Gemini Skills replace Gems: a saved workflow you call by API

If you built a Gem in the Gemini app, Google says it will migrate it to a Skill automatically when Gems go away. If you want a saved workflow that your own backend can call, that is a different object, and on Sume it is a Format: POST /v1/formats/{handle}/{slug}/runs with an instruction and input, answered by a receipt and finished media on media.sume.com.

The Gemini facts come from the Gemini Apps release notes entry dated 2026.09.30, read 2026-10-10. That entry describes Skills as "a reusable set of instructions that tell Gemini how to handle specific tasks" and says nothing about API access, so this post does not claim Skills can or cannot be called by API; it only says the note I read is silent on it.

What the release note says

According to the entry, Skills are saved shortcuts for faster prompting. You can build one from a chat, Gemini can trigger it when a matching prompt appears, and several can be stacked together for a complex task. Skills "will soon replace Gems," and Google says it will automatically migrate your Gems into skills when Gems go away, pointing users to the help center for migration steps.

That is a description of an app feature for a person typing prompts. Nothing in the note covers a spend limit, a webhook, or a machine-readable result, which is why the comparison below leaves those cells as not stated.

What a Sume Format is

A Format is a saved production recipe for one kind of video: a house style, an output contract, and a playbook, stored as a SKILL.md body with reference files. Your backend calls it by name, Sume runs it in a fresh sandbox with the generation tools, and you read back media plus, if you ask, JSON in a schema you supplied.

The recipe is set before your instruction. The agent receives the Format first and your instruction after it, so where the two disagree, the model does what you asked. You do not resend a system prompt on every call. A run is one unattended turn, so it never stops to ask a person a question.

Starting from a ready-made recipe

You do not have to author a Format first. Sume ships a catalog that answers at the reserved sume handle, for example sume-product-commercial, sume-virtual-try-on and sume-video-hook. Any key with formats:write can call one, and the run, its media and its spend belong to your key. Read GET /v1/formats/sume/{slug} first: it returns the description and an io profile such as url_to_video, which tells you whether the Format takes a URL, text, an image or a product.

To change a catalog recipe, fork it in the Format library. Your copy is addressed as {your_handle}/{slug}, and you call it the same way.

What migrating a Gem does not mean

Moving a Gem to a Skill is Google's migration inside Gemini. Sume does not import Gems or Skills, and a Format is not a general chat shortcut: it is built for media production, and a run is billed against your workspace wallet within its cap. Authoring is a separate surface from calling: you write the recipe in the Agents dashboard, in chat, or over the Contents API, while the run endpoints only execute it.

Two practical limits are worth knowing before you plan around it. A Format outside your key's workspace answers 404 format_not_found, and a team-owned Format needs a key created in that workspace. Long video runs usually take 15 to 30 minutes, so design for a webhook or polling from the start.

A one-call sketch

This is the shape of a catalog call, using a Format from the docs list. Replace the slug with one you have read, and set a cap you accept:

curl -sS -X POST "https://api.sume.com/v1/formats/sume/sume-video-hook/runs" \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: gems-to-formats-001" \
  -d '{"instruction":"9:16 hook for a reusable water bottle.","input":{"product_name":"Trail Bottle"},"generation_spend_cap_usd":20}'