> For the complete documentation index, see [llms.txt](https://docs.stacks.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.stacks.co/reference/stacks.js/stacks-bitcoin-staking/fetch/fetchbondmembership.md).

# fetchBondMembership

Calls the pox-5 `get-bond-membership` read-only and returns the staker's protocol bond membership, or `undefined` if the staker has no membership or its bond has ended.

***

### Usage

```ts
import { fetchBondMembership } from '@stacks/bitcoin-staking';

const membership = await fetchBondMembership({
  address: 'SP2J6ZY48GV1EZ5V2V5RB9MP66SW86PYKKNRV9EJ7',
  network: 'mainnet',
});

if (membership) {
  membership.bondIndex;
  membership.amountSats; // sats, as a bigint
  membership.isL1Lock; // true for a Bitcoin L1 lockup, false for sBTC
}
```

#### Notes

* Reads the `protocol-bond-memberships` map through [`get-bond-membership`](https://github.com/stacks-network/stacks-core/blob/10474cdec9f9c0bdf05841b58cffc89cdad87a9b/stackslib/src/chainstate/stacks/boot/pox-5.clar#L3065-L3079). The contract returns `none` when no entry exists, and also once the current reward cycle reaches the bond's first reward cycle plus 12 (`BOND_LENGTH_CYCLES`). Both cases resolve to `undefined`.
* A membership for a bond that has not started yet is returned.
* To read the entry after the bond ends, use [fetchProtocolBondMemberships](/reference/stacks.js/stacks-bitcoin-staking/fetch/fetchprotocolbondmemberships.md), which reads the map directly. `unstake-sbtc` also reads the map directly ([L1267-L1269](https://github.com/stacks-network/stacks-core/blob/10474cdec9f9c0bdf05841b58cffc89cdad87a9b/stackslib/src/chainstate/stacks/boot/pox-5.clar#L1267-L1269)), without this expiry filter.
* After `announce-l1-early-exit`, the entry is still returned with `amountSats` set to `0n` ([L1235-L1237](https://github.com/stacks-network/stacks-core/blob/10474cdec9f9c0bdf05841b58cffc89cdad87a9b/stackslib/src/chainstate/stacks/boot/pox-5.clar#L1235-L1237)).
* Throws an `Error` if the node returns a non-2xx status (the message starts with `Error calling read-only function.`) or answers `okay: false` (the message is the node's `cause`).

[**Reference Link**](https://github.com/stx-labs/stacks.js/blob/6101c99efe5a9616ce7e16cef68e28fd10676e7e/packages/bitcoin-staking/src/fetch.ts#L154-L179)

***

### Signature

```ts
function fetchBondMembership(
  opts: { address: string } & NetworkClientParam
): Promise<BondMembership | undefined>;
```

`opts` is a [NetworkClientParam](/reference/stacks.js/stacks-network/network/networkclientparam.md) plus `address`.

***

### Returns

`Promise<BondMembership | undefined>`

Resolves to a [BondMembership](/reference/stacks.js/stacks-bitcoin-staking/types/bondmembership.md), or `undefined` when the contract returns `none`.

***

### Parameters

#### opts.address (required)

* **Type**: `string`

Stacks address of the staker. A contract principal (`<address>.<contract-name>`) is also accepted.

#### opts.network (optional)

* **Type**: `StacksNetworkName | StacksNetwork`

The network to query: a name such as `'mainnet'` or `'testnet'`, or a [StacksNetwork](/reference/stacks.js/stacks-network/network/stacksnetwork.md) object. Defaults to `'mainnet'`.

#### opts.client (optional)

* **Type**: `{ baseUrl?: string; fetch?: FetchFn }`

Overrides the API base URL or the `fetch` function, for example to query your own node. Fields you set replace the network's defaults.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.stacks.co/reference/stacks.js/stacks-bitcoin-staking/fetch/fetchbondmembership.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.