feat: custom merkle proof

[sczembor]

Description

Closes: #46

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Summary by Sourcery

Replace merkletreejs with a custom BitcoinMerkleTree implementation and update the indexer and SuiClient to use it for Merkle proof generation and validation

New Features:

• Introduce BitcoinMerkleTree for constructing Bitcoin-style Merkle trees and generating proofs

Enhancements:

• Refactor Indexer to use BitcoinMerkleTree, include merkle root in proof data, and strengthen proof validation logic
• Update SuiClient proof encoding to use direct little-endian buffer arrays

Tests:

• Add unit tests for BitcoinMerkleTree root calculation and proof generation
• Revise indexer tests to assert proof path structure and root matching

[sourcery-ai]

Reviewer's Guide

This PR replaces the external merkletreejs dependency with a custom BitcoinMerkleTree implementation for constructing and verifying Bitcoin Merkle proofs, refactors the Indexer’s proof generation and validation logic to use the new tree, and updates the test suite accordingly.

Sequence diagram for Merkle proof generation with custom BitcoinMerkleTree

sequenceDiagram
    participant Indexer
    participant BitcoinMerkleTree
    participant Block
    participant Transaction
    Indexer->>Block: Get transactions
    Indexer->>BitcoinMerkleTree: constructMerkleTree(block)
    BitcoinMerkleTree->>Transaction: Get hashes
    BitcoinMerkleTree-->>Indexer: Return tree
    Indexer->>BitcoinMerkleTree: getTxProof(tree, targetTx)
    BitcoinMerkleTree-->>Indexer: Return proofPath
    Indexer->>Block: Compare calculated root with block.merkleRoot

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Class diagram for the new BitcoinMerkleTree and Indexer changes

classDiagram
    class BitcoinMerkleTree {
        -tree: MerkleNode[][]
        -root: Buffer
        +constructor(transactions: Transaction[])
        +getRoot(bigEndian: boolean): Buffer
        +getProof(targetTx: Transaction): Buffer[]
    }
    class MerkleNode {
        +hash: Buffer
        +preimage: Buffer
    }
    class Indexer {
        +constructMerkleTree(block: Block): BitcoinMerkleTree | null
        +getTxProof(tree: BitcoinMerkleTree, targetTx: Transaction): Buffer[] | null
    }
    BitcoinMerkleTree o-- MerkleNode
    Indexer --> BitcoinMerkleTree

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Class diagram for ProofResult structure update

classDiagram
    class ProofResult {
        +proofPath: Buffer[]
        +merkleRoot: string
    }

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File-Level Changes

Change	Details	Files
Add custom BitcoinMerkleTree class	Implemented tree building and proof generation from raw bitcoin-js transactions Double-SHA256 hashing logic handling odd sibling duplication API for getRoot (big/little endian) and getProof for a target transaction	btcindexer/src/bitcoin-merkle-tree.ts
Refactor Indexer to use BitcoinMerkleTree	constructMerkleTree returns BitcoinMerkleTree instead of merkletreejs getTxProof now returns Buffer[] and handles errors Soundness check compares block.merkleRoot with calculated root and logs detailed mismatch Storage payload adjusted to include proofPath and hex merkleRoot	btcindexer/src/btcindexer.ts
Update tests for the new Merkle proof flow	Replaced merkletreejs imports and SHA256 usage with custom tree and sha256 helper Refactored checkTxProof to verify proofPath array and merkleRoot only Removed extraneous console.log and test signature mismatches Added new unit tests in bitcoin-merkle-tree.test.ts for root and proof verification	btcindexer/src/btcindexer.test.ts btcindexer/src/bitcoin-merkle-tree.test.ts

Possibly linked issues

• #0: The PR introduces a custom Bitcoin Merkle tree and modifies the proof generation, directly matching the issue's need for updated proof construction logic due to new SPV logic.

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[sourcery-ai]

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[Copilot]

Pull Request Overview

This PR replaces the merkletreejs library with a custom BitcoinMerkleTree implementation to generate Bitcoin-style Merkle proofs and handle proof validation.

Key Changes:

• Implements custom BitcoinMerkleTree class for constructing Merkle trees and generating proofs
• Updates proof data structure to include merkle root alongside proof path
• Simplifies SuiClient proof encoding by removing unnecessary byte reversal operations

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/btcindexer/src/bitcoin-merkle-tree.ts	New custom implementation of Bitcoin Merkle tree with proof generation
packages/btcindexer/src/bitcoin-merkle-tree.test.ts	Unit tests for the new BitcoinMerkleTree implementation
packages/btcindexer/src/btcindexer.ts	Refactored to use BitcoinMerkleTree and updated proof validation logic
packages/btcindexer/src/btcindexer.test.ts	Updated test assertions to work with new proof structure
packages/btcindexer/src/sui_client.ts	Simplified proof encoding by removing buffer reversal
packages/btcindexer/src/sui_client.test.ts	Updated test to use new proof structure with merkle root

Comments suppressed due to low confidence (1)

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[robert-zaremba]

There are a few linter issues - see github comments in the PR (in files, not above)

[vuvoth]

lgtm!