> ## Documentation Index
> Fetch the complete documentation index at: https://docs.peaq.xyz/llms.txt
> Use this file to discover all available pages before exploring further.
# Monetize: Presence heartbeat
> The machine-side heartbeat client: sign and push a presence heartbeat at a configurable interval, and query any machine's presence.
export const KeyTerms = ({all = {}, ids = [], title = "Key terms in this guide"}) =>
{title}
{ids.map(id => {
const t = all[id] || ({});
return
{t.term}. {t.def}
;
})}
;
export const G = {
onchain: {
id: "onchain",
cat: "chain-infra",
term: "On-chain vs off-chain",
def: "On-chain means written to the shared public ledger every machine agrees on: permanent and readable by anyone. Off-chain means kept on a normal private server instead."
},
blockchain: {
id: "blockchain",
cat: "chain-infra",
term: "Chain / blockchain",
def: "A shared, tamper-resistant public database maintained by a whole network of computers with no single owner. Different chains are separate such networks."
},
peaqChain: {
id: "peaqChain",
cat: "chain-infra",
term: "peaq chain",
def: "The machine-focused blockchain peaqOS uses as home base for identity and credit records."
},
transaction: {
id: "transaction",
cat: "chain-infra",
term: "Transaction (tx) / tx hash",
def: "A single signed request that changes the ledger. Its hash is a unique, receipt-like ID you can use to look it up later."
},
rpcUrl: {
id: "rpcUrl",
cat: "chain-infra",
term: "RPC URL / endpoint",
def: "The network address your code calls to read from or write to a chain, like the base URL of the chain's API server."
},
mainnet: {
id: "mainnet",
cat: "chain-infra",
term: "Mainnet / testnet (agung)",
def: "Mainnet is the real, live network where tokens have real value. Testnet is a free practice copy with worthless tokens; peaq's is called agung."
},
evm: {
id: "evm",
cat: "chain-infra",
term: "EVM / EVM-compatible",
def: "The Ethereum Virtual Machine: the standard runtime many chains share, so the same 0x... addresses and tools work across all of them. peaq is EVM-compatible."
},
node: {
id: "node",
cat: "chain-infra",
term: "Node (RPC node)",
def: "A server running the blockchain software that holds a copy of the ledger and answers queries. NOT a ROS 2 node, despite the shared word."
},
chainId: {
id: "chainId",
cat: "chain-infra",
term: "Chain ID",
def: "A number that uniquely labels a chain so software doesn't confuse networks (peaq is 3338, Base is 8453)."
},
precompile: {
id: "precompile",
cat: "chain-infra",
term: "Precompile",
def: "A built-in function baked into the chain at a fixed address that acts like a contract but runs as faster native code. The batch one bundles several actions into one all-or-nothing transaction."
},
dataHash: {
id: "dataHash",
cat: "chain-infra",
term: "Data hash (keccak256)",
def: "A short, fixed-length fingerprint of a file, stored on-chain instead of the file itself, so data can be verified later while the raw data stays off-chain."
},
wallet: {
id: "wallet",
cat: "wallet-keys",
term: "Wallet",
def: "An account on the chain, identified by a public address, that holds a machine's funds and approves its actions. Really just a pair of keys, not a place money is stored."
},
keypair: {
id: "keypair",
cat: "wallet-keys",
term: "Keypair",
def: "The two matched secrets behind a wallet: a public address you can share, and a private key you keep secret that signs actions."
},
privateKey: {
id: "privateKey",
cat: "wallet-keys",
term: "Private key",
def: "The secret string that proves you control a wallet. Anyone who has it has full control, like a master password that can never be reset."
},
sign: {
id: "sign",
cat: "wallet-keys",
term: "Sign / signature",
def: "Using your private key to produce a cryptographic stamp proving you approved a specific action, without ever revealing the key."
},
signer: {
id: "signer",
cat: "wallet-keys",
term: "Signer / signing identity",
def: "The wallet whose private key authorizes an action: the account the network treats as the one taking it. NOT a file or an app."
