feat: Add support for public channels and auto-cleanup on channel deletion

- Allow joining public channels (starting with #) without encryption key
  - Frontend: Make key field optional with validation for # channels
  - Backend: Update API to accept optional key parameter
  - CLI wrapper: Build meshcli command dynamically based on key presence

- Implement automatic message cleanup when deleting channels
  - Add delete_channel_messages() function to remove channel history
  - Integrate cleanup into DELETE /api/channels endpoint
  - Prevents message leakage when reusing channel slots

- Update documentation with new features and usage instructions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

README.md

@@ -17,6 +17,7 @@ A lightweight web interface for meshcore-cli, providing browser-based access to
 - ✉️ **Send messages** - Publish to any channel (140 byte limit for LoRa)
 - 📡 **Channel management** - Create, join, and switch between encrypted channels
 - 🔐 **Channel sharing** - Share channels via QR code or encrypted keys
+- 🔓 **Public channels** - Join public channels (starting with #) without encryption keys
 - 🎯 **Reply to users** - Quick reply with `@[UserName]` format
 - 🧹 **Clean contacts** - Remove inactive contacts with configurable threshold
 - 📦 **Message archiving** - Automatic daily archiving with browse-by-date selector
@@ -197,11 +198,27 @@ Access channel management:
 3. Others can join using the "Join Existing" option
 
 #### Joining a Channel
+
+**For private channels:**
 1. Click "Join Existing"
 2. Enter the channel name and encryption key (received from channel creator)
 3. Click "Join Channel"
 4. The channel will be added to your available channels
 
+**For public channels (starting with #):**
+1. Click "Join Existing"
+2. Enter the channel name (e.g., `#test`, `#krakow`)
+3. Leave the encryption key field empty (key is auto-generated based on channel name)
+4. Click "Join Channel"
+5. You can now chat with other users on the same public channel
+
+#### Deleting a Channel
+1. In the Channels modal, click the delete icon (trash) next to any channel
+2. Confirm the deletion
+3. The channel configuration and **all its messages** will be permanently removed
+
+**Note:** Deleting a channel removes all message history for that channel from your device to prevent data leakage when reusing channel slots.
+
 #### Switching Channels
 Use the channel selector dropdown in the navbar to switch between channels. Your selection is remembered between sessions.
 

app/meshcore/cli.py

@@ -222,28 +222,29 @@ def add_channel(name: str) -> Tuple[bool, str, Optional[str]]:
     return True, stdout or stderr, None
 
 
-def set_channel(index: int, name: str, key: str) -> Tuple[bool, str]:
+def set_channel(index: int, name: str, key: Optional[str] = None) -> Tuple[bool, str]:
     """
-    Set/join a channel at specific index with name and key.
+    Set/join a channel at specific index with name and optional key.
 
     Args:
         index: Channel slot number
         name: Channel name
-        key: 32-char hex key
+        key: 32-char hex key (optional for channels starting with #)
 
     Returns:
         Tuple of (success, message)
     """
-    # Validate key format
-    if not re.match(r'^[a-f0-9]{32}$', key.lower()):
-        return False, "Invalid key format (must be 32 hex characters)"
+    # Build command arguments
+    cmd_args = ['set_channel', str(index), name]
 
-    success, stdout, stderr = _run_command([
-        'set_channel',
-        str(index),
-        name,
-        key.lower()
-    ])
+    # Add key if provided
+    if key:
+        # Validate key format
+        if not re.match(r'^[a-f0-9]{32}$', key.lower()):
+            return False, "Invalid key format (must be 32 hex characters)"
+        cmd_args.append(key.lower())
+
+    success, stdout, stderr = _run_command(cmd_args)
 
     return success, stdout or stderr
 

app/meshcore/parser.py

@@ -254,3 +254,55 @@ def filter_messages_by_days(messages: List[Dict], days: int) -> List[Dict]:
 
     logger.info(f"Filtered {len(filtered)} messages from last {days} days (out of {len(messages)} total)")
     return filtered
+
+
+def delete_channel_messages(channel_idx: int) -> bool:
+    """
+    Delete all messages for a specific channel from the .msgs file.
+
+    Args:
+        channel_idx: Channel index to delete messages from
+
+    Returns:
+        True if successful, False otherwise
+    """
+    msgs_file = config.msgs_file_path
+
+    if not msgs_file.exists():
+        logger.warning(f"Messages file not found: {msgs_file}")
+        return True  # No messages to delete
+
+    try:
+        # Read all lines
+        lines_to_keep = []
+        deleted_count = 0
+
+        with open(msgs_file, 'r', encoding='utf-8') as f:
+            for line_num, line in enumerate(f, 1):
+                line = line.strip()
+                if not line:
+                    continue
+
+                try:
+                    data = json.loads(line)
+                    # Keep messages from other channels
+                    if data.get('channel_idx', 0) != channel_idx:
+                        lines_to_keep.append(line)
+                    else:
+                        deleted_count += 1
+                except json.JSONDecodeError as e:
+                    # Keep malformed lines (don't delete them)
+                    logger.warning(f"Invalid JSON at line {line_num}, keeping: {e}")
+                    lines_to_keep.append(line)
+
+        # Write back the filtered lines
+        with open(msgs_file, 'w', encoding='utf-8') as f:
+            for line in lines_to_keep:
+                f.write(line + '\n')
+
+        logger.info(f"Deleted {deleted_count} messages from channel {channel_idx}")
+        return True
+
+    except Exception as e:
+        logger.error(f"Error deleting channel messages: {e}")
+        return False

