RequestEvent

A remote function begins with decoded input, although the request often carries context of its own. A session cookie may identify the caller, while locals may contain data prepared by a server hook.

SER exposes the current SvelteKit request as the RequestEvent effect service. Yield it inside a remote handler to read the request that triggered that call.

Read the current request

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RequestEvent includes cookies, getClientAddress, locals, params, platform, request, route, and url.

import { Effect } from "effect";
import { Query, RequestEvent } from "svelte-effect-runtime";

export const GetSession = Query(
	Effect.gen(function* () {
		const event = yield* RequestEvent;
		const session_id = event.cookies.get("session") ?? null;

		return {
			session_id,
			path: event.url.pathname,
		};
	}),
);

The value is the request for this invocation of GetSession(). Another request receives another service value, even though both handlers run through the same server runtime.

Change a cookie

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The cookie API is SvelteKit's own. A command can delete the session cookie before it returns:

import { Effect } from "effect";
import { Command, RequestEvent } from "svelte-effect-runtime";

export const SignOut = Command(
	Effect.gen(function* () {
		const event = yield* RequestEvent;

		event.cookies.delete("session", { path: "/" });
	}),
);

SvelteKit still applies its usual cookie rules, including an explicit path when deleting a cookie.

Read it from a helper

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An effect called by the handler inherits the same request context. This keeps request access inside the effect graph without threading the event through every function argument.

import { Effect } from "effect";
import { RequestEvent } from "svelte-effect-runtime";

export const ReadSessionId = Effect.gen(function* () {
	const event = yield* RequestEvent;

	return event.cookies.get("session") ?? null;
});

import { ReadSessionId } from "$lib/server/session";
import { Query } from "svelte-effect-runtime";

export const GetSessionId = Query(ReadSessionId);

Request scope

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SER installs the current RequestEvent value around each remote handler effect. Concurrent calls can share one ServerRuntime, yet each handler reads cookies and locals from its own request.

Outside a remote handler

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Yielding RequestEvent during module initialization, runtime startup, or another effect without a remote request throws RequestEventUnavailableError.

That error means the effect was evaluated before SER installed request context. Move the yield* RequestEvent into the remote handler or an effect reached from that handler.