},
address: {
id: "address",
cat: "wallet-keys",
term: "Address (0x...)",
def: "The public 0x... identifier of a wallet or contract you can freely share so others can send to it or look it up, like an account number."
},
eoa: {
id: "eoa",
cat: "wallet-keys",
term: "EOA (externally owned account)",
def: "A plain wallet controlled directly by a private key, as opposed to one controlled by code. Here, the account that IS the machine."
},
ows: {
id: "ows",
cat: "wallet-keys",
term: "OWS / wallet vault",
def: "An open standard for storing wallet keys in an encrypted local file (a vault) with a backup phrase and an activity log, instead of a bare key in a text file."
},
passphrase: {
id: "passphrase",
cat: "wallet-keys",
term: "Passphrase (OWS_PASSPHRASE)",
def: "The password that unlocks the encrypted wallet vault so its key can be used to sign."
},
mnemonic: {
id: "mnemonic",
cat: "wallet-keys",
term: "Mnemonic / seed phrase",
def: "A list of 12 or 24 ordinary words that encodes a wallet's secret key, used to back it up and recover it. Whoever has the words controls the wallet."
},
derivation: {
id: "derivation",
cat: "wallet-keys",
term: "Derivation path",
def: "The deterministic recipe that turns one backup phrase into many specific keys and addresses, one per network or index."
},
challenge: {
id: "challenge",
cat: "wallet-keys",
term: "Challenge (sign-to-prove)",
def: "A login-style handshake: the server sends a random message, you sign it with your key, and the signature proves you control the account without sending the key."
},
eip191: {
id: "eip191",
cat: "wallet-keys",
term: "EIP-191 / personal_sign",
def: "A standard way to sign a plain message to prove you control an account, without sending any on-chain transaction."
},
did: {
id: "did",
cat: "identity",
term: "DID / peaqID",
def: "A globally unique, self-owned ID for a machine that lives on the chain and isn't issued by any single company. peaqID is peaq's version, written did:peaq:0x..."
},
register: {
id: "register",
cat: "identity",
term: "Register a machine",
def: "Putting a machine on the network for the first time, which gives it an ID, a DID, an ownership token, and a locked deposit. registerMachine is self-managed; registerFor is on someone else's behalf."
},
machineId: {
id: "machineId",
cat: "identity",
term: "Machine ID",
def: "The number the network assigns your machine when it registers, used as its handle in every later call."
},
ownerOperator: {
id: "ownerOperator",
cat: "identity",
term: "Owner / operator",
def: "The owner owns a machine; the operator runs it. They can be the same account (self-managed) or different (proxy-managed)."
},
proxyOperator: {
id: "proxyOperator",
cat: "identity",
term: "Proxy operator",
def: "One account that registers and manages many machines on behalf of their owners, so a fleet operator can handle a whole fleet from one wallet."
},
didAttributes: {
id: "didAttributes",
cat: "identity",
term: "DID attributes",
def: "Public name-value facts (a docs link, a data endpoint) attached to a machine's DID and stored on-chain for anyone to read. Writing them is a separate transaction from registration."
},
pairing: {
id: "pairing",
cat: "identity",
term: "Pairing / pairing token",
def: "The verified link between an AI agent and a machine, set up by signing a challenge. The pairing token is the signed credential the agent sends with each request, like a temporary access badge."
},
hardwareAttestation: {
id: "hardwareAttestation",
cat: "identity",
term: "Hardware attestation",
def: "A tamper-resistant chip on the machine cryptographically vouching that it's genuine hardware, so its identity can't be faked in software. This is the Verify layer."
},
gas: {
id: "gas",
cat: "tokens-economics",
term: "Gas",
def: "The small fee, paid in the chain's token, that every action writing to the ledger costs, like a per-write transaction cost."
},
peaqToken: {
id: "peaqToken",
cat: "tokens-economics",
term: "PEAQ (token)",
def: "The peaq network's own token, used to pay gas fees and to lock up as the deposit when registering a machine."
