Bump persistent storage TTL for active escrow contracts to prevent eviction

[mikewheeleer]

Description

Active escrows are written via env.storage().persistent().set(&DataKey::Contract(id), ...) but lib.rs never calls extend_ttl on persistent entries, while ttl.rs only handles temporary storage. Long-running contracts risk persistent-entry eviction (and fund-state loss) on Soroban. Add explicit TTL extension on contract reads/writes.

Requirements and context

• Scoped to TalentTrust escrow Soroban contract (contracts/escrow).
• On each mutating access to DataKey::Contract(id) (and related milestone keys), call extend_ttl with a deterministic bump threshold/extend-to policy documented in ttl.rs.
• Ensure the policy covers DataKey::MilestoneReleased, DataKey::Reputation, and DataKey::AccumulatedProtocolFees.
• Invariant: any contract touched within its TTL window remains live; eviction cannot strand active escrow accounting.
• Must be secure, tested, and documented.

Suggested execution

• Fork the repo and create a branch:
  • git checkout -b security/persistent-ttl-bump
• Implement changes:
  • contracts/escrow/src/ttl.rs
  • Tests: contracts/escrow/src/test/persistence.rs
  • Docs: docs/escrow/storage-ttl.md
  • Include rustdoc/NatSpec-style doc comments on public functions
  • Validate security assumptions (auth, overflow, fail-closed state machine, storage TTL, fee accounting)

Test and commit

• Run tests: cargo test
• Cover edge cases (unauthorized callers, double release/refund, expired approvals, fee rounding, paused state)
• Include test output and security notes in the PR

Example commit message

feat(escrow): bump persistent TTL on active contracts

Guidelines

• Minimum 95% test coverage on new/changed code
• Clear documentation
• Timeframe: 96 hours from assignment

[Harbduls]

@Harbduls has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Please allow me to fix this
I am a smart contracts developer
I can fix this

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

[drips-wave]

Congratulations, @Harbduls! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Harbduls: 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

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