active-svelte/demos/dating/web/_lib/context.ts

/**
 * Svelte context bridge for the Nexo runtime: the `DatingAppHandle`
 * (App + API) plus a session cell owned by the shell layout. Nested
 * pages and components consume both via `getNexoContext()` instead of
 * each rebuilding their own.
 *
 * Symbol-keyed (instead of `setContext('app', ...)`) so it can't
 * collide with whatever else the surrounding SvelteKit app registers.
 *
 * `session` is exposed as a getter — pages call `nexo.session()` so
 * `$derived(...)` and `$effect(...)` track session-aware UI without
 * each page re-issuing its own `/api/session` probe.
 */

import { getContext, setContext } from 'svelte';
import type { DatingAppHandle } from './app.ts';
import type { DatingRealtimeHandle } from './realtime.ts';
import type { DatingSessionResponse } from './types.ts';

export interface NexoContext extends DatingAppHandle {
	/** Current session snapshot. `null` while the initial probe is in flight. */
	session(): DatingSessionResponse | null;
	/** Replace the session cell after a login / logout / refresh. */
	setSession(next: DatingSessionResponse | null): void;
	/** Re-issue `/api/session`; layout uses it on mount, pages on demand. */
	refreshSession(): Promise<DatingSessionResponse | null>;
	/**
	 * Shared WebSocket subscription to `/api/realtime`. Pages call
	 * `realtime().subscribe(...)` to react to server-pushed events
	 * (new chat messages, match updates, …). The layout owns the
	 * single underlying connection.
	 */
	realtime(): DatingRealtimeHandle;
}

const NEXO_CONTEXT_KEY = Symbol('nexo.context');

export function setNexoContext(value: NexoContext): NexoContext {
	return setContext(NEXO_CONTEXT_KEY, value);
}

export function getNexoContext(): NexoContext {
	const value = getContext<NexoContext | undefined>(NEXO_CONTEXT_KEY);
	if (value === undefined) {
		throw new Error('Nexo context is not set. Did you mount /dating without its layout?');
	}
	return value;
}

// Back-compat aliases — pages that only need the App handle keep the
// terser names. New code uses `getNexoContext()` for the session
// surface too.
export const setNexoApp = setNexoContext;
export const getNexoApp = getNexoContext;