refactor(csharp): post-merge review + simplify pass on codegen

Quality-gate pass (code-reviewer + code-simplifier) on the view-DDL / FK /
@storage / object-field codegen units. Fixes from review:

- Composite PRIMARY KEY and UNIQUE indexes now follow the identity's declared
  @fields order instead of field-declaration order (matches the FK path and the
  TS reference; was a latent wrong-key-shape bug, previously untested).
- CodegenRunner errors on duplicate generated output paths (mirrors codegen-ts
  runGen); value-object POCO emission had widened the silent-clobber surface.
- ObjectNavProperty routes its required-check through CSharpNaming.IsRequired,
  consistent with ScalarProperty.

Simplifications (output byte-identical; conformance + codegen string asserts green):
- Hoisted the triplicated private StripPkg into CSharpNaming.StripPkg.
- Extracted ResolveRelation shared by ToManyFk/ToOneFk; ToOneFk match reads
  against the resolved target name.

Adds a composite-key ordering test. Full solution green (282 tests).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dmealing

server/csharp/MetaObjects.Codegen.Tests/PostgresSchemaTests.cs

@@ -114,6 +114,30 @@ public void CreateTable_omits_foreign_key_for_logical_only_reference()
         Assert.DoesNotContain("CONSTRAINT tags_", sql);
     }
 
+    [Fact]
+    public void Composite_pk_and_unique_index_preserve_declared_field_order()
+    {
+        // @fields order ("b","a") differs from field-declaration order ("a","b");
+        // the DDL must follow @fields, not declaration order.
+        const string m = """
+        { "metadata.root": { "package": "acme", "children": [
+          { "object.entity": { "name": "Link", "children": [
+            { "source.dbTable": { "@name": "links" } },
+            { "field.long": { "name": "a" } },
+            { "field.long": { "name": "b" } },
+            { "identity.primary": { "@fields": ["b", "a"] } },
+            { "identity.secondary": { "name": "byBA", "@fields": ["b", "a"], "@unique": true } }
+          ]}}
+        ]}}
+        """;
+        var r = new MetaDataLoader().Load([new InMemorySource(m, id: "ck.json")]);
+        Assert.Empty(r.Errors);
+        var sql = PostgresSchema.BuildSchema(r.Root);
+
+        Assert.Contains("PRIMARY KEY (b, a)", sql);
+        Assert.Contains("CREATE UNIQUE INDEX links_byBA_uniq ON links (b, a);", sql);
+    }
+
     [Fact]
     public void Flattened_object_field_expands_to_prefixed_columns()
     {

server/csharp/MetaObjects.Codegen/CSharpNaming.cs

@@ -47,6 +47,17 @@ public static class CSharpNaming
     public static string Pascal(string name) =>
         name.Length == 0 ? name : char.ToUpperInvariant(name[0]) + name[1..];
 
+    /// <summary>
+    /// The bare object name from a possibly package-qualified reference (the segment
+    /// after the last <c>::</c>), for resolving an <c>@objectRef</c>/<c>@references</c>
+    /// against <see cref="MetaRoot.FindObject"/>. Shared by the schema + generators.
+    /// </summary>
+    public static string StripPkg(string name)
+    {
+        var i = name.LastIndexOf("::", StringComparison.Ordinal);
+        return i < 0 ? name : name[(i + 2)..];
+    }
+
     /// <summary>
     /// Cosmetic pluralization for a DbSet property name + the route collection
     /// segment (the table name itself comes from [Table]). Shared so the DbContext

server/csharp/MetaObjects.Codegen/CodegenRunner.cs

@@ -29,12 +29,20 @@ public static RunResult Run(GenConfig config, MetaRoot root, IReadOnlyList<IGene
 
         Directory.CreateDirectory(config.OutDir);
         var results = new List<WriteResult>();
+        // Two generators (or a name collision between an entity and a value-object
+        // POCO) writing the same path would silently clobber each other; error
+        // instead, mirroring codegen-ts's runGen duplicate-path check.
+        var emitted = new Dictionary<string, string>(StringComparer.Ordinal);
 
         foreach (var generator in generators)
         {
             foreach (var file in generator.Generate(ctx))
             {
                 var full = Path.GetFullPath(Path.Combine(config.OutDir, file.Path));
+                if (!emitted.TryAdd(full, generator.Name))
+                    throw new InvalidOperationException(
+                        $"duplicate generated output path \"{file.Path}\" — emitted by both " +
+                        $"\"{emitted[full]}\" and \"{generator.Name}\".");
                 if (File.Exists(full) && !File.ReadAllText(full).Contains(GeneratedMarker, StringComparison.Ordinal))
                 {
                     warnings.Add($"refusing to overwrite hand-written file: {file.Path}");

