feat: Implement Soroban State Archive Compression & Merkle Accumulator Proof Verification Engine

[Mosas2000]

Area

Soroban contracts / Backend API

What problem does this solve?

As state commitments grow across multiple bridge operators and Soroban contracts, storing and querying historical Merkle roots for reserve backing proofs causes ledger footprint inflation and RPC query slowdowns. Currently, verifying historical Merkle proofs requires iterating over uncompressed leaf hashes in TimescaleDB or on-chain storage.

Proposed solution

1. Develop an on-chain compact Merkle Mountain Range (MMR) accumulator contract in Soroban (contracts/soroban/mmr_accumulator).
2. Implement MMR leaf insertion, peak aggregation, and append-only state compression algorithms.
3. Build a backend service mmrAccumulator.service.ts to compute append-only proof peaks from historical reserve commitments.
4. Expose verification endpoints (POST /api/v1/reconciliation/verify-mmr-proof) and Soroban contract method verify_mmr_proof to validate inclusion with logarithmic space complexity ($O(\log N)$).
5. Write integration test suites verifying proof generation and Soroban contract validation across multi-thousand leaf trees.

Alternatives considered

Keeping flat Merkle tree leaves stored on-chain, but MMR accumulators drastically reduce ledger storage footprint and provide verifiable historical state proofs.

[TS-mfon]

GM

i'm a blockchain developer

please can i work on this issue

[unlimitedengineer]

I'd like to work on this issue. I have experience with Soroban smart contracts, backend services, and blockchain data structures, and I can implement the MMR accumulator, integrate the backend verification flow, add comprehensive tests, and ensure the solution is efficient, secure, and aligned with the project's architecture.

[akinboyewaSamson]

Hello maintainer I’d love to help out with this issue.

[grantfox-oss]

🦊 GrantFox — @unlimitedengineer has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #1002)
2. Your PR will be reviewed by the StellaBridge maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@unlimitedengineer's PR #1004 was approved and merged by @Mosas2000.

🏆 @unlimitedengineer: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (293 total points). Track your full progress on GrantFox.

👏 Great work, @unlimitedengineer! Keep contributing to StellaBridge.