What this automation does
The calendar is where people plan. The automation does the typing, formatting and queueing in between, and makes sure nothing goes out unapproved.
- Brief. A marketer adds a row to the calendar: date, networks, goal, key message, link and asset from Google Drive.
- Draft. The workflow sends the brief to an LLM with your voice guide and each network’s rules. It returns a caption per network, alt text for each image, and a first comment if you use one.
- Check. Code validates character counts, confirms links resolve, confirms the image meets the network’s aspect ratio, and flags any brief missing an asset.
- Approve. The row moves to Needs Approval and a Slack message tags the approver with a preview. Approve or request changes from Slack or from the calendar.
- Queue. Approved posts are sent to the scheduler at the planned slot, and the scheduler’s post ID is written back to the row.
- Report back. After publishing, the workflow fetches basic engagement where the scheduler exposes it and writes it to the same row, so the calendar doubles as a log.
When it is worth building
This makes sense when the same person spends Monday afternoons copying captions between tools, resizing images and chasing approvals over email. It is also a strong fit for agencies juggling several client calendars, where a missed approval means a late post and an awkward client call.
If you post to one network a few times a week, skip the build. Your scheduler’s own drafting and approval features are enough. And if the real problem is having nothing to say, look at the content repurposing pipeline first, since scheduling faster does not help an empty calendar.
Architecture
| Layer | What we use | Why |
|---|---|---|
| Calendar | Airtable or Notion | Planners need a visual calendar view, and both have solid APIs |
| Assets | Google Drive | Designers already save finals there; the workflow reads the file by link |
| Orchestration | n8n | Built-in Airtable, Notion, Drive and Slack nodes, plus HTTP Request for scheduler APIs |
| Drafting | Claude Haiku 5.5 for captions, Sonnet 5.5 for longer posts | Short captions do not need the largest model; cost stays low per post |
| Approval | Slack interactive message | Approvers act in seconds without opening another tool |
| Publishing | Buffer or Hootsuite API, or official platform APIs | The scheduler owns account connections and network-specific posting rules |
How to build it
- Design the calendar schema. Fields for date, time zone, networks, brief, asset link, status, approver, caption per network, alt text, scheduler post ID and a global paused flag.
- Confirm API access. Before building, confirm your scheduler plan exposes an API and which networks it can post to through it. Some schedulers gate API access by plan or require app registration, and APIs change: Buffer, for example, closed new access to its legacy REST API and launched a new GraphQL API in 2026. Check this first, because it changes the design.
- Write per-network prompt rules. Character limits, link handling, hashtag policy, tone shifts (LinkedIn is not Instagram). Store these as config, not inside the prompt text.
- Build drafting and validation. Draft on status change to Ready to Draft. Validate lengths, links and image dimensions in code, and send failures back to the planner with the reason.
- Build the approval loop. Post a preview to Slack with Approve and Request Changes buttons. Record who approved and when on the row.
- Queue with idempotency. Use the calendar row ID as a dedupe key so a retry never creates a second post. Write back the scheduler’s post ID immediately.
- Build the pause switch. One checkbox or Slack command that unschedules every pending post through the scheduler API and marks the rows Paused.
The downloadable starter template below covers Airtable drafting, the Slack approval message and queueing to a scheduler over HTTP.
What breaks in production
- Expired account connections. Social tokens expire or get revoked when someone changes a password or leaves. Check connection status daily and alert before a post fails silently.
- Double posting on retries. A timeout after the scheduler accepted the post triggers a retry and a duplicate. The dedupe key on the row prevents this.
- Time zone and daylight saving errors. A post planned for 9am Eastern goes out at 8am after the clocks change. Store every time with an explicit zone and convert at queue time.
- Rejected media. Wrong aspect ratio, oversized video or unsupported format gets rejected at publish time. Validate dimensions and size before approval, not after.
- Approved but stale. A post approved two weeks ago references a sale that ended. Re-check linked pages and dates the day before publishing.
Timeline and cost
A calendar with AI drafting, Slack approval and one scheduler integration usually takes two to three weeks. Lumeor builds this in the range of $4,000 to $10,000, depending on the number of networks and accounts, whether you post through a scheduler or direct platform APIs, and whether engagement data flows back. Model usage for captions is small at a normal posting volume, but scheduler seats are a separate subscription you should price from the vendor’s current plans. Agencies who also need client-facing results can extend this with client reporting.
How to measure success
- Posts published versus posts planned each week
- Median hours from brief to approved post
- Approval rounds per post (fewer means the drafts fit the voice)
- Failed or duplicate publishes per month, target zero
- Time spent by the social lead on mechanics versus planning