server/csharp/MetaObjects.Codegen/Generators/DbContextGenerator.cs

@@ -72,7 +72,7 @@ public IEnumerable<EmittedFile> Generate(GenContext ctx)
     // when @objectRef can't be resolved.
     private string? OwnedTypeConfig(MetaObject entity, MetaField field, GenContext ctx)
     {
-        if (field.ObjectRef is not { } oref || ctx.Root.FindObject(StripPkg(oref)) is not { } vo)
+        if (field.ObjectRef is not { } oref || ctx.Root.FindObject(CSharpNaming.StripPkg(oref)) is not { } vo)
         {
             ctx.Warn($"{Name}: object-typed field \"{entity.Name}.{field.Name}\" has an unresolved @objectRef \"{field.ObjectRef}\" — no owned-type config emitted.");
             return null;
@@ -95,10 +95,4 @@ public IEnumerable<EmittedFile> Generate(GenContext ctx)
         sb.Append("        });");
         return sb.ToString();
     }
-
-    private static string StripPkg(string s)
-    {
-        var i = s.LastIndexOf("::", StringComparison.Ordinal);
-        return i < 0 ? s : s[(i + 2)..];
-    }
 }

server/csharp/MetaObjects.Codegen/Generators/EntityGenerator.cs

@@ -164,14 +164,14 @@ private static string ScalarProperty(MetaObject owner, MetaField field, IReadOnl
     // a warning) when the @objectRef can't be resolved.
     private string? ObjectNavProperty(MetaObject owner, MetaField field, GenContext ctx)
     {
-        if (field.ObjectRef is not { } oref || ctx.Root.FindObject(StripPkg(oref)) is not { } target)
+        if (field.ObjectRef is not { } oref || ctx.Root.FindObject(CSharpNaming.StripPkg(oref)) is not { } target)
         {
             ctx.Warn($"{Name}: object-typed field \"{owner.Name}.{field.Name}\" has an unresolved @objectRef \"{field.ObjectRef}\" — skipped.");
             return null;
         }
         var typeName = CSharpNaming.Pascal(target.Name);
         var propName = CSharpNaming.Pascal(field.Name);
-        var required = field.OwnAttr(FIELD_ATTR_REQUIRED) is true;
+        var required = CSharpNaming.IsRequired(owner, field);
         return required
             ? $"    public {typeName} {propName} {{ get; set; }} = default!;"
             : $"    public {typeName}? {propName} {{ get; set; }}";
@@ -201,17 +201,11 @@ private static List<MetaObject> ReferencedValueObjects(IReadOnlyList<MetaObject>
         void Enqueue(string? objectRef)
         {
             if (objectRef is null) return;
-            var target = ctx.Root.FindObject(StripPkg(objectRef));
+            var target = ctx.Root.FindObject(CSharpNaming.StripPkg(objectRef));
             // Only plain value objects (no source) become POCOs; entities/projections
             // are already in `mapped`.
             if (target is null || !target.IsValue() || target.DbView is not null) return;
             if (seen.Add(target.Name)) queue.Enqueue(target);
         }
     }
-
-    private static string StripPkg(string s)
-    {
-        var i = s.LastIndexOf("::", StringComparison.Ordinal);
-        return i < 0 ? s : s[(i + 2)..];
-    }
 }

server/csharp/MetaObjects.Codegen/Schema/PostgresSchema.cs

@@ -59,7 +59,6 @@ public static string CreateTable(MetaObject entity, MetaRoot root)
     {
         var table = entity.DbTable ?? entity.Name;
         var pk = entity.PrimaryIdentity();
-        var pkCols = (pk?.Fields ?? []).ToHashSet(StringComparer.Ordinal);
 
