feat(09-06): serve admin form schemas and match Winter relations

- GET schema/form localizes the compiled form after the permission check
- relation: genre resolves to the exported Go field without changing the YAML key

cabana/http.go

@@ -125,6 +125,8 @@ func (s *service) mount(r pact.Router) {
 		g.Get("/auth/me", s.me)
 		g.Get("/{vendor}/{plugin}/{controller}/schema/list", s.listSchema)
 		constrainController(g)
+		g.Get("/{vendor}/{plugin}/{controller}/schema/form", s.formSchema)
+		constrainController(g)
 		g.Get("/{vendor}/{plugin}/{controller}", s.list)
 		constrainController(g)
 		g.Post("/{vendor}/{plugin}/{controller}", s.create)
@@ -146,6 +148,25 @@ func constrainController(g pact.Router) {
 	g.Where("controller", "[A-Za-z0-9_-]+")
 }
 
+func (s *service) formSchema(w http.ResponseWriter, r *http.Request) {
+	s.protect(w, r, func(cc *CompiledController) {
+		if cc.Form == nil {
+			WriteError(w, http.StatusNotFound, "not_found", msgNotFound)
+			return
+		}
+		view, err := cc.Form.Localize(r.Context(), s.translator(), dropdownProvider(cc.Controller))
+		if err != nil {
+			WriteError(w, http.StatusInternalServerError, "error", msgServerError)
+			return
+		}
+		meta := map[string]any{}
+		if view.Meta.Locale != "" {
+			meta["locale"] = view.Meta.Locale
+		}
+		WriteData(w, http.StatusOK, view, meta)
+	})
+}
+
 func (s *service) listSchema(w http.ResponseWriter, r *http.Request) {
 	s.protect(w, r, func(cc *CompiledController) {
 		schema := cc.List

cabana/list_schema.go

@@ -330,6 +330,9 @@ func listModelContract(ctl pact.AdminController) (map[string]struct{}, map[strin
 		}
 		if isListRelation(field.Type) {
 			rels[field.Name] = struct{}{}
+			// Winter YAML spells relations in lowercase (relation: genre)
+			// while the Go field is exported (Genre).
+			rels[strings.ToLower(field.Name)] = struct{}{}
 			continue
 		}
 		name := gormColumn(field)

cabana/query.go

@@ -125,8 +125,11 @@ func ExecuteList(ctx context.Context, db *gorm.DB, cc *CompiledController, in Li
 	}
 	q = applyListOrder(q, cc.List, model, sortCol, sortDesc)
 	for _, col := range cc.List.Columns {
-		if col.Relation != "" {
-			q = q.Preload(col.Relation)
+		if col.Relation == "" {
+			continue
+		}
+		if field, ok := relationFieldName(model, col.Relation); ok {
+			q = q.Preload(field)
 		}
 	}
 	offset := (page - 1) * per
@@ -230,9 +233,13 @@ func applyListOrder(db *gorm.DB, schema *ListSchema, model any, column string, d
 			if col.Key != column || col.Relation == "" {
 				continue
 			}
-			orderTable = col.Relation
+			field, ok := relationFieldName(model, col.Relation)
+			if !ok {
+				continue
+			}
+			orderTable = field
 			orderColumn = col.Select
-			db = db.Joins(col.Relation)
+			db = db.Joins(field)
 			break
 		}
 		db = db.Order(clause.OrderByColumn{
@@ -269,15 +276,16 @@ func applyListSearch(db *gorm.DB, schema *ListSchema, model any, term string) (*
 		table := main
 		column := col.Key
 		if col.Relation != "" {
-			if _, ok := relatedTable(model, col.Relation); !ok || !identifier(col.Select) {
+			field, ok := relationFieldName(model, col.Relation)
+			if !ok || !identifier(col.Select) {
 				return nil, listInvalid("search", "is not searchable")
 			}
-			// GORM aliases the joined association with the relation field name.
-			table = col.Relation
+			// GORM aliases the joined association with the Go field name.
+			table = field
 			column = col.Select
-			if _, done := joined[col.Relation]; !done {
-				db = db.Joins(col.Relation)
-				joined[col.Relation] = struct{}{}
+			if _, done := joined[field]; !done {
+				db = db.Joins(field)
+				joined[field] = struct{}{}
 			}
 		} else if !identifier(column) {
 			return nil, listInvalid("search", "is not searchable")
@@ -439,33 +447,30 @@ func tableName(model any) string {
 	return ""
 }
 
-func relatedTable(model any, relation string) (string, bool) {
+// relationFieldName resolves a Winter relation key onto the exported Go field.
+// Exact names win; otherwise the match is case-insensitive, so relation: genre
+// selects field Genre.
+func relationFieldName(model any, relation string) (string, bool) {
 	t := reflect.TypeOf(model)
 	for t != nil && t.Kind() == reflect.Pointer {
 		t = t.Elem()
 	}
-	if t == nil || t.Kind() != reflect.Struct {
+	if t == nil || t.Kind() != reflect.Struct || relation == "" {
 		return "", false
 	}
-	field, ok := t.FieldByName(relation)
-	if !ok {
-		return "", false
+	if field, ok := t.FieldByName(relation); ok && isListRelation(field.Type) {
+		return field.Name, true
 	}
-	rt := field.Type
-	for rt.Kind() == reflect.Pointer {
-		rt = rt.Elem()
-	}
-	if rt.Kind() == reflect.Slice {
-		rt = rt.Elem()
-		for rt.Kind() == reflect.Pointer {
-			rt = rt.Elem()
+	for i := 0; i < t.NumField(); i++ {
+		field := t.Field(i)
+		if field.PkgPath != "" || !isListRelation(field.Type) {
+			continue
+		}
+		if strings.EqualFold(field.Name, relation) {
+			return field.Name, true
 		}
 	}
-	if rt.Kind() != reflect.Struct {
-		return "", false
-	}
-	name := tableName(reflect.New(rt).Interface())
-	return name, name != ""
+	return "", false
 }
 
 func primaryColumn(model any) string {
@@ -501,7 +506,11 @@ func relatedSelect(row reflect.Value, col ListColumn) (any, bool) {
 	if row.Kind() != reflect.Struct || col.Relation == "" {
 		return nil, false
 	}
-	field := row.FieldByName(col.Relation)
+	name, ok := relationFieldName(row.Interface(), col.Relation)
+	if !ok {
+		return nil, false
+	}
+	field := row.FieldByName(name)
 	if !field.IsValid() {
 		return nil, false
 	}