zeroclaw-labs/zeroclaw · error · anyhow::Error

inbound attachment exceeds {} MB limit

Error message

inbound attachment exceeds {} MB limit

What it means

The WeChat channel enforces a hard inbound attachment cap: after fully reading the downloaded bytes it compares the length against WECHAT_MEDIA_MAX_BYTES (100 MB, defined as 100 * 1024 * 1024 at wechat.rs:74) and bails when exceeded. The message interpolates the limit in MB (100). It protects the process from buffering unbounded media in memory.

Source

Thrown at crates/zeroclaw-channels/src/wechat.rs:1559

        &self,
        spec: &InboundAttachmentSpec,
    ) -> anyhow::Result<Vec<u8>> {
        let resp = self
            .client
            .get(self.cdn_download_url(&spec.encrypted_query_param))
            .timeout(API_TIMEOUT)
            .send()
            .await?;

        if !resp.status().is_success() {
            let status = resp.status();
            let body = resp.text().await.unwrap_or_default();
            anyhow::bail!("attachment download failed ({status}): {body}");
        }

        let bytes = resp.bytes().await?.to_vec();
        if bytes.len() as u64 > WECHAT_MEDIA_MAX_BYTES {
            anyhow::bail!(
                "inbound attachment exceeds {} MB limit",
                WECHAT_MEDIA_MAX_BYTES / (1024 * 1024)
            );
        }

        match spec.aes_key.as_deref() {
            Some(aes_key) if !aes_key.is_empty() => {
                let key = parse_aes_key(aes_key)?;
                decrypt_aes_ecb(&bytes, &key)
            }
            _ => Ok(bytes),
        }
    }

    async fn try_build_attachment_content(
        &self,
        items: &[serde_json::Value],
        message_id: &str,

View on GitHub (pinned to 88bb9c8533)

Solutions

1. Reply to the sender that the file exceeds the bot's 100 MB limit and ask for a link instead
2. If larger inbound media is genuinely required, raise WECHAT_MEDIA_MAX_BYTES in crates/zeroclaw-channels/src/wechat.rs (line ~74) and rebuild, after confirming the memory budget can absorb larger buffers
3. Handle the error per-attachment so the rest of the message (text, smaller parts) is still processed

Example fix

// before (crates/zeroclaw-channels/src/wechat.rs)
const WECHAT_MEDIA_MAX_BYTES: u64 = 100 * 1024 * 1024;
// after (deliberately raise the cap, then rebuild)
const WECHAT_MEDIA_MAX_BYTES: u64 = 200 * 1024 * 1024;

// Pre-check the size reported in the inbound message metadata before triggering the download
const WECHAT_MEDIA_MAX_BYTES: u64 = 100 * 1024 * 1024;
if let Some(size) = inbound.attachment_reported_size() {
    if size as u64 > WECHAT_MEDIA_MAX_BYTES {
        reply(chat, "File too large for this bot (max 100 MB). Please share a link.").await;
        return Ok(());
    }
}

Catch the 'inbound attachment exceeds' bail per attachment, reply with a size-limit notice, and continue processing the rest of the message.

When it happens

Trigger: Any inbound WeChat attachment whose downloaded byte length exceeds 100 MB — typically large videos or file transfers forwarded to the bot.

Common situations: Users sending HD video files or archives; forwarding WeChat files that can be far larger than the bot cap; the limit is a compile-time constant, so changing it requires editing the crate and rebuilding.

Related errors

• media aes_key must decode to 16 raw bytes or 32 hex chars, g
• attachment Content-Length ({len} bytes) exceeds {} MB limit
• attachment exceeds {} MB limit
• WeCom max_file_size_bytes is zero
• WeCom attachment download failed: kind={} msg_id={} url_targ

AI-assisted analysis of zeroclaw-labs/zeroclaw@88bb9c8533 (2026-08-23). Data as JSON: /api/errors/502cea474e2983b7. Report an issue: GitHub.