feat(admin): implement expert verification whitelist gatekeeper

[ussyalfaks]

🧠 SkillSphere Pull Request 🌐

• Closes Implement "Add Expert" Feature #1
• Added tests (if necessary)
• Ran cargo test (All tests passed)
• Evidence attached (Screenshots, Logs, or Transaction Hashes)
• Commented the code

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📌 Type of Change

• 📚 Documentation (updates to README, docs, or comments)
• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ Enhancement (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🏗️ Refactor (code improvement/cleanup without logical changes)

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📝 Changes Description

Overview

This PR implements the core expert verification functionality, establishing the Admin as the gatekeeper for whitelisting expert addresses on the SkillSphere platform.

What Changed

• Expert Verification Logic (src/contract.rs): Implemented verify_expert(env, expert)

  • Retrieves Admin from storage and enforces authentication via require_auth()
  • Returns NotInitialized if Admin not configured
  • Prevents duplicate verification with RegistryError::AlreadyVerified
  • Updates expert status to Verified in persistent storage
  • Emits ExpertStatusChanged event on success

• Public Interface (src/lib.rs): Exposed add_expert(env, expert) for contract interaction

• Test Suite (src/test.rs): Implemented test_add_expert

  • Initializes contract with Admin
  • Validates Admin can successfully verify experts
  • Rejects non-admin verification attempts with panic
  • Confirms ExpertStatusChanged event emission

Impact on Storage & Gas

• Adds one storage record per expert verification (ExpertStatus::Verified)
• Minimal gas impact: Single auth check + storage write + event emission
• No breaking changes to existing storage schema

Acceptance Criteria Met

• Function fails if caller is not the Admin
• Expert status updates to Verified in persistent storage
• ExpertStatusChanged event emitted on successful verification
• Returns NotInitialized if Admin not set
• Returns RegistryError::AlreadyVerified for duplicate verification
• All unit tests pass (auth, rejection, event validation)

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📸 Evidence

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Thank you for contributing to SkillSphere! 🌍

We are glad you have chosen to help us democratize access to knowledge on the Stellar network. Your contribution brings us one step closer to a trustless, peer-to-peer consulting economy. Let's build the future together! 🚀

Summary by CodeRabbit

• New Features

  • Administrators can now add experts to the identity registry with verification
  • Status change events are emitted to track expert verifications

• Tests

  • Comprehensive test coverage added for expert addition, authorization workflows, and status change event tracking

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR introduces expert verification functionality, adding a new verify_expert function restricted to admins that updates an expert's status to Verified and emits a status change event. The feature is exposed via a public add_expert API method and covered by comprehensive unit tests for authorization and event verification.

Changes

Cohort / File(s)	Summary
Core Expert Verification Logic contracts/identity-registry-contract/src/contract.rs	Added verify_expert() function that enforces admin authentication, reads current expert status, prevents re-verification, updates status to Verified, and emits a status_change event with previous/new statuses.
Public API Exposure contracts/identity-registry-contract/src/lib.rs	Added add_expert() public method to IdentityRegistryContract that delegates to verify_expert() for admin-only expert whitelisting.
Test Coverage contracts/identity-registry-contract/src/test.rs	Added three new test cases: test_add_expert() verifies authorized invocation, test_add_expert_unauthorized() validates authorization enforcement, and test_expert_status_changed_event() confirms event emission. Expanded imports to support authorization and event testing utilities.

Possibly related issues

• Implement "Add Expert" Feature #1 — Directly implements the verify_expert function and add_expert public API with matching unit tests as specified.
• Implement Read-Only Public Getters #3 — Related through shared use of ExpertStatus storage for expert verification status management.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 A hop, a skip, experts now shine bright,
Admin whispers "verified" with all their might,
Status updates bloom, events take flight,
Tests confirm the logic—all checks in sight! ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: implementing expert verification as an admin-controlled whitelist gatekeeper function.
Docstring Coverage	✅ Passed	Docstring coverage is 87.50% which is sufficient. The required threshold is 80.00%.
Description check	✅ Passed	The pull request description follows the repository template with all required sections completed: checkboxes marked, type of change specified, comprehensive changes description, acceptance criteria validation, and evidence provided.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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