Support partitioned cookies

[jmortlock]

Changes

Allows creation of partitioned cookies, https://developer.mozilla.org/en-US/docs/Web/Privacy/Guides/Privacy_sandbox/Partitioned_cookies.

This is provided in the underlying library:
https://github.com/jshttp/cookie?tab=readme-ov-file#partitioned

Testing

• Added unit tests
• Using this patch on my own servers

Docs

Will need to update https://docs.astro.build/en/reference/api-reference/#cookies

/cc @withastro/maintainers-docs for feedback!

[changeset-bot]

🦋 Changeset detected

Latest commit: ebd311a

The changes in this PR will be included in the next version bump.

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[codspeed-hq]

Merging this PR will not alter performance

✅ 9 untouched benchmarks

---

_{Comparing jmortlock:support-partitioned-cookies (ebd311a) with main (37ab65a)¹}

Footnotes

1. No successful run was found on main (7f449b7) during the generation of this report, so 37ab65a was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[Princesseuh]

This will need to be a minor, unfortunately!

Suggested change

	'astro': patch
	'astro': minor

[Princesseuh]

Looks great, thank you very much!

[sarah11918]

Thank you for this cool feature @jmortlock ! This sounds like a great option to have.

I've left a comment below as an example to help you create our typical changeset to help promote the feature and make sure people understand what it is, and see how they can use it in their project right away.

As for documentation, you're right that we'll want a new API reference entry at https://docs.astro.build/en/reference/api-reference/#astrocookiesetoptions in a separate PR to the docs repo. (https://github.com/withastro/docs) You can follow the existing model there, but note that you'll also need to add a <Since /> component to show that this was added at a later date than the other options. You can find contributing docs for our API reference format (including yes, that weird blank line 😅 at https://contribute.docs.astro.build/reference/api-references/ if you need to check anything!)

[sarah11918]

Lucky you, this is a minor feature so... that means time to hype! 🥳

For a minor release of a new feature, we'd usually hype it up a bit more, focusing on what a user can now do (with an example usage shown) rather than implementation details. You can see a model of this in our contributing docs:

• Quick sentence to shout "New! Shiny!" and grab people's attention without a lot of visual clutter
• describe the problem it solves or ability it unlocks and why that's cool
• show an example that people could copy into their projects right away to try it out so that it's easy for them to get started
• link to the docs for the new thing

So maybe something like... (just rough wording to get the idea of the structure across!)

Suggested change

	Updates the `AstroCookieSetOptions` type exported from `astro` to allow partitioned cookies
	Adds a new `partition` option that can be passed when setting a cookie to allow creating partitioned cookies
	[Partitioned cookies](https://developer.mozilla.org/en-US/docs/Web/Privacy/Guides/Privacy_sandbox/Partitioned_cookies) can only be read within the context of the top-level site they were set on. This allows cross-site tracking to be blocked, while still enabling legitimate uses of third-party cookies.
	You can create a partitioned cookie by passing `partition` when setting the cookie:
	```
	// a code example of what this would look like in Astro code
	```
	For more information, see the [`AstroCookieSetOptions` API reference](https://docs.astro.build/en/reference/api-reference/#astrocookiesetoptions)

[sarah11918]

(It's only been a few days so no rush, but just a reminder that there's a Docs PR required for this PR, and a changeset comment to address!)