Implement Soroban Event Backfill Service

[mijinummi]

🧠 Concept

Backfill missed Soroban events after indexer downtime.

⚠️ Problem

Temporary RPC or service failures can leave gaps in indexed bridge events.

📁 Implementation Scope

• src/indexer/soroban/backfill/
• src/indexer/recovery/
• tests/indexer/soroban/backfill/

✅ Requirements

• Detect indexing gaps
• Determine missing ledger ranges
• Fetch historical events
• Deduplicate recovered events
• Update indexing cursors

🎯 Acceptance Criteria

• Event backfill service implemented
• Missing ranges detected
• Historical events recovered
• Duplicate events prevented
• Cursor state updated correctly

[Venrable18]

@Venrable18 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Good day maintainer..

I’m a full-stack and test integration developer…. 

Please assign this task to me…



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[ghg001]

@ghg001 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer! I’m interested in contributing to this task and can work toward delivering a clean solution on time.

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[DevZee404]

@DevZee404 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

can i work on this

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Congratulations, @DevZee404! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Third Campaign campaign!

@DevZee404's PR #1072 was approved and merged by @mijinummi.

🏆 @DevZee404: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (602 total points). Track your full progress on GrantFox.

👏 Great work, @DevZee404! Keep contributing to MDTechLabs.

[drips-wave]

This issue has been completed by @DevZee404 as part of the Stellar Wave Program's 8th Wave 🥳

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