WasmExample (Template)

This is a template WASM extension meant to be copied and modified. No Python code from the extension is executed. The host only exposes the explicit permissions you declare in config.json.

What You Change First

• Update config.json permissions to the APIs you need.
• Update kv_schema for the keys your extension will store.
• Replace the UI in templates/ and static/.
• Replace the WASM module in wasm/.

What It Cannot Do

• Access the filesystem.
• Access environment variables or LNbits settings (outside of the API for fetching settings).
• Make outbound network calls.
• Execute Python or shell commands.

Permissions (Summary)

• ext.db.read_write controls access to the extension KV store.
• api.METHOD:/path lets the extension call internal LNbits endpoints through the proxy (exact path match). Check /openapi.json or /docs for available endpoints.
• ext.payments.watch lets the extension register backend payment watchers.

Permissions are shown at enable time and must be explicitly approved.

Internal API Proxy

WASM extensions can call any internal LNbits endpoint by declaring the matching permission and using:

POST /{ext_id}/api/v1/proxy

Example:

{
  "method": "POST",
  "path": "/api/v1/payments",
  "body": {"out": false, "amount": 10, "memo": "Example"}
}

Build WASM

You can compile in any language that targets WASM. This template includes:

• wasm/module.wat (minimal WAT)
• wasm/rust-example/ (Rust)
• wasm/assemblyscript-example/ (AssemblyScript)

Each example folder includes build instructions.