},
gasStation: {
id: "gasStation",
cat: "tokens-economics",
term: "Gas Station / faucet",
def: "A peaq service that hands a brand-new, empty wallet a tiny starting amount of tokens so it can afford its first network fees. Gated by 2FA."
},
bond: {
id: "bond",
cat: "tokens-economics",
term: "Bond",
def: "A refundable deposit (currently 1 PEAQ) you lock up to register a machine, proving skin in the game, like a security deposit. Bonded means the deposit is in place."
},
nft: {
id: "nft",
cat: "tokens-economics",
term: "NFT",
def: "A unique, one-of-a-kind ownership token recorded on the chain. Unlike a coin, no two are interchangeable."
},
mint: {
id: "mint",
cat: "tokens-economics",
term: "Mint / minting",
def: "Creating a brand-new token on the chain and assigning it to an owner, like stamping a fresh serial-numbered certificate into existence."
},
machineNft: {
id: "machineNft",
cat: "tokens-economics",
term: "Machine NFT",
def: "The unique token representing one specific physical machine and its financial profile. It can be sold or bridged on its own, separate from the machine's identity."
},
identityNft: {
id: "identityNft",
cat: "tokens-economics",
term: "Identity NFT",
def: "A non-transferable (soulbound) token minted automatically when a machine registers, representing its identity. Its token ID equals the machine ID."
},
tokenId: {
id: "tokenId",
cat: "tokens-economics",
term: "Token ID",
def: "The unique number identifying one specific token within a collection, like a serial number."
},
mcr: {
id: "mcr",
cat: "tokens-economics",
term: "Machine Credit Rating (MCR)",
def: "A creditworthiness score for a machine (a Moody's-style grade AAA down to NR, plus a 0-100 number) computed from its recorded earnings and activity. Like a credit score for a robot."
},
mcrApi: {
id: "mcrApi",
cat: "tokens-economics",
term: "MCR API",
def: "The public web service you call to fetch a machine's credit score and profile as JSON, and the one place a machine's monetization is switched on or off with a signed message. No login needed: reads are open, and the write is authorized by the signature itself."
},
provisioned: {
id: "provisioned",
cat: "tokens-economics",
term: "Provisioned / NR (Not Rated)",
def: "Early MCR statuses. Provisioned means registered and bonded but with too little history to score yet. NR means no grade, because the score is too low or the machine isn't bonded."
},
event: {
id: "event",
cat: "tokens-economics",
term: "Event (revenue / activity)",
def: "A recorded data point about a machine's work, submitted to the chain to feed its credit score. Revenue events report money earned; activity events report work with no money. NOT a ROS topic message."
},
trustLevel: {
id: "trustLevel",
cat: "tokens-economics",
term: "Trust level",
def: "A label on each submitted event saying how strongly its truth is backed: the machine's word (0), a checkable on-chain record (1), or tamper-proof hardware proof (2)."
},
escrow: {
id: "escrow",
cat: "tokens-economics",
term: "Escrow",
def: "Holding a buyer's payment in a neutral locked place until the service is delivered, then releasing it, so neither side has to trust the other first."
},
paymentRail: {
id: "paymentRail",
cat: "tokens-economics",
term: "Payment rail",
def: "The specific method or channel a payment moves through, like choosing card vs bank transfer vs a particular token."
},
x402: {
id: "x402",
cat: "tokens-economics",
term: "x402",
def: "A web payment standard where a server answers 'payment required' with exact instructions, and the buyer's wallet signs an authorization instead of sending a separate transaction — built for machines and agents paying per request."
},
usdt: {
id: "usdt",
cat: "tokens-economics",
term: "USDT",
def: "A stablecoin token meant to hold a value of one US dollar, used to pay service providers without price swings."
},
fractionalize: {
id: "fractionalize",
cat: "tokens-economics",
term: "Fractionalize (ERC-3643)",
def: "Splitting ownership of one machine into many small tradable shares so multiple people can each own a piece. ERC-3643 is the regulated-securities token standard used to do it."
