[Contract] Guild Treasury Withdrawal Approval Delay (Timelock)

[gabito1451]

Independence Note: Implement using a simple flag and sequence check in a mock test.

Context:
Even after a withdrawal is authorized (via multi-sig or admin), it should have a 24-hour mandatory "Timelock" window during which it can be cancelled by other members, preventing 'stealth' drains.

Objective:
Enforce a time delay for large treasury withdrawals.

Acceptance Criteria:

• For any withdrawal over a certain threshold, set an earliest_execution_ledger sequence.
• In the final execute_withdrawal function, assert that current sequence > earliest sequence.
• Provide a cancel_withdrawal method allowed for the first 24 hours only.
• Write unit tests demonstrating that the withdrawal fails if called too early.

Technical Pointers:

• Timelocks are a fundamental security primitive in decentralized finance.

[Banx17]

@Banx17 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Good day Maintainer, Kindly assign this issue to me, thanks.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Banx17 to this issue.

[drips-wave]

Congratulations, @Banx17! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @Banx17: 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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[drips-wave]

This issue has been marked as completed by a Drips Wave moderator for @Banx17 as part of the Stellar Wave Program's 4th Wave 🥳

Moderator's reason: [Auto-assessed] The PR has been open for over 24 hours without maintainer objection and comprehensively addresses all acceptance criteria of the issue. The contributor implemented the 24-hour timelock logic, the cancellation mechanism within the permitted window, and provided thorough unit tests for all scenarios.

😎 @Banx17: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here.

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ℹ️ Note: This issue was marked complete via moderation. Points were issued even though the GitHub issue remains open.