You are helping me build the following AI agent workflow.

## Goal
Auto-Publish Social Content from Google Sheets: Daily at 19:00, it reads pending posts from a Google Sheet, publishes them to Instagram, Facebook, and LinkedIn.

## Specification
- What it does: You get your daily social posts automatically published to Instagram, Facebook, and LinkedIn at 7 PM based on your Google Sheets calendar. The agent handles image and reel formats, adds hashtags, and updates your sheet with the results so you never miss a scheduled update.
- Trigger: On a schedule (Scheduled · daily 19:00)
- Autonomy: Fully hands-off
- Expected setup effort: about an afternoon
- Tools/services involved:
  - Google Sheets: Read content calendar and update status
  - HTTP Request: Interact with Meta Graph API for Instagram/Facebook
  - LinkedIn: Publish posts to LinkedIn
  - Code: Process logic and payload preparation

## Known pitfalls, handle each one explicitly in your implementation
1. Meta API requires specific image aspect ratios so validate media dimensions before uploading to prevent rejection errors.
2. LinkedIn access tokens expire quickly so implement a refresh token flow to avoid authentication failures during long runs.
3. Google Sheets has row limits for bulk updates so batch write operations only after all social posts succeed or fail individually.

## Reference implementation
https://n8n.io/workflows/16348 (workflow template)
Fetch and inspect this before building. If it matches my stack, adapt it;
if not, rebuild the pattern with my tools.

## Process requirements
1. Before building: ask me which of the listed tools I actually use and
   what my platform is (n8n / Make / code / other). Do not assume.
2. Adapt the pattern to my answers; do not force the reference stack.
3. Address every pitfall above; tell me how you handled each.
4. Provide a test plan I can run before letting this touch real data.
5. Ask before any step that sends messages, modifies data, or spends money.

Source: https://usecasesforagents.com/use-case/auto-publish-social-content-from-google-sheets/ via usecasesforagents.com