24 lines
1.2 KiB
Markdown
24 lines
1.2 KiB
Markdown
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# 0017. Coin selection, fee and confirmation policy
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- **Status:** Accepted
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- **Area:** Wallet
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- **Recorded:** 2026-11-03 (retroactive: reconstructed from code, comments and changelog)
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## Context
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Fund safety depends on never spending immature or unverified coins and on producing standard, relayable transactions.
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## Decision
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`TransactionFactory` supports automatic or manual UTXO selection, a fixed fee rate in sat/vByte, send-all with the fee subtracted, change on the internal chain, and RBF enabled on every transaction. It rejects transactions above 100,000 vbytes. `UtxoSpendability.IsSpendable` is the single gate shared by coin selection and balance reporting: a coinbase output needs maturity + 1 confirmations (121 on mainnet), a regular output needs `MinConfirmations` (policy, not consensus), frozen UTXOs are excluded, and the Merkle proof must be verified (0008).
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## Consequences
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- Balances and coin selection cannot disagree.
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- Users may see "insufficient funds" despite a larger visible balance when part of it is immature or unverified.
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- RBF is set but fee bumping is not exposed in the UI (see `SECURITY.md`).
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## References
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- `src/Core/Wallet/TransactionFactory.cs`
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- `src/Core/Wallet/UtxoSpendability.cs`
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