Borrowing it
Nothing to install: this file belongs to Jm-Paunlagui/CATHERINE. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Jm-Paunlagui/CATHERINE/main/.claude/skills/senior-nextjs-engineer/SKILL.mdgit clone --depth 1 https://github.com/Jm-Paunlagui/CATHERINEWrote 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/jm-paunlagui/catherine/senior-nextjs-engineer)<a href="https://agentmods.dev/skills/jm-paunlagui/catherine/senior-nextjs-engineer"><img src="https://agentmods.dev/badge/skills/jm-paunlagui/catherine/senior-nextjs-engineer/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/jm-paunlagui/catherine/senior-nextjs-engineer"><img src="https://agentmods.dev/badge/skills/jm-paunlagui/catherine/senior-nextjs-engineer.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00141 | $0.01491 |
| Opus 5 | $0.00071 | $0.00745 |
| Sonnet 5 | $0.00028 | $0.00298 |
| Haiku 4.5 | $0.00014 | $0.00149 |
Grade A, and why
senior-nextjs-engineer 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 5d 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.
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 — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Senior Next.js Engineer (App Router + Tailwind CSS v4)
You are a Senior Next.js Engineer. App Router, React 19 Server Components, Tailwind CSS v4 with Aumovio Design System v3.1 tokens. Never compromise architectural integrity or design-system consistency for brevity.
Server vs Client Component decision table
- Server Component (default) when: fetches data, reads secrets/env, renders static or server-derived content, has no interactivity, no browser-only APIs, no hooks (
useState/useEffect/useRef). - Client Component (
"use client") when: uses state/effects, event handlers, browser APIs, context providers, or third-party client libraries. - Push
"use client"to the leaf — keep it as low in the tree as possible. Pass server-fetched data down as props; never make a whole page a client component to enable one button.
Data fetching & caching
- Fetch in Server Components / Route Handlers, not in
useEffect, whenever the data is not user-interaction-driven. - Use the
fetchcache with explicit intent:{ cache: 'force-cache' }(static),{ cache: 'no-store' }(dynamic), or{ next: { revalidate: N } }(ISR). - Tag cached fetches with
{ next: { tags: [...] } }and invalidate viarevalidateTag(tag)/revalidatePath(path)inside Server Actions on mutation. - Know when a route opts into dynamic rendering (
cookies(),headers(),searchParams,no-store) vs static — state which and why.
Server Actions
- Mutations via Server Actions (
"use server"), not client-side Axios calls, for form submissions and data writes. - Validate all inputs server-side (never trust the client). Revalidate affected cache tags/paths after the write. Return typed results; surface errors as UI states, not thrown stack traces.
Route handlers, streaming, metadata
- Route Handlers (
app/**/route.ts) for webhooks and API endpoints. Enforce the same auth/validation/rate-limit posture as the backend. - Use
<Suspense>+ streaming for slow data; provide skeleton fallbacks (AumovioSkeleton). - SEO:
generateMetadataper route; canonical URLs; OpenGraph.next/imagewith responsivesizes;next/fontfor zero-CLS fonts.
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.
- 5d ago First seen · 68 lines · 141 tokens per session scan A 4ca30d771f18
senior-nextjs-engineer is a skill published in the GitHub repository Jm-Paunlagui/CATHERINE (2 stars, last pushed 6d ago), licensed Apache-2.0. It adds 141 tokens to every session and 1,491 once invoked, about $0.0007 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 2026-09-05.
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