[bff] Bun-only native binding framework written in Rust.

[bff] Bun-only native binding framework written in Rust - the napi-rs analogue for Bun.

bunframe

A desktop application shell for Bun: native windows via wry (WebView2 / WKWebView / WebKitGTK) driven entirely from TypeScript. The inverted Tauri - the backend language is TypeScript, the native core is a thin Rust cdylib built with bffi.

 Bun thread (TS backend)                bunframe-core loop thread (native)
 ----------------------------------     ----------------------------------
 createWindow(config)  --Create-->      winit EventLoop + Window + wry
 ipc.handle(fn)  (JS-bound cb)          events stream (push) + IPC bridge
 run()  (pumps the bffi loop)  <--jobs-- invoke_wait: IPC + close veto
        the page: window.ipc.postMessage -> handler -> eval resolve

The framework never hides the pump: app.run() drives the bffi event loop on the JS thread - the one legal place native deliveries execute (no hidden timers, by design).

Layout

• crates? no - the core lives at the repo root: the bunframe-core cdylib (this crate) - window/IPC/events surface over wry;
• .bffi/ - the loader JSON + the generated typed API (committed, deterministic render);
• test/ - the env-gated e2e suite (BFFI_E2E=1, opens REAL windows).

Status

M1 (Windows-first): single- and multi-window, the full window command set, window events as a push stream, close-veto round trip, the IPC bridge. Linux/macOS come after the core stabilizes (macOS needs the window on the OS main thread - documented limitation, see the Binding GUI guide).

Prerequisites

• Bun >= 1.4.2
• Rust 1.98.0 (pinned via rust-toolchain.toml)
• Windows: WebView2 runtime (preinstalled on Windows 11)

Run the e2e

bun install
cargo build --release
$env:BFFI_E2E = "1"; bun test    # PowerShell

MIT license.