app/routes/api.py

@@ -495,7 +495,7 @@ def join_channel():
 
     JSON body:
         name (str): Channel name (required)
-        key (str): 32-char hex key (required)
+        key (str): 32-char hex key (optional for channels starting with #)
         index (int): Channel slot (optional, auto-detect if not provided)
 
     Returns:
@@ -504,14 +504,21 @@ def join_channel():
     try:
         data = request.get_json()
 
-        if not data or 'name' not in data or 'key' not in data:
+        if not data or 'name' not in data:
             return jsonify({
                 'success': False,
-                'error': 'Missing required fields: name, key'
+                'error': 'Missing required field: name'
             }), 400
 
         name = data['name'].strip()
-        key = data['key'].strip().lower()
+        key = data.get('key', '').strip().lower() if 'key' in data else None
+
+        # Validate: key is optional for channels starting with #
+        if not name.startswith('#') and not key:
+            return jsonify({
+                'success': False,
+                'error': 'Key is required for channels not starting with #'
+            }), 400
 
         # Auto-detect free slot if not provided
         if 'index' in data:
@@ -548,7 +555,7 @@ def join_channel():
                 'channel': {
                     'index': index,
                     'name': name,
-                    'key': key
+                    'key': key if key else 'auto-generated'
                 }
             }), 200
         else:
@@ -568,7 +575,7 @@ def join_channel():
 @api_bp.route('/channels/<int:index>', methods=['DELETE'])
 def delete_channel(index):
     """
-    Remove a channel.
+    Remove a channel and delete all its messages.
 
     Args:
         index: Channel index to remove
@@ -577,13 +584,19 @@ def delete_channel(index):
         JSON with result
     """
     try:
+        # First, delete all messages for this channel
+        messages_deleted = parser.delete_channel_messages(index)
+        if not messages_deleted:
+            logger.warning(f"Failed to delete messages for channel {index}, continuing with channel removal")
+
+        # Then remove the channel itself
         success, message = cli.remove_channel(index)
 
         if success:
             invalidate_channels_cache()  # Clear cache to force refresh
             return jsonify({
                 'success': True,
-                'message': f'Channel {index} removed'
+                'message': f'Channel {index} removed and messages deleted'
             }), 200
         else:
             return jsonify({

app/static/js/app.js

@@ -172,13 +172,30 @@ function setupEventListeners() {
         const name = document.getElementById('joinChannelName').value.trim();
         const key = document.getElementById('joinChannelKey').value.trim().toLowerCase();
 
+        // Validate: key is optional for channels starting with #, but required for others
+        if (!name.startsWith('#') && !key) {
+            showNotification('Channel key is required for channels not starting with #', 'warning');
+            return;
+        }
+
+        // Validate key format if provided
+        if (key && !/^[a-f0-9]{32}$/.test(key)) {
+            showNotification('Invalid key format. Must be 32 hex characters.', 'warning');
+            return;
+        }
+
         try {
+            const payload = { name: name };
+            if (key) {
+                payload.key = key;
+            }
+
             const response = await fetch('/api/channels/join', {
                 method: 'POST',
                 headers: {
                     'Content-Type': 'application/json'
                 },
-                body: JSON.stringify({ name: name, key: key })
+                body: JSON.stringify(payload)
             });
 
             const data = await response.json();

app/templates/base.html

@@ -143,12 +143,11 @@
                                     <input type="text" class="form-control" id="joinChannelName" required>
                                 </div>
                                 <div class="mb-2">
-                                    <label for="joinChannelKey" class="form-label">Channel Key (32 hex chars)</label>
+                                    <label for="joinChannelKey" class="form-label">Channel Key (32 hex chars) <small class="text-muted">- optional for channels starting with #</small></label>
                                     <input type="text" class="form-control" id="joinChannelKey"
-                                           placeholder="485af7e164459d280d8818d9c99fb30d"
+                                           placeholder="485af7e164459d280d8818d9c99fb30d (leave empty for # channels)"
                                            pattern="[a-fA-F0-9]{32}"
-                                           maxlength="32"
-                                           required>
+                                           maxlength="32">
                                 </div>
                                 <div class="d-flex gap-2">
                                     <button type="submit" class="btn btn-success">