Add `get_referral_stats` SDK method

[Levi-Ojukwu]

Description:

The contract tracks referral counts per referral code (at lib.rs:915-920). When a freelancer submits an invoice with a referral code, the count for that code is incremented. The SDK does not expose a method to query these counts.

The contract implementation:

pub fn get_referral_stats(env: Env, code: BytesN<32>) -> u64 {
    env.storage()
        .persistent()
        .get(&DataKey::ReferralCount(code))
        .unwrap_or(0)
}

The referral code is a BytesN<32> (32-byte hash). The SDK method should:

1. Accept a hex-encoded string referral code
2. Convert it to BytesN<32> for the contract call
3. Return the count as a number

Why it matters: Referral tracking is a growth mechanism. Affiliates and marketing teams need to query referral performance to optimize campaigns.

Acceptance Criteria:

• Create a function that accepts a hex string referral code
• Convert hex string to BytesN<32> using Stellar SDK utilities
• Call the contract's get_referral_stats view
• Return Promise<number>
• Add tests

Relevant Files: contracts/invoice_liquidity/src/lib.rs:915-920, sdk/src/index.ts

---

[Okorie2000-code]

Hi Maintainer,

I'd like to work on this issue. I have experience with SDK development and Stellar integrations, and I can submit a clean PR within 48 hours.

[therealjhay]

Hi maintainer, I’d like to work on this issue to expose the get_referral_stats view method in the TypeScript SDK. I will implement a new function in sdk/src/index.ts that accepts a hex-encoded string referral code, safely converts it into a Buffer or BytesN<32> array using standard Stellar SDK utilities, invokes the contract's on-chain view function, and returns the referral count as a parsed Promise<number> (handling u64 conversions gracefully). To round out the implementation, I will write comprehensive unit tests verifying successful hex parsing, handling of malformed hex strings, and proper contract call formatting to ensure marketing teams can reliably audit campaign performance. Given my experience building Web3 developer tools and working with Stellar types, I can have a clean, tested PR ready within 1 to 2 days—let me know if I can go ahead and get started!

[grantfox-oss]

🦊 GrantFox — @therealjhay 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 #412)
2. Your PR will be reviewed by the Invoice-Liquidity-Network 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!

@therealjhay's PR #451 was approved and merged by @Levi-Ojukwu.

🏆 @therealjhay: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (347 total points). Track your full progress on GrantFox.

👏 Great work, @therealjhay! Keep contributing to Invoice-Liquidity-Network.