# HTML srcdoc Ancestor Sandbox Union Flag Verifier

> HTML srcdoc Ancestor Sandbox Union Flag Verifier is a paid API for AI agents from detect.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-11-04).

Verifies the declared union of sandbox attribute flags across nested srcdoc documents without issuing security judgments or performing navigation

## Facts

- Endpoint: POST https://detect.halowerk.com/u/html-srcdoc-ancestor-sandbox-union?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-04
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/html-srcdoc-ancestor-sandbox-union-flag-verifier-ac57a44a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5O8nRMlii8xhStJxYmnjj

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability html-srcdoc-ancestor-sandbox-union-flag-verifier-ac57a44a -d '<json body>'
```

Example prompt: Can you check whether the declared sandbox flag union in the nested srcdoc iframes at https://example.com/page is correct — just validate the attribute declarations, no security verdict needed?

## When to prefer this

Use this endpoint when you need to programmatically verify the declared union of sandbox attribute flags in nested srcdoc iframe documents without triggering navigation or receiving a security verdict. It is appropriate for static analysis, pre-deployment auditing, or conformance checking of sandbox policy declarations in HTML documents.

## Known failure modes

- Invalid or unreachable URL returns an error
- URL exceeds 2048 character limit
- Document does not contain srcdoc iframes — no flags to union
- Malformed HTML may result in inconclusive verification
- Network timeout if the target URL is slow to respond

## How this service works

Prüft die deklarierte Vereinigung von Sandbox-Attributflags in verschachtelten srcdoc-Dokumenten; kein Sicherheitsurteil und keine Navigation.

## Output

Returns the verified union of declared sandbox attribute flags across nested srcdoc documents, indicating whether the declared flag combinations are consistent — without issuing a security judgment or triggering navigation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "maxLength": 2048
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/html-srcdoc-ancestor-sandbox-union-flag-verifier-ac57a44a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from detect.halowerk.com](https://www.zero.xyz/host/detect.halowerk.com/llms.txt)