},
smartContract: {
id: "smartContract",
cat: "smart-contracts",
term: "Smart contract / contract address",
def: "A program deployed on the chain that runs exactly as written and that anyone can call, identified by its own 0x... address."
},
registryContracts: {
id: "registryContracts",
cat: "smart-contracts",
term: "Registry contracts",
def: "On-chain programs that each keep an official, lookup-able list: IdentityRegistry tracks which machines exist, EventRegistry stores their events, IdentityStaking holds their deposits."
},
smartAccount: {
id: "smartAccount",
cat: "smart-contracts",
term: "Smart account (ERC-4337)",
def: "A programmable wallet controlled by code instead of a single key, so it can enforce rules like spending limits. Each machine gets one at activation."
},
submitEvent: {
id: "submitEvent",
cat: "smart-contracts",
term: "submitEvent / batchSubmitEvents",
def: "The calls that record one or many of a machine's revenue or activity entries onto the chain."
},
revert: {
id: "revert",
cat: "smart-contracts",
term: "Revert",
def: "When an on-chain call is rejected and fully undone because a rule was broken, leaving no changes and usually a named error."
},
soulbound: {
id: "soulbound",
cat: "smart-contracts",
term: "Soulbound",
def: "A token that can never be transferred or sold and stays permanently attached to one owner. The Identity NFT is soulbound."
},
bridge: {
id: "bridge",
cat: "cross-chain",
term: "Bridge / bridging",
def: "Moving a token from one chain to another, so the same Machine NFT can exist on a different chain. peaq and Base are live today; bridging is mainnet-only."
},
base: {
id: "base",
cat: "cross-chain",
term: "Base",
def: "Another blockchain network (built by Coinbase) that peaqOS can move Machine NFTs to and from. Paying fees on Base needs Base ETH."
},
omniChain: {
id: "omniChain",
cat: "cross-chain",
term: "Omni-chain / cross-chain",
def: "Working across many separate chains at once, so a machine's identity and credit created on peaq can be read or used on other chains."
},
homeChain: {
id: "homeChain",
cat: "cross-chain",
term: "Home chain",
def: "The chain where a record's canonical, authoritative copy lives. For peaqOS that is peaq chain; every other chain holds a mirror."
},
satelliteChain: {
id: "satelliteChain",
cat: "cross-chain",
term: "Satellite chain",
def: "A chain carrying a read-only, automatically synced mirror of home-chain records, so apps there can use them without crossing back to the home chain."
},
sourceChainId: {
id: "sourceChainId",
cat: "cross-chain",
term: "sourceChainId / sourceTxHash",
def: "Two fields recording which chain an action happened on and its hash there, so a cross-chain event can be traced back and verified."
},
machineAgent: {
id: "machineAgent",
cat: "general-web3",
term: "Machine Agent",
def: "A third-party AI program (Claude, OpenAI, a custom bot) paired to a machine and given limited permission to find, buy, and pay for services on its behalf."
},
delegationPolicy: {
id: "delegationPolicy",
cat: "general-web3",
term: "Delegation policy",
def: "The rules an owner gives an AI agent that cap how much it can spend per transaction and per day and which services it may use, so it transacts within guardrails."
},
machineMarkets: {
id: "machineMarkets",
cat: "general-web3",
term: "Machine Markets / Service Registry",
def: "peaqOS's marketplace where machines list services they offer (Service Registry) and where agents discover, order, pay for, and run services from others."
},
sdk: {
id: "sdk",
cat: "general-web3",
term: "SDK (peaq-os-sdk)",
def: "peaq's code library (Python and JS) you install to call all this functionality without writing low-level blockchain calls yourself."
},
stream: {
id: "stream",
cat: "data-stream",
term: "Stream (Data-as-a-Service)",
def: "The peaqOS function where a machine sells the data it generates: it signs the data, encrypts what's sensitive, and grants buyers access. Selling data, as opposed to selling capacity (that's Monetize)."
