# NXST

Transfer save data between two Nintendo Switch consoles over local Wi-Fi.

Pick a game, pick a user. One Switch sends; the other receives. The sender backs up its own save first, so you can never lose data in transit.

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## Install

1. Download `NXST.nro` from [Releases](../../releases).
2. Copy it to `/switch/NXST/NXST.nro` on your SD card.
3. Launch via hbmenu (hold R while starting any game, or Album).

Both Switches must be on the same Wi-Fi network. No router configuration needed — discovery uses UDP multicast.

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## Usage

**Sender** (the Switch whose save you want to copy):

1. Open NXST → select a title → press **A** → **Transfer**.
2. Wait for "Waiting for receiver…" to change to "Transferring…".

**Receiver** (the Switch that will receive the save):

1. Open NXST → select the same title → press **A** → **Receive**.
2. Wait. The save is restored automatically when the transfer finishes.

Press **B** on either side to cancel mid-transfer.

Logs are written to `/switch/NXST/log.log`.

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## Build

**Prerequisites:** [devkitPro](https://devkitpro.org/wiki/Getting_Started) with `switch-dev` and `switch-portlibs` packages, plus `cmake ≥ 3.20`.

```bash
# Clone (Plutonium UI fetched automatically by CMake)
git clone https://github.com/your-username/NXST.git
cd NXST

# Configure (once)
cmake --preset switch

# Build
cmake --build build

# Send to Switch via nxlink (Switch must be on same network, nxlink running)
cmake --build build --target send
```

Output: `build/NXST.nro`

---

## Architecture

See [`docs/ARCHITECTURE.md`](docs/ARCHITECTURE.md) for the layer diagram, threading model, and key types.

See [`docs/PROTOCOL.md`](docs/PROTOCOL.md) for the wire protocol (UDP multicast discovery + TCP file stream).

```
ui/          — TitlesLayout, UsersLayout, TransferOverlay, HeaderBar
service/     — TransferService (all network threads and state)
infra/net/   — Socket RAII, sendAll/recvAll
infra/fs/    — io::backup, io::restore, directory iterator, RAII handles
infra/sys/   — nxst::log (printf-checked, timestamped)
domain/      — Title, Account, Result<T>, TransferState, protocol constants
```

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## Credits

- **[Plutonium](https://github.com/XorTroll/Plutonium)** — Switch UI framework by XorTroll
- **[Checkpoint](https://github.com/BernardoGiordano/Checkpoint)** — save management library by Bernardo Giordano / FlagBrew; several files in `src/infra/fs/` and `src/domain/` are derived from Checkpoint

---

## License

GPLv3 — see [`LICENSE`](LICENSE).

NXST includes code derived from Checkpoint (GPLv3). All original NXST code is released under the same license to satisfy the GPL inheritance requirement.