Blink Wallet

Blink Skill

Bitcoin Lightning wallet operations via the Blink API. Enables agents to check balances, receive payments via invoices, send payments over Lightning, track transactions, monitor prices, and automatically pay for L402-gated web services.

What is Blink?

Blink is a Bitcoin Lightning wallet with a GraphQL API. Accounts are either custodial (Blink holds the keys; this is the default and what most commands target) or non-custodial (Spark) (the user holds a seed). See references/non-custodial.md for the non-custodial commands (resolve-receiver, create-invoice-lnaddress, and the seed-gated spark-* commands). Key concepts:

• API Key — authentication token (format: blink_...) with scoped permissions (Read, Receive, Write)
• BTC Wallet — balance denominated in satoshis
• USD Wallet — balance denominated in cents (stablecoin pegged to USD)
• Lightning Invoice — BOLT-11 payment request string (lnbc...) used to receive payments
• Lightning Address — human-readable address (user@domain) for sending payments without an invoice
• LNURL — protocol for interacting with Lightning services via encoded URLs
• L402 — HTTP payment protocol (RFC draft) that gates resources behind a Lightning invoice. Servers return HTTP 402 with a macaroon + invoice; clients pay and retry with the token.

Environment

• Requires bash and Node.js 18+ (Node 22+ for the non-custodial spark-* commands and for WebSocket subscriptions; Node 20+ can use --experimental-websocket).
• Credentials depend on the command — no single env var is required skill-wide:
  • Credential-free (no key, no seed): resolve-receiver, create-invoice-lnaddress. These use public LNURL-pay on blink.sv.
  • Custodial commands need BLINK_API_KEY with the appropriate scopes.
  • Non-custodial (Spark) commands (spark-balance, spark-send, spark-transactions, spark-subscribe) need SPARK_MNEMONIC (the account seed — spend authority) plus BREEZ_API_KEY.
• Zero required runtime npm dependencies. The custodial and credential-free commands use only Node.js built-ins (node:util, node:fs, node:path, node:child_process). Two optional, lazy-loaded dependencies exist solely for the spark-* commands and are loaded only when one runs: @breeztech/breez-sdk-spark and bip39.

Use this skill for concrete wallet operations, not generic Lightning theory.

Getting Started

1. Get your API key

1. Create a free account at dashboard.blink.sv.
2. Go to API Keys and create a key with the scopes you need.
3. Set it in your environment:

export BLINK_API_KEY="blink_..."

API Key Scopes:

• Read — query balances, transaction history, price, account info
• Receive — create invoices
• Write — send payments (use with caution)

Tip: Start with Read + Receive only. Add Write when you need to send payments.

2. Verify it works

node {baseDir}/scripts/balance.js

If you see JSON with your wallet balances, you're ready.

3. Staging / Testnet (recommended for first-time setup)

To use the Blink staging environment (signet) instead of real money:

export BLINK_API_URL="https://api.staging.blink.sv/graphql"

Create a staging API key at dashboard.staging.blink.sv. The staging environment uses signet bitcoin (no real value) — perfect for testing payment flows safely.

If BLINK_API_URL is not set, production (https://api.blink.sv/graphql) is used by default.

API key resolution

Scripts read BLINK_API_KEY from the process environment only:

1. process.env.BLINK_API_KEY

No filesystem fallback: shell rc files (~/.bashrc, ~/.profile, etc.) are never read. Export the key in your shell or agent environment before running scripts.

Optional: CLI wrapper (full GitHub repo only)

If you have cloned the full GitHub repo, you can optionally install a blink CLI command:

npm install   # install dev dependencies (eslint, prettier)
npm link      # creates global 'blink' command
blink --help  # verify

Note: npm link modifies global npm state. This is optional — all functionality is available by running scripts directly with node {baseDir}/scripts/<script>.js. The ClawHub-installed version does not require or use npm link.

Agent Safety Policy

These rules are mandatory for any AI agent using this skill:

