Feat: Implement Emergency Circuit Breaker (Pause/Unpause)

[gelluisaac]

closes #39
This PR implements an Emergency Circuit Breaker (frequently known as a "Pausable" pattern) for the Vaultix smart contracts. This provides a vital safety layer, allowing administrators to freeze state-changing operations if a vulnerability is detected or during extreme market volatility.

PR Description: Emergency Circuit Breaker Implementation
🎯 Overview
This PR introduces the ability to pause and unpause contract functionality. By implementing an emergency stop mechanism, we mitigate the risk of fund loss during potential exploits, fulfilling the requirement for operational control over immutable code.

📋 Features Implemented

1. State Management
   Storage Update: Added a ContractState enum (Active, Paused) to the contract's persistent storage.

Admin Control: Implemented set_paused(env, bool), restricted exclusively to the Admin via authentication checks.

2. Guard Logic
   Circuit Breaker Helper: Created an ensure_not_paused(env) helper function that validates the current state.

Function Level Security: Integrated the pause check into all state-changing operations:

create_escrow: Prevents new funds from entering the contract while paused.

release_funds / confirm_delivery: Freezes movement of existing assets during an investigation.

3. Read-Only Access
   Non-Blocking Getters: All "view" or "getter" functions remain accessible while the contract is paused, ensuring users and external systems can still verify status and balances.

🏗️ Technical Implementation
Logic Flow
Auth: The set_paused function verifies the caller is the registered Admin.

Panic Mechanism: The check_active helper triggers a contract panic (revert) if the state is Paused, effectively blocking transaction completion.

[Cedarich]

Hi @gelluisaac, thanks for the PR! 👋

I reviewed the code, and it looks like this implementation addresses Issue #5 (Milestone-Based Escrow) rather than your assigned task, Issue #8 (Emergency Circuit Breaker).

While the milestone logic looks solid, we need to strictly follow the assigned issues to manage the project roadmap and avoid overlapping with other contributors.

Action Required:
Please strictly focus on the requirements for Issue #8 in this PR.

1. Please stash or move your current Milestone code to a separate branch (e.g., feat/milestone-escrow) so it's safe for later.
2. On this branch, please revert the changes and implement the Circuit Breaker functionality as requested (Admin pause/unpause logic).

Let's get the Circuit Breaker merged first as planned. Thanks!

[gelluisaac]

@Cedarich i think i missed up the issue earlier but i have updated it now

[Cedarich]

Kindly resolve conflicts

[gelluisaac]

@Cedarich conflicts resolved

[gelluisaac]

@Cedarich PR ready

[gelluisaac]

@Cedarich PR awaiting your approval

[gelluisaac]

@Cedarich My PR has ready for a while now

[Cedarich]

Hey @gelluisaac Thanks for working on this. You've got the core structure right with the ContractState enum and the admin function—that part looks solid.

However, I ran into a few issues when I tried to test it locally that we need to fix before merging:

1. The build is currently broken : The code is trying to return Error::ContractPaused in your helper function, but that error hasn't been added to the Error enum definition yet, so the compiler is complaining.
2. Missing a safety check : I noticed you added the pause check to create_escrow , which is great, but deposit_funds is still unprotected. Since that’s a state-changing function that locks user funds, we definitely need the ensure_not_paused check there too.
3. We need to see it fail : Since this is a security feature, tests are super important here. Please add a test case in test.rs that explicitly pauses the contract and verifies that calling create_escrow (or deposit_funds ) actually fails.
   Once you push those fixes, ping me and I'll take another look! 🚀

[gelluisaac]

@Cedarich all test now are passing

[gelluisaac]

@Cedarich you take a look at it

[Cedarich]

Thank you for contributing! LGTM