# CYRE Guardian Circuit Breaker Heartbeat

> CYRE Guardian Circuit Breaker Heartbeat is a paid API for AI agents from cyre.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Sends a heartbeat ping to prove an agent loop is alive and returns a rotated circuit token with a fresh lastBeatAt timestamp

## Facts

- Endpoint: GET https://cyre.dev/api/circuit/heartbeat
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cyre-guardian-circuit-breaker-heartbeat-28f3d47a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Zc0vJMCe_1TDVbxVwSZXd

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 cyre-guardian-circuit-breaker-heartbeat-28f3d47a
```

Example prompt: Send a heartbeat to my CYRE Guardian circuit breaker using my current token so it knows the agent loop is still alive and gives me back a fresh rotated token.

## When to prefer this

Use this endpoint when your agent needs to prove liveness and maintain an active circuit breaker session with CYRE Guardian. Prefer it over a full circuit-breaker check when you only need to refresh the heartbeat and rotate the token without evaluating spend policy or payment readiness.

## Known failure modes

- Missing or invalid token query parameter returns an authentication or bad-request error
- Expired or already-rotated token may be rejected, requiring re-initialization of the circuit
- Service unavailability returns a 5xx error, causing the agent to treat the circuit as open
- Payment failure (x402) if the 0.001 USDC micro-payment is not correctly attached

## How this service works

Guardian Circuit Breaker heartbeat — prove the agent loop is alive; returns rotated circuit token with fresh lastBeatAt. Patterns, not verdicts. Agent guide: https://cyre.dev/SKILL.md

## Output

Returns a rotated circuit token and a fresh lastBeatAt timestamp confirming the agent loop is alive. The new token must be used in subsequent circuit breaker checks.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "token"
     ],
     "properties": {
      "token": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cyre-guardian-circuit-breaker-heartbeat-28f3d47a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from cyre.dev](https://www.zero.xyz/host/cyre.dev/llms.txt)