sponge

Sponge

Sponge is the financial infrastructure for the agent economy. Master keys create and manage agent wallets; scoped agent keys execute wallet actions — transfers, swaps, card issuance, x402/MPP payments, Hyperliquid/Polymarket trades.

Official docs: https://docs.paysponge.com

When to Use

Use this skill when you need to:

Provision a new agent wallet from a master account
List, inspect, or rotate the agent keys in a Sponge platform
Move funds between Sponge wallets or onto external addresses
Issue or fetch a Sponge Card / virtual card for an agent
Pay an x402- or MPP-enabled endpoint on behalf of an agent

Prerequisites

Connect the Sponge connector at app.vm0.ai/connectors.

Troubleshooting: If requests fail, run zero doctor check-connector --env-name SPONGE_MASTER_KEY or zero doctor check-connector --url https://api.wallet.paysponge.com/api/agents --method GET

Environment Variables

Variable	Description
`SPONGE_MASTER_KEY`	Platform-level master key (prefix `sponge_master_...`). Used for control-plane operations and for fetching scoped agent keys.

The master key is the only credential vm0 stores. Agent keys are looked up at runtime through the master key — never hard-code them.

How to Use

Base URL: https://api.wallet.paysponge.com

All Sponge endpoints use a Bearer header: Authorization: Bearer <master-or-agent-key>.

1. List agents on the platform

curl -s -X GET "https://api.wallet.paysponge.com/api/agents" --header "Authorization: Bearer $SPONGE_MASTER_KEY" | jq '.agents[] | {id, name, description}'

2. Create a new agent

Write to /tmp/sponge_agent.json:

{
  "name": "trading-bot-1",
  "description": "Created by vm0 agent",
  "dailySpendingLimit": "100"
}

curl -s -X POST "https://api.wallet.paysponge.com/api/agents" --header "Authorization: Bearer $SPONGE_MASTER_KEY" --header "Content-Type: application/json" -d @/tmp/sponge_agent.json | jq '{agentId: .agent.id, apiKey}'

The response includes a scoped apiKey — store it; this is the only chance to read it.

3. Fetch (or rotate) an agent's API key

Replace <agent-id> with the agent id from step 2.

curl -s -X GET "https://api.wallet.paysponge.com/api/agents/<agent-id>/api-key" --header "Authorization: Bearer $SPONGE_MASTER_KEY"

Rotate:

curl -s -X POST "https://api.wallet.paysponge.com/api/agents/<agent-id>/api-key/regenerate" --header "Authorization: Bearer $SPONGE_MASTER_KEY"

4. Get current agent (acts as a token health check)

When called with an agent key the endpoint returns the agent identity; when called with a master key it errors. Use it to verify a key before using it.

curl -s -X GET "https://api.wallet.paysponge.com/api/agents/me" --header "Authorization: Bearer <agent-key>"

5. Read agent wallet balances

Use the agent key returned from step 2 — the master key cannot move funds.

curl -s -X GET "https://api.wallet.paysponge.com/api/wallet/balances" --header "Authorization: Bearer <agent-key>"

6. Send an EVM transfer

Replace <agent-key> with the agent's runtime key.

Write to /tmp/sponge_transfer.json:

{
  "chain": "base",
  "token": "USDC",
  "to": "0x0000000000000000000000000000000000000000",
  "amount": "1.00"
}

curl -s -X POST "https://api.wallet.paysponge.com/api/transfers/evm" --header "Authorization: Bearer <agent-key>" --header "Content-Type: application/json" -d @/tmp/sponge_transfer.json

7. Fetch a paid endpoint via x402 auto-pay

Sponge handles 402-payment-required upstream APIs automatically when you proxy the call through x402/fetch.

Write to /tmp/sponge_x402.json:

{
  "url": "https://api.example.com/paid-resource",
  "method": "GET",
  "maxAmount": "0.50"
}

curl -s -X POST "https://api.wallet.paysponge.com/api/x402/fetch" --header "Authorization: Bearer <agent-key>" --header "Content-Type: application/json" -d @/tmp/sponge_x402.json

Guidelines

Treat SPONGE_MASTER_KEY as the control-plane credential — never embed it in agent runtime traffic. Use it to mint or look up a scoped agent key, then switch.
Agent keys are scoped to a single agent — one per persona, never shared across agents.
Set dailySpendingLimit, weeklySpendingLimit, or monthlySpendingLimit on agent creation to bound autonomous spend.
Prefer the official SDKs (@paysponge/sdk TypeScript / paysponge Python) for non-trivial flows — they handle pagination, polling, and bridge state transitions.
For sustained agent-to-API spend, prefer the MPP or x402 flow over manual card issuance — fewer round trips and better failure handling.