         var lines = new List<string>();
         foreach (var f in entity.Fields())
@@ -76,7 +75,8 @@ public static string CreateTable(MetaObject entity, MetaRoot root)
         }
         if (pk is not null && pk.Fields.Count > 0)
         {
-            var cols = entity.Fields().Where(f => pkCols.Contains(f.Name)).Select(Col);
+            // Preserve the identity's declared @fields order (not field-declaration order).
+            var cols = pk.Fields.Select(name => ResolveColumn(entity, name));
             lines.Add($"  PRIMARY KEY ({string.Join(", ", cols)})");
         }
         // FOREIGN KEY constraints from enforced identity.reference children.
@@ -93,7 +93,7 @@ public static string CreateTable(MetaObject entity, MetaRoot root)
         // UNIQUE indexes from secondary identities marked unique.
         foreach (var sec in entity.SecondaryIdentities().Where(i => i.Unique))
         {
-            var cols = entity.Fields().Where(f => sec.Fields.Contains(f.Name)).Select(Col);
+            var cols = sec.Fields.Select(name => ResolveColumn(entity, name));
             sb.AppendLine($"CREATE UNIQUE INDEX {table}_{sec.Name}_uniq ON {table} ({string.Join(", ", cols)});");
         }
         return sb.ToString();
@@ -106,7 +106,7 @@ public static string CreateTable(MetaObject entity, MetaRoot root)
     private static IEnumerable<string> ObjectFieldColumns(MetaObject entity, MetaField f, MetaRoot root)
     {
         if (f.Storage == STORAGE_FLATTENED && f.ObjectRef is { } oref &&
-            root.FindObject(StripPkg(oref)) is { } nested)
+            root.FindObject(CSharpNaming.StripPkg(oref)) is { } nested)
         {
             var prefix = Col(f) + "_";
             foreach (var nf in nested.Fields().Where(n => CSharpNaming.ScalarFor(n.SubType) is not null))
@@ -127,7 +127,7 @@ private static IEnumerable<string> ObjectFieldColumns(MetaObject entity, MetaFie
     private static string? ForeignKeyClause(MetaObject entity, MetaReferenceIdentity fk, MetaRoot root)
     {
         if (fk.TargetEntity is not { } targetName || fk.Fields.Count == 0) return null;
-        var target = root.FindObject(StripPkg(targetName));
+        var target = root.FindObject(CSharpNaming.StripPkg(targetName));
         if (target is null) return null;
 
         var fkCols = fk.Fields.Select(js => ResolveColumn(entity, js)).ToList();
@@ -173,17 +173,17 @@ public static string CreateView(MetaObject projection, MetaRoot root, Action<str
             if (origin is MetaPassthroughOrigin pt && pt.Via is null && pt.From is { } from && from.Contains('.'))
             {
                 var (ent, field) = SplitDot(from);
-                baseEntity ??= StripPkg(ent);
-                if (StripPkg(ent) != baseEntity) { blocked = "passthrough from multiple base entities"; break; }
+                baseEntity ??= CSharpNaming.StripPkg(ent);
+                if (CSharpNaming.StripPkg(ent) != baseEntity) { blocked = "passthrough from multiple base entities"; break; }
                 cols.Add($"  {ResolveColumn(root.FindObject(baseEntity), field)} AS {Col(f)}");
             }
             // passthrough WITH via → forward a field from a to-one related entity (correlated subquery).
             else if (origin is MetaPassthroughOrigin ptv && ptv.Via is { } pvia && ptv.From is { } pfrom &&
                      pvia.Contains('.') && pfrom.Contains('.'))
             {
                 var (baseEnt, relName) = SplitDot(pvia);
-                baseEntity ??= StripPkg(baseEnt);
-                if (StripPkg(baseEnt) != baseEntity) { blocked = "passthrough via a different base entity"; break; }
+                baseEntity ??= CSharpNaming.StripPkg(baseEnt);
+                if (CSharpNaming.StripPkg(baseEnt) != baseEntity) { blocked = "passthrough via a different base entity"; break; }
                 if (ToOneFk(root, baseEntity, relName) is not { } fk)
                 { blocked = $"unresolved to-one FK for @via \"{pvia}\" (base needs an identity.reference)"; break; }
                 var srcCol = ResolveColumn(fk.Target, SplitDot(pfrom).Tail);
@@ -194,8 +194,8 @@ public static string CreateView(MetaObject projection, MetaRoot root, Action<str
                      of.Contains('.') && via.Contains('.'))
             {
                 var (baseEnt, relName) = SplitDot(via);
-                baseEntity ??= StripPkg(baseEnt);
-                if (StripPkg(baseEnt) != baseEntity) { blocked = "aggregate over a different base entity"; break; }
+                baseEntity ??= CSharpNaming.StripPkg(baseEnt);
+                if (CSharpNaming.StripPkg(baseEnt) != baseEntity) { blocked = "aggregate over a different base entity"; break; }
                 if (ToManyFk(root, baseEntity, relName) is not { } fk)
                 { blocked = $"unresolved to-many FK for @via \"{via}\" (target needs an identity.reference back to {baseEntity})"; break; }
                 var ofCol = ResolveColumn(fk.Target, SplitDot(of).Tail);
@@ -205,9 +205,9 @@ public static string CreateView(MetaObject projection, MetaRoot root, Action<str
             else if (origin is MetaCollectionOrigin coll && coll.Via is { } cvia && cvia.Contains('.') && f.ObjectRef is { } objRef)
             {
                 var (baseEnt, relName) = SplitDot(cvia);
-                baseEntity ??= StripPkg(baseEnt);
-                if (StripPkg(baseEnt) != baseEntity) { blocked = "collection over a different base entity"; break; }
-                var nested = root.FindObject(StripPkg(objRef));
+                baseEntity ??= CSharpNaming.StripPkg(baseEnt);
+                if (CSharpNaming.StripPkg(baseEnt) != baseEntity) { blocked = "collection over a different base entity"; break; }
+                var nested = root.FindObject(CSharpNaming.StripPkg(objRef));
                 if (ToManyFk(root, baseEntity, relName) is not { } fk || nested is null)
                 { blocked = $"unresolved collection @via \"{cvia}\" / @objectRef \"{objRef}\""; break; }
                 var pairs = nested.Fields()
@@ -238,29 +238,31 @@ private static (string Head, string Tail) SplitDot(string s)
         return (s[..i], s[(i + 1)..]);
     }
 
