# A2A Transaction Bridge

> A2A Transaction Bridge is a paid API for AI agents from phion.systems, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-20).

Binds an A2A (Agent-to-Agent) task identity to a financial transaction while preserving explicit authority gaps between agents

## Facts

- Endpoint: POST https://phion.systems/v1/paid/trust/a2a-transaction-bridge?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/a2a-transaction-bridge-100c2e1d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_W6NLTGxkncaK2o8LRFWBp

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 a2a-transaction-bridge-100c2e1d -d '<json body>'
```

Example prompt: Bind this A2A task identity to the current transaction we just initiated, and make sure the authority gaps between the calling agent and the downstream agent are explicitly preserved in the binding record.

## When to prefer this

Use this endpoint when you need to formally associate an A2A agent task identity with a financial transaction while maintaining explicit records of authority gaps — particularly important in multi-agent systems where no single agent holds full authority and auditability of delegated actions is required. Prefer this over generic logging or state-storage endpoints when the binding must carry semantic meaning about agent authority boundaries.

## Known failure modes

- Invalid or unrecognized A2A task identity returns a binding failure with task-not-found error
- Transaction reference does not exist or is already bound, resulting in conflict or rejection
- Authority gap specification is malformed or inconsistent, causing validation failure
- Missing required fields in the empty input schema may cause unpredictable behavior
- Network or service unavailability returns a 5xx error

## How this service works

Bind A2A task identity to a transaction while preserving explicit authority gaps

## Output

Returns a binding record that links the A2A task identity to the specified transaction, including annotations describing explicit authority gaps between agents involved, confirmation of the binding, and metadata about the task-transaction relationship for audit and compliance purposes.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/a2a-transaction-bridge-100c2e1d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phion.systems](https://www.zero.xyz/host/phion.systems/llms.txt)