musistudio/claude-code-router · error

The CCR artifact endpoint returned a non-media content type.

Error message

The CCR artifact endpoint returned a non-media content type.

What it means

The Content-Type returned by the CCR artifact endpoint is not a recognized image/* or video/* MIME type. mediaKind() maps declared MIME types to 'image' or 'video'; anything else (application/octet-stream, text/html, JSON error payloads) fails this guard before any bytes are buffered.

Source

Thrown at packages/core/src/agents/codex/media-preview-bridge.ts:308

  return { artifactId, url };
}

async function loadCodexMediaArtifact(validated: ValidatedArtifactUrl, signal: AbortSignal): Promise<LoadedMediaArtifact> {
  let response: Response;
  try {
    response = await fetch(validated.url, {
      headers: { accept: "image/*, video/*" },
      redirect: "error",
      signal
    });
  } catch {
    throw new Error("The CCR artifact request failed.");
  }
  if (!response.ok) throw new Error(`The CCR artifact endpoint returned HTTP ${response.status}.`);
  if (response.redirected) throw new Error("The CCR artifact endpoint attempted a redirect.");
  const declaredMimeType = (response.headers.get("content-type") || "").split(";", 1)[0].trim().toLowerCase();
  const declaredKind = mediaKind(declaredMimeType);
  if (!declaredKind) throw new Error("The CCR artifact endpoint returned a non-media content type.");
  const maxBytes = declaredKind === "video" ? codexMediaPreviewMaxVideoBytes : codexMediaPreviewMaxImageBytes;
  const declaredLength = Number(response.headers.get("content-length") || "0");
  if (declaredLength && (!Number.isSafeInteger(declaredLength) || declaredLength < 1 || declaredLength > maxBytes)) {
    throw new Error("The CCR media artifact exceeds the inline preview size limit.");
  }
  if (response.headers.get("content-encoding") && response.headers.get("content-encoding") !== "identity") {
    throw new Error("Compressed CCR media artifacts are not accepted for inline preview.");
  }
  if (!response.body) throw new Error("The CCR artifact response had no body.");
  const reader = response.body.getReader();
  const chunks: Buffer[] = [];
  let total = 0;
  while (true) {
    const part = await reader.read();
    if (part.done) break;
    if (!part.value?.byteLength) continue;
    total += part.value.byteLength;
    if (total > maxBytes) {

View on GitHub (pinned to 99f24806c6)

Solutions

1. Manually fetch the URL and inspect the raw Content-Type header to see what the server actually sends
2. If the server mislabels media as application/octet-stream, fix the artifact upload to set the correct MIME type
3. If the response is an HTML/JSON error page, investigate why the endpoint returned 200 with an error body
4. Only request artifacts that are actually images or videos

async function declaresMediaType(url: string): Promise<boolean> {
  const res = await fetch(url, { method: 'HEAD' });
  const ct = (res.headers.get('content-type') || '').split(';', 1)[0].trim().toLowerCase();
  return ct.startsWith('image/') || ct.startsWith('video/');
}

function isNonMediaTypeRejection(e: unknown): boolean {
  return e instanceof Error && e.message.includes('non-media content type');
}

try {
  const media = await bridge.artifact(ref);
} catch (e) {
  if (isNonMediaTypeRejection(e)) return renderAsDownload(ref);
  throw e;
}

When it happens

Trigger: The server serves the artifact with application/octet-stream or a missing/garbage Content-Type; the endpoint actually returned a JSON/HTML error page with a 200 status; a genuinely non-media artifact was referenced.

Common situations: CDN or object storage defaulting to application/octet-stream when metadata wasn't set; error pages that return 200; referencing an attachment whose kind isn't image or video.

Related errors

• The CCR media artifact exceeds the inline preview size limit
• Compressed CCR media artifacts are not accepted for inline p
• The CCR artifact response was empty.
• The CCR artifact content did not match its declared media ty
• duration is required for ${target.protocol}.

AI-assisted analysis of musistudio/claude-code-router@99f24806c6 (2026-08-27). Data as JSON: /api/errors/eb42230703d474e8. Report an issue: GitHub.