feat: deprecate Slice Machine and redirect to the Prismic CLI

[angeloashmore]

Resolves: Slice Machine Deprecation Steps

Description

Before this PR, npx @slicemachine/init created new Slice Machine projects, and AI agents trained before the Prismic CLI existed still reach for it.

After this PR, every Slice Machine package says it is deprecated and points to the Prismic CLI and the Type Builder. Creating a new project stops unless someone deliberately chooses Slice Machine. Existing projects keep working, with a notice they can turn off.

Checklist

• If my changes require tests, I added them.
• If my changes affect backward compatibility, it has been discussed.
• If my changes require an update to the CONTRIBUTING.md guide, I updated it.

Preview

$ npx @slicemachine/init --repository my-repo
Slice Machine is deprecated. The @slicemachine/init command is replaced by prismic init, which models content in the Type Builder:

  npx prismic init --repo my-repo

--force sets up a project with the deprecated Slice Machine. It is not recommended:

  npx @slicemachine/init --repository my-repo --force

Working with an AI agent? Install the Prismic skill so it knows the current workflow:

  npx skills add --global --yes prismicio/skills

Docs: https://prismic.io/docs/cli
Existing Slice Machine projects: https://prismic.io/docs/slice-machine

$ npx @slicemachine/init --repository my-repo --force
Slice Machine is deprecated. Continuing because --force was passed.

The @slicemachine/init command is replaced by prismic init, which models content in the Type Builder:

  npx prismic init --repo my-repo

Docs: https://prismic.io/docs/cli

? Which framework do you want to use? …

$ npx start-slicemachine
Slice Machine is deprecated. This project still works, but Slice Machine is no longer updated.

New projects use the Type Builder, and this project can move to it with the Prismic CLI:

  npx prismic init

Working with an AI agent? Install the Prismic skill so it knows the current workflow:

  npx skills add --global --yes prismicio/skills

Docs: https://prismic.io/docs/slice-machine#migrate-to-the-type-builder
Set PRISMIC_IGNORE_SLICE_MACHINE_DEPRECATION=1 to hide this notice.

Slice Machine started at http://localhost:9999

How to QA ¹

Run yarn build-essential, then node packages/init/bin/slicemachine-init.js --help. The message prints and the exit code is 1. Run yarn workspace @slicemachine/init build, then node packages/init/bin/slicemachine-init.js --force --version. The notice prints, then the version. Run yarn workspace start-slicemachine build, then node packages/start-slicemachine/bin/start-slicemachine.js --version. The notice prints, then the version. Run it again with PRISMIC_IGNORE_SLICE_MACHINE_DEPRECATION=1 and only the version prints.

🤖 Generated with Claude Code

https://claude.ai/code/session_0154ki8C9BX9VcoQFgARKJFp

Footnotes

1. Please use these labels when submitting a review:
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Project	Deployment	Actions	Updated
slice-machine	Ready	Preview	Sep 17, 2026 10:27pm UTC

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[lihbr]

LGMT but an important suggestion, see below

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