Class BSV::Wallet::FeeEstimator ¶

Inherits: Object

Estimates transaction fees before a {BSV::Transaction::Transaction} object exists.

Wraps {BSV::Transaction::FeeModels::SatoshisPerKilobyte} to provide pre-construction fee estimation given only input and output counts. Once a real {Transaction} is available, delegates directly to the underlying SDK fee model via {#estimate_for_tx}.

The default rate is 100 sat/kB, matching the ARC mining policy endpoint and the SDK's own {SatoshisPerKilobyte} default.

@example Pre-construction estimate

estimator = BSV::Wallet::FeeEstimator.new
fee = estimator.estimate(p2pkh_inputs: 2, p2pkh_outputs: 3)
# => 41 (at 100 sat/kB, ceil(408/1000 * 100) = 41)

@example Custom rate

estimator = BSV::Wallet::FeeEstimator.new(sats_per_kb: 50)
fee = estimator.estimate(p2pkh_inputs: 1, p2pkh_outputs: 1)
# => 10 (ceil(192/1000 * 50) = 10)

Constants¶

DEFAULT_SATS_PER_KB ¶

Default fee rate in satoshis per kilobyte, matching ARC's mining policy endpoint (/v1/policy → miningFee 100/1000).

EF_INPUT_OVERHEAD ¶

Extended Format (BRC-30/EF) adds source_satoshis (8 bytes) + varint(25) (1 byte) + P2PKH locking script (25 bytes) = 34 bytes per input. ARC validates fees against the EF size, not raw.

EF_VERSION_OVERHEAD ¶

EF version marker: 6 bytes (x00x00x00x00x00xEF) follows the 4-byte version field, adding 6 bytes of fixed overhead.

FIXED_OVERHEAD ¶

Fixed overhead in bytes for version (4) + EF marker (6) + lock_time (4).

OVERHEAD ¶

Approximate overhead including typical 1-byte varints for input/output counts. Retained for backward compatibility with code that referenced FeeModel::OVERHEAD.

P2PKH_INPUT_SIZE ¶

Total estimated input size including EF overhead. This is the size ARC sees and charges fees against.

P2PKH_OUTPUT_SIZE ¶

Estimated size in bytes of a P2PKH output (8 satoshis + varint(25) + 25-byte script).

P2PKH_RAW_INPUT_SIZE ¶

Estimated size in bytes of an unsigned P2PKH input in raw format.

Attributes¶

sats_per_kb [R] ¶

• @return [Integer] the satoshis-per-kilobyte rate used for estimation

Public Instance Methods¶

dust_floor() ¶

Minimum viable change output value at the configured rate.

An output is economically viable only if its value exceeds twice the cost of spending it. The cost to spend a single P2PKH input is estimated as the fee for a minimal 1-input / 1-output transaction. - @return [Integer] minimum satoshis for a change output to be worth creating

estimate(p2pkh_inputs:, p2pkh_outputs:, extra_bytes: = 0) ¶

Estimate the fee for a transaction described by input and output counts.

Computes the serialised byte size using standard P2PKH sizes and correct Bitcoin varint encoding for the input/output count fields, then applies the configured sat/kB rate. Returns at least 1 satoshi. - @param p2pkh_inputs [Integer] number of P2PKH inputs - @param p2pkh_outputs [Integer] number of P2PKH outputs - @param extra_bytes [Integer] additional bytes to include (e.g. OP_RETURN data) - @return [Integer] estimated fee in satoshis (minimum 1)

estimate_for_tx(tx) ¶

Compute the fee for a fully-constructed transaction.

Delegates to the underlying {BSV::Transaction::FeeModels::SatoshisPerKilobyte} model, which uses {BSV::Transaction::Transaction#estimated_size} internally. - @param tx [BSV::Transaction::Transaction] the transaction to compute the fee for - @return [Integer] fee in satoshis

initialize(sats_per_kb: = DEFAULT_SATS_PER_KB) ¶

• @param sats_per_kb [Integer] fee rate in satoshis per kilobyte
• @raise [ArgumentError] if sats_per_kb is zero or negative
• @return [FeeEstimator] a new instance of FeeEstimator