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.
npx agentmods add skills/fusengine/agents/react-19npx skills add fusengine/agents --skill react-19git clone --depth 1 https://github.com/fusengine/agentsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/fusengine/agents/react-19)<a href="https://agentmods.dev/skills/fusengine/agents/react-19"><img src="https://agentmods.dev/badge/skills/fusengine/agents/react-19.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00034 | $0.02082 |
| Opus 5 | $0.00017 | $0.01041 |
| Sonnet 5 | $0.00007 | $0.00416 |
| Haiku 4.5 | $0.00003 | $0.00208 |
Grade A, and why
react-19 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.
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.
How it starts
The opening of the file, as written. The whole thing — 244 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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.
React 19.2 Core Features
Agent Workflow (MANDATORY)
Before ANY implementation, use TeamCreate to spawn 3 agents:
- fuse-ai-pilot:explore-codebase - Analyze existing React patterns and component structure
- fuse-ai-pilot:research-expert - Verify latest React 19.2 docs via Context7/Exa
- mcp__context7__query-docs - Check use(), useOptimistic, useActionState, Activity patterns
After implementation, run fuse-ai-pilot:sniper for validation.
What's New in React 19.2
New Hooks
| Hook | Purpose | Guide |
|---|---|---|
use() |
Read promises/context in render | references/new-hooks.md |
useOptimistic |
Optimistic UI updates | references/new-hooks.md |
useActionState |
Form action state management | references/new-hooks.md |
useFormStatus |
Form pending state (child components) | references/new-hooks.md |
useEffectEvent |
Non-reactive callbacks in effects | references/new-hooks.md |
→ See references/new-hooks.md for detailed usage
Classic Hooks (React 18+)
State Hooks
| Hook | Purpose | Guide |
|---|---|---|
useState |
Local component state | references/use-state.md |
What ships with it
44 files 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.
- references/actions-api.md 1.8 KB
- references/activity-component.md 1.6 KB
- references/context-improvements.md 2.3 KB
- references/custom-hooks-patterns.md 2.5 KB
- references/document-metadata.md 1.4 KB
- references/hooks-improved.md 1.8 KB
- references/lazy-loading.md 2.5 KB
- references/migration-18-19.md 2.3 KB
- references/new-hooks.md 3.3 KB
- references/profiling.md 2.9 KB
- references/react-compiler.md 2.2 KB
- references/ref-as-prop.md 1.2 KB
- references/resource-loading.md 1.8 KB
- references/suspense-patterns.md 2.3 KB
- references/templates/action-form.md 4.5 KB
- references/templates/activity-tabs.md 5.4 KB
- references/templates/custom-hooks.md 8.6 KB
- references/templates/document-metadata.md 3.6 KB
- references/templates/effect-patterns.md 16 KB
- references/templates/error-boundary.md 7.2 KB
- references/templates/external-store.md 8.9 KB
- references/templates/lazy-components.md 5.8 KB
- references/templates/optimistic-update.md 4.4 KB
- references/templates/profiling-devtools.md 6.3 KB
- references/templates/ref-as-prop.md 6.6 KB
- references/templates/ref-patterns.md 4.7 KB
- references/templates/resource-loading.md 4.5 KB
- references/templates/state-patterns.md 14 KB
- references/templates/use-context.md 7.4 KB
- references/templates/use-deferred-value.md 5.3 KB
- references/templates/use-effect-event.md 7.0 KB
- references/templates/use-promise.md 4.9 KB
- references/templates/use-transition-async.md 6.4 KB
- references/templates/virtual-list.md 7.4 KB
- references/use-callback.md 2.5 KB
- references/use-effect.md 3.0 KB
- references/use-id.md 1.9 KB
- references/use-imperative-handle.md 1.9 KB
- references/use-layout-effect.md 2.0 KB
- references/use-memo.md 2.4 KB
- references/use-ref.md 1.9 KB
- references/use-state.md 2.3 KB
- references/use-sync-external-store.md 2.0 KB
- references/virtualization.md 2.3 KB
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.
- yesterday First seen · 244 lines · 34 tokens per session scan A a7f668f2c03b
react-19 is a skill published in the GitHub repository fusengine/agents (25 stars, last pushed 1mo ago), licensed MIT. It adds 34 tokens to every session and 2,082 once invoked, about $0.0002 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 2026-09-03.
Other skills, from other repositories
vibes
Self-contained app generator — invoke this skill directly, do not decompose into sub-steps. Generates React web apps with TinyBase reactive data store. Use when creating new web applications, adding components, or working with real-time data. Ideal for quick prototypes and single-page apps that need real-time data…
radin-record
Log feedback, bugs, follow-ups, or ideas raised mid-session as structured backlog entries, so they survive past the conversation. Use for /radin-record, "log this to the backlog", "add as follow-up/bug/idea", "record what we just found", "note this for later", "add findings to backlog". Triggers even on vague asks…
ink-playing-cards
Use when building terminal card games with ink-playing-cards, working with card components, deck management, zone systems, event systems, effect systems, or any card game logic using Ink and React for CLI rendering.
radin-doctor
Check that radin's own install under /.claude is complete and its optional companion tools are reachable. Use for /radin-doctor, "check my radin install", "is radin installed correctly", "radin doctor", "verify radin install".
designing-interfaces
Creates a design system for software with a UI. Use when a project has a user interface and architecture is confirmed — whether creating from scratch or extracting patterns from existing code.
managing-product
Extracts product requirements and produces a PRD. Use when a user wants to build software and needs to define what to build before architecture or implementation, when scoping an MVP, or when translating a vague idea into a buildable specification.