Backend - Marketplace listing creation enforce seller ownership and prevent duplicate listing

[1nonlypiece]

Description

Ensure POST /api/marketplace/listings verifies seller owns the commitment, blocks double-listing, and returns correct 403/409 errors.

Requirements and context

• Must be secure, tested, and documented

Suggested execution

• Add ownership check via contracts service
• Add uniqueness constraint in storage/service
• Normalize errors into canonical contract

Test and commit

• Add tests for forbidden and conflict cases

Example commit message

feat: enforce ownership and uniqueness on marketplace listing creation

Guidelines

• Minimum 95 percent test coverage
• Timeframe: 96 hours

[Kenlachy]

@Kenlachy has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I have experience implementing authorization logic in backend systems, ensuring that actions like creation or modification are tied to verified ownership or permissions. I understand how to validate that the authenticated user matches the asset owner before allowing listing creation.

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

[samuelgodsgift]

@samuelgodsgift has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I have 5+ years of experience in this field. I would love to handle this task! Kindly assign

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

[drips-wave]

Congratulations, @samuelgodsgift! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @samuelgodsgift: 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.

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