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.
npx agentmods add skills/coroboros/agent-skills/frontend-devnpx skills add coroboros/agent-skills --skill frontend-devgit clone --depth 1 https://github.com/coroboros/agent-skillsWrote 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/skills/coroboros/agent-skills/frontend-dev)<a href="https://agentmods.dev/skills/coroboros/agent-skills/frontend-dev"><img src="https://agentmods.dev/badge/skills/coroboros/agent-skills/frontend-dev.svg" alt="Measured on agentmods" 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 | $0.00121 | $0.03387 |
| Opus 5 | $0.00060 | $0.01693 |
| Sonnet 5 | $0.00024 | $0.00677 |
| Haiku 4.5 | $0.00012 | $0.00339 |
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 today.
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 — 185 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Frontend Dev
Important — Engineering discipline
These rules govern how this skill changes code — apply them whenever it writes, edits, or proposes a fix.
- Minimal scope. Only what's directly requested or clearly necessary — no extra files, no abstraction for one use, no configurability nobody asked for, no error handling for states that can't happen. Validate at system boundaries; trust internal code.
- General solution, not the test cases. Implement the real logic for all valid inputs; never hard-code to inputs or bolt on workaround scripts to make a test pass. Tests verify the solution; they don't define it. A test is wrong? Say so — don't bend correct code to a broken test.
- Investigate before claiming. Never speculate about code you haven't opened; read the referenced file before answering. Ground every claim in what you actually read, not a plausible guess.
Critical — Label hygiene
Internal planning labels are author coordinates, not reader coordinates. Strip them from every shipped artifact this skill emits — code, comments, commit subjects/bodies, PR titles/descriptions, release notes, doc paragraphs, non-trivial comments.
- Workstream and task labels —
WS-N,Phase-A,Step-3, issue or ticket numbers, plan phase names from the source spec, issue body, or planning artifact. Translate to the domain noun (Runs the battery script (WS-2)→Runs the battery script). - Process language — "the rebuild", "the prior
<file>", "carried verbatim from", "the cleanup pass", "the audit", "spec AC" standalone. Replace with the concrete fact (carries the routing from the prior aggregation→routes via the merge keys in the synthesis module). - Plan-internal references — "as the brief says", "per the workstream", "from the forge artifact". Drop the reference; state the fact directly.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- today First seen · 185 lines · 121 tokens per session scan A 6c313e362a80
frontend-dev is a skill published in the GitHub repository coroboros/agent-skills (4 stars, last pushed 2d ago), licensed MIT. It adds 121 tokens to every session and 3,387 once invoked, about $0.0006 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 2026-09-03.
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