> For the complete documentation index, see [llms.txt](https://docs.twistly.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.twistly.ai/custom-templates-pro-and-team/how-templates-are-processed.md).

# How Templates Are Processed

When you upload a template, Twistly analyzes it in stages. Knowing what happens when saves confusion:

## 1. Layout detection (immediate)

Your file is split into layouts — one per distinct slide design. **Near-duplicate layouts are automatically marked as skipped**; use the toggle on any layout to include or exclude it manually. At least one layout must stay included.

## 2. Preview thumbnails (a minute or two)

Previews render progressively — it's normal to see them appear one by one.

* **You can't save while previews are still rendering** — wait for them to finish and try again; your upload is kept.
* A **warning** on some layouts still lets you save; those layouts may render less accurately.
* An **error** means the file needs to be re-uploaded.
* **Templates with embedded fonts take noticeably longer** to preview — that's expected, not a hang.

## 3. AI layout descriptions (background, after saving)

After you save, the AI studies each layout and writes internal guidance on when to use it (this is how Twistly picks the right layout for each slide it generates). These fill in over the next few minutes — you can use the template right away; layout selection just gets smarter once they're done.

## If the upload fails

* "At least 1 slide is required" — the file contains no usable slides.
* File too large — the limit is **100 MB**.
* Processing unavailable — a temporary service issue; try again in a few minutes, and [contact us](/help/contact-us.md) if it persists.