Give packs an identity so create can refuse missing deps and load in a stable order.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/HSchool.Server/Api/ModEndpoints.cs

@@ -11,8 +11,16 @@ internal static class ModEndpoints
 {
     public static void MapModEndpoints(this IEndpointRouteBuilder builder)
     {
-        builder.MapGet("/api/mods", (ModContent mods) =>
-            new ModsResponse(mods.ListPacks().Select(pack => new ModInfoResponse(pack.Id, pack.Required)).ToArray()))
+        builder.MapGet("/api/mods", (string? lang, ModContent mods) =>
+            {
+                var locale = string.Equals(lang, "en", StringComparison.OrdinalIgnoreCase) ? "en" : "ru";
+                return new ModsResponse(mods.ListPacks(locale).Select(pack => new ModInfoResponse(
+                    pack.Id,
+                    pack.Required,
+                    pack.Label,
+                    pack.Version,
+                    pack.Requires)).ToArray());
+            })
             .WithName("GetMods");
 
         builder.MapGet("/api/catalog", (string? lang, string? mods, ModContent content) =>
@@ -31,7 +39,19 @@ internal static class ModEndpoints
                 return Problem(StatusCodes.Status400BadRequest, "invalid-catalog", "The core pack is missing.");
             }
 
-            var packIds = content.NormalizePackIds(extras);
+            IReadOnlyList<string> packIds;
+            try
+            {
+                packIds = content.ResolveSelectedPacks(extras);
+            }
+            catch (PackDependencyException ex)
+            {
+                return PackProblem(ex);
+            }
+            catch (ContentLoadException ex)
+            {
+                return Problem(StatusCodes.Status400BadRequest, "invalid-catalog", ex.Message);
+            }
             DefCatalog catalog;
             MapLayout map;
             try
@@ -69,6 +89,17 @@ internal static class ModEndpoints
         return mods.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
     }
 
+    private static IResult PackProblem(PackDependencyException ex) =>
+        Results.Problem(
+            detail: ex.Message,
+            statusCode: StatusCodes.Status400BadRequest,
+            title: ex.Code,
+            extensions: new Dictionary<string, object?>
+            {
+                ["code"] = ex.Code,
+                ["missing"] = ex.MissingPackId,
+            });
+
     private static IResult Problem(int statusCode, string code, string detail) =>
         Results.Problem(detail: detail, statusCode: statusCode, title: code, extensions: new Dictionary<string, object?>
         {
@@ -78,7 +109,12 @@ internal static class ModEndpoints
 
 internal sealed record ModsResponse(IReadOnlyList<ModInfoResponse> Mods);
 
-internal sealed record ModInfoResponse(string Id, bool Required);
+internal sealed record ModInfoResponse(
+    string Id,
+    bool Required,
+    string Label,
+    string Version,
+    IReadOnlyList<string> Requires);
 
 internal sealed record CatalogResponse(
     IReadOnlyList<DefInfoResponse> Territories,

src/HSchool.Server/Api/SchoolEndpoints.cs

@@ -80,6 +80,14 @@ internal static class SchoolEndpoints
                     Problem(StatusCodes.Status400BadRequest, "unknown-name-set", "The selected name set is not in the catalog."),
                 SchoolCreationError.UnknownNativeLanguage =>
                     Problem(StatusCodes.Status400BadRequest, "unknown-native-language", "The selected native language is not in that name set."),
+                SchoolCreationError.MissingMod =>
+                    Problem(
+                        StatusCodes.Status400BadRequest,
+                        "missing-mod",
+                        $"Mod '{outcome.MissingPackId}' is required but was not selected.",
+                        missing: outcome.MissingPackId),
+                SchoolCreationError.ModCycle =>
+                    Problem(StatusCodes.Status400BadRequest, "mod-cycle", "Selected mods have a cyclic dependency."),
                 _ => Results.Problem("Unknown error."),
             };
         })
@@ -468,7 +476,12 @@ internal static class SchoolEndpoints
         return true;
     }
 
-    private static IResult Problem(int statusCode, string code, string detail, StaffingOutcome? staffing = null)
+    private static IResult Problem(
+        int statusCode,
+        string code,
+        string detail,
+        StaffingOutcome? staffing = null,
+        string? missing = null)
     {
         var extensions = new Dictionary<string, object?> { ["code"] = code };
         if (staffing is not null)
@@ -479,6 +492,11 @@ internal static class SchoolEndpoints
             extensions["attempted"] = staffing.Attempted;
         }
 
+        if (missing is not null)
+        {
+            extensions["missing"] = missing;
+        }
+
         return Results.Problem(detail: detail, statusCode: statusCode, title: code, extensions: extensions);
     }
 }
@@ -492,10 +510,16 @@ internal sealed record CreateSchoolRequest(
     string? NameSetId,
     string? NativeLanguage);
 
-internal sealed record SchoolResponse(int Id, string Name, DateTime GameTime, bool Running, byte SpeedIndex)
+internal sealed record SchoolResponse(
+    int Id,
+    string Name,
+    DateTime GameTime,
+    bool Running,
+    byte SpeedIndex,
+    IReadOnlyList<string> ModIds)
 {
     public static SchoolResponse From(SchoolState school) =>
-        new(school.Id, school.Name, school.GameTime, school.Running, school.SpeedIndex);
+        new(school.Id, school.Name, school.GameTime, school.Running, school.SpeedIndex, school.ModIds);
 }
 
 /// <summary>Everything the main menu needs in one request.</summary>