docs: add comprehensive guide for adding new configuration items

Add a new section to settings.md that provides a complete checklist for adding new configuration items to the system. This guide covers all aspects from UI to persistence to functionality, based on implementation experience.

Signed-off-by: Eric Wheeler <[email protected]>

Author: Eric Wheeler

cline_docs/settings.md

@@ -178,3 +178,68 @@ These steps ensure that:
 - The setting's value is properly synchronized between the webview and extension
 - The setting has a proper UI representation in the settings view
 - Test coverage is maintained for the new setting
+
+## Adding a New Configuration Item: Summary of Required Changes
+
+To add a new configuration item to the system, the following changes are necessary:
+
+1. **Feature-Specific Class** (if applicable)
+
+    - For settings that affect specific features (e.g., Terminal, Browser, etc.)
+    - Add a static property to store the value
+    - Add getter/setter methods to access and modify the value
+
+2. **Schema Definition**
+
+    - Add the item to globalSettingsSchema in schemas/index.ts
+    - Add the item to globalSettingsRecord in schemas/index.ts
+
+3. **Type Definitions**
+
+    - Add the item to exports/types.ts
+    - Add the item to exports/roo-code.d.ts
+    - Add the item to shared/ExtensionMessage.ts
+    - Add the item to shared/WebviewMessage.ts
+
+4. **UI Component**
+
+    - Create or update a component in webview-ui/src/components/settings/
+    - Add appropriate slider/input controls with min/max/step values
+    - Ensure the props are passed correctly to the component in SettingsView.tsx
+    - Update the component's props interface to include the new settings
+
+5. **Translations**
+
+    - Add label and description in webview-ui/src/i18n/locales/en/settings.json
+    - Update all other languages
+    - If any language content is changed, synchronize all other languages with that change
+    - Translations must be performed within "translation" mode so change modes for that purpose
+
+6. **State Management**
+
+    - Add the item to the destructuring in SettingsView.tsx
+    - Add the item to the handleSubmit function in SettingsView.tsx
+    - Add the item to getStateToPostToWebview in ClineProvider.ts
+    - Add the item to getState in ClineProvider.ts with appropriate default values
+    - Add the item to the initialization in resolveWebviewView in ClineProvider.ts
+
+7. **Message Handling**
+
+    - Add a case for the item in webviewMessageHandler.ts
+
+8. **Implementation-Specific Logic**
+
+    - Implement any feature-specific behavior triggered by the setting
+    - Examples:
+        - Environment variables for terminal settings
+        - API configuration changes for provider settings
+        - UI behavior modifications for display settings
+
+9. **Testing**
+
+    - Add test cases for the new settings in appropriate test files
+    - Verify settings persistence and state updates
+
+10. **Avoiding Duplicates**
+    - Be careful to avoid duplicate handlers or UI components when adding new settings
+    - Check for existing similar settings to maintain consistent patterns