Add webhook retry delay helper with exponential backoff and structured error logging on exhaustion

[Chucks1093]

Summary

Webhook retries compute their delay inline and emit no structured log when all attempts are exhausted. A shared delay helper and a dedicated exhaustion log together make the retry system both consistent and observable.

Scope

• Add computeRetryDelay(attempt: number, baseMs: number, maxMs: number): number — delay doubles per attempt up to maxMs, plus random jitter up to 20% of the computed delay; add unit tests for attempt 0, 1, 2, and maxMs capping
• Emit a structured error log on retry exhaustion with fields: webhook_id, creator_id, event_type, total_attempts, last_error_code, flagged_at; callback URL must be absent from the log
• The exhaustion log emits once per exhaustion event — not on each individual retry failure
• Replace all inline delay calculations with the new helper

Acceptance Criteria

• Helper doubles delay per attempt and caps at maxMs
• Jitter within 20% applied correctly
• Unit tests pass for attempt 0, 1, 2, and cap scenario
• Exhaustion log emitted exactly once with all six fields
• Callback URL absent from exhaustion log
• Inline delay calculations removed

ETA: 12 hours

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Coordinate on Telegram

[charlesedeh021-cell]

Hi maintainers!
I’d love to help out with this issue. I’ve checked the current codebase/documentation and know exactly what needs to be updated to make this clearer. I will ensure everything aligns perfectly with your existing contribution guidelines.

[nomsoscript]

Hi maintainers!
I’d love to help out with this issue. I’ve checked the current codebase/documentation and know exactly what needs to be updated to make this clearer. I will ensure everything aligns perfectly with your existing contribution guidelines.

[sebas11042]

Hi, I’d like to work on this issue.

I would extract the retry timing into a shared computeRetryDelay helper with exponential backoff, max-delay capping, and bounded jitter, then replace the existing inline calculations. I would also add a single structured exhaustion log containing the required fields while ensuring sensitive callback URLs are never included, with focused tests for delay behavior, jitter bounds, capping, and exactly-once logging.

Thanks!

[wheval]

Hello i would love to work on this.

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #597)
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