Agent Skills
› fanfan-de/anybox
› vercel-functions
vercel-functions
GitHub提供 Vercel Functions 专家指导，涵盖 Serverless、Edge、Bun、Rust 运行时及 Fluid Compute。用于配置、调试和优化 Vercel 平台上的服务端代码，包括流式处理、定时任务及性能调优。
Trigger Scenarios
Vercel 函数配置与调试
选择 Node.js 或 Edge 运行时
优化 Fluid Compute 性能
解决冷启动或超时问题
Install
npx skills add fanfan-de/anybox --skill vercel-functions -g -y
SKILL.md
Frontmatter
{
"name": "vercel-functions",
"chainTo": [
{
"message": "Direct AI provider SDK in route handler — loading AI SDK guidance for unified streaming and tool support.",
"pattern": "from\\s+['\\\"](openai|@anthropic-ai\/sdk|anthropic)['\"]|new\\s+(OpenAI|Anthropic)\\(",
"targetSkill": "ai-sdk"
},
{
"message": "Long-running or polling logic in serverless handler — loading Workflow DevKit for durable execution.",
"pattern": "setTimeout\\s*\\(|setInterval\\s*\\(|await\\s+new\\s+Promise\\s*\\([^)]*setTimeout",
"targetSkill": "workflow"
},
{
"message": "Local filesystem write in serverless function — loading Vercel Storage guidance for platform-native persistence.",
"pattern": "writeFile(Sync)?\\(|createWriteStream\\(|from\\s+['\\\"](multer|formidable)['\"]|fs\\.writeFile",
"targetSkill": "vercel-storage"
},
{
"message": "@vercel\/postgres and @vercel\/kv are sunset — loading Vercel Storage guidance for Neon and Upstash migration.",
"pattern": "from\\s+['\"\"]@vercel\/(postgres|kv)['\"\"]",
"targetSkill": "vercel-storage"
},
{
"message": "Deprecated AI SDK v5 API detected — loading AI SDK v6 guidance for migration.",
"pattern": "generateObject\\s*\\(|streamObject\\s*\\(|toDataStreamResponse|maxSteps\\b|CoreMessage\\b",
"targetSkill": "ai-sdk"
},
{
"message": "Polling loop in serverless function detected — loading Workflow DevKit for durable, crash-safe execution with pause\/resume.",
"pattern": "while\\s*\\(\\s*true\\s*\\)\\s*\\{|for\\s*\\(\\s*;\\s*;\\s*\\)\\s*\\{|setInterval\\s*\\(\\s*async",
"targetSkill": "workflow",
"skipIfFileContains": "use workflow|use step|from\\s+['\"]workflow['\"]"
},
{
"message": "Express.js detected — loading Vercel Functions guidance for Web Request\/Response API route handlers that replace Express middleware and routing.",
"pattern": "from\\s+['\"]express['\"]|require\\s*\\(\\s*['\"]express['\"]",
"targetSkill": "vercel-functions",
"skipIfFileContains": "export\\s+(async\\s+)?function\\s+(GET|POST|PUT|PATCH|DELETE)"
},
{
"message": "In-process memory cache in serverless function — loading Runtime Cache guidance for region-aware caching that persists across invocations.",
"pattern": "from\\s+['\"\"](lru-cache|node-cache|memory-cache)['\"\"]|new\\s+(LRUCache|NodeCache|Map)\\(\\s*\\).*cache",
"targetSkill": "runtime-cache",
"skipIfFileContains": "getCache|from\\s+['\"\"]\\@vercel\/functions['\"\"]"
},
{
"message": "Manual retry logic in serverless handler — loading Workflow DevKit guidance for automatic retries with durable execution.",
"pattern": "maxRetries\\s*[=:]|retryCount\\s*[=:]|retry\\s*\\(\\s*|for\\s*\\([^)]*retry|while\\s*\\([^)]*retry",
"targetSkill": "workflow",
"skipIfFileContains": "use workflow|use step|@vercel\/workflow|from\\s+['\"\"](workflow)['\"\"]"
}
],
"metadata": {
"docs": [
"https:\/\/vercel.com\/docs\/functions",
"https:\/\/vercel.com\/docs\/functions\/runtimes"
],
"sitemap": "https:\/\/vercel.com\/sitemap\/docs.xml",
"priority": 8,
"bashPatterns": [
"\\bvercel\\s+dev\\b",
"\\bvercel\\s+logs\\b"
],
"pathPatterns": [
"api\/**\/*.*",
"pages\/api\/**",
"src\/pages\/api\/**",
"app\/**\/route.*",
"src\/app\/**\/route.*",
"apps\/*\/api\/**\/*.*",
"apps\/*\/app\/**\/route.*",
"apps\/*\/src\/app\/**\/route.*",
"apps\/*\/pages\/api\/**",
"vercel.json",
"apps\/*\/vercel.json"
]
},
"validate": [
{
"message": "Use named exports (GET, POST, PUT, DELETE) instead of default export for route handlers",
"pattern": "export\\s+default\\s+function",
"severity": "error"
},
{
"message": "NextApiRequest\/NextApiResponse are Pages Router types — use Web API Request\/Response",
"pattern": "NextApiRequest|NextApiResponse",
"severity": "error"
},
{
