# VCDIFF Window Address Cache Validator

> VCDIFF Window Address Cache Validator is a paid API for AI agents from detect.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-21).

Validates a delivered VCDIFF API delta against committed target bytes, checking RFC-compliant address caches and window bounds.

## Facts

- Endpoint: POST https://detect.halowerk.com/v1/integration/api-vcdiff-window-address-cache?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vcdiff-window-address-cache-validator-d7c7cff4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XsTX4SB1IuaIxnrzmelc8

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 vcdiff-window-address-cache-validator-d7c7cff4 -d '<json body>'
```

Example prompt: Check this VCDIFF delta contract for me — I need to confirm it uses the RFC default256 instruction table, has valid bounded windows, and that the SELF/HERE/NEAR/SAME address caches and overlapping target copy all line up with the committed target bytes.

## When to prefer this

Choose this endpoint when you need strict RFC 3284 VCDIFF delta validation with explicit checks on address cache state (SELF/HERE/NEAR/SAME), window bounding, and target byte commitment — especially when no custom tables or secondary compression are in use. Prefer this over generic diff validators when VCDIFF binary patch conformance and delta integrity are the primary concern.

## Known failure modes

- Invalid or malformed vcdiff_contract object causes rejection
- Custom instruction tables or secondary compression present triggers non-compliance error
- Window bounds exceed allowed limits returns bounds violation
- Address cache entries inconsistent with target bytes returns cache mismatch error
- Missing required vcdiff_contract field returns 400 bad request
- Payment not provided or insufficient returns 402 payment required

## How this service works

Geliefertes VCDIFF-API-Delta gegen zugesagte Zielbytes prüfen.

## Output

Returns a structured validation report indicating whether the VCDIFF delta conforms to RFC default256 rules, including the status of address caches (SELF, HERE, NEAR, SAME), window bound compliance, overlapping target copy correctness, and whether the delta matches the committed target bytes. No custom tables or secondary compression are supported.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "artifact": {
   "type": "object",
   "required": [
    "vcdiff_contract"
   ],
   "properties": {
    "vcdiff_contract": {
     "type": "object",
     "description": "RFC default256 instruction table, bounded windows, SELF/HERE/NEAR/SAME address caches and overlapping target copy. No custom tables or secondary compression.",
     "additionalProperties": true
    }
   },
   "additionalProperties": true
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vcdiff-window-address-cache-validator-d7c7cff4/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)