Reject seals whose Drand round falls outside the commit window

[karagozemin]

Goal

Refuse a bid seal, both off-chain and in the round contract, when its Drand quicknet round is not the round the auction committed to open.

Why this is High

Sealing lives in @sub-rosa/tlock and the on-chain check lives in the Soroban drand module. A seal that opens too early or never opens breaks the sealed-bid assumption. Both sides must share one window rule.

Requirements

• Define the allowed reveal round as the round stored on the auction, not a caller-supplied value.
• Reject seals before commit in the tlock package and again inside the contract.
• Return stable errors for too-early, too-late, and malformed round numbers.
• Add vectors that use the quicknet chain parameters already in the repo.

Acceptance criteria

• A seal for a different Drand round cannot be committed.
• The contract and the TypeScript helper reject the same fixture set.
• Overflowing or zero round numbers fail before any escrow lock.
• Existing happy-path seal tests still pass.

Pointers

• packages/tlock/src/seal.ts
• packages/tlock/src/quicknet.ts
• packages/tlock/src/freshness.ts
• contracts/round/src/drand.rs
• services/drand-tools/src/quicknet.ts

Validation

• tlock package tests and pnpm contract:test

Drips

• Drips Complexity: High
• Expected Drips Points: 200
• Add this issue from the Drips maintainer dashboard and set complexity to High.
• Do not apply the Stellar Wave label on GitHub. That path defaults the issue to Trivial (100 points).

[Muyideen-js]

@Muyideen-js has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi, I can fix this

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

[CollinsKRO]

@CollinsKRO has applied to work on this issue as part of the Stellar Wave Program's 9th wave.

Hi Maintainer, I can fix this pls assign. ETA 5hrs

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

[drips-wave]

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

🧑‍💻 @CollinsKRO: 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.

Warning

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🌊 Happy Wave 🌊

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@CollinsKRO's PR #464 was approved and merged by @karagozemin.

🏆 @CollinsKRO: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (411 total points). Track your full progress on GrantFox.

👏 Great work, @CollinsKRO! Keep contributing to Sub-Rosa-Issue.