EchoHub/docs/changelog/v0.2.12.md

# v0.2.12

Private channels are now genuinely private: password-protected channels are end-to-end encrypted, so the server (and its operators) can gate joins and measure storage but cannot read message or file contents. The IRC gateway grows real MODE/TOPIC support and channel keys, and the client gets image "save original", a transparent-light theme, drag-and-drop file sending, Ctrl+V paste, and a fix for the intermittent Ctrl+W crash.

## New Features

- **End-to-end encrypted channels** — creating a channel with a password now provisions a zero-knowledge room:
  - The passphrase never leaves the client. It derives (PBKDF2-SHA256, 210k iterations) two keys: an *auth key* sent to the server as the join credential, and a *key-encryption key* that never leaves the machine.
  - A random room content key encrypts every message and file with AES-256-GCM. The server only ever stores the room key *wrapped* under the passphrase, so it can gate joins and report a channel's message count, storage size, and attachments — but cannot decrypt any of it. Even the server owner cannot read a private room's contents.
  - Members' clients cache the derived room key locally (in the per-server config, like saved sessions) so the passphrase isn't retyped every launch; joining on a new device prompts for it once.
  - Change the passphrase with `/passwd <old> <new>` (channel creator only). The room key is re-wrapped, not rotated, so **existing history stays readable** and members who join later with the new passphrase can still read older messages.
  - Files and images are encrypted client-side before upload; for images the ASCII-art preview is rendered on the client and stored room-encrypted too. Sending images by URL is disabled in encrypted channels (the server can't fetch-and-render without the key).
  - End-to-end encrypted channels cannot be joined over the IRC gateway (that would require the server to hold the room key) — IRC `JOIN` returns `475` directing users to the EchoHub client.
- Password-protected channels — set an optional password when creating a channel (masked field in the Create Channel dialog, `password` on `POST /api/channels`). Passwords are BCrypt-hashed server-side; the join gate applies on first join only (existing members and the creator are unaffected). Protected channels show a `*` marker in the channel list and `+k` in the status bar
- Save original images — image messages now show a clickable "[↓ save original]" line under the ASCII-art preview that downloads the full-resolution original to your Downloads folder (decrypting locally in encrypted channels)
- **Messages with attachments (Discord-style)** — a message is now text **plus** a list of attachments instead of being either text or a single file. One message can carry a caption and several files (images, audio, docs) together:
  - Compose with a **staging tray**: `/send <file>` or dropping files onto the terminal stages them (shown on the input bar); the next Enter sends your typed caption and all staged files as one message. `/clear` drops staged files. `/send <URL>` still posts an image immediately.
  - Each image attachment renders its own ASCII preview with its own "save original" action; audio/file attachments each get their own play/download line.
  - In encrypted channels every attachment is encrypted individually (blob + ASCII preview), and the caption is room-encrypted — the server still stores only ciphertext and can report count/size but not contents.
  - Up to 10 attachments per message.
- **Message deletion** — press Delete on a selected message to remove it. You can always delete your own messages; moderators and above can delete others' messages, but only from users **below their own role** (a mod can't delete an admin's or owner's message). Deleting a message also removes its attachment blobs from server storage.
- **Customizable download folder** — `/downloadpath` opens your OS-native folder picker (Windows Explorer / macOS Finder / Linux GTK or KDE) to choose where downloaded attachments and saved images go; `/downloadpath <path>` sets it directly (the fallback when no native picker is available). Downloaded files now land in that folder (with automatic `(n)` de-duplication) instead of a temp directory.
- `/join <channel> [password]` — join protected channels inline, or let the client prompt: joining a protected channel without a password opens a masked prompt that re-prompts on a wrong password
- IRC channel keys — `JOIN #room <key>` works against room passwords (RFC 1459 comma-paired key lists supported); keyless or wrong-key joins get `475 ERR_BADCHANNELKEY`
- IRC `MODE` implemented — `MODE #chan` reports `+k`/`+`, `MODE #chan +k <key>` sets and `-k` clears the room password (channel creator or admin only), ban-list probes get a clean empty reply, and `CHANMODES` is advertised in ISUPPORT
- IRC `TOPIC` set support — the channel creator can change the topic from IRC; the change broadcasts to connected TUI clients (previously topic changes were rejected with a stub error)
- Attach a file by drag & drop or by pasting — drop a file onto the terminal, or **copy a file in your file manager and press Ctrl+V**, to stage it as an attachment (the next Enter sends it with your caption). Multiple files at once are supported. Ctrl+V still pastes text when the clipboard holds text; Ctrl+Y is a paste alias. On Windows the copied-file paste reads the clipboard's file list directly (Windows Terminal never pastes copied files as text), with `xclip`/`wl-paste` used on Linux
- New `TransparentLight` theme — dark characters on a transparent background, for light terminal color schemes (`/theme transparentlight`)
- Timestamps in messages are now aware of the current culture and display the short time pattern for today's messages and the short date+time pattern for older messages.

## Bug Fixes

- Fixed intermittent crash on Ctrl+W — Terminal.Gui binds Ctrl+W to clipboard-cut, and Windows clipboard contention (another app holding the clipboard) threw an unhandled `Win32Exception` that took the app down. Ctrl+W now deletes the previous word (readline behavior, no clipboard), and all clipboard shortcuts (Ctrl+X/C/V/Y) are guarded so transient clipboard failures log a warning instead of crashing
- Fixed emoji shortcode replacement permanently disabling itself if a cursor update threw mid-replacement
- IRC `LIST` no longer leaks private channels; protected channels are marked `[+k]`

## API Changes

- `ChannelDto` gains `isProtected` and `isEncrypted`; `CreateChannelRequest` gains optional `password`, `encryptionSalt`, and `wrappedRoomKey`; SignalR `JoinChannel` takes an optional second `password` argument and `JoinChannelResult` gains `passwordRequired`, `encryptionSalt`, and `wrappedRoomKey` (older clients must update to join over SignalR)
- New endpoints: `GET /api/channels/{channel}/crypto` (public crypto metadata — salt only, never the wrapped key) and `POST /api/channels/{channel}/rekey` (creator-only passphrase change)
- The upload endpoint accepts `type` and `content` form fields for encrypted channels, where the client supplies the declared message type and room-encrypted content
- `ImageToAsciiService` and `FileValidationHelper` moved from `EchoHub.Server` to `EchoHub.Core` so the client can render ASCII art and detect file types for encrypted uploads
- **Message shape change**: `MessageDto` drops `Type`/`AttachmentUrl`/`AttachmentFileName`/`AttachmentFileSize` and gains `Attachments` (a list of `AttachmentDto { Kind, Url, FileName, FileSize, AsciiPreview }`, null/empty for plain text). New `Attachment` entity + table with a cascade FK to `Message`
- New endpoint `POST /api/channels/{channel}/messages` (multipart: `content` + N `files`, plus `kind`/`preview` per file for encrypted channels) replaces the single-file `upload` endpoint; `DELETE /api/moderation/messages/{id}` now enforces the own-or-higher-role rule
- New EF migrations `AddChannelPasswordHash`, `AddChannelEncryptionEnvelope`, and `AddMessageAttachments` (applied automatically on server start); a one-time startup data migration folds legacy single-attachment messages into the new model