Instruction file imported from Broo37/EDF6ModLoaderWpf (.github/instructions/service-layer.instructions.md). Copyright stays with the author.

Service Layer Conventions

File Path Handling

Always use case-insensitive comparison for file paths — Windows filesystem is case-insensitive:

new Dictionary<string, T>(StringComparer.OrdinalIgnoreCase);
new HashSet<string>(StringComparer.OrdinalIgnoreCase);

Exclude mod_info.json when enumerating mod files:

.Where(f => !f.EndsWith("mod_info.json", StringComparison.OrdinalIgnoreCase))

BuildWinnerMap Contract

The winner map determines which mod's file gets deployed. It must:

1. Filter to IsActive mods only
2. Iterate in ascending LoadOrder order (lowest first)
3. Use last-writer-wins — higher LoadOrder overwrites earlier entries
4. Return Dictionary<string, ModEntry> keyed on relative file path

Apply Workflow

Any operation that changes mod state must follow this sequence:

BuildWinnerMap → CleanManagedFiles → CopyWinners → SaveRegistry → UpdateStatuses

Never skip steps or reorder them.

File Operation Retry

Use retry logic for copy/delete operations to handle transient file locks:

• 5 attempts maximum
• 200ms exponential backoff: delay = 200 * (attempt + 1)
• Catch IOException and UnauthorizedAccessException per attempt
• Rethrow on final attempt failure

Service Design

• Services are registered as Singletons — do not store per-request state in fields
• Use static for pure utility methods that don't need instance state (e.g., GetModRelativeFiles, BuildWinnerMap)
• Accept dependencies via constructor injection
• JSON persistence: use System.Text.Json with WriteIndented = true
• Always Directory.CreateDirectory(destDir) before writing files

Standard Subfolders

The valid mod subfolders in [GameRoot]\Mods\ are: DEFAULTPACKAGE, MainScript, Mission, Object, Patches, Plugins, Weapon

Reference via FileService.StandardSubfolders — don't hardcode elsewhere.