VS Code extension: live AADL rendering with WASM

[avrabe]

Context

All building blocks exist:

• spar LSP server (spar lsp) for editing support
• spar-wasm compiles to wasm32-wasip2 (1.3MB)
• spar-render produces interactive HTML with ports, orthogonal routing, pan/zoom/selection
• etch HTML wrapper is self-contained (no external deps)

VS Code now supports WASM language servers via wasm-wasi-core.

Proposal

VS Code extension that:

1. Activates on .aadl files
2. Runs spar LSP (native binary or WASM) for syntax/diagnostics/go-to-def
3. Opens a WebviewPanel with live architecture diagram (interactive HTML from etch)
4. Re-renders on file save (onDidSaveTextDocument)
5. Supports ?highlight= for click-to-navigate between code and diagram

Architecture options

• A: Native binary — extension bundles spar binary, shells out for render. Simpler, cross-platform via release binaries
• B: WASM — loads spar-wasm in VS Code's WASI runtime. No binary distribution needed, but WASI support is newer
• C: Hybrid — WASM for LSP, native for render (render needs filesystem access)

References

• VS Code WebviewPanel API
• VS Code WASM language server support
• spar-wasm WIT: pulseengine:rivet/renderer