"message": "Direct AI provider SDK detected in route handler. Use the Vercel AI SDK for streaming, tools, and provider abstraction.",
"pattern": "from\\s+['\"](openai|@anthropic-ai\/sdk|anthropic)['\"]|new\\s+(OpenAI|Anthropic)\\(",
"severity": "recommended",
"upgradeWhy": "Replace vendor-locked provider SDKs with @ai-sdk\/openai or @ai-sdk\/anthropic for unified streaming and tool support.",
"upgradeToSkill": "ai-sdk",
"skipIfFileContains": "@ai-sdk\/|from\\s+['\"](ai)['\"]|import.*from\\s+['\"](ai)['\"]|streamText|generateText"
},
{
"message": "Long-running or polling logic detected in a serverless handler. Functions have execution time limits.",
"pattern": "setTimeout\\s*\\(|setInterval\\s*\\(|await\\s+new\\s+Promise\\s*\\([^)]*setTimeout",
"severity": "recommended",
"upgradeWhy": "Move delayed\/polling logic to Vercel Workflow for durable execution with pause, resume, retries, and crash safety.",
"upgradeToSkill": "workflow",
"skipIfFileContains": "use workflow|use step|@vercel\/workflow"
},
{
"message": "Local filesystem write detected. Serverless functions have ephemeral, read-only filesystems.",
"pattern": "writeFile(Sync)?\\(|createWriteStream\\(|from\\s+['\"](multer|formidable)['\"]|fs\\.writeFile",
"severity": "error",
"upgradeWhy": "Replace local filesystem writes with Vercel Blob, Neon, or Upstash for persistent, platform-native storage.",
"upgradeToSkill": "vercel-storage",
"skipIfFileContains": "@vercel\/blob|@upstash\/|@neondatabase\/"
},
{
"message": "Route handler has no observability instrumentation. Add logging and error tracking for production debugging.",
"pattern": "export\\s+(async\\s+)?function\\s+(GET|POST|PUT|PATCH|DELETE)\\b",
"severity": "warn",
"skipIfFileContains": "console\\.error|logger\\.|captureException|Sentry|@vercel\/otel|withTracing"
},
{
"message": "In-process memory cache detected in serverless function. Process memory is not shared across invocations.",
"pattern": "from\\s+['\"\"](lru-cache|node-cache|memory-cache)['\"\"]|new\\s+(LRUCache|NodeCache|Map)\\(\\s*\\).*cache",
"severity": "recommended",
"upgradeWhy": "Replace in-process caches with Vercel Runtime Cache (getCache from @vercel\/functions) for region-aware caching that persists across invocations.",
"upgradeToSkill": "runtime-cache",
"skipIfFileContains": "getCache|from\\s+['\"\"]\\@vercel\/functions['\"\"]"
},
{
"message": "Manual retry logic detected. Use Vercel Workflow DevKit for automatic retries with durable execution.",
"pattern": "maxRetries\\s*[=:]|retryCount\\s*[=:]|retry\\s*\\(\\s*|for\\s*\\([^)]*retry|while\\s*\\([^)]*retry",
"severity": "recommended",
"upgradeWhy": "Replace manual retry loops with Workflow DevKit steps that provide automatic retries, crash safety, and observability.",
"upgradeToSkill": "workflow",
"skipIfFileContains": "use workflow|use step|@vercel\/workflow|from\\s+['\"\"](workflow)['\"\"]"
},
{
"message": "Express.js detected in a Vercel project. Vercel Functions use the Web Request\/Response API — Express middleware, req\/res, and app.listen() do not work in serverless.",
"pattern": "from\\s+['\"](express)['\"\"]|require\\s*\\(\\s*['\"](express)['\"\"\\)]",
"severity": "recommended",
"upgradeWhy": "Replace Express with Next.js route handlers (export async function GET\/POST) or Vercel Functions using the Web Request\/Response API.",
"upgradeToSkill": "vercel-functions",
"skipIfFileContains": "export\\s+(async\\s+)?function\\s+(GET|POST|PUT|PATCH|DELETE)|from\\s+['\"\"](next\/server|@vercel\/functions)['\"\"]"
}
],
"retrieval": {
"aliases": [
"serverless functions",
"api routes",
"edge functions",
"lambda"
],
"intents": [
"create serverless function",
"configure function runtime",
"optimize cold starts",
"add api route"
],
"entities": [
"Serverless Functions",
"Edge Functions",
"Fluid Compute",
"streaming",
"Cron Jobs"
]
},
"description": "Vercel Functions expert guidance — Serverless Functions, Edge Functions, Fluid Compute, streaming, Cron Jobs, and runtime configuration. Use when configuring, debugging, or optimizing server-side code running on Vercel."
