Support disabling selected code to be visible by the chat by default

Core/Sources/ChatContextCollector/ActiveDocumentChatContextCollector.swift

@@ -19,7 +19,7 @@ public struct ActiveDocumentChatContextCollector: ChatContextCollector {
                 ```
                 """
             }
-            
+
             if selectionRange.start == selectionRange.end,
                UserDefaults.shared.value(for: \.embedFileContentInChatContextIfNoSelection)
             {
@@ -34,19 +34,40 @@ public struct ActiveDocumentChatContextCollector: ChatContextCollector {
                     """
                 } else {
                     return """
-                    File Content Not Available: The file is longer than \(maxLine) lines, \
-                    it can't fit into the context. \
+                    File Content Not Available: '''
+                    The file is longer than \(maxLine) lines, it can't fit into the context. \
                     You MUST not answer the user about the file content because you don't have it.\
                     Ask user to select code for explanation.
+                    '''
                     """
                 }
             }
 
+            if UserDefaults.shared.value(for: \.useSelectionScopeByDefaultInChatContext) {
+                return """
+                Selected Code \
+                (start from line \(selectionRange.start.line)):```\(content.language.rawValue)
+                \(content.selectedContent)
+                ```
+                """
+            }
+
+            if prompt.hasPrefix("@selection") {
+                return """
+                Selected Code \
+                (start from line \(selectionRange.start.line)):```\(content.language.rawValue)
+                \(content.selectedContent)
+                ```
+                """
+            }
+
             return """
-            Selected Code \
-            (start from line \(selectionRange.start.line)):```\(content.language.rawValue)
-            \(content.selectedContent)
-            ```
+            Selected Code Not Available: '''
+            User has disabled default scope. \
+            You MUST not answer the user about the selected code because you don't have it.\
+            Ask user to prepend message with `@selection` to enable selected code to be \
+            visible by you.
+            '''
             """
         }()
 

Core/Sources/HostApp/FeatureSettings/ChatSettingsView.swift

@@ -14,6 +14,8 @@ struct ChatSettingsView: View {
         var embedFileContentInChatContextIfNoSelection
         @AppStorage(\.maxEmbeddableFileInChatContextLineCount)
         var maxEmbeddableFileInChatContextLineCount
+        @AppStorage(\.useSelectionScopeByDefaultInChatContext)
+        var useSelectionScopeByDefaultInChatContext
 
         @AppStorage(\.chatFeatureProvider) var chatFeatureProvider
         @AppStorage(\.chatGPTModel) var chatGPTModel
@@ -165,6 +167,10 @@ struct ChatSettingsView: View {
     @ViewBuilder
     var contextForm: some View {
         Form {
+            Toggle(isOn: $settings.useSelectionScopeByDefaultInChatContext) {
+                Text("Use selection scope by default in chat context.")
+            }
+
             Toggle(isOn: $settings.embedFileContentInChatContextIfNoSelection) {
                 Text("Embed file content in chat context if no code is selected.")
             }

Core/Sources/Preferences/Keys.swift

@@ -225,6 +225,10 @@ public extension UserDefaultPreferenceKeys {
     var maxEmbeddableFileInChatContextLineCount: PreferenceKey<Int> {
         .init(defaultValue: 100, key: "MaxEmbeddableFileInChatContextLineCount")
     }
+
+    var useSelectionScopeByDefaultInChatContext: PreferenceKey<Bool> {
+        .init(defaultValue: true, key: "UseSelectionScopeByDefaultInChatContext")
+    }
 }
 
 // MARK: - Custom Commands