1. Ask before spending. Never execute pay-invoice, pay-lnaddress, pay-lnurl, swap-execute, or spark-send without explicit user confirmation of the amount and recipient.
   • Non-custodial seed is sacred. SPARK_MNEMONIC grants full spend authority over a self-custodial account. Never log, echo, display, transmit, or write it. It is read only from the environment variable, never from files.
2. Dry-run first. For swaps, always run with --dry-run before executing for real unless the user explicitly says to skip it.
3. Check balance before sending. Always run balance before any payment or swap to verify sufficient funds.
4. Probe fees before paying. Run fee-probe before pay-invoice to show the user the fee cost.
5. Use minimum scopes. Only request Write-scoped API keys when send operations are actually needed.
6. Never log or display the API key. Treat BLINK_API_KEY as a secret. Do not echo it, include it in messages, or write it to files.
7. Prefer staging for testing. When the user is testing or learning, suggest setting BLINK_API_URL to the staging endpoint.
8. Respect irreversibility. Warn the user that Lightning payments and swaps cannot be reversed once executed.
9. L402 auto-pay requires configuration and confirmation. l402-pay fails closed: it refuses to pay unless an explicit spending budget (BLINK_BUDGET_HOURLY_SATS / BLINK_BUDGET_DAILY_SATS) and a non-empty domain allowlist (BLINK_L402_ALLOWED_DOMAINS or blink budget allowlist add) are configured. It also refuses when the invoice amount cannot be decoded, since no limit can be applied to an unknown sum. Never call l402-pay without dry-running first (--dry-run) and confirming the satoshi amount with the user. The token cache (~/.blink/l402-tokens.json) means subsequent calls may reuse a paid token silently — inform the user when a cached token is used.

Bitcoin Units

• BTC wallet amounts are always in satoshis (sats). 1 BTC = 100,000,000 sats.
• USD wallet amounts are always in cents. $1.00 = 100 cents.
• When displaying amounts to users, use the formatted fields from output JSON (e.g. btcBalanceUsdFormatted, usdBalanceFormatted).
• Do not perform manual BTC-to-USD conversion math — use blink price <sats> or the btcBalanceUsd field from balance output instead.
• For swap amounts, the --unit flag controls interpretation: sats for BTC, cents for USD.

Workflow

1. Pick the operation path first:

• Receive payments (invoice creation, QR codes, payment monitoring).
• Send payments (invoice pay, Lightning Address, LNURL, BTC or USD wallet).
• Swap between wallets (BTC <-> USD internal conversion).
• Read-only queries (balance, transactions, price, account info).

2. Configure API access from blink-api-and-auth:

• Set BLINK_API_KEY with the correct scopes for your operation.
• Optionally set BLINK_API_URL for staging/testnet.
• Verify connectivity with blink balance.

3. For sending payments, follow payment-operations:

• Check balance before sending.
• Probe fees with blink fee-probe.
• Choose BTC or USD wallet with --wallet flag.
• Execute payment and verify in transaction history.

4. For receiving payments, follow invoice-lifecycle:

• Create BTC or USD invoice.
• Parse two-phase output (invoice created, then payment resolution).
• Generate QR code and send to payer.
• Monitor via auto-subscribe, polling, or standalone subscription.

5. For swapping between wallets, follow swap-operations:

• Quote first with blink swap-quote.
• Review quote terms (amountIn/amountOut, exchange rate).
• Execute with blink swap-execute (use --dry-run first).
• Verify settlement from postBalance/balanceDelta.

6. For accessing L402-gated services:

• Discover price with blink l402-discover <url> (no payment needed).
• Dry-run with blink l402-pay <url> --dry-run and confirm cost with user.
• Pay with blink l402-pay <url> --max-amount <sats> (Write scope required).
• Token is cached; subsequent requests reuse it without re-paying.

7. Apply safety constraints:

• Use minimum API key scopes for the task.
• Test on staging before production.
• Always check balance before sending.
• Payments are irreversible once settled.

Quick Commands

# Check balances
blink balance

# Create BTC invoice (auto-subscribes to payment)
blink create-invoice 1000 "Payment for service"

# Pay a Lightning invoice
blink pay-invoice lnbc1000n1...

# Pay from USD wallet
blink pay-invoice lnbc1000n1... --wallet USD

# Get current BTC/USD price
blink price

# Swap 1000 sats to USD
blink swap-execute btc-to-usd 1000

# Get swap quote without executing
blink swap-quote usd-to-btc 500 --unit cents

# Probe an L402-gated URL (discover price without paying)
blink l402-discover https://api.example.com/resource

# Pay for an L402-gated resource (dry-run first)
blink l402-pay https://api.example.com/resource --dry-run
blink l402-pay https://api.example.com/resource --max-amount 1000

# List cached L402 tokens
blink l402-store list

Core Commands

Check Wallet Balances

blink balance

Returns JSON with all wallet balances (BTC in sats, USD in cents), wallet IDs, pending incoming amounts, and a pre-computed USD estimate for the BTC wallet. Use btcBalanceUsd for the BTC wallet's USD value — do not calculate it yourself.

Create Lightning Invoice (BTC)

blink create-invoice <amount_sats> [--timeout <seconds>] [--no-subscribe] [memo...]

