feat!: split functions package

[eduardoboucas]

Breaks up the @netlify/functions module into two:

• @netlify/functions: production runtime logic, published from the packages/functions/prod directory
• @netlify/functions-dev: local development emulation logic, published from the packages/functions/dev directory

I've opted for the nested directory setup, where functions has both dev and prod as opposed to top-level functions and functions-dev directories, as a way to convey the relationship between the packages. I'm hoping that release-please will be okay with this setup, but I haven't actually tested.

If that works and we're okay with this setup, we can apply the same logic to the other packages.

Part of https://linear.app/netlify/issue/FRB-2012/separate-types-and-public-methods-from-internal-dependencies.

BREAKING CHANGE

The /dev export, introduced in version 3.1.0, has been removed.

The local development functionality has been extracted into a new @netlify/functions-dev package. If your application relies on that logic, you should npm install @netlify/functions-dev and update your import:

-import { FunctionsHandler } from "@netlify/functions/dev"
+import { FunctionsHandler } from "@netlify/functions-dev"

No other changes are needed.

[pieh]

I've opted for the nested directory setup, where functions has both dev and prod as opposed to top-level functions and functions-dev directories, as a way to convey the relationship between the packages. I'm hoping that release-please will be okay with this setup, but I haven't actually tested.

If that works and we're okay with this setup, we can apply the same logic to the other packages.

I think it's doable to make release please happy, I just tried adjusting config on top of the current changes ( c9110e9 ) and run npx release-please release-pr --token="$(gh auth token)" --repo-url=netlify/primitives --dry-run --target-branch=feat/split-functions-release-please-test and it produced following:

dev: 5.0.0

5.0.0 (2025-10-13)

⚠ BREAKING CHANGES

• split functions package

Features

• split functions package (4a5d768)

Dependencies

• The following workspace dependencies were updated
  • dependencies
    • @netlify/functions bumped from 4.3.0 to 5.0.0

functions: 5.0.0

5.0.0 (2025-10-13)

⚠ BREAKING CHANGES

• split functions package

Features

• split functions package (4a5d768)

functions-dev: 5.0.0

5.0.0 (2025-10-13)

⚠ BREAKING CHANGES

• split functions package

Features

• split functions package (4a5d768)

Dependencies

• The following workspace dependencies were updated
  • dependencies
    • @netlify/functions bumped from 4.3.0 to 5.0.0

nuxt: 0.2.1

0.2.1 (2025-10-13)

Dependencies

• The following workspace dependencies were updated
  • dependencies
    • @netlify/dev bumped from ^4.6.0 to ^5.0.0

vite-plugin: 2.7.1

2.7.1 (2025-10-13)

Dependencies

• The following workspace dependencies were updated
  • dependencies
    • @netlify/dev bumped from 4.6.0 to 5.0.0

vite-plugin-tanstack-start: 1.1.1

1.1.1 (2025-10-13)

Dependencies

• The following workspace dependencies were updated
  • dependencies
    • @netlify/vite-plugin bumped from ^2.7.0 to ^2.7.1

---

This PR was generated with Release Please. See documentation.

---

only question is what the initial version of functions-dev package should be? We can skip putting any version in manifest and the it will produce 1.0.0 as initial version

Also note that I did have to bump last release sha in config, as otherwise functions-dev get bunch of outdated entries in changelog like so:

functions-dev: 1.0.0

1.0.0 (2025-10-13)

⚠ BREAKING CHANGES

• split functions package

Features

• add support for edge functions (#233) (c80d77d)
• Adds W3C trace context propagation to tracer provider (#471) (afe4656)
• move primitives into monorepo (#101) (93b72b1)
• split functions package (4a5d768)

[serhalp]

Definitely on board with this!

So good:
13 direct deps → 1 direct dep
311 transitive deps → 1 transitive dep
82 MB install size → 84 KB install size

[eduardoboucas]

Also note that I did have to bump last release sha in config, as otherwise functions-dev get bunch of outdated entries in changelog like so:

@pieh do you mind committing this?

[pieh]

@pieh do you mind committing this?

To not mess up your ongoing work - #476 is PR against this branch so you can merge whenever it's convenient