# Cache Headers Check Watch

> Cache Headers Check Watch is a paid API for AI agents from intel.rallylive.ca, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Monitors a URL's HTTP caching headers over time and returns a diff when they change, compared against the previous check result stored for 90 days.

## Facts

- Endpoint: GET https://intel.rallylive.ca/watch/site/cache-headers
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cache-headers-check-watch-c6a2f98e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pXx6_NSh68Ki1ZYIUYgXu

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 cache-headers-check-watch-c6a2f98e
```

Example prompt: Check if the caching headers on https://example.com have changed since the last time you checked, and tell me exactly which fields changed and what the before and after values were.

## When to prefer this

Use this endpoint when you need to detect changes in HTTP caching headers for a specific URL over time, especially on a scheduled basis. Prefer it over a one-shot cache headers check when you want automatic diffing and change detection without managing state yourself. It is ideal for alerting workflows, CI/CD post-deploy validation, or SEO monitoring where you care about the delta between checks rather than just the current state.

## Known failure modes

- URL is unreachable or returns a non-200 response — check may fail or return empty headers
- No previous result stored (first call) — 'changed' will be false or indeterminate with no diff
- URL missing from input — request rejected with validation error
- Rate limits or payment issues — call rejected before check is performed
- Headers present but identical to previous call — changed returns false with empty diff

## How this service works

Change watch for cache headers check: runs the check and compares it with the result from your previous call for the same url (kept 90 days), returning the current answer, changed true/false, exactly which fields changed with before/after values, and when it was last seen. Call it on a schedule to be told when caching headers check changes. $0.01 per check.

## Output

Returns the current cache headers check result for the URL, a boolean 'changed' flag indicating whether results differ from the previous call, a field-level diff listing exactly which headers changed with before/after values, and a timestamp of when the result was last seen. Previous results are retained for 90 days.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cache-headers-check-watch-c6a2f98e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from intel.rallylive.ca](https://www.zero.xyz/host/intel.rallylive.ca/llms.txt)