react-19 SKILL.md skillA
react-19 from fusengine/agents is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add fusengine/agents/react-19@v19.3.0Pins v19.3.0 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- fusengine/agents
- Path
plugins/react-expert/skills/react-19/SKILL.md- Versions recorded
- 6
- Latest version
- v19.3.0, committed Sep 27, 2026
- First version recorded
- Jan 31, 2026
- Size
- 10,151 bytes
- Repository stars
- 36
- License
- MIT
Use when implementing React 19.3 patterns — use(), useOptimistic, useActionState, useEffectEvent, Activity, ViewTransition, Fragment refs, use(browser()), React Compiler.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
<objective>
Covers React 19.3's hooks and features: `use()` for reading promises/context in render, `useOptimistic` for instant UI updates, `useActionState` for form action state, `useFormStatus` for child-component pending state, `useEffectEvent` for non-reactive effect callbacks, the `Activity` component for hiding/showing UI while preserving state, `<ViewTransition>` + `addTransitionType` animations, Fragment refs and `use(browser())` browser-only rendering (new in 19.3), and the React Compiler's automatic memoization (making manual `useMemo`/`useCallback` mostly obsolete).
Also documents all classic hooks (useState, useEffect, useLayoutEffect, useRef, useImperativeHandle, useMemo, useCallback, useId, useSyncExternalStore) and React 18→19 breaking changes (`ref` as a prop instead of `forwardRef`, `<Context value={}>` instead of `<Context.Provider>`). This is the core React hooks/features skill — for global state see react-state, for forms see react-forms, and for SOLID architecture rules see solid-react.
</objective>
# React 19.3 Core Features
## Agent Workflow (MANDATORY)
Before ANY implementation, spawn 3 agents in parallel, one `Agent` call each with a `name`:
…Read the whole file at its exact version.
How to install
mdr add fusengine/agents/react-19@sha256:c3331dc7d26331deThe line at the top of this page pins the label v19.3.0, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_lubqrcexd6tyz6ss)
4 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 6 versions of this file, between Jan 31, 2026 and Sep 27, 2026, about one every 48 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v19.3.0 latest | 2026-09-27 | 43a351c | 10,151 B | A | view · diff |
| v19.2.0 | 2026-09-04 | 5f1d30f | 8,936 B | A | view · diff |
| v19.2.0 | 2026-07-29 | 3b91eed | 8,907 B | A | view · diff |
| v19.2.0 | 2026-02-07 | 0a3cd21 | 8,004 B | A | view · diff |
| v19.2.0 | 2026-01-31 | 7d8568c | 7,988 B | A | view · diff |
| v19.2.0 | 2026-01-31 | 9cb1933 | 6,999 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (10151 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
fusengine/agents · 36 stars · license MIT · pushed 2026-10-30 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_lubqrcexd6tyz6ss GET https://markdownregistry.com/api/v1/resolve?ref=fusengine/agents/react-19 GET https://markdownregistry.com/api/v1/blob/c3331dc7d26331deb2ac94ae567126cddd67e9df601d2034d9e8aec01ba8eb8b
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.