Generates a BOLT-11 Lightning invoice for the specified amount in satoshis. Returns the paymentRequest string that can be paid by any Lightning wallet. The BTC wallet ID is resolved automatically.

Auto-subscribe: After creating the invoice, the script automatically opens a WebSocket subscription and waits for payment. It outputs two JSON objects to stdout:

1. Immediately — {"event": "invoice_created", ...} with paymentRequest, paymentHash, etc.
2. When resolved — {"event": "subscription_result", "status": "PAID"|"EXPIRED"|"TIMEOUT", ...}

The agent should read the first JSON to share the invoice/QR with the user right away, then wait for the second JSON to confirm payment.

• amount_sats — amount in satoshis (required)
• --timeout <seconds> — subscription timeout (default: 300). Use 0 for no timeout.
• --no-subscribe — skip WebSocket auto-subscribe, just create the invoice and exit
• memo... — optional description attached to the invoice (remaining args joined)

Create Lightning Invoice (USD)

blink create-invoice-usd <amount_cents> [--timeout <seconds>] [--no-subscribe] [memo...]

Creates a Lightning invoice denominated in USD cents. The sender pays in BTC/Lightning, but the received amount is locked to a USD value at the current exchange rate. Credited to the USD wallet. Expires in ~5 minutes due to exchange rate lock.

Auto-subscribe: Same two-phase output as create-invoice — first JSON is the created invoice, second JSON is the payment resolution (PAID/EXPIRED/TIMEOUT).

• amount_cents — amount in USD cents, e.g. 100 = $1.00 (required)
• --timeout <seconds> — subscription timeout (default: 300). Use 0 for no timeout.
• --no-subscribe — skip WebSocket auto-subscribe, just create the invoice and exit
• memo... — optional description attached to the invoice (remaining args joined)

Check Invoice Status

blink check-invoice <payment_hash>

Checks the payment status of a Lightning invoice by its payment hash. Use after creating an invoice to detect when it has been paid. Returns status: PAID, PENDING, or EXPIRED.

• payment_hash — the 64-char hex payment hash from create-invoice output (required)

Pay Lightning Invoice

blink pay-invoice <bolt11_invoice> [--wallet BTC|USD]

Pays a BOLT-11 Lightning invoice from the BTC or USD wallet. Returns payment status: SUCCESS, PENDING, FAILURE, or ALREADY_PAID. The wallet ID is resolved automatically.

• bolt11_invoice — the BOLT-11 payment request string, e.g. lnbc... (required)
• --wallet BTC|USD — wallet to pay from (default: BTC). When USD is selected, the Blink API debits the USD equivalent from the USD wallet.

Requires Write scope on the API key.

AGENT: This command spends funds. Always run balance and fee-probe first, then confirm amount and recipient with the user before executing.

Pay to Lightning Address

blink pay-lnaddress <lightning_address> <amount_sats> [--wallet BTC|USD]

Sends satoshis to a Lightning Address (e.g. user@blink.sv). Returns payment status. The wallet ID is resolved automatically.

• lightning_address — recipient in user@domain format (required)
• amount_sats — amount in satoshis (required)
• --wallet BTC|USD — wallet to pay from (default: BTC). When USD is selected, the amount is still specified in satoshis; the Blink API debits the USD equivalent from the USD wallet automatically.

Requires Write scope on the API key.

AGENT: This command spends funds. Always run balance first, confirm the Lightning Address and amount with the user, then execute.

Pay to LNURL

blink pay-lnurl <lnurl> <amount_sats> [--wallet BTC|USD]

Sends satoshis to a raw LNURL payRequest string. For Lightning Addresses (user@domain), use pay-lnaddress instead.

• lnurl — LNURL string, e.g. lnurl1... (required)
• amount_sats — amount in satoshis (required)
• --wallet BTC|USD — wallet to pay from (default: BTC). When USD is selected, the amount is still specified in satoshis; the Blink API debits the USD equivalent from the USD wallet automatically.

Requires Write scope on the API key.

AGENT: This command spends funds. Always run balance first, confirm the LNURL and amount with the user, then execute.

Estimate Payment Fee

blink fee-probe <bolt11_invoice> [--wallet BTC|USD]

Estimates the fee for paying a Lightning invoice without actually sending. Use before pay-invoice to check costs. Payments to other Blink users and direct-channel nodes are free (0 sats).

• bolt11_invoice — the BOLT-11 payment request string (required)
• --wallet BTC|USD — wallet to probe from (default: BTC). When USD is selected, uses lnUsdInvoiceFeeProbe to estimate fees from the USD wallet's perspective.

