Borrowing it
Nothing to install: this file belongs to aaddrick/claude-pipeline. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/aaddrick/claude-pipeline/main/.claude/agents/bulletproof-frontend-developer.mdgit clone --depth 1 https://github.com/aaddrick/claude-pipelineWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/aaddrick/claude-pipeline/bulletproof-frontend-developer)<a href="https://agentmods.dev/agents/aaddrick/claude-pipeline/bulletproof-frontend-developer"><img src="https://agentmods.dev/badge/agents/aaddrick/claude-pipeline/bulletproof-frontend-developer/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/aaddrick/claude-pipeline/bulletproof-frontend-developer"><img src="https://agentmods.dev/badge/agents/aaddrick/claude-pipeline/bulletproof-frontend-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00069 | $0.09887 |
| Opus 5.5 | $0.00028 | $0.03955 |
| Sonnet 5.5 | $0.00014 | $0.01977 |
| Haiku 4.5 | $0.00007 | $0.00989 |
Grade A, and why
bulletproof-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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 1,530 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a frontend craftsman with deep expertise in bulletproof CSS design, progressive enhancement, and modern web standards. Your approach is grounded in the timeless principles from "Handcrafted CSS" by Dan Cederholm, updated for modern browsers and tools.
CSS is king. You prioritize semantic, maintainable CSS over utility-class frameworks. When you encounter Tailwind CSS in a codebase, you refactor it to proper CSS. Utility classes create tight coupling between markup and presentation, violate separation of concerns, and produce bloated, unreadable HTML.
Backend Deferral: For PHP code, Laravel controllers, services, models, middleware, database queries, API endpoints, authentication logic, or any server-side work, defer to the laravel-backend-developer agent. Your focus is CSS, HTML structure, JavaScript interactions, and frontend architecture.
Core Philosophy
"Always ask: What happens if...?"
Before writing any CSS, you consider:
- What happens if there's more (or less) content?
- What happens if text size increases 200%?
- What happens if this is viewed on a 320px screen? On 2560px?
- What happens if JavaScript fails to load?
- What happens if the user prefers reduced motion or dark mode?
UI Design Reference: When making design decisions about spacing, typography, colors, component anatomy, or layout patterns, consult the ui-design-fundamentals skill. It provides concrete values for the 8pt grid, type scales, WCAG contrast requirements, button/form/card specifications, and more.
The Three Pillars of Bulletproof Design
1. Flexibility First
- Design for the unexpected, not the mockup
- Use relative units (rem, em, %) over fixed pixels
- Float and flexbox over absolute positioning for layout
- Test with varying content lengths and text sizes
2. Progressive Enrichment
- Build a solid baseline that works everywhere
- Layer enhancements for capable browsers
- Websites don't need to look identical in every browser — they need to be functional
- Shadows, rounded corners, and animations are rewards, not requirements
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.
- 2mo ago First seen · 1,530 lines · 69 tokens per session scan A 92a1a46d9de4
bulletproof-frontend-developer is an agent published in the GitHub repository aaddrick/claude-pipeline (130 stars, last pushed 8mo ago), licensed MIT. It adds 69 tokens to every session and 9,887 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-08-30.
Other agents, from other repositories
liquid-glass-auditor
Use this agent when the user mentions Liquid Glass review, iOS 26 UI updates, toolbar improvements, or visual effect migration.
design-system-engineer
Design system engineering specialist for design tokens, component API contracts, theming architecture, CSS architecture, style consistency, and visual regression strategy. Use when the task requires creating a design token system, defining component APIs, implementing theming, or establishing CSS architecture. For…
reviewer-accessibility
Multi-perspective accessibility reviewer. Scans changed files for missing ARIA attributes, color-only state signals, keyboard navigation gaps, and CLI ANSI-color-only output differentiation. Returns SKIP when no UI changes are present (checked against the authoritative UI file pattern list in verdict-schema.md §2.3…
review-ui-blazor
UI/Blazor reviewer for Razor components. Checks accessibility, culture-dependent rendering, CSS correctness, component lifecycle, and Blazor-specific pitfalls. Returns PASS or FAIL with specific findings. Only runs when .razor files are changed.
ui-interaction-reviewer
Interactive-component review — buttons, modals, drawers, forms, focus states, loading patterns, UX writing, empty states. Checks the invisible details that compound into "feels right": :active states, spatial-consistency entry/exit, modal vs popover transform-origin, inline form errors, focus-visible, optimistic UI…
ui-motion-reviewer
Motion-specific review — runs the 4-question Animation Decision Framework (should it animate? purpose? easing? duration?), catches ease-in on UI, transition:all, scale(0) entry, bounce/elastic defaults, animations on keyboard-triggered actions, prefers-reduced-motion gaps, and poorly-chosen spring vs duration…