Implement dispute-resolution flow for failed deductions on /api/billing/deduct

[greatest0fallt1me]

Description

This is a backend issue for the GrantFox campaign. Add /api/billing/disputes endpoints to open/resolve disputes referencing usage_event ids.

Requirements and Context

• Open dispute → state OPEN
• Resolve → REFUNDED/UPHELD
• Audit trail in dispute_events
• RBAC: developer can open, admin resolves
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/dispute-resolution

2. Implement changes
   • src/routes/billing/disputes.ts (new)
   • src/services/disputeService.ts (new)
   • prisma/schema.prisma
3. Test and commit
   • Run the repo's standard test suite and lint
   • Cover edge cases; include output in the PR

Example commit message

feat: add billing dispute resolution flow

Acceptance Criteria

• States transition correctly
• Audit trail written
• RBAC enforced
• Tests cover paths

Guidelines

• Minimum 90% test coverage on changed lines
• Input validation at the boundary; standardized error envelope
• Structured logging with correlation IDs
• Clear documentation and inline comments
• Timeframe: 96 hours

[Abba073]

@Abba073 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello Sir,

I came across your project and will love to have the opportunity to work on it

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Abba073 to this issue.

[drips-wave]

Congratulations, @Abba073! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Abba073: 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

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🌊 Happy Wave 🌊

[drips-wave]

This issue has been completed by @Abba073 as part of the Stellar Wave Program's 6th Wave 🥳

😎 @Abba073: You earned 100 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.

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