Show HN: TeXbrain, a LaTeX editor that runs pdfTeX in the browser via WASM

TeXbrain runs pdfTeX compiled to WebAssembly in the browser, editing local files via the File System Access API and handling Git with isomorphic-git. Its 1.8 MB engine retrieves missing packages from a service-worker cache, a bundled subset, a jsDelivr-mirrored TeX Live 2020 tree, or a SwiftLaTeX fallback, allowing offline use after initial load. It supports only pdfTeX, excludes XeTeX/LuaTeX, fontspec, polyglossia, bibtex, and biber, and locks packages to the 2020 TeX Live release.