💭 Second Thought

Build wealth by thinking twice before you buy

🏆 Built for Google DeepMind Gemini 3 Hackathon

The Problem

Americans spend about $5,400 per year on impulse purchases, according to national consumer surveys. E-commerce platforms use sophisticated psychological tactics—fake urgency, manipulative discounts, and frictionless checkout—to exploit our cognitive biases.

Source: Slickdeals / OnePoll consumer survey (reported by CNBC).

Our Solution

Second Thought is an AI-powered browser extension that intervenes at the moment of highest risk: the checkout button. Using Google Gemini 3, it analyzes purchases in real-time, calculates opportunity costs, detects predatory pricing, and enforces 24-hour cool-down periods.

$5,400
Average impulse spending per year (U.S.)
$22K
Saved in 20 years (10% reduction, 7% growth)
≈400ms
AI analysis time (Gemini 3, typical benchmark)
🤖

AI-Powered Analysis

Google Gemini 3 analyzes purchase necessity based on your financial goals, providing personalized, empathetic guidance in near real-time.

📈

Opportunity Cost Calculator

See what your money could become if invested. That $300 smartwatch? It's $1,161 in 20 years at 7% growth.

⚠️

Predatory Pricing Detection

Exposes fake discounts, urgency manipulation, and psychological tricks retailers use to pressure you into buying.

⏰

24-Hour Cool-Down

Enforces a waiting period for non-essential purchases. Behavioral research suggests cooling-off delays (e.g., 24–48 hours) reduce impulsive buys by giving time for reflection.

🎯

Personalized Insights

Tailored to your financial goals—saving for a house, paying off debt, or building an emergency fund.

📊

Full Observability

Integrated with Opik for comprehensive tracing, LLM-as-judge evaluations, and quality monitoring.

📦 Installation Guide

Step 1: Download the Extension

Clone or download the repository from GitHub: 

git clone https://github.com/todorakai/second-thought-gemini
cd second-thought-gemini

Or download as ZIP and extract it.

Step 2: Open Chrome Extensions

In Google Chrome, navigate to: 

chrome://extensions/

Or click the three dots menu → Extensions → Manage Extensions

Step 3: Enable Developer Mode

Toggle the "Developer mode" switch in the top right corner.

Developer Mode

Step 4: Load the Extension

  1. Click the "Load unpacked" button
  2. Navigate to the downloaded folder
  3. Select the "extension" folder inside the project
  4. Click "Select Folder"

⚠️ Important: Make sure to select the extension folder, not the root project folder!

Step 5: Verify Installation

You should see the Second Thought extension card appear with:

  • 💭 Second Thought icon
  • Version 1.0.0
  • Status: Enabled

The extension icon should also appear in your Chrome toolbar (top right).

✅ You're All Set!

Now visit any e-commerce site (Amazon, eBay, Walmart, etc.) and browse a product over $20. Second Thought will automatically intervene with AI-powered insights!

Try it now: Visit Amazon.com and click on any product.

🎯 Quick Test

Test the Extension:

  1. Visit Amazon.com
  2. Search for any product (e.g., "smartwatch", "headphones")
  3. Click on a product that costs more than $20
  4. Wait 2-3 seconds
  5. The Second Thought panel will slide in from the right! 🎉

⚙️ Configuration (Optional)

Click the Second Thought icon in your toolbar to customize settings:

💰

Spending Threshold

Set the minimum price for intervention (default: $20)

🎯

Financial Goals

Add your goals: "Save for house", "Pay off debt", etc.

📊

Monthly Budget

Set your budget for personalized insights

❓ Troubleshooting

Extension doesn't appear?

  • Make sure the product costs more than $20
  • Reload the extension in chrome://extensions/
  • Refresh the product page
  • Check browser console (F12) for errors

Extension not loading?

  • Verify you selected the extension folder, not the root folder
  • Make sure Developer mode is enabled
  • Try removing and re-adding the extension

Need more help?

Check the full documentation on GitHub or open an issue.

🛠️ Tech Stack

AI Google Gemini 3 (gemini-3-flash-preview)
Frontend Chrome Extension (Manifest V3)
Backend Next.js 16 + TypeScript
Database Supabase (PostgreSQL)
Observability Opik (Tracing & Evaluation)
Testing Vitest + fast-check (85 tests)

How It Works

  1. Detect - Extension identifies product pages on major e-commerce sites
  2. Extract - Captures product details, price, and urgency indicators
  3. Analyze - Gemini 3 evaluates necessity vs. impulse in <500ms (typical benchmark)
  4. Calculate - Shows opportunity cost (5, 10, 20-year projections)
  5. Warn - Detects predatory pricing tactics and manipulation
  6. Intervene - Displays intervention panel with personalized guidance
  7. Protect - Enforces 24-hour cool-down for non-essential purchases

Gemini 3 Integration

Second Thought leverages Gemini 3's enhanced reasoning capabilities to understand nuanced financial contexts, detect subtle manipulation tactics, and generate empathetic, personalized guidance.

The model's low-latency benchmarks make near real-time intervention possible without disrupting the shopping experience. Gemini 3 is central to every feature—from analyzing purchase necessity to generating supportive messages that users actually listen to.