fenic: Skill for Claude Code

.claude/skills/update-fenic-skill/SKILL.md

update-fenic-skill is a skill for Claude Code from typedef-ai/fenic. It costs 74 tokens per session (857 once invoked), scanned A, original, Apache-2.0.

A maintenance guide for updating the fenic-mechanics skill after the fenic library changes. It regenerates API reference files from the installed version and reviews the hand-written guidance for outdated advice.

In plain words
What is it for?
Checking the installed fenic version, regenerating its API reference, reviewing changes, and updating the related skill documentation.
Why use it?
It helps keep the coding instructions aligned with the version of fenic actually installed.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: reads .claude/ paths.

This is typedef-ai/fenic's own configuration. It tells Claude Code how to work on fenic itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything fenic configures →

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is uv run --project . python .claude/skills/fenic-mechanics/scripts/generate_reference.py.

Part of the fenic plugin — 2 skills, 2 agents shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to typedef-ai/fenic. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/typedef-ai/fenic/main/.claude/skills/update-fenic-skill/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/typedef-ai/fenic

Made for: Claude Code.

Or install fenic, the plugin that ships this one along with the rest of its 2 skills, 2 agents.

Wrote 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.

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README.md
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Your own site
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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.

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Your own site · 80×15
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Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 857 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Agent Snooping · line 25
    Skill reads from agent configuration directories (.claude/, .codex/, .gemini/). These directories may contain API keys, personal settings, and other credentials that the skill has no legitimate need to access.
    Fix: Remove all code or instructions that access agent configuration directories (.claude/, .codex/, .gemini/). If configuration values are needed, pass them explicitly as parameters or environment variabl
How audits are shown
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 5.1 $0.00074 $0.00857
Opus 5 $0.00037 $0.00428
Sonnet 5 $0.00015 $0.00171
Haiku 4.5 $0.00007 $0.00086

Measured 11d ago against content hash 6c7cc82b2ad8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

update-fenic-skill 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 11d 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.

.claude/skills/update-fenic-skill/SKILL.md · 76 lines

How it starts

The opening of the file, as written. The whole thing — 76 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Update the fenic-mechanics skill for a new fenic version

The fenic-mechanics skill is hybrid: a generated reference (.claude/skills/fenic-mechanics/reference/*.md, introspected from the installed fenic — never edit by hand) plus hand-authored judgment (SKILL.md, gotchas.md — the namespace law, calling conventions, and silent traps). When fenic changes version, regenerate the first and re-review the second.

Procedure

  1. Confirm the installed version changed.

    uv run --project . python -c "from importlib import metadata; print(metadata.version('fenic'))"
    cat .claude/skills/fenic-mechanics/reference/VERSION
    
  2. Regenerate the reference (deterministic — only real API changes will diff):

    uv run --project . python .claude/skills/fenic-mechanics/scripts/generate_reference.py
    
  3. Inspect the API deltas:

    git diff --stat .claude/skills/fenic-mechanics/reference/
    git diff .claude/skills/fenic-mechanics/reference/
    

    Classify each change: added symbol, removed symbol, renamed symbol, or changed signature (param added/removed/renamed/retyped).

  4. Re-review the hand-authored judgment against the deltas. Update SKILL.md / gotchas.md only where a delta touches them:

    • Namespace/import law — did any namespace move, or did a function become a method (or vice-versa)? (e.g. something leaving/entering fc.arr, fc.dt, fc.semantic).
    • The 4 silent traps — re-verify each still holds: fc.json.jq still returns ArrayType(JsonType); semantic templates still Jinja2 {{ }}; fc.dt.datediff(end, start) arg order; fc.dt.to_timestamp format dialect. A changed signature on any of these is high-priority.
    • Model/config — provider classes, input_tpm/output_tpm vs tpm, default_* requirements.
    • The "wrote X, meant Y" table — drop rows whose anti-pattern is now impossible, and add rows for new traps the signature changes introduce.

Read the full file on GitHub · 76 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. 11d ago First seen · 76 lines · 74 tokens per session scan A 6c7cc82b2ad8

Subscribe to this mod's changes

update-fenic-skill is a skill published in the GitHub repository typedef-ai/fenic (672 stars, last pushed 2d ago), licensed Apache-2.0. It adds 74 tokens to every session and 857 once invoked, about $0.0004 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 2026-08-30.

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