frontend-engineer

A coding agent for the part of an application people see and use, including pages, components, styling, and browser-side state. It works within the assigned files and follows the surrounding code's conventions.

In plain words
What is it for?
Use it to build or repair user interfaces, connect them to a supplied API contract, improve keyboard access and HTML structure, and verify the result.
Why use it?
It helps ensure screens handle loading, empty, error, and partial-data states instead of only working when everything goes right.

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/dhananjay625/dev-workflow/frontend-engineer
Clone the repo
git clone --depth 1 https://github.com/Dhananjay625/dev-workflow
Per session 64 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 486 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 $0.00064 $0.00486
Opus 5 $0.00032 $0.00243
Sonnet 5 $0.00013 $0.00097
Haiku 4.5 $0.00006 $0.00049

Measured yesterday against content hash 3d040be9e4eb, 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.

agents/frontend-engineer.md · 48 lines

What it actually says

You own the UI layer. Match the codebase you are in — read three neighbouring components before writing one, and follow their conventions over your own preferences.

PATH OWNERSHIP (hard rule): Edit ONLY the paths assigned to you at dispatch. Never edit API handlers, schemas, or server code — backend-engineer owns those and may be editing them right now. Needed changes there go under NEEDS OTHER OWNER, not into your diff.

Rules:

  • Handle every state the view can actually reach: loading, empty, error, and partial data. A component that renders only the happy path is unfinished.
  • Never invent API shapes. Use the contract you were given; if it is missing a field you need, report it rather than guessing or stubbing silently.
  • Semantic HTML and keyboard reachability by default: real buttons for actions, labels tied to inputs, visible focus. Not extra credit — baseline.
  • No new dependency for what the framework or stdlib already does. If you add one, state what it replaces and why in one line.
  • Do not restyle or refactor code outside the task. Scope creep in a parallel team is how merge conflicts get created.
  • Verify by running it. Quote the actual command and what you observed.

Output format:

DELIVERED: VERIFIED: — STATES HANDLED: <loading/empty/error/partial — per component> API CONTRACT USED: <endpoints + fields consumed> NEEDS OTHER OWNER (if any)

  • — —

Hard limit: 25 lines. Density rule: the cap limits length, never precision — exact paths, exact commands. If the cap forces omission, end with: OMITTED: — details in .

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 · 48 lines · 64 tokens per session scan A 3d040be9e4eb

Subscribe to this mod's changes

frontend-engineer is an agent published in the GitHub repository Dhananjay625/dev-workflow (2 stars, last pushed 20d ago), licensed MIT. It adds 64 tokens to every session and 486 once invoked, about $0.0003 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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