agentmods.dev

react-sync

A process for building a local React checkout into the versions that Next.js consumes, then copying those builds into a local Next.js checkout. A checkout is a local copy of a code repository.

In plain words
What is it for?
It is for validating React changes with Next.js, running React's build-for-Next process, and synchronizing the resulting builds into a Next.js source tree.
Why use it?
It lets developers test React changes inside Next.js before those changes are released. It also keeps stable and experimental React variants synchronized for integration testing.

Skill for Claude CodeCodex

142k yesterday A scan 67 tokens original MIT
View the source file vercel/next.js
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/vercel/next.js/react-sync
Any agent
npx skills add vercel/next.js --skill react-sync
Clone the repo
git clone --depth 1 https://github.com/vercel/next.js

Made for: Claude Code, Codex.

Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 460 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00067 $0.00460
Opus 5 $0.00034 $0.00230
Sonnet 5 $0.00013 $0.00092
Haiku 4.5 $0.00007 $0.00046

Measured yesterday against content hash daa4810a08cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

react-sync scanned grade A with 0 findings 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 yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/build-for-next.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/react-sync/SKILL.md · 54 lines

What it actually says

Sync React to Next.js

Use this skill when syncing a local React checkout into this Next.js checkout.

Build and sync

  1. Build React from its own checkout. Pass this skill's script by its absolute path, because the working directory must be the React repository.

    cd <react-repo>
bash <next-repo>/.agents/skills/react-sync/scripts/build-for-next.sh

    This creates build/oss-stable and build/oss-experimental with the bundle variants that Next.js consumes.

  2. Sync the build into Next.js:

    cd <next-repo>
PATH="$(dirname "$(command -v corepack)"):$PATH" \
  pnpm sync-react --version <react-repo>

    Work around a Codex PATH-precedence bug by keeping the directory containing the active Corepack shim first on PATH. Codex injects a separate bundled pnpm executable ahead of the user's Corepack shim, and command lookup happens before Corepack reads the repository's packageManager field. The prefix makes both this command and sync-react's nested pnpm install resolve through Corepack to the repository-pinned pnpm version. Invoking only the outer command with corepack pnpm is insufficient because the nested command still resolves pnpm from PATH.

  3. Inspect the sync result before testing. Preserve unrelated changes in both checkouts. Rebuild Next.js when required, then run the focused test command matching the changed behavior.

  • $react-vendoring - vendored React runtime and type boundaries after syncing.
Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. yesterday First seen · 54 lines · 67 tokens per session scan A daa4810a08cd

Subscribe to this mod's changes

react-sync is a skill published in the GitHub repository vercel/next.js (142,020 stars, last pushed yesterday), licensed MIT. It adds 67 tokens to every session and 460 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

E-commerceFrontendReActTestingcomponentsnodeserver-renderinguniversal
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