docs(frontend): Update frontend/GEMINI.md with comprehensive architecture and authentication details

frontend/GEMINI.md

@@ -1,18 +1,44 @@
 # Election Analytics Chatbot - Frontend Guide
 
 ## Overview
-This document serves as a guide for the frontend implementation of the Election Analytics Chatbot.
+This document serves as a guide for the frontend implementation of the Election Analytics Chatbot. The frontend is a modern React SPA designed for seamless user interaction and real-time data visualization.
 
 ## Key Technologies
-- **React**: UI library.
-- **TypeScript**: Static typing.
-- **Vite**: Build tool and dev server. Use v8.
-- **Tailwind CSS**: Styling (if used, need to verify). Use v4.
+- **React 18+**: For building the component-based UI.
+- **TypeScript**: Ensuring type safety across the codebase.
+- **Vite**: Modern build tool providing a fast development experience.
+- **Tailwind CSS v4**: Utility-first styling with the latest features.
+- **Shadcn UI**: High-quality, accessible UI components.
+- **React Router**: Client-side routing for authentication and main application views.
+- **Axios**: HTTP client for API communication, configured for cookie-based sessions.
+
+## Project Structure
+- `src/components/`:
+  - `auth/`: Login, Registration, and OIDC callback forms/pages.
+  - `layout/`: Main application layout including the sidebar navigation.
+  - `ui/`: Reusable primitive components (buttons, cards, inputs, etc.) via Shadcn.
+- `src/services/`:
+  - `api.ts`: Axios instance configuration with `/api/v1` base URL and interceptors.
+  - `auth.ts`: Authentication logic (Login, Logout, OIDC, User Profile).
+- `src/lib/`:
+  - `validations/`: Zod schemas for form validation.
+  - `utils.ts`: Core utility functions.
+- `src/hooks/`: Custom React hooks (e.g., `useIsMobile`).
+
+## Authentication System
+The frontend utilizes a secure, cookie-based authentication strategy:
+- **HttpOnly Cookies**: JWT tokens are stored in `access_token` cookies, protected from XSS.
+- **Axios Configuration**: `withCredentials: true` is enabled to ensure cookies are sent with every request.
+- **401 Interceptor**: A global response interceptor automatically handles session expiration by redirecting to the login view.
+- **OIDC/SSO**: Supports OAuth2/OpenID Connect flows with a dedicated `/auth/callback` route for token exchange.
 
 ## Integration
-The frontend communicates with the backend API to stream agent responses and display analysis results, including charts and dataframes.
+The frontend communicates with the backend's `/api/v1` endpoints:
+- **Streaming**: Consumes Server-Sent Events (SSE) for real-time agent reasoning and response delivery.
+- **Visualization**: Renders Matplotlib plots either from base64 strings in the event stream or binary retrieval from `/artifacts/plots`.
 
 ## Development
 - `npm install`: Install dependencies.
 - `npm run dev`: Start development server.
 - `npm run build`: Build for production.
+- `npm run test`: Run Vitest unit tests.