Add refund mechanism for canceled events

[manoahLinks]

Description

The event_manager has a cancel_event function that sets is_canceled = true, but there is no refund logic. Attendees who purchased tickets for a canceled event have no way to get their funds back.

Expected Behavior

When an event is canceled:

1. Ticket holders should be able to claim refunds
2. Or the organizer should be able to batch-refund all ticket holders
3. The refund amount should match the ticket_price paid

Implementation Options

• Pull model: Add claim_refund(event_id) — attendee calls to get refund
• Push model: Organizer calls process_refunds(event_id) to refund all holders
• Track payment token address per event to refund in the correct token

Files

• soroban-contract/contracts/event_manager/src/lib.rs

Acceptance Criteria

• Refund function implemented (pull or push model)
• Only works for canceled events
• Prevents double-refund claims
• Tests for refund flow

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[Stephan-Thomas]

@Stephan-Thomas has applied to work on this issue as part of the Stellar Wave Program's 2nd wave.

hi, can i work on this?

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[dinahmaccodes]

@dinahmaccodes has applied to work on this issue as part of the Stellar Wave Program's 2nd wave.

GM!
My name is Dinah and I am a smart contract dev. I am used to working with events. Can i be assigned this issue?

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Congratulations, @dinahmaccodes! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on February 26, 2026.

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[bakarezainab]

@bakarezainab has applied to work on this issue as part of the Stellar Wave Program's 2nd wave.

Hi. I'm a web3 full stack developer. Kindly assign this issue to me

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[Otaiki1]

@Otaiki1 has applied to work on this issue as part of the Stellar Wave Program's 2nd wave.

I would like to work on this I am super eager and fast to drop a PR as soon as possible

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Congratulations, @Otaiki1! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on February 26, 2026.

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