Streams

A stream is a continuous flow of money between two wallets, denominated in a rate per unit time. Unlike transfers, which are discrete events, streams accrue value every second. Streams are ideal for:

Payroll / contractor pay — the recipient withdraws earned balance on their own schedule
Subscriptions — cancel any moment, get refunded for unused time
Service-tier SLAs — pay-per-millisecond for AI inference, compute, bandwidth
Agent-to-agent retainers — one agent pays another to keep availability

Anatomy

┌─────────────────┐
│ Sender wallet   │
│  (wrapped       │
│   funds)        │
└────────┬────────┘
         │ flows at rate
         ▼
┌─────────────────┐        ┌─────────────────┐
│ Stream          │──────▶ │ Recipient       │
│  • flow_rate    │        │  balance        │
│  • buffer       │        │  (withdrawable) │
│  • runway       │        └─────────────────┘
└─────────────────┘

Key numbers on every stream:

flow_rate — amount per second (e.g. "0.00005" USDC = $0.00005/s ≈$ 4.32/day)
wrapped_balance — sender’s locked-up funds powering the stream
buffer — reserved slack to prevent accidental underrun
runway_seconds — time until the wrapped balance runs out at current flow rate
recipient_balance — accrued, withdrawable by the recipient

Create a stream

curl -X POST https://sandbox.getsly.ai/v1/streams \
  -H "Authorization: Bearer pk_test_..." \
  -H "Content-Type: application/json" \
  -d '{
    "from_wallet_id": "wal_sender_...",
    "to_wallet_id": "wal_recipient_...",
    "flow_rate": "0.00005",
    "currency": "USDC",
    "initial_deposit": "1000.00",
    "buffer": "50.00"
  }'

This locks

1000 into the stream, starts flowing at

0.00005/s, and keeps a

50 buffer. The recipient accrues ~

4.32/day and can withdraw at any point.

Recipient withdraws

curl -X POST https://api.getsly.ai/v1/streams/str_.../withdraw \
  -H "Authorization: Bearer pk_live_..." \
  -d '{ "amount": "10.00" }'  # omit to withdraw all accrued

Withdrawal creates a stream_withdraw transfer into the recipient’s wallet.

Top up or adjust

# Add more funds
curl -X POST /v1/streams/str_.../topup -d '{ "amount": "500.00" }'

# Change flow rate (reflective of new runway)
curl -X PATCH /v1/streams/str_... -d '{ "flow_rate": "0.0001" }'

Pause and resume

curl -X POST /v1/streams/str_.../pause
curl -X POST /v1/streams/str_.../resume

Paused streams don’t accrue. Wrapped funds remain locked until cancellation.

Cancel

curl -X POST /v1/streams/str_.../cancel

Accrued balance transfers to the recipient
Unused wrapped funds return to the sender
The stream record remains for audit

Runway and alerts

When runway_seconds drops below a threshold, Sly fires a stream_alert webhook and pushes a stream_alert SSE event to any connected agents that manage the stream:

{
  "event": "stream_alert",
  "severity": "warning",
  "stream_id": "str_...",
  "runway_seconds": 3600,
  "message": "Stream will exhaust in 1 hour"
}

Severity levels: warning (<24h), critical (<1h), exhausted (runway=0).

Agent permissions

When an agent creates or manages a stream, their wallet policy grants them granular permissions:

streams:create — open new streams
streams:modify — change flow rate, topup
streams:pause — pause/resume
streams:terminate — cancel

See wallet policies for how to scope these.

Why streams over periodic transfers

	Stream	Batch of transfers
Granularity	Per-second	Per period (daily/weekly/monthly)
Refunds	Automatic (cancel returns unused)	Manual (via refunds API)
Gas / fees	Paid once on wrap	Paid per transfer
Recipient cash flow	Continuous	Lumpy
Auditability	Every second is on-ledger	Per-transfer

For anything ongoing, prefer a stream.

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Resources

Anatomy

Create a stream

Recipient withdraws

Top up or adjust

Pause and resume

Cancel

Runway and alerts

Agent permissions

Why streams over periodic transfers

​Anatomy

​Create a stream

​Recipient withdraws

​Top up or adjust

​Pause and resume

​Cancel

​Runway and alerts

​Agent permissions

​Why streams over periodic transfers

Anatomy

Create a stream

Recipient withdraws

Top up or adjust

Pause and resume

Cancel

Runway and alerts

Agent permissions

Why streams over periodic transfers