frontend-specialist

An agent for designing and building maintainable React and Next.js user interfaces. It covers components, styling, responsive layouts, state management, accessibility, and frontend performance.

In plain words
What is it for?
Use it when building or reviewing web pages, components, responsive behaviour, animations, or frontend architecture.
Why use it?
It helps prevent fragile interface code and encourages measured performance, consistent design, and long-term maintainability.

Agent

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 agents/felipeslo/opencode-kit/frontend-specialist
Clone the repo
git clone --depth 1 https://github.com/felipeslo/opencode-kit
Per session 59 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 6,250 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 95% copy Near-identical to another mod 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 $0.00059 $0.06250
Opus 5 $0.00030 $0.03125
Sonnet 5 $0.00012 $0.01250
Haiku 4.5 $0.00006 $0.00625

Measured 2d ago against content hash 3ecf18efca72, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-specialist 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 2d 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.

Origin

This is a copy

95% identical to frontend-specialist — 454 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.opencode/agents/frontend-specialist.md · 629 lines

How it starts

The opening of the file, as written. The whole thing — 629 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Senior Frontend Architect

You are a Senior Frontend Architect who designs and builds frontend systems with long-term maintainability, performance, and accessibility in mind.

Quick Navigation

Design Process

Technical Implementation

Quality Control


Your Philosophy

Frontend is not just UI -- it's system design. Every component decision affects performance, maintainability, and user experience. You build systems that scale, not just components that work.

Your Mindset

When you build frontend systems, you think:

  • Performance is measured, not assumed: Profile before optimizing
  • State is expensive, props are cheap: Lift state only when necessary
  • Simplicity over cleverness: Clear code beats smart code
  • Accessibility is not optional: If it's not accessible, it's broken
  • Type safety prevents bugs: TypeScript is your first line of defense
  • Mobile is the default: Design for smallest screen first

Read the full file on GitHub · 629 lines

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. 2d ago First seen · 629 lines · 59 tokens per session scan A 3ecf18efca72

Subscribe to this mod's changes

frontend-specialist is an agent published in the GitHub repository felipeslo/opencode-kit (2 stars, last pushed 5mo ago), licensed MIT. It adds 59 tokens to every session and 6,250 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to frontend-specialist, differing in 454 lines, and is treated as a copy.

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