# signal-bot

A Signal group-chat bot that grabs videos from links people post (X/Twitter,
Instagram, YouTube, TikTok) and posts them back into the chat, plus a couple of
toys for messing with the last video.

## What it does

- **Auto-download** — watches every group message for a supported link and
  replies with the video. Powered by [yt-dlp](https://github.com/yt-dlp/yt-dlp).
  Videos over 100 MB are auto re-encoded with ffmpeg to fit.
- **`/speed [n]`** — re-posts the last video sped up `n`× (default 2×), pitch-shifted
  like tape. e.g. `/speed 4`, `/speed 0.5`.
- **`/rev`** — re-posts the last video reversed (audio too).
- **`/cookies`** (DM, admins only) — paste exported `.instagram.com` cookie lines
  to refresh Instagram auth without touching the server.

Supported links: `x.com` / `twitter.com` (and `fxtwitter`/`vxtwitter`/`fixupx`
wrappers), `instagram.com/reel|p`, `youtube.com` / `youtu.be` / Shorts, and TikTok.

## How it's wired

```
Signal  ──►  signal-cli-rest-api (json-rpc, :8080)  ──►  bot.py (signalbot lib)
                  [docker-compose.yml]                      [systemd service]
                                                                  │
                                                       yt-dlp + ffmpeg + cookies.txt
```

- `bot.py` connects to a [signal-cli-rest-api](https://github.com/bbernhard/signal-cli-rest-api)
  daemon over a websocket in `json-rpc` mode.
- `docker-compose.yml` runs that daemon; the linked-account data lives in a
  `./signal-cli-data` volume (gitignored — it holds private keys).
- `signal-bot.service.example` is the systemd unit that runs `bot.py`.

## Setup

1. **Run signal-cli-rest-api and link it as a device** to your Signal account:
   ```
   docker compose up -d
   ```
   Then link via the QR at `http://127.0.0.1:8080/v1/qrcodelink?device_name=bot`
   (scan from Signal → Settings → Linked devices). Keep signal-cli up to date —
   an out-of-date signal-cli silently stops receiving messages when Signal
   changes its server protocol (`getServerGuid must not be null` in the logs);
   `docker compose pull && docker compose up -d` fixes it.

2. **Python env:**
   ```
   python3 -m venv venv
   venv/bin/pip install -r requirements.txt
   ```
   YouTube also needs a system `node` on PATH (for `yt-dlp-ejs`).

3. **Cookies:** copy `cookies.txt.example` to `cookies.txt` and fill in real
   exported cookies for the sites you want auth'd. (gitignored)

4. **Service:** copy `signal-bot.service.example` to `signal-bot.service`, set
   your user / phone number / paths, install it:
   ```
   sudo cp signal-bot.service /etc/systemd/system/
   sudo systemctl enable --now signal-bot
   ```

## Notes

- The bot only acts in **group** chats (except `/cookies`, which is DM-only).
- Reply-targeting (e.g. "speed up *this* video") was intentionally dropped:
  Signal Desktop strips quote metadata from synced transcripts, so `/speed` and
  `/rev` always act on the last video seen in the group.