[BE-029] Design auto-sweep scheduler background worker

[ONEONUORA]

Description

Implement a recurring task that automatically sweeps idle available stablecoins into the yield vault.

Files to Edit/Create

• backend/src/services/sweep_worker.rs (new file)

Acceptance Criteria

• Loop periodically checking users with auto-earn enabled.
• Identify idle balances and transfer to earning contracts.

Guidance / Hints

Use tokio-cron-scheduler or simple loop with select/sleep.

[aliyuHabibu]

@aliyuHabibu has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, I'm a software engineer. I have gone through the issue and I can resolve it, assign it to me. Thank you

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

[ositaemmanuel653-netizen]

@ositaemmanuel653-netizen has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello maintainers I'm a full stack developer with experience in building scalable systems I can handle this perfectly if assigned.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @ositaemmanuel653-netizen to this issue.

[legend-esc]

@legend-esc has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Please assign me I can work on this

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

[josephchimebuka]

@josephchimebuka has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi GM, I have reviewed this issue and taken the time to understand the requirements, current implementation, and the expected outcome. Based on my analysis, I believe this is something I can successfully handle and contribute to... Kindly assign

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

[drips-wave]

Congratulations, @josephchimebuka! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @josephchimebuka: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊

[josephchimebuka]

Implemented in #426 — will close this issue when merged.

[drips-wave]

This issue has been completed by @josephchimebuka as part of the Stellar Wave Program's 6th Wave 🥳

😎 @josephchimebuka: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.