YLSpec for Visual Studio Code

Language support for standalone .ylspec files. The extension validates documents with the same C11 reference implementation used by the Python, JavaScript, Java, and Kotlin libraries, compiled to bundled WebAssembly.

Features

Feature	Behavior
File association	`.ylspec` opens in the YLSpec language mode
Syntax highlighting	Tables, keys, strings, multiline strings, escapes, numbers, temporal literals, booleans, comments
Diagnostics	TOML syntax, envelope versions, structure, configured limits, and mandatory features
Profile handling	`core.data` is validated; unsupported custom profiles produce a warning and remain editable
Metadata completion	Standard keys and their initial values inside `[_ylspec]`
Hover documentation	Descriptions of the four standard metadata keys
Snippets	`ylspec`, `ylmanifest`, and `ylextension`
Commands	YLSpec: New Document and YLSpec: Validate Document
Optional formatter	Canonical semantic serialization through C; removes comments and rewrites whitespace

Validation runs in a worker thread after a short editing delay. The extension parses the open document only. It does not execute configuration values, include files, resolve environment variables, run project tools, or send document content to a server. No telemetry is collected. WebAssembly and its notices are packaged inside the VSIX; initialization does not download a parser.

Install

Download ylspec-0.1.2.vsix from a verified GitHub Release. In VS Code, open Extensions → … → Install from VSIX…, then select that file. Alternatively:

code --install-extension ylspec-0.1.2.vsix

Marketplace availability requires a separately registered publisher and a successful Marketplace upload. A packaged VSIX is usable without that upload. The package identifier is ylvsmp.ylspec, published by YoungLion (ylvsmp).

Start a document

Run YLSpec: New Document, or type ylspec in an empty .ylspec file and select the snippet:

[_ylspec]
version = "0.1"
profile = "core.data"
profile_version = "0.1"

[data]
name = "Example"
enabled = true

Application-specific keys belong in data. Extra namespaces belong in extensions. The extension does not invent a schema for project data.

Settings

Setting	Default	Purpose
`ylspec.validation.enabled`	`true`	Automatic diagnostics; explicit validation remains available
`ylspec.validation.delay`	`350`	Debounce delay in milliseconds; 100–5000
`ylspec.maxDocumentBytes`	`16777216`	UTF-8 source byte limit; configurable up to 64 MiB
`ylspec.maxDepth`	`64`	Value depth; maximum 128
`ylspec.format.enabled`	`false`	Enable formatting that discards comments and changes layout

To opt into semantic formatting and select this formatter:

{
  "ylspec.format.enabled": true,
  "[ylspec]": {
    "editor.defaultFormatter": "ylvsmp.ylspec"
  }
}

Formatting preserves values, including exact temporal text and signed 64-bit integers. Comments, whitespace, literal spelling, and key layout are not retained. Invalid documents are not reformatted. Automatic format-on-save is not enabled by the extension.

Compatibility and scope

VS Code 1.95+ desktop and remote workspace extension hosts are supported. Language coloring and snippets are declarative; active validation requires a Node-enabled extension host. Browser-only vscode.dev execution is not an advertised target. Virtual and untrusted workspaces are supported because validation requires no project execution or arbitrary file access.

Only standalone text documents are edited. Binary .ylplugin, .ylpkg, frame discovery, archive editing, custom profile code loading, and embedded payload modification are outside the extension's scope. Custom profiles need their own validators in the consuming application; the editor reports their unsupported validation status as a warning.

Verification and publishing

The repository workflow tests the real TextMate grammar with Oniguruma, tests Unicode diagnostic positions, launches a VS Code Extension Host under a virtual display, and verifies diagnostics, completions, formatting, and the bundled C engine. It then packages the universal VSIX as a required release asset.

See the repository's editor guide and registry publishing guide for reproducible packaging and account setup.

License

Copyright 2026 Cavanşir Qurbanzadə. Original code and documentation are licensed under Apache-2.0. The bundled tomlc17 parser retains its MIT license and original notice in engine/licenses/tomlc17/LICENSE. See the distributed NOTICE and THIRD_PARTY_NOTICES.md files.