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PROJECT_RULES.md

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+# Project Rules & Guidelines
+
+## 1. Client-Side First Policy (Privacy & Security)
+- **Generators & Simple Utilities:**
+  - Logic for generating data (e.g., passwords, UUIDs, random strings) or processing simple text (e.g., JSON formatting, URL encoding) **MUST** be implemented on the **Client-side (Frontend)** whenever possible.
+  - **Reason:** To protect user privacy, prevent sensitive data (like passwords) from ever touching the network/server, and improve responsiveness.
+  - **Exception:** Operations requiring heavy computation (e.g., Image/Video processing) or specific server-side libraries (e.g., specific Python ecosystem tools not available in JS) may use the Backend.
+
+## 2. Server-Side Data Handling
+- **Statelessness:** The server should remain stateless.
+- **Temporary Files:** If file upload is necessary for processing (e.g., Image Compression), files must be stored in a dedicated temporary directory (`backend/temp_uploads`) and **automatically cleaned up** after a short period (e.g., 10 minutes) or immediately after processing/download.
+
+## 3. UI/UX
+- **Navigation:** Use the Global Navigation Bar (GNB) for main navigation. Avoid complex sidebars (LNB) for simple utility sites.
+- **Feedback:** Always provide visual feedback for actions (loading states, success/error messages).