feat(sdk-core): add EddsaMPCv2Utils.createKeychainsWithExternalSigner

[bitgo-ai-agent-dev]

What

• Add EddsaMPCv2Utils.createKeychainsWithExternalSigner to modules/sdk-core/src/bitgo/utils/tss/eddsa/eddsaMPCv2.ts
• The method orchestrates EdDSA MPCv2 DKG via callbacks (initialize → round1 → WP round1 → round2 → WP round2 → finalize) and registers the resulting user, backup, and BitGo keychains with isMPCv2: true
• Add 7 unit tests covering callback invocation order, argument threading, keychain registration, and error paths (mismatched keychain, session-ID mismatch, missing BitGo GPG key)

Why

• Part of the EdDSA MPCv2 external-signer key generation flow (WCI-888). The external signer pattern allows AWS Managed Wallets to own all WASM/GPG/DKG logic via offline callbacks while the SDK orchestrates the WP round-trips — matching the already-shipped ECDSA MPCv2 equivalent (EcdsaMPCv2Utils.createKeychainsWithExternalSigner)
• This orchestrator is the binding layer that connects the EddsaMPCv2KeyGenCallbacks type definitions (WCI-894, base branch) to actual WP API calls, enabling ME to supply a callback factory (WCI-895) and BitGoJS to route wallet generation through it (WCI-917)

Implementation notes

• Uses eddsaMpcv2PublicKey (the Ed25519 GPG key) not mpcv2PublicKey (the secp256k1 key) — using the wrong key causes a WASM "Invalid Input" error in the DKG WASM
• WP round-2 response field is commonPublicKeychain (not commonKeychain) — matches the existing createKeychains usage at line 137
• Messages are MPSTypes.MPSSignedMessage passed directly — no formatBitgoBroadcastMessage / formatP2PMessage wrapping (EdDSA MPS uses GPG detached signatures, not DKLs auth-enc)
• Asserts that commonKeychain from finalizeCallback matches commonPublicKeychain from WP before registering keychains

Test plan

• Unit tests pass: nix develop /workspace/BitGoJS --command bash -c "cd /workspace/BitGoJS/modules/sdk-core && ../../node_modules/.bin/mocha --require tsx --timeout 20000 test/unit/bitgo/utils/tss/eddsa/eddsaMPCv2.ts --grep 'createKeychainsWithExternalSigner'" → 7 passing
• Full eddsaMPCv2 test suite: 55 passing
• TypeScript type check: no errors (tsc --noEmit)

Ticket: WCI-916

[linear-code]

WCI-916

[Marzooqa]

@claude

[github-actions]

Claude finished @Marzooqa's task —— View job

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Code Review Analysis

Since no specific instructions were provided, I'll conduct a comprehensive code review of the PR changes.

Todo List:

• Read repository guidelines (CLAUDE.md)
• Review implementation changes in eddsaMPCv2.ts
• Review test changes in eddsaMPCv2.ts test file
• Analyze code quality and security
• Provide comprehensive feedback

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Summary

This PR adds EddsaMPCv2Utils.createKeychainsWithExternalSigner method with comprehensive test coverage. The implementation follows the existing ECDSA MPCv2 pattern and enables external signers to manage EdDSA MPCv2 key generation through callbacks.

Code Review Findings

✅ Strengths

1. Excellent Documentation: Implementation notes in PR clearly explain key design decisions (Ed25519 vs secp256k1 keys, field naming conventions)

2. Comprehensive Test Coverage: 7 new unit tests covering happy path, error cases, and edge conditions:

   • Callback invocation order and argument threading
   • Keychain registration with isMPCv2: true
   • Session ID mismatch detection
   • Missing BitGo GPG key handling
   • Common keychain validation

3. Security Best Practices:

   • Proper assertion of GPG key availability before use
   • Session ID validation between rounds
   • Common keychain validation in finalize step
   • Correct use of Ed25519 GPG keys (not secp256k1)

4. Consistent Architecture: Mirrors existing EcdsaMPCv2Utils.createKeychainsWithExternalSigner pattern

🔍 Areas for Consideration

Critical Issues: None found

Minor Suggestions:

1. Line 280: Consider using assert.strictEqual() instead of assert.equal() for session ID comparison to match the test pattern (line 289 uses strictEqual)

2. Error Handling: The method propagates errors from callbacks naturally, but consider if more specific error messages would help with debugging callback implementation issues

3. Type Safety: Good use of NonEmptyString.is() validation for GPG public keys

🧪 Test Quality Assessment

Excellent test coverage with realistic scenarios:

• Integration-style tests: Tests use real MPS WASM operations and GPG operations
• Callback verification: Tests verify exact arguments passed to each callback
• Error path coverage: Comprehensive error scenarios including mismatched keychains and missing GPG keys
• State validation: Tests verify keychain registration parameters and isMPCv2 flags

Test patterns follow established conventions from existing EdDSA MPCv2 tests.

🔒 Security Analysis

No security issues identified:

• Proper GPG key validation before operations
• Session ID integrity checks prevent round confusion
• Common keychain validation prevents registration of mismatched keys
• Uses Ed25519 GPG keys correctly (avoiding secp256k1 WASM errors)

📋 Code Quality

High quality implementation:

• Clear variable naming and code structure
• Appropriate error messages with context
• Consistent with existing codebase patterns
• Good separation of concerns (orchestration vs callback logic)

Recommendation

✅ APPROVE - This is a well-implemented feature that:

• Follows established patterns and conventions
• Has comprehensive test coverage
• Implements proper security validations
• Is well-documented and maintainable

The minor suggestions above are optional improvements and don't block approval.

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Job run | Branch: wci-916-add-eddsampcv2utils-createkeychainswithexternalsigner