refactor(backend): complete phase 1 - full AppError migration (100%)
Finalized the backend error handling refactoring by migrating all remaining
modules to use AppError, eliminating all temporary error conversions.
## Changes
### Fully Migrated Modules
- **mcp.rs** (129 lines changed)
- Migrated 13 functions from Result<T, String> to Result<T, AppError>
- Added AppError::McpValidation for domain-specific validation errors
- Functions: validate_server_spec, validate_mcp_entry, upsert_in_config_for,
delete_in_config_for, set_enabled_and_sync_for, sync_enabled_to_claude,
import_from_claude, import_from_codex, sync_enabled_to_codex
- Removed all temporary error conversions
- **usage_script.rs** (143 lines changed)
- Migrated 4 functions: execute_usage_script, send_http_request,
validate_result, validate_single_usage
- Used AppError::Message for JS runtime errors
- Used AppError::InvalidInput for script validation errors
- Improved error construction with ok_or_else (lazy evaluation)
- **lib.rs** (47 lines changed)
- Migrated create_tray_menu() and switch_provider_internal()
- Simplified PoisonError handling with AppError::from
- Added error logging in update_tray_menu()
- Improved error handling in menu update logic
- **migration.rs** (10 lines changed)
- Migrated migrate_copies_into_config()
- Used AppError::io() helper for file operations
- **speedtest.rs** (8 lines changed)
- Migrated build_client() and test_endpoints()
- Used AppError::Message for HTTP client errors
- **app_store.rs** (14 lines changed)
- Migrated set_app_config_dir_to_store() and migrate_app_config_dir_from_settings()
- Used AppError::Message for Tauri Store errors
- Used AppError::io() for file system operations
### Fixed Previous Temporary Solutions
- **import_export.rs** (2 lines changed)
- Removed AppError::Message wrapper for mcp::sync_enabled_to_codex
- Now directly calls the AppError-returning function (no conversion needed)
- **commands.rs** (6 lines changed)
- Updated query_provider_usage() and test_api_endpoints()
- Explicit .to_string() conversion for Tauri command interface
## New Error Types
- **AppError::McpValidation**: Domain-specific error for MCP configuration validation
- Separates MCP validation errors from generic Config errors
- Follows domain-driven design principles
## Statistics
- Files changed: 8
- Lines changed: +237/-122 (net +115)
- Compilation: ✅ Success (7.13s, 0 warnings)
- Tests: ✅ 4/4 passed
## Benefits
- **100% Migration**: All modules now use AppError consistently
- **Domain Errors**: Added McpValidation for better error categorization
- **No Temporary Solutions**: Eliminated all AppError::Message conversions for internal calls
- **Performance**: Used ok_or_else for lazy error construction
- **Maintainability**: Removed ~60 instances of .map_err(|e| format!("...", e))
- **Debugging**: Added error logging in critical paths (tray menu updates)
## Phase 1 Complete
Total impact across 3 commits:
- 25 files changed
- +671/-302 lines (net +369)
- 100% of codebase migrated from Result<T, String> to Result<T, AppError>
- 0 compilation warnings
- All tests passing
Ready for Phase 2: Splitting commands.rs by domain.
Co-authored-by: Claude <noreply@anthropic.com>
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