0007 · The module is handed a project, whole, on every call

Status: accepted, 2026-08-30. Issue: #69

Two shapes were considered for getting a multi-file project into the WebAssembly module.

Pass it in whole — a length-prefixed list of name and bytes, on every call. Stateless, no imported functions.

Call back into the host per file. The only thing this buys is not knowing the file set in advance — and the host is an editor, which is the thing that opened the files. Measured against a real monograph: 388 KB across 20 files, checked in 71 ms including twenty process starts; in-process there is nothing to save. And WebAssembly imports are synchronous, so a file arriving over a network cannot be awaited from inside one without heavy machinery. The shape that appears to serve the network case serves it worst.

So: the project is passed in whole. The wire format is in wasm.md — little-endian, length-prefixed, unaligned, readable with a DataView and a loop.

Two consequences worth naming:

1. The pipeline moved into the core. check_project — transitive imports, the author’s \include edges, the bibliography, the label inventory — lived in the CLI and is now xtex_core::project, parameterised over SourceLoader. The CLI’s loader answers from the filesystem; the module’s from the bundle. The parity test compares the CLI binary on a project on disk against the module on the same project as a bundle: two hosts, one answer, byte for byte.
2. Assets are present by name. A figure’s PDF is listed with empty data. Existence is the only question ever asked of an asset, and omitting it would make a correct src field a false hard error.