-    private static string StripPkg(string s)
-    {
-        var i = s.LastIndexOf("::", StringComparison.Ordinal);
-        return i < 0 ? s : s[(i + 2)..];
-    }
-
     private static string ResolveColumn(MetaObject? obj, string fieldName) =>
         obj?.Fields().FirstOrDefault(f => f.Name == fieldName)?.DbColumn ?? fieldName;
 
+    // Resolve a named relationship on the base entity to its (base, target) objects.
+    private static (MetaObject Base, MetaObject Target)? ResolveRelation(
+        MetaRoot root, string baseEntity, string relName)
+    {
+        var baseObj = root.FindObject(baseEntity);
+        var rel = baseObj?.Relationships().FirstOrDefault(r => r.Name == relName);
+        if (baseObj is null || rel?.ObjectRef is not { } objRef) return null;
+        var target = root.FindObject(CSharpNaming.StripPkg(objRef));
+        return target is null ? null : (baseObj, target);
+    }
+
     // Resolve a to-many relationship to the FK that lives on the *target* entity:
     // the target carries an identity.reference back to the base. Used by aggregate
     // and collection origins (subquery scans the target, filtered by the base PK).
     private static (MetaObject Target, string TargetTable, string FkCol, string ParentCol)? ToManyFk(
         MetaRoot root, string baseEntity, string relName)
     {
-        var baseObj = root.FindObject(baseEntity);
-        var rel = baseObj?.Relationships().FirstOrDefault(r => r.Name == relName);
-        if (baseObj is null || rel?.ObjectRef is not { } objRef) return null;
-        var target = root.FindObject(StripPkg(objRef));
-        if (target is null) return null;
+        if (ResolveRelation(root, baseEntity, relName) is not { } rel) return null;
+        var (baseObj, target) = rel;
 
         var fkRef = target.ReferenceIdentities()
-            .FirstOrDefault(r => r.TargetEntity is { } te && StripPkg(te) == baseEntity);
+            .FirstOrDefault(r => r.TargetEntity is { } te && CSharpNaming.StripPkg(te) == baseEntity);
         if (fkRef is null || fkRef.Fields.Count == 0) return null;
 
         var fkCol = ResolveColumn(target, fkRef.Fields[0]);
@@ -278,14 +280,11 @@ private static (MetaObject Target, string TargetTable, string FkCol, string Pare
     private static (MetaObject Target, string TargetTable, string TargetKeyCol, string BaseFkCol)? ToOneFk(
         MetaRoot root, string baseEntity, string relName)
     {
-        var baseObj = root.FindObject(baseEntity);
-        var rel = baseObj?.Relationships().FirstOrDefault(r => r.Name == relName);
-        if (baseObj is null || rel?.ObjectRef is not { } objRef) return null;
-        var target = root.FindObject(StripPkg(objRef));
-        if (target is null) return null;
+        if (ResolveRelation(root, baseEntity, relName) is not { } rel) return null;
+        var (baseObj, target) = rel;
 
         var fkRef = baseObj.ReferenceIdentities()
-            .FirstOrDefault(r => r.TargetEntity is { } te && StripPkg(te) == StripPkg(objRef));
+            .FirstOrDefault(r => r.TargetEntity is { } te && CSharpNaming.StripPkg(te) == target.Name);
         if (fkRef is null || fkRef.Fields.Count == 0) return null;
 
         var baseFkCol = ResolveColumn(baseObj, fkRef.Fields[0]);