},
edgeAgent: {
id: "edgeAgent",
cat: "data-stream",
term: "peaqOS Edge Agent",
def: "Software that runs on the machine itself (as a ROS 2 node) and signs, encrypts, and ships the data it produces. The on-machine half of Stream."
},
dataPackage: {
id: "dataPackage",
cat: "data-stream",
term: "Signed data package",
def: "A bundle of machine data stamped with the machine's identity (DID, timestamp, sequence number) and a signature, so anyone can prove which machine produced it and that it wasn't altered."
},
dataEventMap: {
id: "dataEventMap",
cat: "data-stream",
term: "Data Event Map",
def: "The policy file a machine owner writes to control what streams out: which topics to read, which fields to keep, drop, or encrypt, and where the signed data goes."
},
chunk: {
id: "chunk",
cat: "data-stream",
term: "Chunk",
def: "A bounded, individually encrypted slice of a data stream (by time window or size). The unit a buyer actually purchases and decrypts."
},
chunkChain: {
id: "chunkChain",
cat: "data-stream",
term: "Chunk chain",
def: "A run of chunks linked in order, each referencing the one before it, so missing, reordered, or edited chunks are detectable. Tamper-evidence for a continuous stream."
},
manifest: {
id: "manifest",
cat: "data-stream",
term: "Manifest",
def: "A signed record describing a chunk or dataset — its hashes, storage location, and encryption details — without the data itself. Buyers verify the manifest before trusting or buying."
},
dataset: {
id: "dataset",
cat: "data-stream",
term: "Dataset",
def: "A group of chunks for one topic and time range, packaged for sale with a single fingerprint (a Merkle root) that covers every chunk in it."
},
merkleRoot: {
id: "merkleRoot",
cat: "data-stream",
term: "Merkle root",
def: "One short hash that stands in for a whole set of items, letting you later prove a specific chunk belongs to a dataset without revealing the rest."
},
envelopeEncryption: {
id: "envelopeEncryption",
cat: "data-stream",
term: "Envelope encryption / key wrapping",
def: "Encrypt the data once with a random key, then lock that key separately for each authorized reader. Granting a buyer access re-locks the key to their public key — the data itself is never re-encrypted."
},
accessGrant: {
id: "accessGrant",
cat: "data-stream",
term: "Access grant",
def: "What a buyer receives after paying: the chunk keys they bought, each locked to their public key. They unlock with their private key and decrypt only those chunks."
},
contextProvider: {
id: "contextProvider",
cat: "data-stream",
term: "Context Provider",
def: "A third party that buys machine data, normalizes it into datasets, and serves or resells it (for example, for AI training). The buyer side of Stream, such as DataHive."
},
computeProvider: {
id: "computeProvider",
cat: "monetize",
term: "Compute provider",
def: "A machine that rents out its processing power to a compute network. Instead of sitting idle, the machine runs other people's workloads and earns for it."
},
provisioningManifest: {
id: "provisioningManifest",
cat: "monetize",
term: "Provisioning manifest",
def: "A published, step-by-step install plan that turns a machine into a compute provider: the checks to run first, the commands to execute, and the probes that prove it worked. The machine pulls it on demand and runs it locally."
},
heartbeat: {
id: "heartbeat",
cat: "monetize",
term: "Heartbeat",
def: "A short signed 'I'm here' message a machine sends out at a regular interval. As long as heartbeats keep arriving, the machine counts as online; if they stop, it's marked offline automatically."
},
aggregator: {
id: "aggregator",
cat: "monetize",
term: "Aggregator",
def: "A network that pools capacity from many machines and sells it on, such as a decentralized compute marketplace. Machines connect to an aggregator, which then dispatches work to them."
},
machineWallet: {
id: "machineWallet",
cat: "monetize",
term: "Machine wallet",
def: "The wallet that belongs to the machine itself, separate from its owner's or operator's wallet. Earnings from the machine's work land here by default."
},
walrus: {
id: "walrus",
cat: "chain-infra",
term: "Walrus",
def: "A decentralized storage network where encrypted data chunks can be parked, referenced by walrus:// links. The data stays off the blockchain; only its reference and fingerprint are tracked on-chain."