Render Invoice QR Code

blink qr <bolt11_invoice>

Renders a terminal QR code for a Lightning invoice (BOLT-11) to stderr and generates a PNG image file to /tmp. The stdout JSON includes a pngPath field with the absolute path to the PNG file.

Sending the QR image to a user: After running this script, use the pngPath from the JSON output to send the PNG as a media attachment to the user in the current chat. The agent should use its native message-send capability with the file path.

• bolt11_invoice — the BOLT-11 payment request string (required)

Output JSON includes:

• invoice — uppercased invoice string
• qrRendered — always true
• qrSize — QR module count
• errorCorrection — "L" (LOW)
• pngPath — absolute path to the generated PNG file (e.g. /tmp/blink_qr_1234567890.png)
• pngBytes — file size in bytes

List Transactions

blink transactions [--first N] [--after CURSOR] [--wallet BTC|USD]

Lists recent transactions (incoming and outgoing) with pagination. Returns direction, amount, status, type (lightning/onchain/intraledger), and metadata.

• --first N — number of transactions to return (default: 20, max: 100)
• --after CURSOR — pagination cursor from previous response's endCursor
• --wallet BTC|USD — filter to a specific wallet currency

Get BTC/USD Price

blink price [amount_sats]
blink price --usd <amount_usd>
blink price --history <range>
blink price --currencies

Multi-purpose exchange rate tool. All price queries are public (no API key required), though the key is sent if available.

Modes:

• No args — current BTC/USD price and sats-per-dollar rate
• <amount_sats> — convert a satoshi amount to USD (e.g. blink price 1760 → $1.20)
• --usd <amount> — convert a USD amount to sats (e.g. blink price --usd 5.00 → 7350 sats)
• --history <range> — historical BTC price data with summary stats (high/low/change). Ranges: ONE_DAY, ONE_WEEK, ONE_MONTH, ONE_YEAR, FIVE_YEARS
• --currencies — list all supported display currencies (IDs, names, symbols, flags)

Account Info

blink account-info

Shows account level, spending limits (withdrawal, internal send, convert), default wallet, and wallet summary with pre-computed USD estimates for BTC balances. Limits are denominated in USD cents with a rolling 24-hour window.

Realtime Subscriptions

Blink supports GraphQL subscriptions over WebSocket using the graphql-transport-ws protocol. Requires Node 22+ for native WebSocket, or Node 20+ with the --experimental-websocket flag.

Subscribe to Invoice Payment Status

blink subscribe-invoice <bolt11_invoice> [--timeout <seconds>]

Watches a single invoice and exits when it is PAID or EXPIRED. Status updates are printed to stderr. JSON result is printed to stdout.

Subscribe to Account Updates (myUpdates)

blink subscribe-updates [--timeout <seconds>] [--max <count>]

Streams account updates in real time. Each event is output as a JSON line (NDJSON) to stdout. Use --max to stop after N events.

API Reference

API Endpoint: https://api.blink.sv/graphql (production) Authentication: X-API-KEY header

USD wallet notes: The lnInvoicePaymentSend, lnAddressPaymentSend, and lnurlPaymentSend mutations all accept either a BTC or USD wallet ID. When a USD wallet ID is provided, the API debits the USD equivalent automatically. Amounts for lnAddressPaymentSend and lnurlPaymentSend are always specified in satoshis regardless of wallet type.

Output Format

All commands output structured JSON to stdout. Status messages and errors go to stderr. Exit code 0 on success, 1 on failure.

Balance output example

{
  "wallets": [
    { "id": "abc123", "currency": "BTC", "balance": 1760, "unit": "sats" },
    { "id": "def456", "currency": "USD", "balance": 1500, "unit": "cents" }
  ],
  "btcWalletId": "abc123",
  "btcBalance": 1760,
  "btcBalanceSats": 1760,
  "btcBalanceUsd": 1.2,
  "btcBalanceUsdFormatted": "$1.20",
  "usdWalletId": "def456",
  "usdBalance": 1500,
  "usdBalanceCents": 1500,
  "usdBalanceFormatted": "$15.00"
}

Invoice creation output example (two-phase)

First JSON (immediate):

{
  "event": "invoice_created",
  "paymentRequest": "lnbc500n1...",
  "paymentHash": "abc123...",
  "satoshis": 500,
  "status": "PENDING",
  "createdAt": "2026-02-23T00:00:00Z",
  "walletId": "abc123"
}

Second JSON (when payment resolves):

{
  "event": "subscription_result",
  "paymentRequest": "lnbc500n1...",
  "status": "PAID",
  "isPaid": true,
  "isExpired": false,
  "isPending": false
}

