refactor: rename aris to aelis (#59)

Rename all references across the codebase: package names,
imports, source IDs, directory names, docs, and configs.

Co-authored-by: Ona <no-reply@ona.com>

apps/aelis-backend/src/session/user-session.ts

@@ -0,0 +1,104 @@
+import { FeedEngine, type FeedItem, type FeedResult, type FeedSource } from "@aelis/core"
+
+import type { FeedEnhancer } from "../enhancement/enhance-feed.ts"
+
+export class UserSession {
+	readonly engine: FeedEngine
+	private sources = new Map<string, FeedSource>()
+	private readonly enhancer: FeedEnhancer | null
+	private enhancedItems: FeedItem[] | null = null
+	/** The FeedResult that enhancedItems was derived from. */
+	private enhancedSource: FeedResult | null = null
+	private enhancingPromise: Promise<void> | null = null
+	private unsubscribe: (() => void) | null = null
+
+	constructor(sources: FeedSource[], enhancer?: FeedEnhancer | null) {
+		this.engine = new FeedEngine()
+		this.enhancer = enhancer ?? null
+		for (const source of sources) {
+			this.sources.set(source.id, source)
+			this.engine.register(source)
+		}
+
+		if (this.enhancer) {
+			this.unsubscribe = this.engine.subscribe((result) => {
+				this.invalidateEnhancement()
+				this.runEnhancement(result)
+			})
+		}
+
+		this.engine.start()
+	}
+
+	/**
+	 * Returns the current feed, refreshing if the engine cache expired.
+	 * Enhancement runs eagerly on engine updates; this method awaits
+	 * any in-flight enhancement or triggers one if needed.
+	 */
+	async feed(): Promise<FeedResult> {
+		const cached = this.engine.lastFeed()
+		const result = cached ?? (await this.engine.refresh())
+
+		if (!this.enhancer) {
+			return result
+		}
+
+		// Wait for any in-flight background enhancement to finish
+		if (this.enhancingPromise) {
+			await this.enhancingPromise
+		}
+
+		// Serve cached enhancement only if it matches the current engine result
+		if (this.enhancedItems && this.enhancedSource === result) {
+			return { ...result, items: this.enhancedItems }
+		}
+
+		// Stale or missing — re-enhance
+		await this.runEnhancement(result)
+
+		if (this.enhancedItems) {
+			return { ...result, items: this.enhancedItems }
+		}
+
+		return result
+	}
+
+	getSource<T extends FeedSource>(sourceId: string): T | undefined {
+		return this.sources.get(sourceId) as T | undefined
+	}
+
+	destroy(): void {
+		this.unsubscribe?.()
+		this.unsubscribe = null
+		this.engine.stop()
+		this.sources.clear()
+		this.invalidateEnhancement()
+		this.enhancingPromise = null
+	}
+
+	private invalidateEnhancement(): void {
+		this.enhancedItems = null
+		this.enhancedSource = null
+	}
+
+	private runEnhancement(result: FeedResult): Promise<void> {
+		const promise = this.enhance(result)
+		this.enhancingPromise = promise
+		promise.finally(() => {
+			if (this.enhancingPromise === promise) {
+				this.enhancingPromise = null
+			}
+		})
+		return promise
+	}
+
+	private async enhance(result: FeedResult): Promise<void> {
+		try {
+			this.enhancedItems = await this.enhancer!(result.items)
+			this.enhancedSource = result
+		} catch (err) {
+			console.error("[enhancement] Unexpected error:", err)
+			this.invalidateEnhancement()
+		}
+	}
+}