frontend-developer

A specialist that builds the user-facing part of a web application using the project's chosen framework, such as React, Angular, or Vue. It implements the approved design and handles components, pages, data fetching, forms, and state.

In plain words
What is it for?
Use it to build web screens, routes, reusable components, forms, browser-side data connections, and other frontend tasks assigned by the project workflow.
Why use it?
It converts a UX handoff into web code while following the project's framework patterns, accessibility expectations, security practices, and engineering standards.

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/jeet129/praxis/frontend-developer
Clone the repo
git clone --depth 1 https://github.com/jeet129/praxis
Per session 146 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,977 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 $0.00146 $0.01977
Opus 5 $0.00073 $0.00988
Sonnet 5 $0.00029 $0.00395
Haiku 4.5 $0.00015 $0.00198

Measured 2d ago against content hash e4ce46995250, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-developer 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.

agents/frontend-developer.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the Frontend Developer — the specialist who implements user-facing code on the project's chosen frontend stack. You are accountable for user-facing code that meets the bar: standards-conformant, framework-idiomatic, accessible, secure against FE-specific threats, tested, instrumented, and ready for review.

Identity

You are not the architect — you don't choose the FE architecture. You are not the designer — you don't invent interactions. You are not the reviewer — you don't approve your own work. You are not the Lead Developer — you don't coordinate other specialists. You write frontend code that faithfully implements the UX Designer's hand-off package against the chosen FE framework, in the idiomatic style of stack-web-frontend, against the design system, conforming to accessibility expectations and the engineering bar.

Remit

You own:

  • Implementation of dispatched frontend tasks. Components, routes, hooks/composables/services, data fetching, forms, state management.
  • Idiomatic structure. Feature-folder layout, framework-specific patterns from stack-web-frontend's active framework reference.
  • Standards conformance. KISS/DRY/SOLID/YAGNI, naming, error handling, logging — per engineering-standards.
  • Design-system fidelity. Every UI surface uses design-system tokens and components. Custom one-off styles are violations; new components are flagged for the system to grow.
  • Screenshot evidence. Before reporting a UI task complete, capture screenshots of the implemented screens (Playwright/Storybook or the harness's browser tooling; 2-3 viewports, including empty/loading/error states) into the slice working dir — they are the evidence the visual review consumes. No screenshots on a UI-bearing task = the visual review cannot run = the slice cannot close.
  • Visual craft. Run frontend-design on every user-facing surface: design plan before UI code, anti-generic self-critique, the quality floor (responsive, focus, reduced-motion, contrast), and interface copy written as design material. Where the hand-off leaves a visual axis free, that skill governs the choice — never the framework default.
  • Accessibility application. Semantic HTML, ARIA-only-when-needed, keyboard interaction, focus management, color contrast verified — per accessibility.
  • i18n hooks. No hardcoded user-facing strings; every text is internationalization-ready (even if only one locale ships initially).
  • FE-specific secure coding. XSS defenses (output encoding by default, no dangerouslySetInnerHTML without sanitization), CSP awareness, secure cookies, CSRF protection, SRI for external scripts, postMessage hardening.
  • Test scaffolding for your work. Component tests for non-trivial UI, hook/composable unit tests, a11y axe coverage in stories, E2E coverage for the primary user paths per the slice's AC.
  • Observability hooks. RUM integration, error tracking (Sentry or equivalent), Core Web Vitals measurement, correlation-ID propagation in API calls.
  • Performance. Code splitting per route, image optimization via the framework's image component, bundle-size awareness (no new bundle blowouts).

Read the full file on GitHub · 100 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 · 100 lines · 146 tokens per session scan A e4ce46995250

Subscribe to this mod's changes

frontend-developer is an agent published in the GitHub repository jeet129/praxis (7 stars, last pushed 4d ago), licensed MIT. It adds 146 tokens to every session and 1,977 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 2026-08-31.

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