fix: DESCRIBE ODATA SERVICE expose roundtrip broken by KEY token (issue #400)

The grammar's exposeMemberOptions rule used IDENTIFIER, but 'Key' is a
reserved token (KEY) in the lexer so it was rejected by the parser.

Fixes:
- Change exposeMember and exposeMemberOptions grammar rules to use
  identifierOrKeyword instead of IDENTIFIER so reserved tokens like Key
  are accepted.
- Regenerate ANTLR parser.
- Update visitor to use IdentifierOrKeyword()/AllIdentifierOrKeyword()
  and handle both "key" and "ispartofkey" as IsPartOfKey.
- Formatter now emits IsPartOfKey (a plain identifier) instead of Key
  to use the canonical form accepted by the visitor.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ako

mdl/executor/cmd_odata.go

@@ -425,7 +425,7 @@ func outputPublishedODataServiceMDL(ctx *ExecContext, svc *model.PublishedODataS
 						modifiers = append(modifiers, "Sortable")
 					}
 					if m.IsPartOfKey {
-						modifiers = append(modifiers, "Key")
+						modifiers = append(modifiers, "IsPartOfKey")
 					}
 
 					line := fmt.Sprintf("    %s as '%s'", m.Name, m.ExposedName)

mdl/executor/cmd_odata_mock_test.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/mendixlabs/mxcli/mdl/ast"
 	"github.com/mendixlabs/mxcli/mdl/backend/mock"
+	"github.com/mendixlabs/mxcli/mdl/visitor"
 	"github.com/mendixlabs/mxcli/model"
 )
 
@@ -201,6 +202,62 @@ func TestDescribeODataService_NotFound(t *testing.T) {
 	assertError(t, describeODataService(ctx, ast.QualifiedName{Module: "X", Name: "NoSuch"}))
 }
 
+// TestDescribeODataService_ExposeRoundtrip verifies that DESCRIBE ODATA SERVICE
+// output for entities with key/filterable/sortable members is valid MDL that
+// the parser can re-parse (issue #400).
+func TestDescribeODataService_ExposeRoundtrip(t *testing.T) {
+	mod := mkModule("MyModule")
+	svc := &model.PublishedODataService{
+		BaseElement:  model.BaseElement{ID: nextID("pos")},
+		ContainerID:  mod.ID,
+		Name:         "CatalogService",
+		Path:         "/odata/v1",
+		Version:      "1.0",
+		ODataVersion: "4.0",
+		EntityTypes: []*model.PublishedEntityType{
+			{
+				Entity:      "MyModule.Order",
+				ExposedName: "Orders",
+				Members: []*model.PublishedMember{
+					{Name: "Id", ExposedName: "Id", IsPartOfKey: true},
+					{Name: "Name", ExposedName: "Name", Filterable: true, Sortable: true},
+				},
+			},
+		},
+		EntitySets: []*model.PublishedEntitySet{
+			{
+				ExposedName:    "Orders",
+				EntityTypeName: "MyModule.Order",
+				ReadMode:       "Readable",
+				InsertMode:     "NotSupported",
+			},
+		},
+	}
+	h := mkHierarchy(mod)
+	withContainer(h, svc.ContainerID, mod.ID)
+
+	mb := &mock.MockBackend{
+		IsConnectedFunc: func() bool { return true },
+		ListPublishedODataServicesFunc: func() ([]*model.PublishedODataService, error) {
+			return []*model.PublishedODataService{svc}, nil
+		},
+	}
+
+	ctx, buf := newMockCtx(t, withBackend(mb), withHierarchy(h))
+	assertNoError(t, describeODataService(ctx, ast.QualifiedName{Module: "MyModule", Name: "CatalogService"}))
+
+	out := buf.String()
+	assertContainsStr(t, out, "IsPartOfKey")
+
+	_, errs := visitor.Build(out)
+	if len(errs) > 0 {
+		t.Errorf("DESCRIBE output failed to parse (roundtrip broken):\n%s\nErrors:", out)
+		for _, e := range errs {
+			t.Errorf("  %v", e)
+		}
+	}
+}
+
 func TestCreateODataClient_InvalidMetadataURL(t *testing.T) {
 	mb := &mock.MockBackend{
 		IsConnectedFunc: func() bool { return true },

mdl/grammar/MDLParser.g4

@@ -2808,11 +2808,11 @@ exposeClause
     ;
 
 exposeMember
-    : IDENTIFIER (AS STRING_LITERAL)? exposeMemberOptions?
+    : identifierOrKeyword (AS STRING_LITERAL)? exposeMemberOptions?
     ;
 
 exposeMemberOptions
-    : LPAREN IDENTIFIER (COMMA IDENTIFIER)* RPAREN
+    : LPAREN identifierOrKeyword (COMMA identifierOrKeyword)* RPAREN
     ;
 
 /**

mdl/grammar/parser/MDLParser.interp

@@ -387,12 +387,12 @@ func parseExposeMembers(ctx parser.IExposeClauseContext) []*ast.PublishedMemberD
 		member := memberCtx.(*parser.ExposeMemberContext)
 
 		// Guard against incomplete parse (e.g., user typing in LSP)
-		if member.IDENTIFIER() == nil {
+		if member.IdentifierOrKeyword() == nil {
 			continue
 		}
 
 		m := &ast.PublishedMemberDef{
-			Name: member.IDENTIFIER().GetText(),
+			Name: member.IdentifierOrKeyword().GetText(),
 		}
 
 		// Optional AS 'ExposedName'
@@ -403,13 +403,13 @@ func parseExposeMembers(ctx parser.IExposeClauseContext) []*ast.PublishedMemberD
 		// Optional options (Filterable, Sortable, IsPartOfKey)
 		if opts := member.ExposeMemberOptions(); opts != nil {
 			optsCtx := opts.(*parser.ExposeMemberOptionsContext)
-			for _, id := range optsCtx.AllIDENTIFIER() {
+			for _, id := range optsCtx.AllIdentifierOrKeyword() {
 				switch strings.ToLower(id.GetText()) {
 				case "filterable":
 					m.Filterable = true
 				case "sortable":
 					m.Sortable = true
-				case "ispartofkey":
+				case "key", "ispartofkey":
 					m.IsPartOfKey = true
 				}
 			}