feat: add documentation for TUI, messages & attachments, and IRC gateway; update index and TOC

2026-09-04 00:26:07 +02:00 · 2026-07-16 20:02:18 +02:00
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+# IRC Gateway
+
+Every EchoHub server can expose a second door: a built-in **IRC gateway** that speaks the
+classic IRC protocol on port 6667. Any standard IRC client — irssi, WeeChat, HexChat,
+Halloy — can join the same channels as TUI users, see the same messages, and chat with the
+same accounts. Under the hood both protocols call the same chat service, so a message sent
+from IRC appears instantly in the TUI and vice versa (see [Architecture](architecture.md)).
+
+## Enabling the gateway
+
+The gateway is off by default. Enable it in `appsettings.json` (or `Irc__Enabled=true` as an
+environment variable):
+
+```json
+{
+  "Irc": {
+    "Enabled": true,
+    "Port": 6667,
+    "TlsEnabled": false,
+    "TlsPort": 6697,
+    "TlsCertPath": "",
+    "ServerName": "echohub",
+    "Motd": "Welcome to EchoHub IRC Gateway!"
+  }
+}
+```
+
+The plaintext listener always starts on `Port`. The TLS listener on `TlsPort` starts only
+when `TlsEnabled` is `true` **and** `TlsCertPath` points to a PKCS#12 (`.pfx`) certificate.
+See the [configuration reference](configuration.md#irc-gateway) for every option.
+
+## Connecting & authentication
+
+Your IRC **nick is your EchoHub username** and your server password is your **account
+password**. Two flows are supported:
+
+```bash
+# classic PASS/NICK/USER — most clients call this the "server password"
+irssi -c chat.example.com -p 6667 -w <password> -n <username>
+```
+
+or **SASL PLAIN** (advertised via `CAP LS`), where the SASL username/password are the account
+credentials.
+
+A few things worth knowing:
+
+- **Connecting auto-registers.** If the username doesn't exist yet, the gateway creates the
+  account with that password (usernames: 3–50 chars of `a-z 0-9 _ -`; passwords: 6+ chars).
+  The very first account ever created on a server becomes the **Owner**.
+- Because of that, a typo'd password for an *existing* account fails with
+  `Username is already taken` — the gateway tried to log in, couldn't, then tried to register
+  the name. If you see that error, re-check your password.
+- Connecting without a password is rejected: `Password required. Use PASS command or SASL PLAIN.`
+
+## What maps to what
+
+| IRC | EchoHub |
+| --- | --- |
+| `JOIN #room` | Join a channel (history is replayed on join) |
+| `JOIN #room <key>` | Join a password-protected (`+k`) channel |
+| `PART` / `QUIT` | Leave channel / disconnect |
+| `LIST` | Public channels only (password-protected ones show a `[+k]` hint) |
+| `TOPIC` | Read or set the channel topic (permission-checked) |
+| `NAMES` / `WHO` | Online users in the channel |
+| `WHOIS` | Profile: display name, channels, idle time, away status |
+| `AWAY [message]` | Sets your EchoHub status to Away / back to Online |
+| `MODE #room +k <key>` / `-k` | Set / clear the channel password |
+
+Private (unlisted) channels don't appear in `LIST`, but members who know the exact name can
+still `JOIN` them. Channels are not auto-created from IRC — create them from the TUI first.
+
+## How messages look
+
+- **Attachments** arrive as labeled link lines — `[Image: photo.png] https://…`,
+  `♪ [Audio: song.mp3] https://…`, `[File: report.pdf] https://…` — and image attachments
+  additionally render their **ASCII-art preview** using truecolor ANSI escapes, so a modern
+  terminal IRC client shows actual picture previews.
+- **Link embeds** are appended as `│`-prefixed text lines.
+- Long messages are split at word boundaries into IRC-safe lines (~400 bytes each);
+  incoming messages may be up to 2,000 characters like any EchoHub message.
+- Your own messages aren't echoed back (standard IRC convention).
+- Moderation actions surface natively: kicks arrive as `KICK`, bans and channel nukes as
+  server `NOTICE`s.
+
+## Limitations
+
+The gateway bridges what IRC can express — and deliberately refuses what it can't:
+
+- **No end-to-end encrypted rooms.** Joining an [encrypted room](encrypted-rooms.md) fails
+  with *"Cannot join channel — end-to-end encrypted, use the EchoHub client."* Bridging one
+  would require the server to hold the room key, breaking the zero-knowledge design.
+- **No private messages.** `PRIVMSG` to a nick is rejected; EchoHub is channel-based.
+- **Usernames, not display names.** Messages are attributed to the account username;
+  a user's display name is visible via `WHOIS`/`WHO` (realname field).
+- **No client features.** Uploading attachments, profiles, themes, and reactions to status
+  changes are TUI-client features. Other users' status changes aren't pushed to IRC —
+  discover them with `WHOIS`/`WHO`.
+
+## How IRC users appear to TUI users
+
+Users connected *only* through the gateway are tagged `[irc]` in the users panel — a hint
+that they can't receive encrypted content or use client-side features. Someone connected
+with both an IRC client and the TUI shows untagged.