# HTTP/3 Support Change Watch

> HTTP/3 Support Change 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 domain for HTTP/3 and modern-transport support changes, returning current status, a changed flag, and before/after field diffs compared to your last call.

## Facts

- Endpoint: GET https://intel.rallylive.ca/watch/monitor/http3
- 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/http-3-support-change-watch-d42e46c8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FDIRx1bmQwFWX5eaXiJez

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 http-3-support-change-watch-d42e46c8
```

Example prompt: Keep an eye on whether example.com has enabled HTTP/3 — run the check now and tell me if anything changed since the last time you looked, including exactly which fields flipped and what their old and new values are.

## When to prefer this

Choose this endpoint when you need to detect changes in HTTP/3 or modern transport support over time, not just a one-shot status check. It is ideal for scheduled agents that need to react when a domain flips its HTTP/3 configuration, because it handles state comparison server-side (90-day retention) and returns precise field-level diffs rather than requiring the agent to store and compare snapshots itself.

## Known failure modes

- Domain is unreachable or does not resolve — check may return an error or unavailable status
- First-time call for a domain has no prior baseline — 'changed' will be false or indeterminate
- Domain actively blocks probes — results may be inaccurate
- Stale baseline if prior result is older than 90 days — comparison resets
- Payment not attached or insufficient — x402 payment required error

## How this service works

Change watch for http3 support: runs the check and compares it with the result from your previous call for the same domain (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 http/3 and modern-transport support changes. $0.01 per check.

## Output

Returns the current HTTP/3 and modern-transport support answer for the domain, a boolean 'changed' flag indicating whether the result differs from the previous call (stored up to 90 days), a list of exactly which fields changed with their before and after values, and the timestamp of when the status was last seen.

## 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/http-3-support-change-watch-d42e46c8/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)