Fix LSP documentSymbol marking every symbol as deprecated

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## [Unreleased]
 
 - Add LSP completion for `buf.gen.yaml`, `buf.yaml`, and `buf.policy.yaml` files.
+- Fix LSP `textDocument/documentSymbol` marking every symbol as deprecated.
 
 ## [v1.69.0] - 2026-04-29
 

private/buf/buflsp/document_symbol_test.go

@@ -72,6 +72,8 @@ func TestDocumentSymbol(t *testing.T) {
 				{name: "symbols.v1.CreateDocumentResponse.document", kind: protocol.SymbolKindField, line: 39},  // Document document
 				{name: "symbols.v1.LegacyDocument", kind: protocol.SymbolKindClass, line: 42, deprecated: true}, // message LegacyDocument (deprecated)
 				{name: "symbols.v1.LegacyDocument.id", kind: protocol.SymbolKindField, line: 44},                // string id
+				{name: "symbols.v1.ExplicitlyNotDeprecated", kind: protocol.SymbolKindClass, line: 47},          // message ExplicitlyNotDeprecated (option deprecated = false)
+				{name: "symbols.v1.ExplicitlyNotDeprecated.id", kind: protocol.SymbolKindField, line: 49},       // string id
 			},
 		},
 	}
@@ -100,6 +102,15 @@ func TestDocumentSymbol(t *testing.T) {
 				assert.Equal(t, testURI, found.Location.URI, "symbol %s has wrong URI", expectedSymbol.name)
 				assert.Equal(t, expectedSymbol.line, found.Location.Range.Start.Line, "symbol %s has wrong line number", expectedSymbol.name)
 				assert.Equal(t, expectedSymbol.deprecated, found.Deprecated, "symbol %s has wrong deprecated status", expectedSymbol.name)
+				// Tags must only carry SymbolTagDeprecated for symbols that are
+				// actually deprecated. Clients prefer Tags over the legacy
+				// Deprecated field, so an unconditional tag would render every
+				// symbol with a strikethrough.
+				var expectedTags []protocol.SymbolTag
+				if expectedSymbol.deprecated {
+					expectedTags = []protocol.SymbolTag{protocol.SymbolTagDeprecated}
+				}
+				assert.Equal(t, expectedTags, found.Tags, "symbol %s has wrong tags", expectedSymbol.name)
 			}
 		})
 	}

private/buf/buflsp/symbol.go

@@ -377,19 +377,18 @@ func (s *symbol) GetSymbolInformation() protocol.SymbolInformation {
 	default:
 		kind = protocol.SymbolKindVariable
 	}
-	var isDeprecated bool
-	if _, ok := s.ir.Deprecated().AsBool(); ok {
-		isDeprecated = true
+	isDeprecated, _ := s.ir.Deprecated().AsBool()
+	var tags []protocol.SymbolTag
+	if isDeprecated {
+		tags = []protocol.SymbolTag{protocol.SymbolTagDeprecated}
 	}
 	return protocol.SymbolInformation{
 		Name:          string(name),
 		Kind:          kind,
 		Location:      location,
 		ContainerName: containerName,
 		Deprecated:    isDeprecated,
-		Tags: []protocol.SymbolTag{
-			protocol.SymbolTagDeprecated,
-		},
+		Tags:          tags,
 	}
 }
 

private/buf/buflsp/testdata/symbols/symbols.proto

@@ -44,3 +44,8 @@ message LegacyDocument {
   option deprecated = true;
   string id = 1;
 }
+
+message ExplicitlyNotDeprecated {
+  option deprecated = false;
+  string id = 1;
+}