This commit continues the backend refactoring initiative by extracting
configuration management and API speedtest logic into dedicated service
layers, completing phase 4 of the architectural improvement plan.
## Changes
### New Service Layers
- **ConfigService** (`services/config.rs`): Consolidates all config
import/export, backup management, and live sync operations
- `create_backup()`: Creates timestamped backups with auto-cleanup
- `export_config_to_path()`: Exports config to specified path
- `load_config_for_import()`: Loads and validates imported config
- `import_config_from_path()`: Full import with state update
- `sync_current_providers_to_live()`: Syncs current providers to live files
- Private helpers for Claude/Codex-specific sync logic
- **SpeedtestService** (`services/speedtest.rs`): Encapsulates endpoint
latency testing with proper validation and error handling
- `test_endpoints()`: Tests multiple URLs concurrently
- URL validation now unified in service layer
- Includes 3 unit tests for edge cases (empty list, invalid URLs, timeout clamping)
### Command Layer Refactoring
- Move all import/export commands to `commands/import_export.rs`
- Commands become thin wrappers: parse params → call service → return JSON
- Maintain `spawn_blocking` for I/O operations (phase 5 optimization)
- Lock acquisition happens after I/O completes (minimize contention)
### File Organization
- Delete: `import_export.rs`, `speedtest.rs` (root-level modules)
- Create: `commands/import_export.rs`, `services/config.rs`, `services/speedtest.rs`
- Update: Module declarations in `lib.rs`, `commands/mod.rs`, `services/mod.rs`
### Test Updates
- Update 20 integration tests in `import_export_sync.rs` to use `ConfigService` APIs
- All existing test cases pass without modification to test logic
- Add 3 new unit tests for `SpeedtestService`:
- `sanitize_timeout_clamps_values`: Boundary value testing
- `test_endpoints_handles_empty_list`: Empty input handling
- `test_endpoints_reports_invalid_url`: Invalid URL error reporting
## Benefits
1. **Improved Testability**: Service methods are `pub fn`, easily callable
from tests without Tauri runtime
2. **Better Separation of Concerns**: Business logic isolated from
command/transport layer
3. **Enhanced Maintainability**: Related operations grouped in cohesive
service structs
4. **Consistent Error Handling**: Services return `Result<T, AppError>`,
commands convert to `Result<T, String>`
5. **Performance**: I/O operations run in `spawn_blocking`, locks released
before file operations
## Testing
- ✅ All 43 tests passing (7 unit + 36 integration)
- ✅ `cargo fmt --check` passes
- ✅ `cargo clippy -- -D warnings` passes (zero warnings)
## Documentation
Updated `BACKEND_REFACTOR_PLAN.md` to reflect completion of config and
speedtest service extraction, marking phase 4 substantially complete.
Co-authored-by: Claude Code <code@anthropic.com>
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