feat: add GET /api/feed endpoint

Expose the user's current feed via GET /api/feed. Returns
cached feed from engine.lastFeed(), falling back to
engine.refresh() when no cache exists.

Auth middleware is injected as a dependency to allow test
substitution via mockAuthSessionMiddleware.

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

apps/aris-backend/src/feed/http.ts

@@ -0,0 +1,41 @@
+import type { Context, Hono } from "hono"
+
+import { createMiddleware } from "hono/factory"
+
+import type { AuthSessionMiddleware } from "../auth/session-middleware.ts"
+import type { UserSessionManager } from "../session/index.ts"
+
+type Env = { Variables: { sessionManager: UserSessionManager } }
+
+interface FeedHttpHandlersDeps {
+	sessionManager: UserSessionManager
+	authSessionMiddleware: AuthSessionMiddleware
+}
+
+export function registerFeedHttpHandlers(
+	app: Hono,
+	{ sessionManager, authSessionMiddleware }: FeedHttpHandlersDeps,
+) {
+	const inject = createMiddleware<Env>(async (c, next) => {
+		c.set("sessionManager", sessionManager)
+		await next()
+	})
+
+	app.get("/api/feed", inject, authSessionMiddleware, handleGetFeed)
+}
+
+async function handleGetFeed(c: Context<Env>) {
+	const user = c.get("user")!
+	const sessionManager = c.get("sessionManager")
+	const session = sessionManager.getOrCreate(user.id)
+
+	const feed = session.engine.lastFeed() ?? (await session.engine.refresh())
+
+	return c.json({
+		items: feed.items,
+		errors: feed.errors.map((e) => ({
+			sourceId: e.sourceId,
+			error: e.error.message,
+		})),
+	})
+}