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Browser / WASM prototype

Experimental branch that compiles daw2logic to WebAssembly with py2wasm (Nuitka WASI fork) and serves a static web UI on GitHub Pages.

Architecture

Browser (web/)
  └─ @wasmer/sdk runs daw2logic.wasm (WASI)
       └─ stdin: .dawproject zip bytes
       └─ stdout: framed notes + .logicx.zip bytes

Python sources
  wasm/main.py          WASI entry (stdin/stdout)
  daw2logic/wasm_api.py in-memory convert + wire format

The web app never uploads files to a server — conversion runs entirely in the browser once the WASM module is loaded.

Local development

1. Test the in-memory API (no WASM)

python tests/fixtures/build_bitwig_simple.py
pytest tests/test_wasm_api.py -q

2. Build the WASM module

Requires Python 3.11 and a C compiler (clang / gcc).

bash scripts/build_wasm.sh

This installs the Wasmer py2wasm fork into .venv-wasm, compiles wasm/main.py → web/wasm/daw2logic.wasm, and smoke-tests with wasmer run when available.

3. Preview the web UI

Serve the web/ directory over HTTP (required for ES modules + WASM fetch):

python -m http.server 8080 --directory web
open http://localhost:8080

For @wasmer/sdk threading, the page uses coi-serviceworker to enable cross-origin isolation headers locally and on GitHub Pages.

GitHub Pages

Push to main — the wasm-pages workflow:

  1. Checks out submodules (LogicProFormatWriter seeds are required at compile time)
  2. Builds web/wasm/daw2logic.wasm on Ubuntu
  3. Deploys the web/ folder to GitHub Pages

Enable Pages in repo settings: Source → GitHub Actions.

Known constraints / blockers

Topic Status
py2wasm on PyPI Standard PyPI py2wasm is upstream Nuitka without WASI — use the lum1n0us fork via scripts/build_wasm.sh
WASI C extensions Nuitka standalone tries dlopen for stdlib C modules; scripts/patch_nuitka_wasi.py + scripts/build_wasi_zlib.sh link PyInit_zlib for zipfile
Logic seeds at runtime WASM cannot use Nuitka package-data paths; build_wasm.sh copies seeds to web/wasm/logicx/data/ and smoke/CI mount them at /seeds
Python version WASM build requires 3.11 (not 3.12+)
Binary size Full converter + libpython WASM is large (expect tens of MB)
Browser headers Needs COOP/COEP for Wasmer SDK; handled via service worker on Pages
Browser seeds app.js fetches web/wasm/logicx/data/* and mounts them at /seeds for the WASI module
Folder drop UI currently accepts .dawproject files only; folder → zip client-side is TODO
AU sidecars Same as CLI — presets export to sidecar paths inside the bundle zip

If the WASI fork stops working, fallbacks to evaluate: Pyodide (interpreter, easier but slower) or a Rust/WASM rewrite of the hot path.

Wire format

u32 notes_len LE
u32 zip_len LE
notes_utf8[notes_len]
logicx_zip[zip_len]

Implemented in daw2logic/wasm_api.py (pack_conversion_result / unpack_conversion_result).