}
Vercel Functions
You are an expert in Vercel Functions — the compute layer of the Vercel platform.
Function Types
Serverless Functions (Node.js)
- Full Node.js runtime, all npm packages available
- Default for Next.js API routes, Server Actions, Server Components
- Cold starts: 800ms–2.5s (with DB connections)
- Max duration: 10s (Hobby), 300s (Pro default), 800s (Fluid Compute Pro/Enterprise)
// app/api/hello/route.ts
export async function GET() {
return Response.json({ message: 'Hello from Node.js' })
}
Edge Functions (V8 Isolates)
- Lightweight V8 runtime, Web Standard APIs only
- Ultra-low cold starts (<1ms globally)
- Limited API surface (no full Node.js)
- Best for: auth checks, redirects, A/B testing, simple transformations
// app/api/hello/route.ts
export const runtime = 'edge'
export async function GET() {
return new Response('Hello from the Edge')
}
Bun Runtime (Public Beta)
Add "bunVersion": "1.x" to vercel.json to run Node.js functions on Bun instead. ~28% lower latency for CPU-bound workloads. Supports Next.js, Express, Hono, Nitro.
Rust Runtime (Public Beta)
Rust functions run on Fluid Compute with HTTP streaming and Active CPU pricing. Built on the community Rust runtime. Supports environment variables up to 64 KB.
Node.js 24 LTS
Node.js 24 LTS is now GA on Vercel for both builds and functions. Features V8 13.6, global URLPattern, Undici v7 for faster fetch(), and npm v11.
Choosing Runtime
| Need | Runtime | Why |
|---|---|---|
| Full Node.js APIs, npm packages | nodejs |
Full compatibility |
| Lower latency, CPU-bound work | nodejs + Bun |
~28% latency reduction |
| Ultra-low latency, simple logic | edge |
<1ms cold start, global |
| Database connections, heavy deps | nodejs |
Edge lacks full Node.js |
| Auth/redirect at the edge | edge |
Fastest response |
| AI streaming | Either | Both support streaming |
| Systems-level performance | rust (beta) |
Native speed, Fluid Compute |
Fluid Compute
Fluid Compute is the unified execution model for all Vercel Functions (both Node.js and Edge).
Key benefits:
- Optimized concurrency: Multiple invocations on a single instance — up to 85% cost reduction for high-concurrency workloads
- Extended durations: Default 300s for all plans; up to 800s on Pro/Enterprise
- Active CPU pricing: Charges only while CPU is actively working, not during idle/await time. Enabled by default for all plans. Memory-only periods billed at a significantly lower rate.
- Background processing:
waitUntil/afterfor post-response tasks - Dynamic scaling: Automatic during traffic spikes
- Bytecode caching: Reduces cold starts via Rust-based runtime with pre-compiled function code
- Multi-region failover: Default for Enterprise when Fluid is activated
Instance Sizes
| Size | CPU | Memory |
|---|---|---|
| Standard (default) | 1 vCPU | 2 GB |
| Performance | 2 vCPU | 4 GB |
Hobby projects use Standard CPU. The Basic CPU instance has been removed.
