koala73/worldmonitor · error · WidgetBodyTooLargeError

Widget body too large

Error message

Widget body too large

What it means

readRequestBody for the widget-agent proxy reads the incoming request stream and enforces WIDGET_AGENT_MAX_BODY_BYTES. As soon as the cumulative byte count exceeds the cap it throws WidgetBodyTooLargeError, surfacing as 'Widget body too large'. This protects the upstream widget-agent service from oversized payloads and bounds memory use in the edge function.

Solutions

1. Reduce the request payload sent to the widget-agent endpoint below the configured byte cap.
2. Chunk or split the work into multiple smaller widget-agent requests.
3. If the cap is too low for legitimate workloads, raise WIDGET_AGENT_MAX_BODY_BYTES.
4. Strip unnecessary fields/attachments from the payload before sending.

Example fix

// before
await fetch('/api/widget-agent', { method: 'POST', body: JSON.stringify({ html: hugeHtml, ...rest }) });
// after
await fetch('/api/widget-agent', { method: 'POST', body: JSON.stringify({ html: hugeHtml.slice(0, 100_000), ...rest }) });

const body = JSON.stringify(payload);
const bytes = new TextEncoder().encode(body).byteLength;
if (bytes > WIDGET_AGENT_MAX_BODY_BYTES) throw new Error(`payload ${bytes}B exceeds limit`);

try { return await proxyWidgetAgent(req); } catch (e) { if (e instanceof WidgetBodyTooLargeError) return json(413, { error: 'body exceeds limit' }); throw e; }

When it happens

Trigger: POSTing a request body larger than WIDGET_AGENT_MAX_BODY_BYTES to the widget-agent proxy endpoint (proxyWidgetAgent -> readRequestBody).

Common situations: Clients embedding large HTML/JSON payloads in widget generation requests; uploading base64 assets inline; retry loops that keep re-sending an oversized body.

Understand the failure class

Background: payload too large / request exceeds maximum size: why libraries cap bytes and how to fix oversize payloads — this error's family across 50 libraries.

Related errors

• body-too-large
• ${err.message}
• Malformed command: expected an array whose first element is…
• Airport delay filters are not supported
• Airport delay page_size must be 0

AI-assisted analysis of koala73/worldmonitor@e586b8b4b8 (2026-09-22). Data as JSON: /api/errors/d1848fbcca0fa482. Report an issue: GitHub.

Appendix: source

Thrown at api/widget-agent.ts:115

    this.name = 'WidgetBodyTooLargeError';
  }
}

async function readRequestBody(req: Request): Promise<string> {
  if (!req.body) return '';
  const reader = req.body.getReader();
  let timer: ReturnType<typeof setTimeout> | undefined;
  try {
    return await Promise.race([
      (async () => {
        const decoder = new TextDecoder();
        let total = 0;
        let text = '';
        while (true) {
          const { done, value } = await reader.read();
          if (done) return text + decoder.decode();
          total += value.byteLength;
          if (total > WIDGET_AGENT_MAX_BODY_BYTES) throw new WidgetBodyTooLargeError();
          text += decoder.decode(value, { stream: true });
        }
      })(),
      new Promise<never>((_, reject) => {
        timer = setTimeout(() => reject(new Error('widget-agent body read timeout')), WIDGET_AGENT_BODY_TIMEOUT_MS);
      }),
    ]);
  } finally {
    clearTimeout(timer);
    // Do not let a stalled producer's cancellation hold the response open.
    void reader.cancel().catch(() => {});
    reader.releaseLock();
  }
}

async function hasValidWorldMonitorKey(key: string): Promise<boolean> {
  return timingSafeIncludes(key, WORLDMONITOR_VALID_KEYS);
}

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