MemoryPal — Your AI-Powered Second Brain

MemoryPal is a distraction-free note-taking app that lets you capture ideas, curate links, and actually get things back out — powered by Google Gemini AI across your entire knowledge base.

Features

• Global AI Chat — Ask questions across all your notes at once. "What did I save about fundraising?" → synthesized answer from your entire second brain.
• Per-Note AI Assistant — Every note has its own AI companion that knows its specific context, with full chat history.
• Search — Instant search across note titles, descriptions, and tags as you type.
• Tags + Smart Filtering — Add tags manually or let AI suggest them. Filter your dashboard by tag in one click.
• Browser Extension — Right-click any page → "Save to MemoryPal". Auto-fills title and URL. Works on any site.
• Secure Sharing — One-click share links protected behind authentication.
• Distraction-Free Editor — Split-pane layout: write on the left, chat with AI on the right.

Application Flows

User Journey

graph TD
    A[User] --> B{Sign Up / Sign In}
    B --> C[Dashboard]
    C --> D[New Note]
    C --> E[Search & Filter by Tag]
    C --> F[Ask AI — Global Chat]
    D --> G[Editor + AI Assistant]
    G --> H[AI Suggests Tags]
    C --> I[Browser Extension Capture]

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Global AI Chat

sequenceDiagram
    participant User
    participant Frontend
    participant Backend
    participant Gemini

    User->>Frontend: Asks a question
    Frontend->>Backend: POST /api/v1/chat
    Backend->>MongoDB: Fetch all user notes
    MongoDB-->>Backend: Notes with tags + descriptions
    Backend->>Gemini: System prompt with full knowledge base
    Gemini-->>Backend: Synthesized answer
    Backend-->>Frontend: Response
    Frontend-->>User: Display answer

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Per-Note AI Chat

sequenceDiagram
    participant User
    participant Frontend
    participant Backend
    participant Gemini
    participant MongoDB

    User->>Frontend: Opens note, sends message
    Frontend->>Backend: POST /api/v1/content/:id/chat
    Backend->>MongoDB: Fetch note + chat history
    MongoDB-->>Backend: Context + prior messages
    Backend->>Gemini: System prompt scoped to this note
    Gemini-->>Backend: Response
    Backend->>MongoDB: Save user + model messages
    Backend-->>Frontend: Response
    Frontend-->>User: Display in chat pane

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Note Sharing

graph LR
    A[Note Owner] --> B[Click Share]
    B --> C[Copy link with share hash]
    C --> D[Recipient clicks link]
    D --> E{Signed in?}
    E -->|Yes| F[View protected note]
    E -->|No| G[Redirect to sign in]

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Tech Stack

Layer	Technology
Frontend	React 18 + Vite + TypeScript + Tailwind CSS
Backend	Node.js + Express 5 + TypeScript
Database	MongoDB + Mongoose
Auth	JWT (7-day expiry) + bcrypt
AI	Google Gemini 2.0 Flash (with 2.5 / 1.5 fallback)
Browser Extension	Chrome Manifest V3 (plain JS)

Project Structure

MemoryPal/
├── backend/          # Express API
│   └── src/
│       ├── index.ts  # All routes
│       ├── db.ts     # Mongoose models (User, Content, Chat, Tag)
│       ├── middleware.ts
│       └── config.ts
├── frontend/         # React + Vite app
│   └── src/
│       ├── pages/    # Dashboard, Signin, Signup, SharedNote
│       ├── components/  # Card, CreateContentModal, GlobalChatModal, ChatSection, ...
│       └── hooks/    # useContent
└── extension/        # Chrome browser extension
    ├── manifest.json
    ├── popup.html
    ├── popup.js
    └── background.js

API Reference

Method	Endpoint	Description
POST	/api/v1/signup	Register
POST	/api/v1/signin	Login → JWT
GET	/api/v1/content	List notes (supports ?q= search, ?tag= filter)
POST	/api/v1/content	Create note (title, links, description, tags)
PUT	/api/v1/content/:id	Update note
DELETE	/api/v1/content	Delete note
GET	/api/v1/tags	List all tags used by the user
POST	/api/v1/suggest-tags	AI-generated tag suggestions
POST	/api/v1/chat	Global AI chat across all notes
GET	/api/v1/content/:id/chat	Fetch per-note chat history
POST	/api/v1/content/:id/chat	Send message to per-note AI
GET	/api/v1/shared/:hash	View a shared note

Deployment

Backend (Render / Railway)

Set these environment variables:

MONGO_URL=mongodb+srv://...
JWT_PASSWORD=your-secret-key
GEMINI_API_KEY=your-gemini-key
FRONTEND_URL=https://your-frontend.vercel.app
PORT=3000

Frontend (Vercel)

1. Set BACKEND_URL in frontend/src/config.ts to your backend URL.
2. npm run build → deploy the dist/ folder.

Browser Extension (Chrome)

1. Go to chrome://extensions
2. Enable Developer mode
3. Click Load unpacked → select the extension/ folder
4. The MemoryPal icon appears in your toolbar. Right-click any page to save instantly.