WIN-8498: Refactor FLRP Transaction Builders for Better Code Organization

[mohd-kashif]

WIN-8498: Refactor FLRP Transaction Builders for Better Code Organization

This PR refactors the FLRP transaction builders to consolidate common properties and methods into base classes, reducing code duplication and improving maintainability.

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🔄 Changes Overview

1. Consolidated Common Properties to Base Classes

Property	Moved From	Moved To	Storage Location
context()	All 4 builders	TransactionBuilder	transaction._context
feeState()	ExportInPTxBuilder, ImportInPTxBuilder	AtomicTransactionBuilder	transaction._feeState
amount()	ExportInPTxBuilder, ExportInCTxBuilder	AtomicTransactionBuilder	transaction._amount
utxos()	ExportInPTxBuilder, ImportInPTxBuilder	Already in TransactionBuilder	Removed duplicates

2. Added Validation for UTXO Balance

• ExportInPTxBuilder: Validates that totalUtxoAmount >= amount before building
• ImportInCTxBuilder: Validates that totalUtxoAmount > fee to ensure import can pay fees
• ImportInPTxBuilder: Validates that totalUtxoAmount > 0

3. Standardized Error Types

All validation errors now consistently use BuildTransactionError instead of generic Error.

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📁 Files Modified

File	Changes
transaction.ts	Added _feeState: FlrpFeeState and _amount: bigint public properties
atomicTransactionBuilder.ts	Added feeState() and amount() setter methods
ExportInPTxBuilder.ts	Removed duplicate _amount, _feeState, amount(), feeState(), utxos() - now uses base class
ExportInCTxBuilder.ts	Removed duplicate _amount, _context, amount(), context() - now uses base class; fixed utxos() method signature
ImportInPTxBuilder.ts	Removed duplicate _feeState, _context, feeState(), context(), utxos() - now uses base class
ImportInCTxBuilder.ts	Removed duplicate _context, context() - now uses base class; added UTXO balance validation

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✅ Benefits

1. Reduced Code Duplication: Common setters like context(), feeState(), and amount() are now in base classes
2. Consistent Validation: All builders use BuildTransactionError for validation failures
3. Better UTXO Validation: Added balance checks to prevent transactions that would fail on-chain
4. Easier Maintenance: Changes to common functionality only need to be made in one place

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🧪 Testing

All existing unit tests pass. The refactoring maintains backward compatibility - the public API remains unchanged.

[Copilot]

Pull request overview

This PR refactors the FLRP transaction builders to consolidate common properties (context, feeState, amount, utxos) into base classes, reducing code duplication. The refactoring also introduces standardized validation using BuildTransactionError and updates transaction building to use new FlareJS API methods (pvm.e.newImportTx, pvm.e.newExportTx, evm.newImportTx, evm.newExportTxFromBaseFee).

Key changes:

• Moved common setters to TransactionBuilder and AtomicTransactionBuilder base classes
• Changed UTXO handling from DecodedUtxoObj[] to hex string arrays with FlareJS native parsing
• Introduced Context and FlrpFeeState for dynamic fee calculation
• Updated all builders to use FlareJS helper methods instead of manual transaction construction

Reviewed changes

Copilot reviewed 26 out of 27 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
transaction.ts	Added _context, _feeState, _amount public properties; changed fee type to FlrpTransactionFee
transactionBuilder.ts	Moved context() setter and updated utxos() to accept hex strings; refactored validation
atomicTransactionBuilder.ts	Added feeState() and amount() setters; removed createInputOutput() method
ImportInPTxBuilder.ts	Refactored to use pvm.e.newImportTx; removed manual transaction construction
ImportInCTxBuilder.ts	Refactored to use evm.newImportTx; simplified fee calculation
ExportInPTxBuilder.ts	Refactored to use pvm.e.newExportTx; removed manual UTXO selection logic
ExportInCTxBuilder.ts	Refactored to use evm.newExportTxFromBaseFee; simplified construction
utils.ts	Added parseUtxoHex(), parseUtxoHexArray(), utxoToDecoded() for UTXO parsing
iface.ts	Added Context, FlrpTransactionFee, FeeConfig, ExportEVMOptions interfaces
networks.ts	Added flarePublicUrl property; changed txFee from 1261000 to 200000
package.json	Added @bitgo/public-types@5.59.0 dependency
Test files	Updated test data with new transaction formats, context, and feeState

Comments suppressed due to low confidence (1)

modules/sdk-coin-flrp/src/lib/utils.ts:231

• The parameter 'Output' has type 'any', but its name coincides with the imported type Output.

  mapOutputToEntry(network: FlareNetwork): (Output) => Entry {

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