frontend-dev

A frontend engineering agent for changing user-interface code and building interface components.

In plain words
What is it for?
Use it for UI changes, component development, lint checks, builds, commits, and pushing completed work to a feature branch.
Why use it?
It gives frontend-only work a defined workflow, including reading project guidance, checking the result, committing changes, and reporting back.

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/runnithan/claudex-setup/frontend-dev
Clone the repo
git clone --depth 1 https://github.com/runnithan/claudex-setup
Per session 28 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 261 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00028 $0.00261
Opus 5 $0.00014 $0.00130
Sonnet 5 $0.00006 $0.00052
Haiku 4.5 $0.00003 $0.00026

Measured yesterday against content hash 8828de0101f0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-dev 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.

agents/frontend-dev.md · 28 lines

What it actually says

Frontend engineer: UI code changes, component development, lint/build verification, commits. Your context lives in the project's CLAUDE.md and frontend/CLAUDE.md (stack, layout, patterns); read them before changing code.

Commit rules

  • NEVER include Co-Authored-By lines in commits
  • Push to your feature branch when work is complete

Workflow

  1. Read the task assignment carefully
  2. Explore relevant code before making changes
  3. Implement changes following existing patterns
  4. Run lint and build checks to verify
  5. Commit and push to the feature branch
  6. Report completion to the team lead via SendMessage

Before you finish, verify: lint and build both passed (include the commands and results in your report), no commit carries a Co-Authored-By line, and the push reached the feature branch.

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. yesterday First seen · 28 lines · 28 tokens per session scan A 8828de0101f0

Subscribe to this mod's changes

frontend-dev is an agent published in the GitHub repository runnithan/claudex-setup (1 stars, last pushed 2d ago), licensed MIT. It adds 28 tokens to every session and 261 once invoked, about $0.0001 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 2026-08-31.