P12-modular

P12-modular is a skill for Claude Code, Codex from gitRasheed/metis-skill. It costs 0 tokens per session (635 once invoked), scanned A, original, MIT.

A set of coding guidelines that encourages plain data, small focused functions, clear usage, and early planning of code structure. These are defaults that should be adjusted to fit the existing project.

In plain words
What is it for?
Use it when designing, implementing, fixing, refactoring, or reviewing non-trivial code.
Why use it?
It helps prevent tangled abstractions and awkward interfaces before they spread through the codebase.

Skill for Claude CodeCodex

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 skills/gitrasheed/metis-skill/p12-modular
Any agent
npx skills add gitRasheed/metis-skill --skill p12-modular
Clone the repo
git clone --depth 1 https://github.com/gitRasheed/metis-skill

Made for: Claude Code, Codex.

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.

agentmods badge for P12-modular

README.md
[![agentmods](https://agentmods.dev/badge/skills/gitrasheed/metis-skill/p12-modular.svg)](https://agentmods.dev/skills/gitrasheed/metis-skill/p12-modular)
Your own site
<a href="https://agentmods.dev/skills/gitrasheed/metis-skill/p12-modular"><img src="https://agentmods.dev/badge/skills/gitrasheed/metis-skill/p12-modular.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 635 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 $0.00000 $0.00635
Opus 5 $0.00000 $0.00318
Sonnet 5 $0.00000 $0.00127
Haiku 4.5 $0.00000 $0.00064

Measured 4d ago against content hash f917f2fbebcc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

P12-modular 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 4d 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.

evals/cases-v5/skill-permutations/P12-modular/SKILL.md · 31 lines

How it starts

The opening of the file, as written. The whole thing — 31 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Metis

Write code that favors plain data, pure logic, clear call sites, and early architectural thinking. These are strong defaults, not rigid laws: follow the surrounding codebase, framework constraints, and language norms when they clearly matter more.

FIRST, name the phase you are in. THEN read the matching phase file below IN FULL before starting, and hold only it plus the Design principles in mind. Do not read the other phase's file — out-of-phase rules dilute in-phase attention.

  • Implementing, fixing, or building anything: read references/implementing.md now.
  • Reviewing a diff, PR, or another agent's work: read references/reviewing.md now.

Design principles

  1. Start from the call site, by wishful thinking: pretend the perfect helpers already exist, name them the way you would want to call them, and get the top-level usage reading cleanly. If the calling code reads awkwardly, the abstractions are wrong — and you find out before building anything.
  2. Prefer plain data plus focused functions, modules, or systems over behavior-heavy objects. Draw boundaries around what systems do, not what entities are.
  3. Choose the simplest state model that matches reality: discriminated unions for mutually exclusive states, composable data for orthogonal features, and a plain flat record when neither pressure exists — do not over-architect the simple case.
  4. Isolate mutation and I/O near the edges. Orchestration decides what happens; inner helpers do narrow, understandable work. Push ifs up, fors down.
  5. Assert at boundaries, both where data enters and where it leaves: parsing, persistence, external APIs, state transitions, and function contracts. Check what must be true and, when useful, what must not be.
  6. Design for the hardest real requirement first, then simplify downward. When elements of a batch can invalidate each other, classify the whole batch before applying any element.
  7. Trace invariants before adding defensive checks: if an upstream parser, type, or boundary already guarantees the value, do not duplicate the check. Add one only where data crosses a trust boundary or the invariant can drift.
  8. Prefer self-explaining code with clear, not bloated, names. Comments explain a non-obvious why in one line — never what the code already says.

Read the full file on GitHub · 31 lines

Files

What ships with it

2 files 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.

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. 4d ago First seen · 31 lines · 0 tokens per session scan A f917f2fbebcc

Subscribe to this mod's changes

P12-modular is a skill published in the GitHub repository gitRasheed/metis-skill (2 stars, last pushed 12d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 635 tokens. 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.