# FactStamp Watch Portfolio

> FactStamp Watch Portfolio is a paid API for AI agents from factstamp.agentrails.workers.dev, paid per call via x402, $5/call, status unknown (last checked 2026-10-16).

Starts a 30-day standing re-check subscription for up to 25 citations or package versions at once, returning signed receipts for any detected changes

## Facts

- Endpoint: POST https://factstamp.agentrails.workers.dev/watch/portfolio?utm_source=zero.xyz
- Price: $5/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/factstamp-watch-portfolio-a61343df
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bZEP2FXeTauv2yHXa65nE

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 factstamp-watch-portfolio-a61343df -d '<json body>'
```

Example prompt: Set up a 30-day FactStamp portfolio watch for all 25 references in my bibliography — I want signed receipts if anything changes, and the portfolio token so I can check results later.

## When to prefer this

Choose this endpoint when you need to monitor a whole bibliography or dependency manifest — not just a one-time check — and want daily automated re-checks with cryptographically signed change receipts over 30 days. It is more cost-effective than calling single-reference watch endpoints repeatedly for large lists (up to 25 items at $5 flat vs $5 per item). Prefer it over batch single-check endpoints when persistence and change alerting matter, not just a point-in-time answer.

## Known failure modes

- Payment failure via x402 results in no portfolio being created
- Exceeding 25 references in the list returns a validation error
- Invalid or malformed citation/package identifiers may cause individual items to fail verification
- Prepaid pack code invalid or exhausted returns a redemption error
- Portfolio token lost after creation cannot be recovered (shown once only)
- Network timeout during creation may result in ambiguous payment state

## How this service works

Watch a whole list at once, when a bibliography or a dependency manifest has to stay true: up to 25 citations or package versions re-checked every day for 30 days under one token. US$5 a portfolio — 20 cents a reference, under a cent a check. Every reference is answered and signed on purchase, and each real change gets its own signed receipt. Nothing is sent when nothing changed. Pay per call here, or redeem a prepaid pack code (100 credits).

## Output

Returns a one-time portfolio token, a portfolio ID, a read URL for polling current status, a stop URL to cancel, the expiry timestamp (30 days out), the item count, pricing breakdown, and payment settlement confirmation. Subsequent signed receipts are generated per item only when a real change is detected; nothing is sent when nothing changed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "body": {
     "type": "object"
    },
    "type": {
     "const": "http"
    },
    "method": {
     "const": "POST"
    },
    "bodyType": {
     "const": "application/json"
    }
   },
   "additionalProperties": true
  },
  "output": {
   "type": "object",
   "required": [
    "type",
    "example"
   ],
   "properties": {
    "type": {
     "const": "json"
    },
    "example": {
     "type": "object"
    }
   },
   "additionalProperties": true
  }
 },
 "additionalProperties": false
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "token": "fp_7c2a… (shown once)",
  "per_unit": "US$5 for 25 references over 30 days: US$0.20 a reference, about 0.67 of a cent a check.",
  "read_url": "https://factstamp.agentrails.workers.dev/portfolio/3a91c05f8d21e44077",
  "stop_url": "https://factstamp.agentrails.workers.dev/portfolio/3a91c05f8d21e44077/stop",
  "paid_with": {
   "rail": "x402_pay_per_call",
   "settlement": {
    "success": true
   },
   "list_price_usd": 5
  },
  "expires_at": "2026-11-05T06:30:00.000Z",
  "item_count": 25,
  "portfolio_id": "3a91c05f8d21e44077"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/factstamp-watch-portfolio-a61343df/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from factstamp.agentrails.workers.dev](https://www.zero.xyz/host/factstamp.agentrails.workers.dev/llms.txt)