Hmbown/CodeWhale · error · Error

Runtime event frame exceeds the size limit

Error message

Runtime event frame exceeds the size limit

What it means

parseEventStream() enforces a per-frame SSE size limit (2 MiB for thread events). When a single buffered event frame between boundaries exceeds maxFrameChars, it throws. This guards against runaway or malicious events exhausting memory while consuming fleetEvents/threadEvents streams.

Solutions

1. Reduce the size of individual events the runtime emits (truncate tool output/diffs at the source).
2. Upgrade the runtime so large payloads are chunked into smaller events or bounded fragments.
3. Catch the error and skip/replay the problematic thread rather than consuming it whole.
4. If legitimately needed, use a client/path variant with a larger maxFrameChars.

Example fix

// before
for await (const ev of client.threadEvents(id)) handle(ev);
// after
try {
  for await (const ev of client.threadEvents(id)) handle(ev);
} catch (err) {
  if (err.message.includes("exceeds the size limit")) return handleOversizedThread(id);
  throw err;
}

try { for await (const ev of client.threadEvents(id)) handle(ev); } catch (err) { if (err.message.includes("exceeds the size limit")) return quarantineThread(id); throw err; }

When it happens

Trigger: A runtime emits one SSE event whose serialized frame (up to the blank-line boundary) exceeds 2 MiB — e.g. an enormous tool output or diff embedded in a single event during replay.

Common situations: Replaying threads that captured very large tool outputs before truncation policies existed; a buggy runtime writing an unterminated giant event; a compromised endpoint flooding frames.

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

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• ${compactRuntimeError(response.status, body)}
• {err}
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AI-assisted analysis of Hmbown/CodeWhale@433685b202 (2026-09-15). Data as JSON: /api/errors/9759a50640849a6b. Report an issue: GitHub.

Appendix: source

Thrown at npm/runtime-sdk/index.js:244

}

async function readErrorBody(response) {
  try {
    const text = await response.text();
    return text.length > 4096 ? `${text.slice(0, 4096)}...` : text;
  } catch {
    return "";
  }
}

async function* parseEventStream(body, { maxFrameChars = Infinity, requireBoundary = false } = {}) {
  const decoder = new TextDecoder("utf-8", { fatal: requireBoundary });
  let buffer = "";
  for await (const chunk of body) {
    buffer += decoder.decode(chunk, { stream: true });
    let boundary;
    while ((boundary = eventStreamBoundary(buffer)) !== null) {
      if (boundary.index > maxFrameChars) throw new Error("Runtime event frame exceeds the size limit");
      const frame = buffer.slice(0, boundary.index);
      buffer = buffer.slice(boundary.index + boundary.length);
      const event = parseSseFrame(frame);
      if (event !== undefined) {
        yield event;
      }
    }
    if (buffer.length > maxFrameChars) throw new Error("Runtime event frame exceeds the size limit");
  }
  buffer += decoder.decode();
  if (requireBoundary && buffer.trim()) throw new Error("Runtime event stream ended inside a frame");
  const event = parseSseFrame(buffer);
  if (event !== undefined) {
    yield event;
  }
}

function eventStreamBoundary(buffer) {

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