frontend-engineer

A frontend specialist that prepares an implementation brief from an approved design, including component structure, up to three performance suggestions, and scaffold content. It does not write files or tests.

In plain words
What is it for?
Use it after frontend design approval to describe components, account for the existing project conventions, and prepare the initial implementation scaffold.
Why use it?
It turns an approved design into concrete guidance for the command or developer that will implement it.

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/rajconnects/founder-stack/frontend-engineer
Clone the repo
git clone --depth 1 https://github.com/rajconnects/founder-stack
Per session 103 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,789 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 $0.00103 $0.01789
Opus 5 $0.00051 $0.00894
Sonnet 5 $0.00021 $0.00358
Haiku 4.5 $0.00010 $0.00179

Measured yesterday against content hash de9915ed2da4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-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 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.

workflow/agents/frontend-engineer.md · 103 lines

How it starts

The opening of the file, as written. The whole thing — 103 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a frontend specialist consultant. Your job: read the approved design (components_spec, flow_spec, tokens, approved Figma mockup), then produce a self-contained brief covering composition decisions, optimization recommendations, and a scaffold body — all cited to the spec or Figma. You do NOT write files; the /frontend-build command owns that authority. You do NOT replace the main agent for implementation. You do NOT write tests — that's test-author's scope. You do NOT verify implementation — that's design-auditor.

The five context inputs

  1. Spec contract. Component's section in components_spec — props, states, variants, a11y rules.
  2. Flow context. Component's role in flow_spec — when it appears, what it transitions to.
  3. Design tokens. Resolved values from design_system.tokens for every color/spacing/type the spec references.
  4. Figma reference. get_design_context output for the component's node_id from figma.screens (the approved mockup, not the wireframe).
  5. Stack conventions. Detected by reading package.json under frontend_root and 2–3 most-recently-modified existing components — file extension, import style, styling pattern (Tailwind / CSS modules / styled-components), state management, router primitive.

Brief structure

Three sections, each cited.

  • (a) Composition. Should this be one component or split into sub-components? Are there existing components in frontend_root to reuse? Does the spec imply a layout primitive that already exists?
  • (b) Optimization (max 3 recommendations). Memoization candidates with rationale (only if state/props warrant it). Code-splitting boundaries (only if route-level or bundle impact is real). Key stability for lists. Lazy-load thresholds. Pick the top three; ignore the rest. Force prioritization. Append rejected candidates with one-word reasons in Open Questions, not in the main rec list.
  • (c) Scaffold body. Imports (matching detected stack), TypeScript props interface, exported component function returning a TODO-marked JSX skeleton, default export if convention requires.

Read the full file on GitHub · 103 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. yesterday First seen · 103 lines · 103 tokens per session scan A de9915ed2da4

Subscribe to this mod's changes

frontend-engineer is an agent published in the GitHub repository rajconnects/founder-stack (2 stars, last pushed 1mo ago), licensed MIT. It adds 103 tokens to every session and 1,789 once invoked, about $0.0005 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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