# Agent-Exec Handoff — Pay-Per-Use Agent Briefing Storage

> Agent-Exec Handoff — Pay-Per-Use Agent Briefing Storage is a paid API for AI agents from agent-exec.448c.net, paid per call via x402, $0.0053/call, status unknown (last checked 2026-10-13).

Stores a structured agent handoff briefing (done/not-done/in-flight state plus next action) and returns a UUID that a successor agent can use to resume work, billed per-call via x402 micropayment with no account required.

## Facts

- Endpoint: POST https://agent-exec.448c.net/handoff?utm_source=zero.xyz
- Price: $0.0053/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-exec-handoff-pay-per-use-agent-briefing-storage-1e3eabb2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_N5GysXBA6rvfR1f8H82PO

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 agent-exec-handoff-pay-per-use-agent-briefing-storage-1e3eabb2 -d '<json body>'
```

Example prompt: Store a handoff briefing for the next agent: done = ['scraped product catalog (measured: 4,200 rows saved to S3)'], not done = ['enrich prices with competitor data'], in flight = ['deduplication job started at 14:02 UTC'], and tell the successor to start by verifying the deduplication results.

## When to prefer this

Use this endpoint when you need to persist agent state between two agent instances or across a context boundary, especially in multi-agent pipelines where one agent hands off to a successor. It is uniquely suited for accountless, pay-per-call scenarios (x402/USDC micropayments) where registering an account or holding an API key is impractical. Prefer it over in-memory or file-based state transfer when you need a neutral, retrievable, tamper-evident briefing with an expiry guarantee and an on-chain payment receipt for auditability.

## Known failure modes

- 400 HANDOFF_DONE_REQUIRES_MEASURED — a 'done' entry lacks confidence='measured' or has null evidence; fix by ensuring every done item has verified, non-null evidence
- 400 validation error — pickUpFirst is empty or missing; every handoff must specify a concrete next action
- 402 Payment Required — x402 payment not attached or payment insufficient; agent must attach valid USDC payment
- 410 Gone — handoff_id exists but briefing has passed its expiry deadline and is pending sweep
- 404 Not Found — handoff_id never existed or has been fully swept after expiry

## How this service works

Accountless, pay-per-use code execution for software agents: submit source code, get stdout, stderr and exit code back from an isolated, network-less sandbox. No account, no API key -- possession of valid payment is sufficient.

## Output

Returns a JSON object with a UUID handoff_id (share this with the successor agent — it needs nothing else to retrieve the briefing), an expiresAt Unix millisecond timestamp after which the briefing is swept and returns 410 then 404, and a payment object containing the asset, payer wallet address, amount in atomic units, network, and on-chain transaction hash confirming the x402 micropayment.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "done",
  "notDone",
  "inFlight",
  "pickUpFirst"
 ],
 "properties": {
  "done": {
   "type": "array",
   "description": "What is DONE. EVERY entry must have confidence 'measured' with non-null evidence -- a briefing cannot claim something is finished on unverified intent. Violating this is a free 400 (HANDOFF_DONE_REQUIRES_MEASURED), not a silent acceptance."
  },
  "notDone": {
   "type": "array",
   "description": "What is NOT done. May be measured or unverified."
  },
  "inFlight": {
   "type": "array",
   "description": "What was IN FLIGHT at the cut -- neither finished nor abandoned. May be measured or unverified."
  },
  "pickUpFirst": {
   "type": "string",
   "description": "What the successor should do FIRST. Mandatory and non-empty: a briefing with no next action is not a handoff."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "id",
  "expiresAt",
  "payment"
 ],
 "properties": {
  "id": {
   "type": "string",
   "format": "uuid",
   "description": "The handoff_id -- give this to the successor; it needs nothing else."
  },
  "payment": {
   "type": "object",
   "properties": {
    "asset": {
     "type": "string"
    },
    "payer": {
     "type": "string",
     "description": "The paying wallet's address."
    },
    "amount": {
     "type": "string",
     "description": "Atomic units of the settlement asset that were charged."
    },
    "network": {
     "type": "string"
    },
    "transaction": {
     "type": "string",
     "description": "On-chain settlement transaction hash."
    }
   }
  },
  "expiresAt": {
   "type": "integer",
   "description": "Unix ms this briefing is swept. GET /handoff/{id} answers 410 between the deadline and the sweep, then 404."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-exec-handoff-pay-per-use-agent-briefing-storage-1e3eabb2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-exec.448c.net](https://www.zero.xyz/host/agent-exec.448c.net/llms.txt)