Invoice status output example

{
  "paymentHash": "abc123...",
  "paymentStatus": "PAID",
  "satoshis": 500,
  "isPaid": true,
  "isExpired": false,
  "isPending": false
}

Payment output example (BTC wallet)

{
  "status": "SUCCESS",
  "walletId": "abc123",
  "walletCurrency": "BTC",
  "balanceBefore": 50000
}

Payment output example (USD wallet)

{
  "status": "SUCCESS",
  "walletId": "def456",
  "walletCurrency": "USD",
  "balanceBefore": 1500,
  "balanceBeforeFormatted": "$15.00"
}

Price output example

{
  "btcPriceUsd": 68036.95,
  "satsPerDollar": 1470,
  "conversion": {
    "sats": 1760,
    "usd": 1.2,
    "usdFormatted": "$1.20"
  }
}

USD-to-sats conversion output example

{
  "btcPriceUsd": 68036.95,
  "satsPerDollar": 1470,
  "conversion": {
    "usd": 5.0,
    "usdFormatted": "$5.00",
    "sats": 7350
  }
}

Price history output example

{
  "range": "ONE_DAY",
  "dataPoints": 24,
  "summary": {
    "current": 68036.95,
    "oldest": 67500.0,
    "high": 68500.0,
    "low": 67200.0,
    "changeUsd": 536.95,
    "changePct": 0.8
  },
  "prices": [{ "timestamp": 1740000000, "date": "2025-02-20T00:00:00.000Z", "btcPriceUsd": 67500.0 }]
}

Transaction list output example

{
  "transactions": [
    {
      "id": "tx_123",
      "direction": "RECEIVE",
      "status": "SUCCESS",
      "amount": 1000,
      "currency": "BTC",
      "type": "lightning",
      "paymentHash": "abc...",
      "createdAt": 1740000000
    }
  ],
  "count": 1,
  "pageInfo": {
    "hasNextPage": false,
    "endCursor": "cursor_abc"
  }
}

Typical Agent Workflows

Receive a payment (recommended — auto-subscribe + QR image)

# 1. Create invoice — script auto-subscribes and outputs two JSON objects
blink create-invoice 1000 "Payment for service"
# → First JSON: {"event": "invoice_created", "paymentRequest": "lnbc...", ...}
# → Read paymentRequest from first JSON immediately

# 2. Generate QR code PNG
blink qr <paymentRequest>
# → JSON includes "pngPath": "/tmp/blink_qr_123456.png"
# → Send the PNG file to the user as a media attachment in the current chat

# 3. The create-invoice command is still running, waiting for payment
# → Second JSON: {"event": "subscription_result", "status": "PAID", ...}
# → When PAID: notify the user that payment has been received
# → When EXPIRED: notify the user the invoice expired

Important: The create-invoice command outputs two JSON objects separated by a newline. Parse them as separate JSON objects, not as a single JSON array. The first object arrives immediately; the second arrives when payment status resolves.

Receive a payment (polling fallback)

# 1. Create invoice without auto-subscribe
blink create-invoice 1000 --no-subscribe "Payment for service"
# 2. Give the paymentRequest to the payer
# 3. Poll for payment
blink check-invoice <payment_hash>
# 4. Verify balance
blink balance

Receive a USD payment

# Same two-phase pattern as BTC, but using create-invoice-usd
# Note: USD invoices expire in ~5 minutes
blink create-invoice-usd 500 "Five dollars for service"
# → First JSON: {"event": "invoice_created", "amountCents": 500, "amountUsd": "$5.00", ...}
# Generate QR and send to user, then wait for second JSON

Send a payment (with fee check)

# 1. Check current balance
blink balance
# 2. Estimate fee
blink fee-probe lnbc1000n1...
# 3. Send payment
blink pay-invoice lnbc1000n1...
# 4. Verify in transaction history
blink transactions --first 1

Send from the USD wallet

# Pay an invoice from the USD wallet
blink fee-probe lnbc1000n1... --wallet USD
blink pay-invoice lnbc1000n1... --wallet USD

# Send to a Lightning Address from the USD wallet
blink pay-lnaddress user@blink.sv 1000 --wallet USD

# Send via LNURL from the USD wallet
blink pay-lnurl lnurl1... 1000 --wallet USD

# Note: for lnaddress and lnurl, the amount is always in satoshis.
# The Blink API debits the USD equivalent from the USD wallet automatically.

