Add React Native bindings for payjoin-ffi

payjoin-ffi/react-native/.gitignore

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+# Package + build outputs
+node_modules/
+lib/
+artifacts/
+
+# Compiled Rust static libraries (produced by `ubrn build ios`)
+*.xcframework/
+
+# Generated by uniffi-bindgen-react-native (native projects, C++ glue, TS bindings)
+rust_modules/
+cpp/
+android/
+ios/
+*.podspec
+src/generated/
+src/index.tsx
+src/Native*.ts

payjoin-ffi/react-native/.prettierrc

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+{
+    tabWidth: 4
+}

payjoin-ffi/react-native/CONTRIBUTING.md

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+# Contributing
+
+Instructions for building and testing the React Native bindings locally.
+
+## Prerequisites
+
+This assumes you already have Rust and Node.js installed.
+
+Native builds additionally require:
+
+- **Android:** the Android NDK (set `ANDROID_NDK_HOME`) and
+  [`cargo-ndk`](https://github.com/bbqsrc/cargo-ndk) (`cargo install cargo-ndk`).
+- **iOS (macOS only):** Xcode and the iOS Rust targets (added automatically by
+  the build script when using rustup).
+
+## Build Bindings
+
+Follow these steps to clone the repository and build the bindings.
+
+```shell
+git clone https://github.com/payjoin/rust-payjoin.git
+cd rust-payjoin/payjoin-ffi/react-native
+
+# Clean out stale generated output
+npm run clean
+rm -rf node_modules
+
+# Install package dependencies
+npm install
+
+# Build the native libraries and generate the Turbo Module bindings
+bash ./scripts/generate_bindings.sh
+```
+
+The script builds Android for all ABIs and, on macOS, iOS for device and
+simulator, then compiles the generated TypeScript with
+[react-native-builder-bob](https://github.com/callstack/react-native-builder-bob).
+
+## Testing
+
+On-device tests require an example app (not yet included) plus an iOS simulator
+or Android emulator. In a headless environment, typecheck the generated
+bindings:
+
+```shell
+npm run typecheck
+```
+
+## Packaging
+
+The published package ships the native build outputs (the iOS
+`PayjoinRnFramework.xcframework`, the Android libraries, the generated
+`cpp/` glue, and the podspec). These are gitignored and produced by
+`scripts/generate_bindings.sh`. Build and pack the tarball with:
+
+```shell
+bash ./contrib/pack.sh
+```
+
+The script installs dependencies from the lockfile (`npm ci`), generates the
+bindings, verifies the artifacts, and writes the tarball to `artifacts/`.
+`generate_bindings.sh` builds the iOS artifacts only on macOS, so run this
+from a macOS host; on Linux the artifact check aborts rather than shipping a
+tarball with no iOS slice.
+
+As a safety net, `prepack` runs `scripts/check_artifacts.sh` on every
+`npm pack`/`npm publish`, so an ad-hoc pack that skipped the build fails
+instead of shipping a broken tarball.

payjoin-ffi/react-native/README.md

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+# Payjoin React Native Bindings
+
+Welcome to the React Native language bindings for the [Payjoin Dev Kit](https://payjoindevkit.org/)!
+
+These bindings compile `payjoin-ffi` to native libraries (an iOS static
+framework and Android `.so`s) and expose them to React Native through a JSI
+Turbo Module, generated by
+[uniffi-bindgen-react-native](https://github.com/jhugman/uniffi-bindgen-react-native).
+
+> [!NOTE]
+> For web and Node.js environments, use the sibling
+> [`payjoin` JavaScript bindings](../javascript) instead. React Native cannot
+> run the WebAssembly build those bindings produce (Hermes has no
+> `WebAssembly` support), which is why these native bindings exist.
+
+## Requirements
+
+These bindings are a JSI Turbo Module and require React Native's New
+Architecture, which is the default on React Native 0.76 and later. On older
+releases you must enable it yourself. Without the New Architecture the native
+module fails to register and the import throws at startup.
+
+## Usage
+
+### Install
+
+```shell
+npm install payjoin-rn
+```
+
+### Import
+
+```ts
+import payjoinRn, { uniffiInitAsync } from "payjoin-rn";
+
+// Initialize before usage. On native this is a no-op; it exists for parity
+// with the web bindings, which load WebAssembly asynchronously.
+await uniffiInitAsync();
+
+// The bindings are namespaced on the default export.
+const { payjoin } = payjoinRn;
+```
+
+## Building locally
+
+See [CONTRIBUTING.md](./CONTRIBUTING.md).
+
+Made with [uniffi-bindgen-react-native](https://github.com/jhugman/uniffi-bindgen-react-native)

payjoin-ffi/react-native/contrib/pack.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# Build the production package and pack the npm tarball into artifacts/.
+#
+# Unlike the javascript sibling, whose tarball ships only platform-independent
+# wasm + JS, this tarball ships prebuilt native artifacts (the iOS xcframework
+# and Android libraries). generate_bindings.sh builds the iOS half only on
+# macOS, so run this from a macOS host; check_artifacts.sh aborts otherwise.
+
+# Build against the maintained lockfile instead of resolving the dependency
+# graph fresh on every run. use_lockfile copies Cargo-recent.lock into place
+# and restores the previous state when this script exits.
+REPO_ROOT="$(cd "$(dirname "$0")/../../.." && pwd)"
+cd "$REPO_ROOT"
+source contrib/lockfile.sh
+use_lockfile Cargo-recent.lock
+
+cd "$REPO_ROOT/payjoin-ffi/react-native"
+
+echo "==> Installing React Native dependencies..."
+npm ci
+
+echo "==> Generating FFI bindings..."
+bash ./scripts/generate_bindings.sh
+
+# npm pack runs the prepack hook (scripts/check_artifacts.sh), which aborts
+# if any native output is missing, so no separate verification step here.
+echo "==> Packing npm tarball..."
+rm -rf artifacts
+mkdir -p artifacts
+npm pack --pack-destination artifacts

payjoin-ffi/react-native/contrib/test.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# Build against the maintained lockfile instead of resolving the dependency
+# graph fresh on every run. use_lockfile copies Cargo-recent.lock into place
+# and restores the previous state when this script exits.
+REPO_ROOT="$(cd "$(dirname "$0")/../../.." && pwd)"
+cd "$REPO_ROOT"
+source contrib/lockfile.sh
+use_lockfile Cargo-recent.lock
+
+cd "$REPO_ROOT/payjoin-ffi/react-native"
+
+echo "==> Installing React Native dependencies..."
+npm ci
+
+echo "==> Generating FFI bindings..."
+bash ./scripts/generate_bindings.sh
+
+# On-device/simulator tests require the (deferred) example app plus an iOS
+# simulator or Android emulator. Until then, typechecking the generated
+# bindings is the strongest signal we can produce in a headless environment.
+echo "==> Typechecking bindings..."
+npm run typecheck