Build invoice referral system

[Kingsman-99]

Label: complexity: high
Points: 200

Description

Ecosystem growth depends on creators bringing other creators. This issue adds an optional referrer: Option<Address> field to create_invoice() stored on-chain, and a get_referral_count() view function counting how many invoices a given address has referred — enabling off-chain referral reward programs.

Technical Context

Involves types.rs (add referrer: Option<Address>) and lib.rs. After saving the invoice, if referrer is Some, increment persistent key ("ref_count", referrer) by 1. Add get_referral_count(env, referrer: Address) -> u64 returning stored count or 0.

Acceptance Criteria

• create_invoice() accepts optional referrer address
• Referral count incremented for referrer on each invoice creation
• get_referral_count() returns correct count for address with multiple referrals
• Returns 0 for address with no referrals
• referrer = None produces identical behaviour to current implementation
• All existing cargo tests pass
• cargo clippy passes with zero warnings

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[supreme2580]

@supreme2580 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi can I be assigned to this issue?

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[Georgebingi]

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Hi I'm a full stack developer I'll like to work on this issue because It picks my interest and Ive got experience with similar projects I'll have it solved in 24 hours or less

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[deslawson]

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I can handle this issue

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[playmaker410]

@playmaker410 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi Maintainer
I’d love to take this on. I have hands-on experience with Rust, Soroban, Cairo, and TypeScript, and I’m confident I can deliver a solid solution within 24 hours.

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[sonoflawal]

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i would like to work on this issue

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[drips-wave]

Congratulations, @sonoflawal! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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[drips-wave]

This issue has been completed by @sonoflawal as part of the Stellar Wave Program's 5th Wave 🥳

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