Convert sats to USD value

# Check how much 1760 sats is worth in USD
blink price 1760
# → $1.20

Convert USD to sats

# How many sats is $5.00?
blink price --usd 5.00
# → 7350 sats

Swap BTC to USD (internal conversion)

# 1. Get a quote first
blink swap-quote btc-to-usd 2000
# → Shows expected conversion terms (amountIn: 2000 sats, amountOut: ~136 cents)

# 2. Execute the swap (dry-run first)
blink swap-execute btc-to-usd 2000 --dry-run
# → Shows what would happen without moving funds

# 3. Execute for real
blink swap-execute btc-to-usd 2000
# → Converts 2000 sats from BTC wallet to ~$1.36 in USD wallet

# 4. Verify balances
blink balance

Swap USD to BTC (internal conversion)

# Convert $5.00 (500 cents) to BTC
blink swap-execute usd-to-btc 500 --unit cents
# → Converts 500 cents from USD wallet to ~7350 sats in BTC wallet

Pay for an L402-gated service

# 1. Discover what the service costs (no payment)
blink l402-discover https://api.example.com/resource
# → shows satoshis, format, macaroon

# 2. Dry-run to confirm price with user before spending
blink l402-pay https://api.example.com/resource --dry-run
# → {"event": "l402_dry_run", "satoshis": 100, ...}

# 3. Check your balance first
blink balance

# 4. Pay (with optional safety limit)
blink l402-pay https://api.example.com/resource --max-amount 500
# → pays invoice, caches token, returns resource data

# 5. Subsequent calls reuse cached token (no re-payment)
blink l402-pay https://api.example.com/resource
# → {"event": "l402_paid", "tokenReused": true, ...}

Check price history

# Get BTC price over the last 24 hours
blink price --history ONE_DAY
# Get BTC price over the last month
blink price --history ONE_MONTH

Swap Commands (BTC <-> USD)

Swap between your BTC and USD wallets using Blink's intra-ledger transfer. This is an internal conversion (not a Lightning payment), so there are no routing fees — only minor rounding spread.

Get Swap Quote

blink swap-quote <direction> <amount> [--unit sats|cents] [--ttl-seconds N] [--immediate]

Estimates the conversion terms without moving funds. Returns wallet balances, exchange rate snapshot, and the expected amountIn/amountOut in the output JSON.

• direction — btc-to-usd or usd-to-btc (aliases: sell-btc, buy-usd, sell-usd, buy-btc)
• amount — positive integer amount to convert
• --unit sats|cents — unit of the amount (defaults to sats for btc-to-usd, cents for usd-to-btc)
• --ttl-seconds N — quote TTL in seconds (default: 60)
• --immediate — flag the quote for immediate execution

No API key scope beyond Read is required for quotes.

Execute Swap

blink swap-execute <direction> <amount> [--unit sats|cents] [--dry-run] [--memo "text"]

Executes a real BTC <-> USD conversion. First generates a quote, then performs the intra-ledger transfer. Returns pre/post balances, delta, quote terms, and transaction ID.

• direction — same as swap-quote
• amount — positive integer amount to convert
• --unit sats|cents — same as swap-quote
• --dry-run — show what would be swapped without executing the transfer
• --memo "text" — optional memo attached to the transaction

CAUTION: Without --dry-run, this moves real funds between wallets. Requires Write scope.

AGENT: This command moves funds between wallets. Always run with --dry-run first, show the quote to the user, and get explicit confirmation before executing without --dry-run.

Swap Output Examples

Quote output:

{
  "event": "swap_quote",
  "dryRun": true,
  "direction": "BTC_TO_USD",
  "preBalance": {
    "btcWalletId": "abc123",
    "usdWalletId": "def456",
    "btcBalanceSats": 50000,
    "usdBalanceCents": 1500,
    "usdBalanceFormatted": "$15.00"
  },
  "quote": {
    "quoteId": "blink-swap-1709424000-123456",
    "direction": "BTC_TO_USD",
    "requestedAmount": { "value": 1000, "unit": "sats" },
    "amountIn": { "value": 1000, "unit": "sats" },
    "amountOut": { "value": 68, "unit": "cents" },
    "feeSats": 0,
    "feeBps": 0,
    "rateSnapshot": { "satsPerDollar": 1470 },
    "executionPath": "blink:intraLedgerPaymentSend"
  }
}

Execution output:

{
  "event": "swap_execution",
  "dryRun": false,
  "direction": "BTC_TO_USD",
  "status": "SUCCESS",
  "succeeded": true,
  "preBalance": { "btcBalanceSats": 50000, "usdBalanceCents": 1500 },
  "postBalance": { "btcBalanceSats": 49000, "usdBalanceCents": 1567 },
  "balanceDelta": { "btcDeltaSats": -1000, "usdDeltaCents": 67 },
  "execution": {
    "path": "blink:intraLedgerPaymentSend",
    "transactionId": "tx_abc123"
  }
}

L402 Client Commands

L402 is an HTTP payment protocol: a server returns HTTP 402 with a Lightning invoice, the client pays, and retries the request with a proof-of-payment token. This skill can act as an L402 client.

