Add "cancel booking" endpoint returning a refund preview and applying policy per booking type

[thlpkee20-wq]

Description

Add POST /bookings/:id/cancel returning the computed refund per the booking's cancellation policy, and requiring an explicit confirm=true to actually cancel and refund.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Relevant code: src/routes/bookings.ts, src/services/cancellationPolicy.ts

Suggested execution

• Fork the repo and create a branch
• git checkout -b feat/booking-cancel-with-preview
• Implement changes
  • Preview request (confirm=false) returns refund amount + fee breakdown
  • Confirm request (confirm=true) issues refund via existing payments client
  • Emit booking_cancelled_total{policy} metric
• Validate security and correctness assumptions

Test and commit

• Run tests
  • npm test
• Cover edge cases
  • policy = strict (no refund), booking already-completed, refund-fail path, replay of confirm request
• Include test output and notes

Example commit message

feat: cancel booking with refund preview

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[praizeD10]

@praizeD10 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello Maintainer, I'm a full-stack developer and I'm interested in taking this up. I've gone through the requirements and clearly understood it, kindly assign this issue to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @praizeD10 to this issue.

[Baskarayelu]

@Baskarayelu has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I’d love to be assigned this issue and contribute across the relevant areas, whether it involves smart contracts, UI development, backend logic, design implementation, or overall system integration. I’m comfortable working across the full stack and can adapt to the project’s technical requirements to ensure a smooth and consistent contribution.

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

[drips-wave]

Congratulations, @praizeD10! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @praizeD10: 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 🌊

[thlpkee20-wq]

Assigned to @praizeD10 based on their Drips Wave application. This assignment was checked against the limit of 4 active assigned issues without a linked PR across the Chronopay-Org organization. Please open a PR referencing this issue when ready.