fix: Webhook event payload truncation corrupts binary data

[dotunv]

Bug Description

The webhook event payload truncation logic cuts off binary data (such as serialized ScVal bytes) at a fixed character limit without considering UTF-8 or binary boundaries. This corrupts the payload, making it impossible to decode the truncated portion.

Expected Behavior

Truncation should respect binary/UTF-8 character boundaries and append a truncation marker indicating data was cut.

Actual Behavior

Binary payloads are cut at an arbitrary byte position, corrupting the remaining data and making JSON parsing of the truncated payload fail.

Steps to Reproduce

1. Send a webhook with a ScVal binary payload exceeding the truncation limit
2. Check the stored webhook event in the database
3. Attempt to parse the truncated payload — JSON parse error

Impact

Webhook events with large binary payloads are stored in an unusable state, preventing debugging and replay.

Labels

bug, backend, Maybe Rewarded, GrantFox OSS, Official Campaign

[fathiaoyinloye]

@fathiaoyinloye has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Can I work on this now?

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

[CRSabers]

@CRSabers has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi! I’d like to take this issue. I’ll fix the webhook payload truncation logic so it respects binary/UTF-8 boundaries and appends the expected truncation marker without producing undecodable payloads. I’ll add focused regression coverage for binary and boundary cases, run the affected tests, and keep the PR narrowly scoped. Thank you!

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

[0xDamian-dev]

@Damian146967 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello @dev, can you please assign this issue to me!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Damian146967 to this issue.

[drips-wave]

Congratulations, @fathiaoyinloye! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @fathiaoyinloye: 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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