VS Code Extension

The FastYoke VS Code extension makes fy-app.json — the source-of-truth spec for your app's entities and workflows — safe and legible to author, without leaving your editor.

What it does

• Structural IntelliSense — key and enum completion, hover, and validation for fy-app.json.
• Semantic workflow checks — the state-machine mistakes a plain JSON validator can't catch: a transition pointing at a state that isn't declared (with a "did you mean…" quick-fix), unreachable states, duplicate (from, event) pairs, a missing terminal state, and more. The rules are shared with the fy CLI, so the editor and the terminal never disagree.
• Live FSM preview — run FastYoke: Preview FSM (or click the icon in the editor-title bar of a fy-app.json) to open a state-machine diagram beside your spec. It redraws as you type, an entity picker switches between workflows, and clicking a state jumps your cursor to its definition.

Everything runs locally — the preview is a self-contained diagram with no network calls and no telemetry.

Install the beta

1. Download the beta (.vsix) — the current build is 0.1.0.
2. Install it — either:
   • In VS Code, open the Extensions view → the ⋯ (Views and More Actions) menu → Install from VSIX… → choose the downloaded file; or
   • from a terminal:

     code --install-extension fastyoke-vscode.vsix
     

3. Open any fy-app.json and the extension activates automatically.

Editors built on VS Code — Cursor, VSCodium, Windsurf — install the same .vsix the same way.

See also

• CLI — fy, which scaffolds and reads the same fy-app.json.
• fy-app.json spec — the file this extension validates.