generate-custom-instructions-from-codebase

generate-custom-instructions-from-codebase is a skill for Claude Code, Codex from MarieLynneBlock/arcanum-artifex. It costs 37 tokens per session (1,833 once invoked), scanned A, original, no licence file.

A tool for creating GitHub Copilot migration instructions by comparing two versions of a codebase.

In plain words
What is it for?
Use it when upgrading frameworks, refactoring code, changing dependencies, or moving to another technology.
Why use it?
It identifies the project's existing conventions and changes between versions, reducing the need to write migration guidance manually.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it when upgrading frameworks, refactoring code, changing dependencies, or moving to another technology.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase
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.

Any agent
npx skills add MarieLynneBlock/arcanum-artifex --skill generate-custom-instructions-from-codebase
Clone the repo
git clone --depth 1 https://github.com/MarieLynneBlock/arcanum-artifex

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 generate-custom-instructions-from-codebase

README.md
[![agentmods](https://agentmods.dev/badge/skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase/github.svg)](https://agentmods.dev/skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase)
Your own site
<a href="https://agentmods.dev/skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase"><img src="https://agentmods.dev/badge/skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase/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.

agentmods 80×15 button for generate-custom-instructions-from-codebase

Your own site · 80×15
<a href="https://agentmods.dev/skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase"><img src="https://agentmods.dev/badge/skills/marielynneblock/arcanum-artifex/generate-custom-instructions-from-codebase.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,833 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.
Origin unknown 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 $0.00037 $0.01833
Opus 5 $0.00018 $0.00916
Sonnet 5 $0.00007 $0.00367
Haiku 4.5 $0.00004 $0.00183

Measured 10d ago against content hash ce21845b9ec0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

generate-custom-instructions-from-codebase 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 10d 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.

skills/agentic/generate-custom-instructions-from-codebase/SKILL.md · 245 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 10d ago First seen · 245 lines · 37 tokens per session scan A ce21845b9ec0

Subscribe to this mod's changes

generate-custom-instructions-from-codebase is a skill published in the GitHub repository MarieLynneBlock/arcanum-artifex (4 stars, last pushed 5d ago), with no licence file. It adds 37 tokens to every session and 1,833 once invoked, about $0.0002 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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