# SDK reference

Install `@browserlayer/sdk` to **author integrations**. Your backend calls the hosted HTTP API.

| API                                                                          | Purpose                                 | Example                                              |
| ---------------------------------------------------------------------------- | --------------------------------------- | ---------------------------------------------------- |
| `createEndpoint({ description, input, output, exec })`                       | Define an application endpoint          | [Endpoints](/docs/endpoints)                         |
| `createSync({ description, connection, schedule, model, checkpoint, exec })` | Define a scheduled dataset              | [Syncs](/docs/syncs)                                 |
| `ctx.step(id, fn)`                                                           | Record a result; reuse it after a pause | [Steps](/docs/flows)                                 |
| `ctx.run(flow, input)`                                                       | Invoke a discovered child flow          | [Composition](/docs/flows#call-a-connector-flow)     |
| `ctx.input(id, form)`                                                        | Request input and suspend               | [MFA](/docs/input)                                   |
| `form(schema, fields)`                                                       | Declare reusable input fields           | [Authentication](/docs/authentication)               |
| `ctx.browser()`                                                              | Obtain the Playwright page              | [Browser](/docs/browser)                             |
| `ctx.http.get(url, options?)`                                                | Browser-context GET                     | [HTTP](/docs/browser#read-json-through-the-browser)  |
| `ctx.http.request(url, options?)`                                            | Browser-context request                 | [HTTP](/docs/browser#submit-a-request)               |
| `ctx.observe(id, check, { timeoutMs })`                                      | Poll a read-only outcome                | [Observation](/docs/browser#observe-after-an-action) |
| `ctx.connection.data.get/set/delete`                                         | Saved connection data                   | [Authentication](/docs/authentication)               |
| `ctx.getCheckpoint()`                                                        | Read source progress                    | [Checkpoints](/docs/checkpoints)                     |
| `ctx.publish(id, records, options)`                                          | Atomically publish records and progress | [Syncs](/docs/syncs)                                 |
| `FlowError(code, message, userMessage?)`                                     | Structured failure                      | [Debugging](/docs/debugging)                         |
| `createReference(schema)`                                                    | Define private upstream identity        | [References](/docs/references)                       |
| `ctx.references.store(reference, value)`                                     | Get a stable public ID                  | [References](/docs/references#create-public-ids)     |
| `ctx.references.resolve(reference, id)`                                      | Resolve private identity                | [References](/docs/references#resolve-before-acting) |

## Additional entry points

| Import                       | Audience                                       |
| ---------------------------- | ---------------------------------------------- |
| `@browserlayer/sdk/testing`  | Integration tests                              |
| `@browserlayer/sdk/compiler` | Compile an integration directory               |
| `@browserlayer/link/browser` | Optional embedded Link                         |
| `@browserlayer/sync`         | Webhook verification and sync storage adapters |

Low-level `Runtime`, `MemoryStore`, browser adapters and durable engine contracts are for custom hosts. See the installed SDK `RUNTIME.md` for their contract; they are unnecessary for the CLI workflow.

`createFlow({ description, input, output, exec })` defines an internal connector operation. Only these flows can be composed with `ctx.run`; endpoints and syncs are entry points. All three support durable steps and user input.