Sveltekit flags enhancements

[dummdidumm]

This enhances the SvelteKit adapter in several ways:

• use $env/dynamic/private, which means people don't have to pass FLAGS_SECRET manually anymore. This means Vite will have to compile this in the context of the app, but that's not a problem and should happen automatically
• allow a created flag to be called oustide of the lifecycle of the handle hook, with a request object being the key for deduplication etc. This allows it to be called from e.g. edge middleware
• add support for identifiers, including deduplicating their calls. This is achieved by adding a Map onto the context in which flags run, with the identify function being the key. That means calls are deduplicated automatically as soon as you share a stable reference to the function across flags
• add createPrecomputedFlags which is a function for generating permutations, then precomputing one and retrieving it. It's different to the Next.js API because it does not need you to pass the array of flags everywhere, instead you define which flags belong to which route param once and then access methods on the returned object. Using it feels a bit nicer than the Next.js approach IMO, but open to suggestions model precompute API closely after Next.js to align

This needs sveltejs/kit#13477 to land first, so that you can actually precompute something in middleware, and it would be good to also enhance the example SvelteKit app as well then. Makes use of the new async reroute feature in SvelteKit.

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
flags-sdk-snippets	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 12, 2025 10:35am
flags-sdk-sveltekit-snippets	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 12, 2025 10:35am
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[dummdidumm]

Ready for review - let me know if the examples need tweaking / should be aligned in specific ways with the Next examples.

Also, is there anything with regards to the docs we should be updating / adjusting at the same time?

[socket-security]

New, updated, and removed dependencies detected. Learn more about Socket for GitHub ↗︎

Package	New capabilities	Transitives	Size	Publisher
npm/@sveltejs/[email protected] ➜ 4.0.0	None	+1	85 kB	conduitry, dominik_g, rich_harris, ...1 more
npm/@sveltejs/[email protected]	Transitive: filesystem	+14	1.66 MB	conduitry, dominik_g, rich_harris, ...1 more
npm/[email protected] ➜ 4.1.5	Transitive: environment, filesystem	+10	5.59 MB	dummdidumm, orta, svelte-language-tools-deploy
npm/[email protected] ➜ 5.22.6	None	+17	4.6 MB	conduitry, rich_harris, svelte-admin

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