Refactor merchant validation flow to reduce security-check complexity

[Copilot]

The merchant security-check path carried the same estate/merchant retrieval and validation branches across multiple operations, leaving the current implementation with the same maintainability problem as the original PerformSecurityChecks warning. This change consolidates that logic into a single helper and updates merchant operations to use it consistently.

• What changed

  • Introduced GetValidatedMerchantContext(...) in MerchantDomainService to:
    • load the estate aggregate
    • load the merchant aggregate
    • run the existing ValidateEstateAndMerchant(...) checks
    • return both validated aggregates as a single context
  • Replaced repeated inline validation blocks in merchant command handlers with the shared helper.

• Where the refactor applies

  • Merchant operations that previously duplicated the same security-check flow now delegate to the shared context loader, including:
    • device add/swap
    • operator assignment/removal
    • merchant user creation
    • deposit/withdrawal prerequisites
    • contract add/remove
    • merchant/address/contact updates
    • schedule/opening-hours updates

• Behavior preserved

  • No validation rules were changed.
  • Existing error paths and messages still come from the same validation methods; only the orchestration was centralized.

• Illustrative example

  Result<ValidatedMerchantContext> contextResult =
      await this.GetValidatedMerchantContext(command.EstateId, command.MerchantId, cancellationToken);
  
  if (contextResult.IsFailed)
      return ResultHelpers.CreateFailure(contextResult);
  
  MerchantAggregate merchantAggregate = contextResult.Data.MerchantAggregate;

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• f.feedz.io
  • Triggering command: /usr/bin/dotnet dotnet test /home/REDACTED/work/TransactionProcessor/TransactionProcessor/TransactionProcessor.Tests/TransactionProcessor.Tests.csproj --filter VerifyBootstrapperIsValid --no-restore -nologo (dns block)
  • Triggering command: /usr/bin/dotnet dotnet test /home/REDACTED/work/TransactionProcessor/TransactionProcessor/TransactionProcessor.BusinessLogic.Tests/TransactionProcessor.BusinessLogic.Tests.csproj --filter MerchantDomainService_ --no-restore -nologo (dns block)
  • Triggering command: /opt/hostedtoolcache/CodeQL/2.24.3/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp /opt/hostedtoolcache/CodeQL/2.24.3/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Complexity] Method MerchantController::PerformSecurityChecks has a cyclomatic complexity of 11 (limit is 8)</issue_title>
<issue_description>Codacy ID: 6c566c35dda4ec463e3c4620e4f62a4

File: TransactionProcessor/Controllers/MerchantController.cs
Line: 61
Rule: Complexity (Warning)
Commit: 5b8f3e64d731c7b181b225e9d4117fda74faa3ac

Message: Method MerchantController::PerformSecurityChecks has a cyclomatic complexity of 11 (limit is 8)

**Code Snippet:**
```csharp
    private Result PerformSecurityChecks(Guid estateId,Guid merchantId) { 
```

</issue_description>

<agent_instructions>add the maintenance label to the pull request</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Complexity] Method MerchantController::PerformSecurityChecks has a cyclomatic complexity of 11 (limit is 8) #1364

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