Implement textDocument/rename and textDocument/prepareRename for LSP

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## [Unreleased]
 
-- No changes yet.
+- Add `textDocument/rename` and `textDocument/prepareRename` support for `buf lsp serve`.
 
 ## [v1.61.0] - 2025-11-25
 

private/buf/buflsp/file.go

@@ -588,10 +588,12 @@ func (f *file) irToSymbols(irSymbol ir.Symbol) ([]*symbol, []*symbol) {
 		resolved = append(resolved, method)
 
 		input, _ := irSymbol.AsMethod().Input()
+		// Method input must be a single message type.
+		inputAST := irSymbol.AsMethod().AST().AsMethod().Signature.Inputs().At(0)
 		inputSym := &symbol{
 			ir:   irSymbol,
 			file: f,
-			span: irSymbol.AsMethod().AST().AsMethod().Signature.Inputs().Span(),
+			span: inputAST.RemovePrefixes().Span(), // We always strip prefixes in case of streaming.
 			kind: &reference{
 				def:      input.AST(), // Only messages can be method inputs and outputs
 				fullName: input.FullName(),
@@ -600,10 +602,12 @@ func (f *file) irToSymbols(irSymbol ir.Symbol) ([]*symbol, []*symbol) {
 		unresolved = append(unresolved, inputSym)
 
 		output, _ := irSymbol.AsMethod().Output()
+		// Method output must be a single message type.
+		outputAST := irSymbol.AsMethod().AST().AsMethod().Signature.Outputs().At(0)
 		outputSym := &symbol{
 			ir:   irSymbol,
 			file: f,
-			span: irSymbol.AsMethod().AST().AsMethod().Signature.Outputs().Span(),
+			span: outputAST.RemovePrefixes().Span(), // We always strip prefixes in case of streaming.
 			kind: &reference{
 				def:      output.AST(), // Only messages can be method inputs and outputs
 				fullName: output.FullName(),

private/buf/buflsp/server.go

@@ -152,6 +152,9 @@ func (s *server) Initialize(
 			DocumentFormattingProvider: true,
 			HoverProvider:              true,
 			ReferencesProvider:         &protocol.ReferenceOptions{},
+			RenameProvider: &protocol.RenameOptions{
+				PrepareProvider: true,
+			},
 			SemanticTokensProvider: &SemanticTokensOptions{
 				Legend: SemanticTokensLegend{
 					TokenTypes:     semanticTypeLegend,
@@ -559,6 +562,38 @@ func (s *server) DocumentSymbol(ctx context.Context, params *protocol.DocumentSy
 	return anyResults, nil
 }
 
+// PrepareRename is the entry point for checking workspace wide renaming of a symbol.
+//
+// If a symbol can be renamed, PrepareRename will return the range for the rename. Returning
+// an empty range indicates that the requested position cannot be renamed and the client
+// will handle providing feedback to the user.
+//
+// Supported symbol types for renaming are [referenceable], [static], and [reference].
+func (s *server) PrepareRename(ctx context.Context, params *protocol.PrepareRenameParams) (*protocol.Range, error) {
+	symbol := s.getSymbol(ctx, params.TextDocument.URI, params.Position)
+	if symbol == nil {
+		return nil, nil
+	}
+	switch symbol.kind.(type) {
+	case *referenceable, *static, *reference:
+		rnge := reportSpanToProtocolRange(symbol.span)
+		return &rnge, nil
+	}
+	return nil, nil
+}
+
+// Rename is the entry point for workspace wide renaming of a symbol.
+func (s *server) Rename(
+	ctx context.Context,
+	params *protocol.RenameParams,
+) (*protocol.WorkspaceEdit, error) {
+	symbol := s.getSymbol(ctx, params.TextDocument.URI, params.Position)
+	if symbol == nil {
+		return nil, nil
+	}
+	return symbol.Rename(params.NewName)
+}
+
 // getSymbol is a helper function that gets the *[symbol] for the given [protocol.URI] and
 // [protocol.Position].
 func (s *server) getSymbol(

private/buf/buflsp/symbol.go

@@ -307,6 +307,61 @@ func (s *symbol) GetSymbolInformation() protocol.SymbolInformation {
 	}
 }
 
+// Rename returns the [protocol.WorkspaceEdit] for renaming the symbol.
+func (s *symbol) Rename(newName string) (*protocol.WorkspaceEdit, error) {
+	var edits protocol.WorkspaceEdit
+	switch s.kind.(type) {
+	case *referenceable:
+		changes, err := renameChangesForReferenceableSymbol(s, newName)
+		if err != nil {
+			return nil, err
+		}
+		edits.Changes = changes
+	case *static:
+		edits.Changes = map[protocol.DocumentURI][]protocol.TextEdit{
+			s.file.uri: {{
+				Range:   reportSpanToProtocolRange(s.span),
+				NewText: newName,
+			}},
+		}
+	case *reference:
+		// For references, we attempt to rename the definition symbol, if resolved. This would
+		// include this reference symbol.
+		if s.def != nil {
+			changes, err := renameChangesForReferenceableSymbol(s.def, newName)
+			if err != nil {
+				return nil, err
+			}
+			edits.Changes = changes
+		}
+	}
+	// All other symbol types (options, imports, built-ins, and tags) cannot be renamed.
+	return &edits, nil
+}
+
+// renameChangesForReferenceableSymbol is a helper for getting all rename changes for the
+// given referenceable symbol.
+func renameChangesForReferenceableSymbol(s *symbol, newName string) (map[protocol.DocumentURI][]protocol.TextEdit, error) {
+	// At minimum, we would rename the symbol itself.
+	changes := map[protocol.DocumentURI][]protocol.TextEdit{
+		s.file.uri: {{
+			Range:   reportSpanToProtocolRange(s.span),
+			NewText: newName,
+		}},
+	}
+	if def, ok := s.def.kind.(*referenceable); ok {
+		for _, reference := range def.references {
+			changes[reference.file.uri] = append(changes[reference.file.uri], protocol.TextEdit{
+				Range:   reportSpanToProtocolRange(reference.span),
+				NewText: newName,
+			})
+		}
+	} else {
+		return nil, fmt.Errorf("attempting to rename a non-referenceble symbol as a referenceable symbol: %v", s)
+	}
+	return changes, nil
+}
+
 func protowireTypeForPredeclared(name predeclared.Name) protowire.Type {
 	switch name {
 	case predeclared.Bool, predeclared.Int32, predeclared.Int64, predeclared.UInt32,