Add disputes.rs collusion detector flagging stake co-movement across disputers

[greatest0fallt1me]

Description

Coordinated disputers who file with nearly equal stakes at nearly the same ledger are likely colluding. Add a lightweight heuristic in disputes.rs that flags such patterns (configurable stake-delta and time-delta thresholds) and emits a SuspectedCollusionFlag event for off-chain review, without auto-slashing.

Requirements and Context

• Rolling window of recent disputes per market
• Pairwise comparison bounded to last K entries (default K=8)
• No automatic punitive action — flag only
• Must be secure, tested, and documented
• Should be efficient and easy to review

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/dispute-collusion-detector

2. Implement changes
   • contracts/predictify-hybrid/src/disputes.rs
   • contracts/predictify-hybrid/src/tests/dispute_collusion_tests.rs
3. Test and commit
   • cargo test -p predictify-hybrid collusion_detector
   • Cover edge cases
   • Include test output and notes in the PR

Example commit message

feat: flag suspected collusion via stake co-movement heuristic

Acceptance Criteria

• Threshold-driven flag fires on co-movement
• No state changes beyond emitting the flag event
• Test exercises both flag-fires and flag-suppressed cases

Guidelines

• No unwrap() in production paths
• Clear documentation and inline comments
• Timeframe: 96 hours

[GBOYEE]

Hey! I can work on this. I will add a collusion detector to disputes.rs that flags when staking addresses show co-moving behavior across dispute filings. Clean PR incoming shortly.

[laxjovial]

@laxjovial has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I’d love to contribute to this. Please kindly assign

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

[drips-wave]

Congratulations, @laxjovial! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @laxjovial: 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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