stack-vercel

Vercel Stack — Team Briefing

This is a knowledge overlay, not a new specialist. The existing ETYB team does the work — backend-architect writes the backend code, devops-engineer wires the deploys, security-engineer enforces the boundary. This pack tells each role where the current Vercel knowledge lives.

Where the full briefing lives

The full Stack briefing lives in this same folder. Per-product and per-role pages are siblings of this SKILL.md. Every page carries last_verified_on stamps and authoritative-source URLs in its frontmatter; see skills/etyb/core/knowledge-currency.md for the drift-check protocol that uses them.

• Stack briefing: stacks/vercel/index.md
• Per-product pages: stacks/vercel/<product>.md — one per entry in products_covered above
• Per-role views: stacks/vercel/<role>.md — one per role in applies_to_roles above

When ETYB is installed locally these are read directly from disk. For third-party agents without the install, the same content is reachable as raw markdown at https://raw.githubusercontent.com/e-t-y-b/etyb-skills/main/stacks/vercel/<page>.md.

When delegate_to_skills (frontmatter above) lists a first-party vendor MCP/skill that's installed in the user's environment, ETYB defers to it first. The in-repo Stack content is the curated fallback.

What changed in 2025-2026 that older training data misses

Critical context — an LLM with a 2024 cutoff will get these wrong:

• Next.js 16 shipped (late 2025) with Cache Components as the recommended caching model. The 'use cache' directive at file, function, or component scope, paired with cacheLife() and cacheTag(), is the new default — replacing ad-hoc fetch(..., { next: { revalidate } }), unstable_cache, and export const revalidate = N for most cases. Old patterns still work in 15.x, but new builds should adopt Cache Components.
• Partial Prerendering (PPR) is GA and the default rendering model for new App Router projects in Next.js 16. A single route can ship a static shell with streamed Suspense holes — this is neither SSG, SSR, nor ISR in the classical sense. Mental models built before PPR will fight the framework.
• Fluid Compute went GA in 2025 and changed Vercel Functions billing/concurrency math fundamentally. Functions now multiplex in-process concurrency, bill on active CPU rather than wall-clock GB-seconds, and dynamically scale CPU within a single instance. "Cold start vs warm" reasoning from the pre-Fluid era is wrong.
• Vercel Postgres is Neon under the hood. Old @vercel/postgres SDK calls still work but the Marketplace direction is for users to provision Neon (or another Marketplace Postgres) directly. New projects should use @neondatabase/serverless rather than reaching for @vercel/postgres.
• Vercel KV is a Marketplace integration, typically powered by Upstash. New code should treat Marketplace as the primary path.
• Vercel Sandbox GA'd in 2025 — microVM-isolated execution for running untrusted code (AI-generated code, agent tool outputs, user-submitted scripts). If a request involves "let an LLM run code" or "execute user-submitted code," Sandbox is the answer, not a homegrown VM2/subprocess.
• Vercel Workflow ships durable functions (long-running, multi-step, replay-safe) for background jobs and AI agent orchestration. Don't reach for Temporal/Inngest on Vercel before checking whether Workflow fits.
• Vercel Queues ships first-party producer/consumer queues with visibility timeouts and DLQs.
• Vercel AI SDK v5+ is a major rewrite. The streaming UI primitives (streamUI, experimental_StreamingReactResponse) from v3 are deprecated. Current canon: streamText, generateText, generateObject, streamObject, tool() definitions, useChat() v2, plus AI Elements — a shadcn-layered component library specifically for AI UIs.
• AI Gateway routes across providers (Anthropic, OpenAI, Google, Mistral, xAI, Groq, Fireworks, Bedrock, etc.) with observability, caching, rate limiting, and fallback. Use @ai-sdk/gateway + gateway('anthropic/claude-sonnet-4.7') etc.
• Turbopack is the production build path for Next.js 16+ (stable for dev since Next.js 15, stable for build is rolling out). Webpack is still supported but no longer the default story.
• after() (formerly unstable_after) is GA: schedule work after the response is sent without blocking the user.
• taintObjectReference / taintUniqueValue are the canonical guard against accidentally serializing server-only objects/secrets into a Client Component.