[Backend] Wire cancel stream endpoint to Soroban contract

[ogazboiz]

https://t.me/+DOylgFv1jyJlNzM0

Description

The smart contract has a cancel_stream function but no POST /streams/:streamId/cancel route exists in the backend v1 routes. Without this endpoint the frontend cancel UI and any external tooling cannot trigger on-chain cancellation. This issue tracks creating the endpoint, calling sorobanService.cancelStream(), and syncing the DB record to CANCELLED status on success.

Acceptance Criteria

• POST /api/v1/streams/:streamId/cancel route exists and is registered
• Endpoint validates JWT/SIWX session and confirms the caller is the stream sender
• sorobanService.cancelStream(streamId, callerAddress) is invoked; txHash returned in response
• DB stream record status is updated to CANCELLED on successful transaction
• Returns 404 if stream not found, 403 if caller is not the sender, 409 if stream already cancelled/completed
• Covered by at least one integration test

Files to Touch

• app/api/routes/v1/streams/ — add cancel.ts route handler
• app/services/soroban.service.ts — expose cancelStream method if not present
• app/api/routes/v1/streams/index.ts — register the new route
• app/repositories/stream.repository.ts — updateStatus helper
• tests/integration/streams/cancel.test.ts — new test file

[girly-coder01]

@girly-coder01 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

As a full-stack blockchain developer, I have strong experience across both frontend and backend layers of Web3 applications.

I’m confident I can implement this properly and in line with the project’s standards. I’d be glad to own this task and submit a PR once we align on the approach.

Let me know your thoughts or if there are any specific requirements I should keep in mind.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @girly-coder01 to this issue.

[Sulex45]

@Sulex45 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hi please id love to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Sulex45 to this issue.

[Omoboi-dev]

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

I want to work on this issue

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

[drips-wave]

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

🧑‍💻 @Omoboi-dev: 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.

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