Extract Email Tasks with Gmail, ChatGPT-4o and Supabase

Description

📩 Gmail → GPT → Supabase | Task Extractor

This n8n workflow automates the extraction of actionable tasks from unread Gmail messages using OpenAI's GPT API, stores the resulting task metadata in Supabase, and avoids re-processing previously handled emails.

✅ What It Does

Triggers on a schedule to check for unread emails in your Gmail inbox.
Loops through each email individually using SplitInBatches.
Checks Supabase to see if the email has already been processed.
If it's a new email:
Formats the email content into a structured GPT prompt
Calls ChatGPT-4o to extract structured task data
Inserts the result into your emails table in Supabase

🧰 Prerequisites

Before using this workflow, you must have:

An active n8n Cloud or self-hosted instance
A connected Gmail account with OAuth credentials in n8n
A Supabase project with an emails table and:
ALTER TABLE emails ADD CONSTRAINT unique_email_id UNIQUE (email_id);
An OpenAI API key with access to GPT-4o or GPT-3.5-turbo

🔐 Required Credentials

| Name | Type | Description |
|-----------------|------------|-----------------------------------|
| Gmail OAuth | Gmail | To pull unread messages |
| OpenAI API Key | OpenAI | To generate task summaries |
| Supabase API | HTTP | For inserting rows via REST API |

🔁 Environment Variables or Replacements

Supabase_TaskManagement_URI → e.g., https://your-project.supabase.co
Supabase_TaskManagement_ANON_KEY → Your Supabase anon key

These are used in the HTTP request to Supabase.

⏰ Scheduling / Trigger

Triggered using a Schedule node
Default: every X minutes (adjust to your preference)
Uses a Gmail API filter: unread emails with label = INBOX

🧠 Intended Use Case

> Designed for productivity-minded professionals who want to extract, summarize, and store actionable tasks from incoming email — without processing the same email twice or wasting GPT API credits.

This is part of a larger system integrating GPT, calendar scheduling, and optional task platforms (like ClickUp).

📦 Output (Stored in Supabase)

Each processed email includes:
email_id
subject
sender
received_at
body (email snippet)
gpt_summary (structured task)
requires_deep_work (from GPT logic)
deleted (initially false)