Plan campaign targeting and pre-vet ad variants with Spendict, OpenAI, Slack and Google Sheets

Description

Quick Overview
This workflow collects a campaign brief via an n8n form, uses Spendict to generate a targeting strategy, uses OpenAI to draft platform-specific ad variants, then has Spendict score and gate each draft before logging vetted variants to Google Sheets and posting updates to Slack.

How it works
Receives a campaign brief (product, platform, budget, objective, and optional funnel stage/vertical) via an n8n form submission.
Sends the brief to Spendict’s strategize-targeting API to generate a targeting plan with segments, budget split, setup notes, and key risks.
Formats the strategy into a readable message and posts the targeting plan to Slack.
Sends the strategy summary and audience approach to the OpenAI Chat Completions API to generate three ad variants (headline + primary text) for the selected platform.
Assesses each ad variant with Spendict’s assess API to get a score and a deterministic verdict (run, fix_first, or kill).
Logs non-killed variants (including score and top recommended fix) to Google Sheets and posts a Slack message summarizing how many vetted variants were added.

Setup
Add a Spendict API key and configure HTTP Header Auth (Authorization: Bearer …) for both Spendict HTTP requests.
Add an OpenAI API key and configure HTTP Header Auth (Authorization: Bearer …) for the OpenAI HTTP request.
Connect Google Sheets credentials and select the target spreadsheet and sheet in the append step where variants are logged.
Create or choose a Slack Incoming Webhook and replace the webhook URL in both Slack webhook requests.