Borrowing it
Nothing to install: this file belongs to jakubsuplicki/codument. 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/jakubsuplicki/codument/main/.agents/skills/senior-frontend/SKILL.mdgit clone --depth 1 https://github.com/jakubsuplicki/codumentWrote 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/jakubsuplicki/codument/senior-frontend)<a href="https://agentmods.dev/skills/jakubsuplicki/codument/senior-frontend"><img src="https://agentmods.dev/badge/skills/jakubsuplicki/codument/senior-frontend/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/jakubsuplicki/codument/senior-frontend"><img src="https://agentmods.dev/badge/skills/jakubsuplicki/codument/senior-frontend.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00114 | $0.01761 |
| Opus 5 | $0.00057 | $0.00881 |
| Sonnet 5 | $0.00023 | $0.00352 |
| Haiku 4.5 | $0.00011 | $0.00176 |
Grade A, and why
senior-frontend 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 9d 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 — 152 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Frontend Development
This skill is the platform-neutral judgment layer for building UIs. The principles below hold whether you target the web or native. Framework-specific mechanics (the actual API names, files, and config) live in the reference files at the end — read the one that matches your target before writing code.
Component design
The unit of a UI is a component. Get its size and boundaries right and most other problems shrink.
- One component per file, named to match the export. Co-locate its styles, tests, and types.
- Sizing threshold: keep a component focused. When it pushes past ~200 lines or starts doing two unrelated jobs (fetching and laying out and branching on three states), split it. Length is a smell, not a law — a long but linear render is fine; a medium one juggling four concerns is not.
- Extraction threshold: extract a shared component only when it is genuinely reused (the rule of three — pull it out at the third copy, not the first). Premature shared components calcify into the wrong abstraction. Duplication is cheaper to fix than the wrong shape.
- Props are a contract: type them precisely. Prefer a closed set
(
"sm" | "md" | "lg") over an open one (string). The narrower the prop type, the more the compiler does your reviewing for you.
State management
Reach for the least powerful tool that holds the state, and escalate only when you feel the pain. The decision order:
- Local first. State that only one component cares about lives in that component. Most state is local.
- Lift when shared. When two siblings need the same value, lift it to their nearest common parent — and no higher. Lifting too far makes everything below re-render.
- Context for truly global, low-churn state. Theme, auth, locale, current user. Context is for things that are genuinely app-wide and change rarely. It is not a fix for prop drilling through two levels, and it is not a state manager — every consumer re-renders when the value changes.
- External store for high-churn or server-cache state. Cross-cutting state that updates often, or that mirrors the server, belongs in a dedicated store or data-fetching library, not in Context.
What ships with it
2 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.
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.
- 9d ago First seen · 152 lines · 114 tokens per session scan A 448703eeec62
senior-frontend is a skill published in the GitHub repository jakubsuplicki/codument (47 stars, last pushed 18d ago), licensed Apache-2.0. It adds 114 tokens to every session and 1,761 once invoked, about $0.0006 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.
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