refactor: Extract SyncStateCoordinator from SyncEngine

[Copilot]

SyncEngine mixed sync orchestration with state management, progress calculation, and session lifecycle logic. This made the class complex (1200+ lines) and state behavior difficult to test in isolation.

Changes

New Component: ISyncStateCoordinator

• Encapsulates session lifecycle (initialize, complete, fail, cancel)
• Handles progress calculation with transfer speed tracking (rolling 10-sample window)
• Provides observable state updates via BehaviorSubject<SyncState>
• Manages session logging via ISyncSessionLogRepository

SyncEngine Simplification

• Removed 113 lines of state management code
• Replaced internal _progressSubject, _transferHistory, _currentSessionId with coordinator delegation
• Progress observable now proxied from coordinator: public IObservable<SyncState> Progress => _syncStateCoordinator.Progress
• Deleted methods: ReportProgress(), InitializeSyncSessionAsync(), FinalizeSyncSessionAsync(), HandleSyncFailedAsync(), HandleSyncCancelledAsync(), ResetTrackingDetails()

Example Usage

// Before: SyncEngine managed state internally
await InitializeSyncSessionAsync(accountId, enableDetailedLogging, ct);
ReportProgress(accountId, SyncStatus.Running, totalFiles, completedFiles, ...);

// After: Delegated to coordinator
string? sessionId = await _syncStateCoordinator.InitializeSessionAsync(accountId, enableDetailedLogging, ct);
_syncStateCoordinator.UpdateProgress(accountId, SyncStatus.Running, totalFiles, completedFiles, ...);

Testing

• 16 unit tests for SyncStateCoordinator covering progress calculation, speed/ETA, session state transitions
• Updated SyncEngine tests to mock coordinator with reactive BehaviorSubject

Impact

• No breaking changes to ISyncEngine interface
• State logic now independently testable
• SyncEngine constructor gains one dependency: ISyncStateCoordinator

Warning

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

• av-build-tel-api-v1.avaloniaui.net
  • Triggering command: /usr/share/dotnet/dotnet dotnet exec --runtimeconfig /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.1/tools/netstandard2.0/runtimeconfig.json /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.1/tools/netstandard2.0/Avalonia.BuildServices.Collector.dll (dns block)
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  • Triggering command: /usr/share/dotnet/dotnet dotnet exec --runtimeconfig /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.1/tools/netstandard2.0/runtimeconfig.json /home/REDACTED/.nuget/packages/avalonia.buildservices/11.3.1/tools/netstandard2.0/Avalonia.BuildServices.Collector.dll cture/Services/ISyncStateCoordinator.cs ame rgo/bin/git (dns block)

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>refactor: Extract SyncStateCoordinator from SyncEngine</issue_title>
<issue_description>## Description
Extract sync state management and progress reporting from SyncEngine into a dedicated SyncStateCoordinator.

Current State

Sync state management is scattered throughout SyncEngine:

• Progress calculations in multiple methods
• State updates mixed with business logic
• Session lifecycle management embedded in main sync flow

Proposed Changes

Create ISyncStateCoordinator interface and implementation with methods:

• InitializeSessionAsync(accountId) - Create sync session
• UpdateProgress(...) - Calculate and report progress
• RecordCompletion(files, bytes, conflicts) - Record sync completion
• RecordFailure(error) - Record sync failure
• GetCurrentState() - Get current sync state

Benefits

• ✅ Centralizes all state management logic
• ✅ Makes progress calculation testable in isolation
• ✅ Simplifies SyncEngine core sync logic
• ✅ Enables better sync state observability

Dependencies

Dependencies would be:

• ISyncSessionLogRepository - for session persistence
• Progress reporter callback (Action<...>)

Technical Notes

• Manage session lifecycle (start, update, complete/fail)
• Calculate totals (files, bytes, conflicts)
• Handle progress throttling if needed
• Support pause/resume scenarios

Acceptance Criteria

• ISyncStateCoordinator interface created
• SyncStateCoordinator implementation with state management logic
• SyncEngine updated to inject and use the service
• Comprehensive unit tests (targeting 90%+ coverage)
• All existing tests still passing

Related

Part of the SyncEngine architectural refactoring effort following PR #9.</issue_description>

<agent_instructions>Please implement and ensure you follow the .github/copilot-instructions.md styling / coding standards</agent_instructions>

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

• Fixes refactor: Extract SyncStateCoordinator from SyncEngine #12

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[sonarqubecloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[jaybarden1]

I will remove:
private async Task<List> GetAllLocalFiles(string accountId, IReadOnlyList selectedFolders, AccountInfo account)
and cleanup to follow the style guide