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REQUIREMENTS - Please ensure before running:
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1. API KEY: Get a Google API key from https://aistudio.google.com/
   - The user enters their own API key in the extension popup
   - Key is stored locally in chrome.storage.local (never transmitted except to Google)

2. CHROME: Use Google Chrome or any Chromium-based browser (Edge, Brave, etc.)

3. TO INSTALL LOCALLY:
   - Open chrome://extensions/
   - Enable "Developer mode" (top right toggle)
   - Click "Load unpacked" → select this folder
   - The extension icon appears in the toolbar

4. TO TEST:
   - Navigate to any article or news page
   - Click the extension icon in the toolbar
   - Enter your Google API key on first use (stored locally)
   - Click "Summarise This Page"
   - View the summary, key points, and reading time estimate
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Create a Chrome browser extension (Manifest V3) that summarises any web page
in one click using Google Gemini Flash.

When the user clicks the extension icon:
  1. A popup opens showing a "Summarise This Page" button
  2. Clicking it extracts the main text content from the active tab
  3. Sends the text to Gemini Flash API for analysis
  4. Displays a structured summary:
     - One-line headline summary
     - 4-6 key points as bullet points
     - Estimated reading time for the original article
     - Sentiment/tone indicator (neutral, positive, negative, mixed)

Extension structure:
  - manifest.json    — Manifest V3, permissions: activeTab, storage, host for Gemini API
  - popup.html       — Clean dark UI with summary display area
  - popup.js         — Handles button click, API calls, renders results
  - content.js       — Injected into the page to extract main text content
  - icons/           — 16x16, 48x48, 128x128 extension icons (SVG data URIs or inline)

Security:
  - API key entered by the user, stored in chrome.storage.local
  - Never hardcoded, never sent to any server except Google's Gemini API
  - Content script only reads text — no DOM modification
  - Minimal permissions (activeTab only, no broad host access)

The extension popup should have a polished dark theme consistent with the
AI Finance Lab branding (dark background, accent colour highlights).

Analyse 07-Create Browser Extension/geminiflash.txt to understand the Gemini
API call structure and adapt it for the browser extension context (fetch API
instead of Python SDK).