Imported from minghanminghan/jev-demo (AGENTS.md). Install upstream with npx skills add minghanminghan/jev-demo. Copyright stays with the author.

jev demo

Name: jev-demo
Author: minghanminghan

Next.js 16 (App Router, Turbopack) + React 19. One page, no router.

Next is here for one reason: app/api/jev and app/api/llm have to run somewhere other than a browser. Everything else still runs in the tab.

app/layout.tsx → app/page.tsx → components/Studio.tsx. One page.
app/page.tsx loads Studio with next/dynamic and ssr: false. That is load bearing, not an optimisation: every component measures the DOM or reads localStorage, and lib/route-engine.ts runs in the browser. "use client" appears on app/page.tsx only; the whole graph below it inherits it.
@/ resolves to the repo root (tsconfig.json). components/, lib/ and data/ stay at the root rather than moving under app/.
lib/route-engine.ts runs in the browser. Keep node: imports out of lib/ and components/. app/api/, next.config.ts and scripts/ are the only places server or Node code belongs.
data/*.json is imported, not read off disk. Nothing writes a file.
The jev API allows no browser origin, so the SDK is pointed at /api/jev and app/api/jev/[...path]/route.ts passes it through to api.typesafe.ai. The comparison LLM goes through /api/llm, which reads its real endpoint off an x-llm-url header — the provider is whatever the user typed, so the target cannot be fixed at config time. /api/llm forwards only to hosts on the allowlist in app/api/llm/allowlist.ts, and never to link-local addresses. If you change either path, change it in both lib/types.ts (JEV_PROXY_PATH, LLM_PROXY_PATH, LLM_TARGET_HEADER) and the folder name under app/api/.
The app is served under /jev-demo, not at a host root. lib/base-path.ts holds the prefix; next.config.ts feeds it to basePath and lib/types.ts puts it on the front of both proxy paths, because basePath does not touch a hand-written fetch. The personal site rewrites /jev-demo/* through to this project, so a URL without the prefix lands on the site instead of here.
Both routes are relays: they attach whatever key the caller sends to a request the server makes. A deployed copy needs Vercel Deployment Protection or equivalent in front of it. See the README.
lib/route-engine.ts must not learn which engine answered it. It takes an Oracle (lib/oracle.ts); jevOracle and llmOracle are the two. That is what makes the side-by-side comparison worth anything, so keep engine-specific behaviour behind that interface rather than branching in the walk.
The AI SDK builds its request URL as new URL(baseURL + path) with no base to resolve against, so any baseURL handed to a provider has to stay absolute.
Fonts come from next/font in app/layout.tsx, which sets --next-inter and --next-geist-mono on <html>. app/globals.css re-exports both as --font-inter / --font-geist-mono and adds the fallback chain.
data/providers.json is generated — node scripts/snapshot-providers.mjs, which reads models.dev. Do not hand-edit it.
Only models reporting structured_output are snapshotted. That is load bearing: a model that cannot be held to a schema cannot answer the question, and offering one makes the comparison lie.

npm run build is next build, which type-checks as it goes. Run npm run lint too.

next dev wants to append a generated block to this file. agentRules: false in next.config.ts turns that off, so everything here is hand-written. If a  section reappears, that setting was lost.

{ "ocm": "1", "id": "minghanminghan-jev-demo-jev-demo", "kind": "skill", "name": "jev-demo", "description": "Next is here for one reason: `app/api/jev` and `app/api/llm` have to run somewhere other than a browser. Everything else still runs in the tab.", "publisher": "minghanminghan", "version": "1.0.0", "capabilities": { "domains": [ "coding" ], "tags": [ "skill-md", "github-agents" ], "languages": [ "en" ] }, "quality_prior": 0.6, "examples": [ "Next is here for one reason: `app/api/jev` and `app/api/llm` have to run somewhere other than a browser. Everything else still runs in the tab." ], "primary": false, "metadata": { "source": { "provider": "github-agents", "repository": "https://github.com/minghanminghan/jev-demo", "path": "AGENTS.md", "ref": "ef6adb077e3ff3fbfcb2bca16366b684aefadd28", "url": "https://github.com/minghanminghan/jev-demo/blob/ef6adb077e3ff3fbfcb2bca16366b684aefadd28/AGENTS.md", "key": "minghanminghan/jev-demo/AGENTS.md" } }, "instructions": "# jev demo\n\n**Next.js 16** (App Router, Turbopack) + **React 19**. One page, no router.\n\nNext is here for one reason: `app/api/jev` and `app/api/llm` have to run\nsomewhere other than a browser. Everything else still runs in the tab.\n\n- `app/layout.tsx` → `app/page.tsx` → `components/Studio.tsx`. One page.\n- `app/page.tsx` loads Studio with `next/dynamic` and **`ssr: false`**. That is\n load bearing, not an optimisation: every component measures the DOM or reads\n `localStorage`, and `lib/route-engine.ts` runs in the browser. `\"use client\"`\n appears on `app/page.tsx` only; the whole graph belo", "cost": { "context_tokens": 896 } }

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