Supports two L402 formats:

• Lightning Labs — WWW-Authenticate: L402 macaroon="...", invoice="lnbc..."
• l402-protocol.org — JSON body with payment_request_url and offers array

Discover L402 Pricing (no payment)

blink l402-discover <url> [--method GET|POST] [--header key:value]

Probes a URL for L402 payment requirements without paying. Returns the detected format, invoice, and decoded satoshi amount.

• url — the URL to probe (required)
• --method GET|POST — HTTP method to use (default: GET)
• --header key:value — extra request header (repeatable)

No API key required for discovery.

Known public L402 endpoints for testing (use specific paths, not root URLs):

• https://l402.services/geoip/8.8.8.8 — GeoIP lookup, 1 sat, Lightning Labs format
• https://www.l402apps.com/api/apis — L402 API directory, 10 sats, Lightning Labs format

Pay for an L402-Gated Resource

blink l402-pay <url> [options]

Makes an HTTP request. If the server returns 402, automatically parses the challenge, pays the invoice via Blink, caches the token, and retries with the payment proof.

• url — URL to access (required)
• --wallet BTC|USD — wallet to pay from (default: BTC)
• --max-amount <sats> — refuse to pay more than N sats (safety limit)
• --dry-run — discover price without paying; always bypasses the token cache so the current invoice price is always shown even if a cached token exists
• --method GET|POST|PUT|DELETE|PATCH — HTTP method (default: GET)
• --header key:value — extra request header (repeatable)
• --body <string> — request body for POST/PUT
• --no-store — disable token cache (do not read or write ~/.blink/l402-tokens.json)
• --force — pay even if a valid cached token exists
• --probe — run a fee probe (lnInvoiceFeeProbe) before paying to estimate routing fees; warns and continues if the probe fails; adds a feeProbe field to the l402_paid output

Requires Write scope on the API key.

AGENT: Always run with --dry-run first to show the satoshi cost to the user. Confirm the amount and target URL before executing without --dry-run.

Manage Token Cache

blink l402-store list
blink l402-store get <domain>
blink l402-store clear [--expired]

• list — show all cached tokens (masks preimage for security)
• get <domain> — retrieve the full token for a specific domain
• clear — remove all cached tokens
• clear --expired — remove only expired tokens

Token cache location: ~/.blink/l402-tokens.json

L402 Output Examples

l402-discover (Lightning Labs format):

{
  "url": "https://api.example.com/resource",
  "l402_detected": true,
  "format": "lightning-labs",
  "macaroon": "AgELZXhhbXBsZS...",
  "invoice": "lnbc1000n1...",
  "satoshis": 100,
  "satoshisFormatted": "100 sats"
}

l402-pay (dry-run):

{
  "event": "l402_dry_run",
  "url": "https://api.example.com/resource",
  "format": "lightning-labs",
  "invoice": "lnbc1000n1...",
  "satoshis": 100,
  "satoshisFormatted": "100 sats",
  "maxAmount": 1000,
  "withinBudget": true,
  "message": "Dry-run: would pay this invoice to access the resource. No payment made."
}

l402-pay (after payment):

{
  "event": "l402_paid",
  "url": "https://api.example.com/resource",
  "format": "lightning-labs",
  "paymentStatus": "SUCCESS",
  "walletId": "abc123",
  "walletCurrency": "BTC",
  "satoshis": 100,
  "tokenReused": false,
  "retryStatus": 200,
  "data": { "...": "response from the protected resource" }
}

l402-pay (after payment, with --probe):

{
  "event": "l402_paid",
  "url": "https://api.example.com/resource",
  "format": "lightning-labs",
  "paymentStatus": "SUCCESS",
  "walletId": "abc123",
  "walletCurrency": "BTC",
  "satoshis": 100,
  "tokenReused": false,
  "retryStatus": 200,
  "feeProbe": {
    "estimatedFeeSats": 1,
    "error": null
  },
  "data": { "...": "response from the protected resource" }
}

L402 Producer Commands

L402 producer tools let you protect your own API resources behind a Lightning paywall. Issue challenges to clients, then verify their payment proofs before granting access.

