runtime-cache

A guide to Vercel Runtime Cache, a temporary key-value store for data shared across regions and Vercel functions, middleware, and builds. It covers cache strategies beyond the caching built into a web framework.

In plain words
What is it for?
Use it when implementing runtime caching with cache tags, especially across functions, routing middleware, and builds.
Why use it?
It helps developers decide how to store, share, and invalidate temporary data in Vercel applications.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/florianbruniaux/starmapper/runtime-cache
Any agent
npx skills add FlorianBruniaux/starmapper --skill runtime-cache
Clone the repo
git clone --depth 1 https://github.com/FlorianBruniaux/starmapper

Made for: Claude Code, Codex.

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,307 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00043 $0.02307
Opus 5 $0.00022 $0.01154
Sonnet 5 $0.00009 $0.00461
Haiku 4.5 $0.00004 $0.00231

Measured 2d ago against content hash 22fb4be9b3b2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

runtime-cache scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

async fetch(request: Request) {
.agents/skills/runtime-cache/SKILL.md · 283 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 283 lines · 43 tokens per session scan A 22fb4be9b3b2

Subscribe to this mod's changes

runtime-cache is a skill published in the GitHub repository FlorianBruniaux/starmapper (83 stars, last pushed 9d ago), with no licence file. It adds 43 tokens to every session and 2,307 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.