# Send a file
> From the app, from a terminal, and from an agent.
> Source: https://jvoltci.github.io/sparsh/docs/send/

## From the app

Open it on both devices, pair once, then tap the device and choose the file. It
starts immediately: there is no upload step, because there is nowhere to upload
to.

Files of any size. An interrupted transfer resumes where it stopped rather than
starting again, because the receiver keeps a map of which chunks it already has.

## From a terminal

```bash
sparsh send report.pdf --to "Phone"
```

By name, with no code, because the pairing already happened. Several files at
once is several arguments. Exit code 0 means the far side has the bytes on disk
and the hash matched, not that they were sent.

To receive:

```bash
sparsh receive --into ~/Downloads
```

Or leave `sparsh serve` running and the device is simply reachable.

## From an agent

```
sparsh_send(paths: ["/abs/path/report.pdf"], to: "Phone")
```

It returns when the far side has the file. A path inside the working directory
goes straight through. Anything outside asks you first, because reading an
arbitrary path and shipping it is exactly what a prompt-injected agent reaches
for.

Arrived files come back as **paths**, never contents:

```
sparsh_inbox()
```

Read them with your own file tools. A gigabyte base64'd into a tool result is a
context-window fire, not a feature.

## What can go wrong

**The device is offline.** Presence needs a signalling server; on public relays
alone there is no device list and the honest answer is an empty one rather than
a pretend one.

**The pairing predates device keys.** The daemon refuses a session it cannot
verify rather than accepting a weaker one. Run `sparsh invite` once and the
pairing is upgraded for good.

**Both peers are behind a strict NAT.** ICE finds a path or falls back to a TURN
relay over 443. The relay forwards ciphertext; it cannot read a byte.