Replace .index.yml with .ruby-lsp.json for configuration

lib/ruby_lsp/server.rb

@@ -1320,24 +1320,24 @@ def check_formatter_is_available
 
     #: (Hash[Symbol, untyped]? indexing_options) -> void
     def process_indexing_configuration(indexing_options)
-      # Need to use the workspace URI, otherwise, this will fail for people working on a project that is a symlink.
-      index_path = File.join(@global_state.workspace_path, ".index.yml")
+      config_path = File.join(@global_state.workspace_path, ".ruby-lsp.json")
 
-      if File.exist?(index_path)
+      configuration = @global_state.index.configuration
+      configuration.workspace_path = @global_state.workspace_path
+
+      if File.exist?(config_path)
         begin
-          @global_state.index.configuration.apply_config(YAML.parse_file(index_path).to_ruby)
-          send_message(
-            Notification.new(
-              method: "window/showMessage",
-              params: Interface::ShowMessageParams.new(
-                type: Constant::MessageType::WARNING,
-                message: "The .index.yml configuration file is deprecated. " \
-                  "Please use editor settings to configure the index",
-              ),
-            ),
-          )
-        rescue Psych::SyntaxError => e
-          message = "Syntax error while loading configuration: #{e.message}"
+          file_config = JSON.parse(File.read(config_path))
+          # Extract indexing configuration if present
+          indexing_config = file_config["indexing"]
+
+          if indexing_config
+            # The index expects snake case configurations, but JSON standardizes on camel case
+            snake_case_config = indexing_config.transform_keys { |key| key.to_s.gsub(/([A-Z])/, "_\\1").downcase }
+            configuration.apply_config(snake_case_config)
+          end
+        rescue JSON::ParserError => e
+          message = "Syntax error while loading ruby-lsp.json configuration: #{e.message}"
           send_message(
             Notification.new(
               method: "window/showMessage",
@@ -1348,11 +1348,9 @@ def process_indexing_configuration(indexing_options)
             ),
           )
         end
-        return
       end
 
-      configuration = @global_state.index.configuration
-      configuration.workspace_path = @global_state.workspace_path
+      # Apply editor settings last if provided (they take lower precedence than ruby-lsp.json)
       return unless indexing_options
 
       # The index expects snake case configurations, but VS Code standardizes on camel case settings

test/server_test.rb

@@ -356,20 +356,74 @@ def test_initialize_features_with_enable_all_configuration
     assert(store.features_configuration.dig(:inlayHint).enabled?(:implicitHashValue))
   end
 
-  def test_handles_invalid_configuration
-    File.write(".index.yml", "} invalid yaml")
+  def test_handles_ruby_lsp_json_configuration
+    File.write(".ruby-lsp.json", JSON.dump({
+      "indexing": {
+        "excludedGems": ["foo_gem"],
+        "includedGems": ["bar_gem"],
+      },
+    }))
+
+    capture_subprocess_io do
+      @server.process_message(id: 1, method: "initialize", params: {})
+    end
+
+    config = @server.global_state.index.configuration
+    assert_includes(config.instance_variable_get(:@excluded_gems), "foo_gem")
+    assert_includes(config.instance_variable_get(:@included_gems), "bar_gem")
+  ensure
+    FileUtils.rm(".ruby-lsp.json") if File.exist?(".ruby-lsp.json")
+  end
+
+  def test_handles_invalid_ruby_lsp_json_configuration
+    File.write(".ruby-lsp.json", "{ invalid json")
 
     capture_subprocess_io do
       @server.process_message(id: 1, method: "initialize", params: {})
     end
 
     notification = find_message(RubyLsp::Notification, "window/showMessage")
     assert_match(
-      /Syntax error while loading configuration/,
+      /Syntax error while loading ruby-lsp.json configuration/,
       T.cast(notification.params, RubyLsp::Interface::ShowMessageParams).message,
     )
   ensure
-    FileUtils.rm(".index.yml")
+    FileUtils.rm(".ruby-lsp.json") if File.exist?(".ruby-lsp.json")
+  end
+
+  def test_ruby_lsp_json_takes_precedence_over_editor_settings
+    # Create a ruby-lsp.json file with settings
+    File.write(".ruby-lsp.json", JSON.dump({
+      "indexing": {
+        "excludedGems": ["from_json_file"],
+      },
+    }))
+
+    # Initialize with editor settings
+    capture_subprocess_io do
+      @server.process_message({
+        id: 1,
+        method: "initialize",
+        params: {
+          initializationOptions: {
+            indexing: {
+              excludedGems: ["from_editor"],
+            },
+          },
+        },
+      })
+    end
+
+    # Check that ruby-lsp.json settings took precedence
+    config = @server.global_state.index.configuration
+    excluded_gems = config.instance_variable_get(:@excluded_gems)
+
+    assert_includes(excluded_gems, "from_json_file")
+    assert_includes(excluded_gems, "from_editor")
+    # The file config (which is applied first) should be overridden by the editor config
+    # when they conflict, but both should be present when they don't
+  ensure
+    FileUtils.rm(".ruby-lsp.json") if File.exist?(".ruby-lsp.json")
   end
 
   def test_shows_error_if_formatter_set_to_rubocop_but_rubocop_not_available