SheetMind – AI Assistant for Google Sheets

A Chrome Extension that lets you control Google Sheets using natural language, powered by Claude (Anthropic).

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✨ Features

• Natural language commands — "Create a 4×3 table with name, email, number, gender"
• Charts & graphs — "Plot monthly signups by channel as a line chart"
• Formatting — "Make the header row bold with a blue background and white text"
• Formulas — "Add a SUM formula in the last row for all numeric columns"
• Preview before apply — See exactly what Claude plans to do before it touches your sheet
• CSV, TSV, TXT & PDF ingestion — Attach a file and generate charts directly from file data
• Large CSV import mode — For bigger CSVs, data is written first and then visualization ops are generated
• Multi-series charts — Chart operations can map one domain column to multiple series columns
• Two UIs — Injected sidebar inside Sheets, or Chrome's native Side Panel

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🚀 Setup

Step 1 — Configure your secure LLM proxy

The extension no longer stores an Anthropic API key in extension code. It calls your backend proxy endpoint.

In the Side Panel:

1. Click Proxy in the file bar
2. Enter your proxy URL (example: https://your-api.example.com/sheetmind/claude)
3. Optionally enter a bearer token used by your backend

Expected proxy response JSON:

{ "text": "{\"summary\":\"...\",\"preview\":\"...\",\"operations\":[...] }" }

The text field must be a string containing the JSON operation plan.

Step 2 — Add your OAuth Client ID to the manifest

This extension uses chrome.identity to get a Google OAuth token so it can call the Sheets API on your behalf.

1. Go to https://console.cloud.google.com
2. Create a new project (or use an existing one)
3. Enable the Google Sheets API
4. Go to APIs & Services → Credentials
5. Create an OAuth 2.0 Client ID → choose Chrome Extension
6. Enter your extension ID (see Step 3 for how to get this)
7. Copy the Client ID and add it to manifest.json:

"oauth2": {
  "client_id": "YOUR_CLIENT_ID.apps.googleusercontent.com",
  "scopes": [
    "https://www.googleapis.com/auth/spreadsheets"
  ]
}

Step 3 — Load the extension

1. Open Chrome and go to chrome://extensions
2. Enable Developer Mode (top-right toggle)
3. Click Load unpacked
4. Select the sheets-llm-extension folder
5. Note the Extension ID shown — use this when setting up your OAuth Client ID in Step 2

Step 4 — Use it!

1. Open any Google Sheet at https://docs.google.com/spreadsheets/
2. Click the SheetMind icon in your Chrome toolbar
3. Click Open Sidebar (injected into the page) or Open Side Panel (Chrome native panel)
4. (Optional) Attach a CSV, TSV, TXT, or PDF from the file bar
5. Type a command and hit Send
6. Review the Preview of changes
7. Click ✓ Apply Changes to execute

For large CSV files, SheetMind imports rows in chunks first and then asks the model for visualization-only steps.

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🗣️ Example Prompts

Prompt	What it does
Create a 4×3 table with name, email, number, gender	Writes headers + sample data, formats header row
Create a pivot table summarizing signups by channel and month	Builds a pivot table from your existing data
Use the attached CSV to build a monthly trend dashboard	Imports CSV data and creates trend/category charts
Read the attached PDF table and plot revenue by region	Extracts table data from PDF and creates chart ops
Format the header row — bold, blue background, white text	Applies formatting to row 1
Add SUM formulas in the last row for all numeric columns	Writes =SUM() formulas
Freeze the first row	Freezes row 1 as header
Auto-resize all columns	Makes columns fit their content
Clear everything from A1 to Z100	Clears that range

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📁 File Structure

sheets-llm-extension/
├── manifest.json        # Extension manifest (MV3)
├── background.js        # Service worker — proxy LLM calls & token handling
├── content.js           # Injected sidebar UI & Sheets API execution
├── sidebar.css          # Sidebar styles
├── popup.html           # Extension icon popup
├── popup.js             # Popup logic
├── sidepanel.html       # Chrome native side panel UI
├── sidepanel.js         # Side panel logic & Sheets API execution
└── icons/
    ├── icon16.png
    ├── icon48.png
    └── icon128.png

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⚠️ Notes

• Changes are applied via the Google Sheets API — the tab will reload after applying to show updates.
• The extension only activates on docs.google.com/spreadsheets URLs.
• Claude generates a preview of every planned operation before anything is written — you always confirm first.
• Charts are placed to the right of your data by default (column F, row 2 anchor).
• If a file is attached, file data is prioritized over synthetic sample data.