Funding wallet via LNURLp does not always increase balance

[ekzyis]

Hi, I am running breez-sdk-spark v0.2.1 and I noticed that sometimes, when I use the lightning address registered with the seed to fund the wallet, the balance does not increase, see video:

2025-09-29.22-13-47.mp4

bolt11: lnbc1u1p5d469qpp5qy80day0z5qley6dusrs4ea8mhfehzpetl93us2dcchcrnxynsvssp5rntevgxke2dm0ltt9s932y4ypf9wl85e0t8mdjcw36s8w65c8n2sxq9z0rgqnp4qvyndeaqzman7h898jxm98dzkm0mlrsx36s93smrur7h0azyyuxc5rzjq25carzepgd4vqsyn44jrk85ezrpju92xyrk9apw4cdjh6yrwt5jgqqqqrt49lmtcqqqqqqqqqqq86qq9qrzjqwghf7zxvfkxq5a6sr65g0gdkv768p83mhsnt0msszapamzx2qvuxqqqqrt49lmtcqqqqqqqqqqq86qq9qcqzpghp568tju29a20nhd5gr8z7sqf5umsecw5xxq8ahvanlqy5w0v9rzd8s9qyyssqh8pfun99tjdtz743mcpttp8qgt7zy5ezms9rwa6nva2euheekwey26fkqrk4ygm09axy7sgufj0eav53cv8hx2r2cjkqx9tyl9pvpusqdm57qd`

payment hash: 010ef6f48f1501fc934de4070ae7a7ddd39b88395fcb1e414dc62f81ccc49c19

preimage: b880aeb9b57e58ecaf5808936686f99cfbc101b4612770ca160c5a42706c824d

(As you can see, I also encountered a RuntimeError: unreachable error. I got this error for the first time since I used initLogging, so maybe related, maybe not.)

Here is the code I am running in this video. When I click 'next' in the first form, testSendPayment is called:

import init, { initLogging, defaultConfig, connect } from '@breeztech/breez-sdk-spark'

export const name = 'BREEZ_SPARK'

class SdkLogger {
  log = (l) => {
    console.log(`[${l.level}]: ${l.line}`)
  }
}

async function withSdk (mnemonic, cb) {
  await init()
  initLogging(new SdkLogger())

  const config = defaultConfig('mainnet')
  // this API key should be kept a secret on a best effort basis
  config.apiKey = process.env.NEXT_PUBLIC_BREEZ_SDK_API_KEY
  config.lnurlDomain = 'breez.tips'

  const sdk = await connect({
    config,
    seed: { type: 'mnemonic', mnemonic, passphrase: undefined },
    // the SDK will create a IndexedDB with this name to store data
    storageDir: 'breez-sdk-spark'
  })

  const info = await sdk.getInfo({})
  console.log(info)

  const result = await cb(sdk)

  sdk.disconnect()

  return result
}

export async function testSendPayment ({ mnemonic }, { signal }) {
  return await withSdk(
    mnemonic,
    async sdk => {
      const { paymentRequest: sparkAddress } = await sdk.receivePayment({
        // this will always return the same spark address for the same seed
        paymentMethod: { type: 'sparkAddress' }
      })

      const username = getUsername(sparkAddress)

      const available = await sdk.checkLightningAddressAvailable({ username })
      if (available) {
        await sdk.registerLightningAddress({ username, description: 'Running Spark SDK' })
      }

      return { username }
    }
  )
}


function getIdentityPublicKey (sparkAddress) {
  const decoded = bech32m.decode(sparkAddress)
  const pubkey = Buffer.from(bech32m.fromWords(decoded.words)).toString('hex').slice(4)
  return pubkey
}

function getUsername (sparkAddress) {
  const identityPublicKey = getIdentityPublicKey(sparkAddress)
  // max lnurl username length is 64 characters
  // https://github.com/breez/spark-sdk/blob/71b8cb097d2bc846be427599b1bf44eae897786f/crates/breez-sdk/lnurl/src/routes.rs#L326
  return identityPublicKey.slice(0, 64)
}

The code can also be found here: stackernews/stacker.news#2575 (wallets/client/protocols/breezSpark.js)

See video for logs.

[ekzyis]

There is also a bug with sendPayment I want to report where it throws this:

The first argument must be one of type string, Buffer, ArrayBuffer, Array, or Array-like Object. Received type object

but successfully pays a bolt11 invoice.

However, because of this bug where my balance does not increase, I can currently not reproduce it since I need a balance before I can pay a bolt11 invoice.

[JssDWt]

@ekzyis Can you try waiting sleeping a little bit in your app? I think it may not have enough time to synchronize. Generally waiting for the Synced event should give you a good balance.

If that doesn't fix the issue, please provide logs using https://sdk-doc-spark.breez.technology/guide/logging.html

[roeierez]

Thanks @ekzyis for the report.
initLogging should only be called once in the program lifetime (it is static) that's why you get the error.
As for the balance. I see that you are using the sdk in short intervals (connection, do the payment, then disconnect).
It is better to let the sdk run in the background so it can sync in realtime. If you can't do that then waiting for the initial "sync" event and then fetching the balance will work.
We can probably provide a better UX in the future by allowing the user pass a flag to the getInfo function signaling that internally we should wait for the initial sync.

[JssDWt]

@ekzyis Did you have a chance to test out waiting for the synced event yet? Note that in version 0.2.5-dev2 you can pass ensureSynced: true to getInfo to make sure the balance is there.

[ekzyis]

initLogging should only be called once in the program lifetime (it is static) that's why you get the error.

I only added it for debugging, I was originally not calling it when I encountered the perceived bug. I think I will also not call it in production.

If you can't do that then waiting for the initial "sync" event and then fetching the balance will work.

I just tried that out in stackernews/stacker.news@e0ea694 and this seems to indeed have fixed the issue, thanks! Will close this issue.

Note that in version 0.2.5-dev2 you can pass ensureSynced: true to getInfo to make sure the balance is there.

Ahh, that's nice, thanks! But since I'm always connecting and disconnecting and I'm not necessarily interested in the balance, I'm now waiting for the synced event myself now before I call any function.