[SDK] buildUnwrapCalldata + UnwrapERC7984 explain/verify

[0xPrabh]

Description

Adds buildUnwrapCalldata(from, to, encryptedAmount, inputProof) and UnwrapERC7984 transaction support for the ERC-7984 unshield path.

• Encodes unwrap(address,address,bytes32,bytes) with selector 0x5bf4ef06
• Validates checksummed from/to, 32-byte encryptedAmount, non-empty inputProof
• Adds TransactionType.UnwrapERC7984 with builder + classifyTransaction mapping
• Erc7984Token.verifyTransaction unwrap branch (direct + sendMultiSig); self-directed from == to == baseAddress
• Does not set gasLimit (WP owns gas)

Issue Number

CHALO-1155

Parent: CHALO-1135

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• yarn workspace @bitgo/abstract-eth unit-test --grep "buildUnwrapCalldata|Method IDs" (13 passing)
• BITGOJS_TEST_PASSWORD=password yarn workspace @bitgo/sdk-coin-eth unit-test --grep "UnwrapERC7984|verifyTransaction – Unwrap" (12 passing)
• eslint on touched files

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My commits follow Conventional Commits and I have properly described any BREAKING CHANGES
• The ticket or github issue was included in the commit message as a reference
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Made with Cursor

[linear-code]

CHALO-1155

[Venkat-Annavazzala]

@claude

[github-actions]

Claude finished @Venkat-Annavazzala's task —— View job

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Code Review for ERC-7984 Unwrap Implementation ✅

Todo List:

• Read repository guidelines (CLAUDE.md)
• Review core implementation in abstract-eth
• Review ERC-7984 token integration in sdk-coin-eth
• Review test coverage and quality
• Check enum additions in sdk-core
• Provide comprehensive feedback

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Code Review Summary

This PR implements comprehensive ERC-7984 unwrap (unshield) functionality across the BitGoJS SDK. The implementation is well-structured, thoroughly tested, and follows established patterns.

✅ Strengths

1. Comprehensive Implementation

   • Properly integrates across all layers: abstract-eth, sdk-coin-eth, and sdk-core
   • Follows existing patterns from WrapERC7984 implementation
   • Maintains consistency with the codebase architecture

2. Robust Validation

   • Proper address validation with EIP-55 checksum support (modules/abstract-eth/src/lib/zamaUtils.ts:226-234)
   • Input validation for 32-byte encryptedAmount and non-empty inputProof (zamaUtils.ts:236-241)
   • Self-directed transaction validation (from == to == baseAddress) (modules/sdk-coin-eth/src/erc7984Token.ts:354-364)

3. Strong Security Checks

   • Validates wrapper contract address matches expected token contract (erc7984Token.ts:340-347)
   • Enforces zero-value transactions to prevent ETH loss (erc7984Token.ts:367-370)
   • Validates transaction structure for both TSS and multisig paths (erc7984Token.ts:323-347)

4. Excellent Test Coverage

   • 25+ unit tests across both abstract-eth and sdk-coin-eth modules
   • Tests round-trip encoding/decoding (modules/abstract-eth/test/unit/zamaUtils.ts:260-266)
   • Validates both TSS and multisig transaction shapes (modules/sdk-coin-eth/test/unit/erc7984Token.ts:1651-1675)
   • Comprehensive error handling tests for invalid inputs

5. Proper ABI Implementation

   • Correct method ID calculation: 0x5bf4ef06 for unwrap(address,address,bytes32,bytes) (zamaUtils.ts:64)
   • Proper ABI encoding/decoding with buffer handling (zamaUtils.ts:244-248)
   • Transaction classification support (modules/abstract-eth/src/lib/utils.ts:957)

🔍 Technical Details

• Function Signature: unwrap(address from, address to, bytes32 encryptedAmount, bytes inputProof)
• Transaction Types: Supports both direct calls (TSS) and sendMultiSig wrapped calls
• Validation: Self-directed only (Phase 1) - from == to == wallet.baseAddress
• Gas Handling: Correctly omits gasLimit setting as WP owns gas

📚 Code Quality

• Documentation: Comprehensive JSDoc comments explaining functionality and parameters
• Error Messages: Clear, descriptive error messages with context
• TypeScript: Proper interface definitions (UnwrapERC7984Data) and type safety
• Patterns: Follows established SDK patterns for transaction builders and verification

✅ Repository Compliance

• Follows BitGoJS conventional commit standards
• Adheres to TypeScript guidelines (no any types)
• Maintains modular architecture with appropriate abstractions
• Proper enum additions in sdk-core for TransactionType.UnwrapERC7984

Recommendation: APPROVE ✅

This is a high-quality implementation that demonstrates strong engineering practices. The code is production-ready with excellent test coverage, proper validation, and clear documentation. The implementation correctly follows the ERC-7984 standard and integrates seamlessly with the existing BitGoJS architecture.

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Job Run | Branch: CHALO-1155