openclaw/message-split

Message Split Skill

Problem

Many messaging channels (Feishu, Telegram, etc.) have a per-message character limit (~4000 chars for Feishu). When a response exceeds this limit, it either gets truncated or silently fails, leaving the user with no feedback.

Solution

Before sending any message, check its length and split if necessary.

Usage

def send_long_message(text, channel="{active_channel}"):
    """
    Send a message, splitting it into multiple chunks if it exceeds the length limit.
    
    Args:
        text: The message text to send
        channel: Target channel (feishu/telegram/discord/whatsapp/signal/imessage/openclaw-weixin)
    
    Returns:
        Number of chunks sent
    """
    MAX_LEN = 3600  # Feishu limit with margin
    CHUNK_HEADER = "[{i}/{total}]\n"
    
    if len(text) <= MAX_LEN:
        message(action="send", channel=channel, message=text)
        return 1
    
    chunks = split_text(text, MAX_LEN)
    total = len(chunks)
    
    for i, chunk in enumerate(chunks, 1):
        header = f"[{i}/{total}]\n" if total > 1 else ""
        message(action="send", channel=channel, message=header + chunk)
    
    return total


def split_text(text, max_len):
    """
    Split text into chunks of at most max_len characters.
    Attempts to split at sentence boundaries or line breaks for readability.
    """
    import re
    
    # Try to split at sentence-ending punctuation first
    sentence_split = re.split(r'(?<=[。！？.!?])\s+', text)
    
    chunks = []
    current = ""
    
    for sentence in sentence_split:
        if len(current) + len(sentence) + 1 <= max_len:
            current += (" " + sentence if current else sentence)
        else:
            if current:
                chunks.append(current)
            # If single sentence exceeds limit, split by words/characters
            if len(sentence) > max_len:
                for i in range(0, len(sentence), max_len - 100):
                    chunks.append(sentence[i:i + max_len - 100])
                current = ""
            else:
                current = sentence
    
    if current:
        chunks.append(current)
    
    return chunks

Channel Limits Reference

| Channel | Max chars (approx) | Notes | |---------|-------------------|-------| | Feishu | 4000 | Hard limit | | Telegram | 4096 | | | Discord | 2000 | Embed limit 6000 | | WhatsApp | 65000 | But relayed messages get truncated | | Signal | 700 | Very low | | iMessage | ~4000 | Via macOS relay |

Notes

• Always use MAX_LEN = 3600 as a safe default (leaves room for header)
• If channel is unknown, default to feishu behavior
• Splitting is done on word/sentence boundaries when possible to preserve readability
• Sequence headers [{i}/{total}] are only added when total > 1