Two-step workflow:

1. When a client requests a resource, call blink l402-challenge to create a signed payment challenge and return it with HTTP 402.
2. When the client submits a payment token, call blink l402-verify to verify the preimage and macaroon signature.

Note: End-to-end round-trip testing (challenge → pay → verify) requires two separate Blink accounts. Blink does not allow paying your own invoice (CANT_PAY_SELF). Use a second account or wallet to pay the challenge invoice during testing.

Create an L402 Challenge

blink l402-challenge --amount <sats> [options]

Creates a Lightning invoice via Blink and issues a signed macaroon bound to its payment hash. Returns a ready-to-send WWW-Authenticate header.

• --amount <sats> — invoice amount in satoshis (required)
• --wallet <id> — Blink BTC wallet ID (auto-resolved if omitted)
• --memo <text> — invoice memo / description
• --expiry <seconds> — macaroon caveat expiry (e.g. 3600 = 1 hour); controls how long the challenge is valid, not the invoice expiry
• --resource <id> — resource identifier caveat (e.g. /api/v1/data); returned tokens will only be valid for this exact path

Requires Write scope on the API key.

Root key for HMAC signing resolves in this order:

1. BLINK_L402_ROOT_KEY env var (64-char hex, 32 bytes)
2. ~/.blink/l402-root-key (auto-created on first run)

AGENT: Keep BLINK_L402_ROOT_KEY or ~/.blink/l402-root-key stable across server restarts. A different root key will invalidate all previously issued macaroons.

Verify an L402 Payment Token

blink l402-verify --token <macaroon>:<preimage> [options]
blink l402-verify --macaroon <b64> --preimage <hex> [options]

Verifies a client-submitted L402 Authorization token. Performs three layers of verification:

1. Preimage check: SHA-256(preimage) === payment_hash — cryptographic proof the invoice was paid
2. Signature check: HMAC-SHA256 of macaroon body — proves the macaroon was issued by this server
3. Caveat check: expiry not exceeded, resource matches if constrained

• --token <macaroon>:<preimage> — L402 authorization token (colon-separated, from Authorization: L402 <token> header)
• --macaroon <b64> — base64url-encoded macaroon (alternative to --token)
• --preimage <hex> — 64-char hex preimage (alternative to --token)
• --resource <id> — expected resource identifier to check against the macaroon's resource caveat
• --check-api — additionally query the Blink API to confirm PAID status (belt-and-suspenders)

Exit code 0 when valid: true, exit code 1 when valid: false or on error.

Note: The --preimage value must be a 64-character hex string (32 bytes). Passing a plain string like fake_preimage will produce an error explaining the format requirement. For testing rejection, use a valid-format but wrong preimage: 64 zeros (0000...0000).

L402 Producer Output Examples

l402-challenge:

{
  "header": "L402 macaroon=\"AgEL...\", invoice=\"lnbc100n1...\"",
  "macaroon": "AgEL...",
  "invoice": "lnbc100n1...",
  "paymentHash": "abc123...64hex",
  "satoshis": 100,
  "expiresAt": 1735689600,
  "resource": "/api/v1/data"
}

Return this to clients as:

HTTP/1.1 402 Payment Required
WWW-Authenticate: L402 macaroon="AgEL...", invoice="lnbc100n1..."

l402-verify (valid payment):

{
  "valid": true,
  "preimageValid": true,
  "signatureValid": true,
  "caveatsValid": true,
  "paymentHash": "abc123...64hex",
  "resource": "/api/v1/data",
  "expiresAt": 1735689600,
  "expired": false,
  "apiStatus": "NOT_CHECKED"
}

l402-verify (invalid — wrong preimage):

{
  "valid": false,
  "preimageValid": false,
  "signatureValid": true,
  "caveatsValid": true,
  "paymentHash": "abc123...64hex",
  "resource": null,
  "expiresAt": null,
  "expired": false,
  "apiStatus": "NOT_CHECKED"
}

L402 Service Discovery

Find L402-gated APIs that agents can pay for and access. Two directory sources:

• l402.directory (default) — curated registry with rich endpoint schemas, pricing, and consumption instructions
• 402index.io — broader coverage (50+ services), simpler flat schema

Search Services

blink l402-search                              # all live services from l402.directory
blink l402-search video                        # keyword search
blink l402-search --category data              # filter by category
blink l402-search --status all                 # include offline/new services
blink l402-search --format minimal             # compact output
blink l402-search ai --source 402index         # search 402index.io instead

No API key required — both directories have free browse APIs.

AGENT: Use l402-search to find services before using l402-pay. Check pricing in the results before paying.

Get Service Det

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