@1sat/connect SDK Development

@1sat/connect SDK Development Guide

This skill provides guidance for developing the @1sat/connect package — a popup-based wallet SDK that enables dApps to communicate with the 1Sat Wallet at www.1satwallet.com.

Package Architecture

packages/connect/src/
  index.ts       — Public API: exports, createOneSat(), detection helpers
  provider.ts    — OneSatBrowserProvider: popup-based provider implementation
  popup.ts       — PopupManager: opens popups, tracks pending requests, handles timeouts
  messages.ts    — Protocol message format: request/response creation, validation
  types.ts       — All TypeScript interfaces and type exports
  errors.ts      — Typed error classes with numeric codes (4001-4014)
  storage.ts     — localStorage persistence for connection state
  wallet.ts      — Wallet-side utilities (sendResponse, rejectRequest, parsePopupParams)
  transport.ts   — CWI transport layer (embed/redirect for BRC-100 operations)

Popup Communication Protocol

Request Flow

1. dApp calls a provider method (e.g. connect(), signMessage())
2. OneSatBrowserProvider.sendRequest() generates a requestId via crypto.randomUUID()
3. PopupManager.openPopup() builds a URL: {popupUrl}/connect?method=X&requestId=Y&origin=Z&params={...}
4. window.open() opens the popup; returns null if blocked → PopupBlockedError
5. A PendingRequest is stored with resolve/reject callbacks, timeout, and close-check interval
6. OneSatBrowserProvider.handleMessage() listens for window.postMessage from the popup origin
7. On match: resolves or rejects the pending request, cleans up timers

Response Flow (Wallet Side)

1. Popup page calls parsePopupParams(searchParams) to extract requestId, origin, appName, params
2. User approves → sendResponse(requestId, result, origin) which calls window.opener.postMessage()
3. User rejects → rejectRequest(requestId, origin) sends error code 4001
4. Popup closes via window.close()

Message Format

interface ProtocolMessage {
  type: 'onesat'
  version: 1
  requestId: string
  method?: string        // Present in requests
  params?: unknown       // Present in requests with params
  result?: unknown       // Present in success responses
  error?: {              // Present in error responses
    code: number
    message: string
    data?: unknown
  }
}

Adding New RPC Methods

To add a new wallet operation:

1. Define Types in types.ts

// Add request/result interfaces
export interface NewMethodRequest {
  someParam: string
}

export interface NewMethodResult {
  txid: string
}

// Add to RpcMethods object
export const RpcMethods = {
  // ... existing methods
  NEW_METHOD: 'newMethod',
} as const

2. Add Provider Method in provider.ts

async newMethod(request: NewMethodRequest): Promise<NewMethodResult> {
  this.requireConnection()  // Ensure connected first
  return this.sendRequest<NewMethodResult>(RpcMethods.NEW_METHOD, request)
}

3. Update Provider Interface in types.ts

export interface OneSatProvider {
  // ... existing methods
  newMethod(request: NewMethodRequest): Promise<NewMethodResult>
}

4. Export from index.ts

Add the new types to the type exports block.

5. Handle in Wallet Popup

In the 1sat-web repo, handle the new method in the appropriate popup page.

Error System

All errors extend OneSatError with a numeric code:

To add a new error:

1. Add code to ErrorCodes in errors.ts
2. Create error class extending OneSatError
3. Add case to fromErrorResponse() switch
4. Export from index.ts

ConnectParams Challenge Pattern

The connect() method accepts optional ConnectParams with a challenge string. When provided, the wallet popup signs the challenge with BSM during the same user interaction, returning the signature in ConnectResult.signedMessage. This avoids a second window.open() which browsers block.

Critical: This is the recommended pattern for any dApp that needs to verify wallet ownership after connecting. Without it, signMessage() requires a second popup that will be blocked in most browsers.

Build & Publish

# Build
bun run build   # Bundles to dist/ + generates .d.ts

# Publish (use npm-publish skill)
# Current version: check package.json
# npm registry: npm view @1sat/connect version

The build uses bun build for the JS bundle and tsc --emitDeclarationOnly for type declarations.

Key Design Decisions

• DEFAULT_POPUP_URL: https://www.1satwallet.com — must include www due to 307 redirect
• Timeout: 5 minutes (300,000ms) — wallet operations can take time
• Popup check interval: 500ms — checks if popup was closed
• Storage: localStorage for connection persistence across page loads
• CWI Transport: Separate from popup flow — used for BRC-100 operations via embed/redirect

Additional Resources

Reference Files

• references/protocol-spec.md — Detailed protocol message specification
• Root README.md — SDK overview and quick start
• packages/extension/README.md — Browser extension development guide

Related Repos

• 1sat-web (~/code/1sat-web) — Wallet popup pages that handle SDK requests
• sigma-auth (~/code/sigma-auth) — Reference consumer using challenge signing