Background Processing with waitUntil
// Continue work after sending response
import { waitUntil } from '@vercel/functions'
export async function POST(req: Request) {
const data = await req.json()
// Send response immediately
const response = Response.json({ received: true })
// Continue processing in background
waitUntil(async () => {
await processAnalytics(data)
await sendNotification(data)
})
return response
}
Next.js after (equivalent)
import { after } from 'next/server'
export async function POST(req: Request) {
const data = await req.json()
after(async () => {
await logToAnalytics(data)
})
return Response.json({ ok: true })
}
Streaming
Zero-config streaming for both runtimes. Essential for AI applications.
export async function POST(req: Request) {
const encoder = new TextEncoder()
const stream = new ReadableStream({
async start(controller) {
for (const chunk of data) {
controller.enqueue(encoder.encode(chunk))
await new Promise(r => setTimeout(r, 100))
}
controller.close()
},
})
return new Response(stream, {
headers: { 'Content-Type': 'text/event-stream' },
})
}
For AI streaming, use the AI SDK's toUIMessageStreamResponse() (for chat UIs with useChat) which handles SSE formatting automatically.
Cron Jobs
Schedule function invocations via vercel.json:
{
"crons": [
{
"path": "/api/daily-report",
"schedule": "0 8 * * *"
},
{
"path": "/api/cleanup",
"schedule": "0 */6 * * *"
}
]
}
The cron endpoint receives a normal HTTP request. Verify it's from Vercel:
export async function GET(req: Request) {
const authHeader = req.headers.get('authorization')
if (authHeader !== `Bearer ${process.env.CRON_SECRET}`) {
return new Response('Unauthorized', { status: 401 })
}
// Do scheduled work
return Response.json({ ok: true })
}
Configuration via vercel.json
Deprecation notice: Support for the legacy now.json config file will be removed on March 31, 2026. Rename now.json to vercel.json (no content changes required).
{
"functions": {
"app/api/heavy/**": {
"maxDuration": 300,
"memory": 1024
},
"app/api/edge/**": {
"runtime": "edge"
}
}
}
Timeout Limits
All plans now default to 300s execution time with Fluid Compute.
| Plan | Default | Max |
|---|---|---|
| Hobby | 300s | 300s |
| Pro | 300s | 800s |
| Enterprise | 300s | 800s |
Common Pitfalls
- Cold starts with DB connections: Use connection pooling (e.g., Neon's
@neondatabase/serverless) - Edge limitations: No
fs, no native modules, limitedcrypto— use Node.js runtime if needed - Timeout exceeded: Use Fluid Compute for long-running tasks, or Workflow DevKit for very long processes
- Bundle size: Python runtime supports up to 500MB; Node.js has smaller limits
- Environment variables: Available in all functions automatically; use
vercel env pullfor local dev
Function Runtime Diagnostics
Timeout Diagnostics
504 Gateway Timeout?
├─ All plans default to 300s with Fluid Compute
├─ Pro/Enterprise: configurable up to 800s
├─ Long-running task?
│ ├─ Under 5 min → Use Fluid Compute with streaming
│ ├─ Up to 15 min → Use Vercel Functions with `maxDuration` in vercel.json
│ └─ Hours/days → Use Workflow DevKit (DurableAgent or workflow steps)
└─ DB query slow? → Add connection pooling, check cold start, use Edge Config
500 Error Diagnostics
500 Internal Server Error?
├─ Check Vercel Runtime Logs (Dashboard → Deployments → Functions tab)
├─ Missing env vars? → Compare `.env.local` against Vercel dashboard settings
├─ Import error? → Verify package is in `dependencies`, not `devDependencies`
└─ Uncaught exception? → Wrap handler in try/catch, use `after()` for error reporting
Invocation Failure Diagnostics
"FUNCTION_INVOCATION_FAILED"?
├─ Memory exceeded? → Increase `memory` in vercel.json (up to 3008 MB on Pro)
├─ Crashed during init? → Check top-level await or heavy imports at module scope
└─ Edge Function crash? → Check for Node.js APIs not available in Edge runtime
Cold Start Diagnostics
Cold start latency > 1s?
├─ Using Node.js runtime? → Consider Edge Functions for latency-sensitive routes
├─ Large function bundle? → Audit imports, use dynamic imports, tree-shake
├─ DB connection in cold start? → Use connection pooling (Neon serverless driver)
└─ Enable Fluid Compute to reuse warm instances across requests
Edge Function Timeout Diagnostics
"EDGE_FUNCTION_INVOCATION_TIMEOUT"?
├─ Edge Functions have 25s hard limit (not configurable)
├─ Move heavy computation to Node.js Serverless Functions
└─ Use streaming to start response early, process in background with `waitUntil`
Official Documentation
Version History
- 08dc189 Current 2026-07-05 19:12
