fix(creditline): propagate reputation contract call failures to enforce atomic state-reputation invariant

[sublime247]

Summary of Changes

Closes #86

Problem

In contracts/creditline-contract/src/lib.rs, cross-contract calls to the reputation contract in mark_defaulted() (decrease_score) and handle_reputation_increase() (increase_score) used fire-and-forget let _ = env.try_invoke_contract(...) statements. If the reputation contract reverted (e.g. revoked updater status, TTL expiry, or WASM mismatch), the loan would default or settle while the reputation score mutation silently failed, creating state-reputation divergence.

Policy Decision: Option (a) — Propagate Failure

Chosen policy: Option (a) — Propagate failure to enforce atomic loan state and reputation score consistency.

• Matching the error handling pattern in vouching-contract (add_reputation_boost), both invocation and execution results of try_invoke_contract are strictly checked.
• If a reputation contract call fails when configured (Some(reputation_contract)), the contract emits a ScoreUpdateFailed event and panics with panic_with_error!(&env, CreditLineError::ReputationCallFailed).
• This reverts the surrounding transaction, guaranteeing that loan status (Defaulted/Paid) and borrower reputation scores can never diverge.
• If no reputation contract is configured (None), score updates are intentionally skipped with documented rationale, as the protocol is operating without on-chain reputation integration.

Implementation Details

• contracts/creditline-contract/src/errors.rs: Added ReputationCallFailed = 32 error variant.
• contracts/creditline-contract/src/events.rs: Added emit_score_update_failed(&env, borrower, is_increase, amount) helper emitting ScoreUpdateFailed topic.
• contracts/creditline-contract/src/lib.rs: Removed bare let _ = discards in mark_defaulted() and handle_reputation_increase(), enforcing strict result handling, event emission, and atomic panic on failure.
• contracts/creditline-contract/src/tests.rs: Updated test_reputation_call_failure_reverts_repayment and added test_reputation_call_failure_reverts_default simulating reputation contract failure for both increase and decrease paths.
• context/progress-tracker.md: Documented security fix and Policy Option (a) decision under Recently Fixed.

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Verification Results

• cargo test -p creditline-contract: 141 passed; 0 failed
• cargo test (full workspace): 389 passed; 0 failed across all 6 contracts.

[EmeditWeb]

⚠️ @sublime247 this PR now has merge conflicts with the base branch (likely because another PR was merged first).

Please rebase/merge the base branch into your branch and resolve the conflicts — a fresh audit will run automatically once new commits land.

[EmeditWeb]

✅ Automated Audit: solves

@sublime247 Excellent work, thank you! 🎉

The PR genuinely fixes issue #86 by replacing fire-and-forget let _ = discards with strict result handling in both mark_defaulted() and handle_reputation_increase(). On reputation contract failure, it emits ScoreUpdateFailed event and panics with CreditLineError::ReputationCallFailed, atomicating the revert so loan state and scores never diverge. New tests (test_reputation_call_failure_reverts_repayment, test_reputation_call_failure_reverts_default) verify the revert behavior for both paths. All 389 workspace tests pass.

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CI checks: ✅ PASSED: Build and Test Contracts
Merge conflicts: ⚠️ YES — this PR has conflicts with the base branch and cannot be merged. Please resolve the conflicts before this PR can be approved.

_{Audited by stepfi-audit-bot 🤖}

[sublime247]

@EmeditWeb review