fix: handle dust change in max transfer to spending #748
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…spendableBalance to calculate the txFee
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ovitrif
requested changes
Feb 10, 2026
| val address = order.payment?.onchain?.address.orEmpty() | ||
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| // Calculate if change would be dust and we should use sendAll | ||
| val spendableBalance = |
Collaborator
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nit: can be extracted to a private method
Comment on lines
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| // Two-pass fee estimation to match actual order creation | ||
| // First pass: estimate with availableAmount to get approximate clientBalance | ||
| val values1 = blocktankRepo.calculateLiquidityOptions(availableAmount).getOrNull() | ||
| if (values1 == null) { | ||
| _spendingUiState.update { it.copy(isLoading = false) } | ||
| return@launch | ||
| } | ||
| val lspBalance1 = maxOf(values1.defaultLspBalanceSat, values1.minLspBalanceSat) | ||
| val feeEstimate1 = blocktankRepo.estimateOrderFee( | ||
| spendingBalanceSats = availableAmount, | ||
| receivingBalanceSats = _transferValues.value.maxLspBalance | ||
| receivingBalanceSats = lspBalance1, | ||
| ).getOrNull() | ||
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| if (feeEstimate1 == null) { | ||
| _spendingUiState.update { it.copy(isLoading = false) } | ||
| return@launch | ||
| } | ||
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| val lspFees1 = feeEstimate1.networkFeeSat.safe() + feeEstimate1.serviceFeeSat.safe() |
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nit: can also be extracted to a method
Comment on lines
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| val values2 = blocktankRepo.calculateLiquidityOptions(approxClientBalance).getOrNull() | ||
| if (values2 == null || values2.maxLspBalanceSat == 0uL) { | ||
| _spendingUiState.update { it.copy(isLoading = false, maxAllowedToSend = 0) } | ||
| return@launch | ||
| } | ||
| val lspBalance2 = maxOf(values2.defaultLspBalanceSat, values2.minLspBalanceSat) |
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values1/ values2 is not descriptive enough; makes reader have to actually read implementation to understand what it means
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Fixes #745
This PR fixes the "insufficient funds" error that occurs when transferring the maximum balance to spending.
Description
When users tried to transfer their full on-chain balance to Lightning (spending), they would sometimes encounter an "insufficient funds" error even though they had enough sats. This happened because:
Fee estimation mismatch - The LSP fee was estimated using
maxSendableamount, but order creation uses a differentclientBalancevalue. SincelspBalancedepends onclientBalanceSat, this caused off-by-few-sats discrepancies.Dust change handling - When the remaining change after the transfer would be below the dust limit (546 sats), the transaction would fail because Bitcoin nodes reject dust outputs.
Changes:
sendAllwhen remaining change would be below dust limitReference: iOS fix PR #416
Preview
Screen_recording_20260129_085609.webm
not-dust.webm
QA Notes
1. MAX transfer to spending
2. Near-dust change scenarios
sendAllis used (no dust output created)3. Regression - Partial transfers