},
solana: {
id: "solana",
cat: "cross-chain",
term: "Solana",
def: "A high-throughput blockchain. peaqOS wallets can hold a Solana account and sign Solana transactions, and machine-economy payments can settle there."
}
};
The heartbeat client ships in `@peaqos/peaq-os-sdk` 0.5.0+ (JS/TS) and `peaq-os-sdk` 0.5.0+ (Python) under the `monetization` namespace. It talks to the dedicated peaqOS heartbeat service; the peaq-hosted instance is `https://heartbeat.peaq.xyz`, and the base URL stays configuration, never a constant.
A machine that has [opted into monetization](/peaqos/sdk-reference/monetization-opt-in) reports that it is online by pushing a signed heartbeat to the heartbeat service at a regular interval. A valid heartbeat keeps the machine **online**; when heartbeats stop, the server marks it offline. The client does not enforce the opt-in state itself: start it only on an opted-in machine (check with `getMonetization` / `get_monetization`), and stop it when the machine opts out.
## Push, not poll
The machine is a *client* of the heartbeat service: it pushes a signed heartbeat out. It does not host an endpoint that others poll, and it never serves its own availability.
```mermaid theme={"theme":{"light":"github-light-default","dark":"github-dark"}}
sequenceDiagram
participant M as Machine (SDK client)
participant H as Heartbeat service
loop every intervalMs
M->>H: POST /api/v1/heartbeats {machineId, publicKey, sentAt, signature}
H->>H: verify signature, store presence (online for the TTL)
H-->>M: {accepted, online, lastHeartbeatAt}
end
```
## The 180-second TTL and the interval bound
A valid heartbeat marks the machine online for a fixed presence TTL of **180 seconds**. Miss that window and the server flips the machine to offline. To stay online, the machine must heartbeat comfortably more often than the TTL, so the client caps the configured interval:
| Constant | Value | Meaning |
| :--------------- | :---- | :---------------------------------------------------------------------------------------------------------------- |
| Presence TTL | 180 s | Server presence window (`PRESENCE_TTL_MS` in JS, `PRESENCE_TTL_SECONDS` in Python). |
| Heartbeat margin | 60 s | Safety margin absorbing request latency plus one retry (`HEARTBEAT_MARGIN_MS` / `HEARTBEAT_MARGIN_SECONDS`). |
| Max interval | 120 s | The maximum accepted interval, TTL minus margin (`MAX_HEARTBEAT_INTERVAL_MS` / `MAX_HEARTBEAT_INTERVAL_SECONDS`). |
`start` rejects an interval that is zero, negative, or above the maximum. The exact interval within that bound is caller-supplied configuration.
**Offline is server-derived.** The client never self-reports offline. Stopping the client simply stops heartbeating; the server observes the absence and lets presence lapse. Operator-initiated maintenance is expressed the same way: stop the client.
## Request-signing auth
There is no bearer credential. The server authenticates each heartbeat by verifying the `signature` against the `publicKey` in the payload.
* The machine identity **private key** is held only by your signer implementation. The client passes it a canonical message and receives a hex signature; the client never handles or logs the raw key.
* `publicKey`, `signature`, `machineId`, and `sentAt` are not secret and are safe to log.
The signature covers exactly this canonical message, byte for byte (two lines, LF-joined, no trailing newline):
```
machineId: {machineId}
sentAt: {sentAt}
```
Build it with `buildCanonicalMessage` / `build_canonical_message`, the single place this format is defined.
