Add cross-contract invariant coverage for allocation sum consistency

[Baskarayelu]

Description

Expand cross-contract invariant coverage ensuring split allocations remain consistent with downstream recorded amounts.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Validate aggregate sums and category matching across contracts

Suggested execution

• Fork the repo and create a branch
• git checkout -b test/integration-allocation-sum-invariants
• Implement changes
• Write contract: scripts/verify_cross_contract_invariants.py
• Write comprehensive tests: integration_tests/tests/multi_contract_integration.rs
• Add documentation: scripts/README_INVARIANT_TESTS.md
• Include NatSpec-style comments
• Validate security assumptions

Test and commit

• Run tests: python3 scripts/verify_cross_contract_invariants.py && cargo test -p integration_tests
• Cover edge cases
• Include test output and security notes

Example commit message

test: extend cross-contract invariant coverage for allocation consistency

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[drips-wave]

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[emperorsixpacks]

@emperorsixpacks has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I'm Andrew, a fullstack developer with extensive experience in building robust and efficient systems. I would love to contribute to this issue and provide a high-quality solution. I'm available to start immediately.

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[uche102]

@uche102 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

hi i would like to work on this

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[gidson5]

@gidson5 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I can work on thi issue. ETA 1day

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[Uche44]

@Uche44 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Hello.

I am a backend developer with python and I have a fair knowledge of rust. Let me handle this for you.

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[ANAVHEOBA]

@ANAVHEOBA has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I would like to work on this issue because I have experience with smart contract testing and cross-contract validation patterns. I understand the critical importance of ensuring allocation consistency across the remittance split system.

My approach:
• Study remittance_split contract to understand allocation distribution logic
• Implement verify_cross_contract_invariants.py to validate sum consistency across savings_goals, bill_payments, and insurance contracts
• Write comprehensive Rust integration tests in multi_contract_integration.rs covering normal flows, edge cases (zero allocations, rounding), and boundary conditions
• Document all invariants with security rationale in README_INVARIANT_TESTS.md

I'm familiar with Soroban SDK 21.0.0, Rust testing patterns, and can deliver within 96 hours with 95%+ test coverage.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @ANAVHEOBA to this issue.