode-vsix
code --install-extension .release/ontos-protocol-vscode-1.0.0.vsix
See the repository-level
VS Code Extension Publishing runbook for
Open VSX and Visual Studio Marketplace publishing.
Features:
- default tree custom editor for
.ontos files
- automatic switch from a text tab to the tree view when
ontos.defaultEditor
is tree
- Open as Text and Open as Tree commands
- optional Node Tree side view
.ontos language registration
- syntax highlighting
- document symbols and outline
- validation diagnostics
- format command
- export commands for Markdown, HTML, JSON, and OPML
- copy node ID, node path, and node text commands
- context, review, handoff, modify-boundary, and verification pack commands
- Markdown to
.ontos conversion command
- optional interactive tree preview command
Node path, node text, and AI pack commands work from the current tree tab
focus, Node Tree selection, or text cursor. These commands also work before a
node has @id(...); packs for no-ID nodes include a temporary line-based
reference and recommend adding a stable ID.
First Open Behavior
.ontos opens in .ontos Tree by default:
ontos.defaultEditor defaults to tree.
- The extension contributes
workbench.editorAssociations so *.ontos uses
ontos.nativeViewer.
- Workspace opens are the most reliable path for editor associations because
VS Code applies workspace and extension defaults together.
- Single-file opens still promote a plain text
.ontos tab into the tree view
when ontos.defaultEditor is tree.
Use .ontos: Open as Text or set ontos.defaultEditor to text for a
plain-text-only workflow.
UI layers:
- Default:
.ontos Tree custom editor in the main editor tab.
- Optional: Node Tree side view, controlled by
ontos.focusSidebarOnOpen.
- Optional: side Web Preview, controlled by
ontos.autoPreview or the preview
command.
Settings:
ontos.defaultEditor: tree by default, or text for plain text opening
ontos.autoPreview: disabled by default; opens the optional side preview
ontos.focusSidebarOnOpen: disabled by default; focuses the Node Tree side view
ontos.indentGuides: enabled by default for plain text mode
ontos.depthBands: disabled by default; adds subtle nesting bands in plain text mode
The default experience is the tree custom editor. Use Open as Text when editing
source lines directly. VS Code keeps folding controls in the gutter, so text
mode adds indentation guides as a visual aid instead of trying to move the
gutter controls.
Local development smoke check:
npm run validate:vscode
Manual release UX checklist:
docs/VSCODE_EXTENSION_MANUAL_UX_CHECKLIST.md