## Quick start
```ts JavaScript theme={"theme":{"light":"github-light-default","dark":"github-dark"}}
import { HeartbeatClient } from "@peaqos/peaq-os-sdk";
// or: const heartbeat = client.monetization.createHeartbeatClient();
const heartbeat = new HeartbeatClient();
heartbeat.start({
baseUrl: "https://heartbeat.peaq.xyz",
intervalMs: 30_000, // 0 < intervalMs <= 120_000
machineId: "machine-abc-123",
publicKey: "0x04…",
signer, // holds the machine identity private key
onResult: (res) => {
// res: { accepted, online, lastHeartbeatAt }
console.log("online:", res.online);
},
});
// on shutdown or maintenance:
heartbeat.stop();
```
```python Python theme={"theme":{"light":"github-light-default","dark":"github-dark"}}
from peaq_os_sdk.monetization import HeartbeatClient, HeartbeatConfig
heartbeat = HeartbeatClient()
heartbeat.start(HeartbeatConfig(
base_url="https://heartbeat.peaq.xyz",
interval_seconds=30, # 0 < interval_seconds <= 120
machine_id="machine-abc-123",
public_key="0x04…",
signer=signer, # holds the machine identity private key
on_result=lambda res: print("online:", res.online),
))
# on shutdown or maintenance:
heartbeat.stop()
```
Each tick sends exactly `{ machineId, publicKey, sentAt, signature }` and parses `{ accepted, online, lastHeartbeatAt }`, surfaced through the optional result callback.
## Fire-and-forget
A failed push, whether a network error or an `accepted: false` response, is logged and retried on the next tick. It never throws out of the timer and never blocks the machine's other operations. Every parsed response reaches the result callback, including rejections.
A hung push cannot stall the loop either. In JS/TS the whole tick (signing plus push) is time-bounded to 30 seconds, or the interval if shorter. In Python the bound is per request: the transport's 10-second HTTP timeout, with signing cancelled cooperatively rather than forced. A server that accepts the connection but never responds is timed out, logged, and retried on the next tick like any other failure.
`stop()` is the one exception: it cancels the timer, aborts any in-flight request (including one still signing), and is treated as expected cancellation, not a failure. No error log, no result callback, no retry.
## Presence query
`checkPresence` / `check_presence` is a standalone one-shot query with no scheduler and no signing. Pass exactly one of `machineId` or `publicKey`:
```ts JavaScript theme={"theme":{"light":"github-light-default","dark":"github-dark"}}
import { checkPresence } from "@peaqos/peaq-os-sdk";
const presence = await checkPresence(
{ machineId: "machine-abc-123" },
{ baseUrl: "https://heartbeat.peaq.xyz" },
);
// { online, machineId, publicKey, lastHeartbeatAt }
```
```python Python theme={"theme":{"light":"github-light-default","dark":"github-dark"}}
from peaq_os_sdk.monetization import PresenceCheckRequest, check_presence
presence = check_presence(
PresenceCheckRequest(machine_id="machine-abc-123"),
base_url="https://heartbeat.peaq.xyz",
)
# presence.online, .machine_id, .public_key, .last_heartbeat_at
```
When the machine is offline or unknown, `online` is `false` and `publicKey` / `lastHeartbeatAt` are `null`.
## Presence only
The heartbeat payload is a pure presence signal: it carries no status field and no queue depth. Presence is binary under this API: online (a valid heartbeat within 180 seconds) or offline (TTL expired). Utilisation states such as `busy` are not represented, and maintenance is expressed by stopping the client. Do not add extra fields to the payload.
## API summary
| Symbol | Role |
| :-------------------------------------------------------------------- | :------------------------------------------------------- |
| `HeartbeatClient` | `start(config)` / `stop()` presence scheduler. |
| `HeartbeatSigner` | `sign(message)` returning hex; holds the private key. |
| `buildCanonicalMessage` | Byte-for-byte canonical message builder. |
| `HeartbeatTransport` | Wire and HTTP seam; swap it for tests or a custom stack. |
| `checkPresence` | One-shot presence query. |
| `PRESENCE_TTL_MS`, `HEARTBEAT_MARGIN_MS`, `MAX_HEARTBEAT_INTERVAL_MS` | Interval bounds. |
## Related
* [Monetize function](/peaqos/functions/monetize): where the heartbeat fits in the flow
* [Provisioning SDK reference](/peaqos/sdk-reference/provisioning): provision the provider node first
* [Monetization opt-in API](/peaqos/api-reference/put-machine-monetization)