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-1.0.5.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
automatic migration of restored .ontos text tabs from older Cursor/VS Code sessions into the tree editor
Open as Text and Open as Tree commands
default companion 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.
Default companion: Node Tree side view, controlled by ontos.focusSidebarOnOpen.
Optional: side Web Preview, controlled by the preview command. Automatic side preview is only for explicit text-mode workflows.

Settings:

ontos.defaultEditor: tree by default, or text for plain text opening
ontos.autoPreview: disabled by default; only auto-opens the optional side preview when ontos.defaultEditor is text
ontos.focusSidebarOnOpen: enabled by default; opens and focuses the companion Node Tree side view once per .ontos document
ontos.indentGuides: enabled by default for plain text mode
ontos.depthBands: disabled by default; adds subtle nesting bands in plain text mode
ontos.textFolding: disabled by default; enables native text-editor folding only for users who explicitly prefer it

The default experience is one main tree custom editor plus the companion Node Tree side view. Use Open as Text when editing source lines directly. Text mode suppresses VS Code's native folding gutter for .ontos files so users do not see a second set of left-edge disclosure controls competing with the tree editor. If Cursor restores a .ontos text tab from an older session, the extension migrates it back into .ontos Tree unless ontos.defaultEditor is set to text or the current session used .ontos: Open as Text.

Local development smoke check: