# Stumble Inbox – Durable Capture Endpoint

> Stumble Inbox – Durable Capture Endpoint is a paid API for AI agents from stumble.vimabrosta.com, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-13).

Creates a temporary capture inbox that holds any inbound HTTP POST (webhooks, agent callbacks, MCP completions) for up to 7 days and forwards them to your webhook or lets you poll, with optional shared-secret header authentication.

## Facts

- Endpoint: POST https://stumble.vimabrosta.com/v1/inbox
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/stumble-inbox-durable-capture-endpoint-d86693a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_G45OuR_8uPW810e8x-4cv

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 stumble-inbox-durable-capture-endpoint-d86693a4 -d '<json body>'
```

Example prompt: Open a temporary inbox that captures anything POSTed to it for 3 days, forwarding each message as JSON to my webhook at https://myserver.example.com/hooks — and require the header X-Secret with value abc123 on all incoming messages.

## When to prefer this

Choose this endpoint when you need a lightweight, disposable, server-less receive endpoint for async callbacks, webhooks, or agent-to-agent messages without standing up infrastructure. Ideal for agentic workflows where a session ends but a callback is expected later, for buffering GitHub or payment webhooks during server migrations, or for providing a handoff URL to another agent or service that needs to POST a result. It is not suitable for high-volume streaming or messages larger than 64KB.

## Known failure modes

- Inbox capacity exceeded (200 messages) — additional messages are dropped
- Message size exceeds 64KB — oversized payloads rejected
- Webhook delivery failure — stumble retries but eventual non-delivery if target is down
- Inbox expiry — messages older than the configured day limit are deleted
- Invalid require_header config — incoming messages without the correct secret are rejected
- Payment not settled (x402) — inbox not created if USDC payment fails

## How this service works

Open an inbox: a capture URL that holds anything POSTed to it for up to 7 days (an A2A push, an MCP task completion, a GitHub or payment webhook, another agent) and forwards each message to your webhook in a signed envelope, or lets you poll. The durable recipient a finished session cannot be. Up to 200 messages of 64KB, optional shared-secret header. One-time $0.10.

## Output

Returns a unique capture URL that any HTTP client can POST to. The inbox retains up to 200 messages of up to 64KB each for the configured number of days. Each received message is forwarded to the caller's webhook wrapped in a signed envelope, or held for polling. The response includes the inbox identifier and the capture URL to hand off to senders.

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "properties": {
      "days": {
       "type": "integer",
       "maximum": 7,
       "minimum": 1
      },
      "notify": {
       "type": "object",
       "required": [
        "mode"
       ],
       "properties": {
        "url": {
         "type": "string"
        },
        "mode": {
         "enum": [
          "webhook",
          "poll"
         ],
         "type": "string"
        },
        "format": {
         "enum": [
          "json",
          "slack",
          "discord"
         ],
         "type": "string"
        }
       }
      },
      "resume_hint": {
       "type": "string",
       "maxLength": 500
      },
      "require_header": {
       "type": "object",
       "properties": {
        "name": {
         "type": "string"
        },
        "value": {
         "type": "string"
        }
       }
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "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/stumble-inbox-durable-capture-endpoint-d86693a4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from stumble.vimabrosta.com](https://www.zero.xyz/host/stumble.vimabrosta.com/llms.txt)