ijfw-compress

ijfw-compress is a skill for Claude Code from FerroxLabs/ijfw. It costs 20 tokens per session (297 once invoked), scanned A, original, MIT.

A tool that shortens prose in memory and context files while preserving its meaning. It leaves code blocks, links, paths, commands, headings, dates, and technical terms unchanged.

In plain words
What is it for?
Use it to compress Markdown files, keep backups, preserve document structure, and report the measured token savings.
Why use it?
It reduces the amount of text an agent must process without changing executable content or important file references.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the ijfw plugin — 34 skills, 22 commands, 37 agents, 6 hooks shipped together

Good fit Use it to compress Markdown files, keep backups, preserve document structure, and report the measured token savings.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ferroxlabs/ijfw/ijfw-compress
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 FerroxLabs/ijfw --skill ijfw-compress
Clone the repo
git clone --depth 1 https://github.com/FerroxLabs/ijfw

Made for: Claude Code.

Or install ijfw, the plugin that ships this one along with the rest of its 34 skills, 22 commands, 37 agents, 6 hooks.

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 ijfw-compress

README.md
[![agentmods](https://agentmods.dev/badge/skills/ferroxlabs/ijfw/ijfw-compress/github.svg)](https://agentmods.dev/skills/ferroxlabs/ijfw/ijfw-compress)
Your own site
<a href="https://agentmods.dev/skills/ferroxlabs/ijfw/ijfw-compress"><img src="https://agentmods.dev/badge/skills/ferroxlabs/ijfw/ijfw-compress/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 ijfw-compress

Your own site · 80×15
<a href="https://agentmods.dev/skills/ferroxlabs/ijfw/ijfw-compress"><img src="https://agentmods.dev/badge/skills/ferroxlabs/ijfw/ijfw-compress.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 297 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 pass 7 Sept 2026
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 $0.00020 $0.00297
Opus 5 $0.00010 $0.00148
Sonnet 5 $0.00004 $0.00059
Haiku 4.5 $0.00002 $0.00030

Measured 4d ago against content hash 444c9a258ad3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

ijfw-compress 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.

claude/skills/ijfw-compress/SKILL.md · 21 lines

What it actually says

Compress the target file. Preserve all meaning. Reduce tokens.

Rules:

  • Drop: articles (a/an/the), filler (just/really/basically), hedging, pleasantries.
  • Fragments OK. Short synonyms (big not extensive, fix not implement a solution).
  • Arrows for causality (X → Y).
  • Abbreviate common terms (DB/auth/config/req/res/fn/impl/env/deps).
  • Preserve EXACTLY: code blocks, URLs, file paths, commands, headings, dates, versions, technical terms.
  • Only compress prose. Never touch code.

Process:

  1. Back up: cp .original.md
  2. Compress prose sections.
  3. Validate: all headings preserved, all code blocks intact, all URLs unchanged.
  4. Report savings as measured per-artifact: "Compressed: -> tokens (% saved on this artifact)". Report the MEASURED number from wc -w / token-count on the actual files. Do NOT claim a fixed percentage — savings vary widely by input shape (verbose handoffs compress further than dense memory files). v1.5.0 audit removed the legacy hardcoded "50% / 40-50%" framing from this skill in favor of measured-per-receipt reporting.
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 · 21 lines · 20 tokens per session scan A 444c9a258ad3

Subscribe to this mod's changes

ijfw-compress is a skill published in the GitHub repository FerroxLabs/ijfw (210 stars, last pushed 2d ago), licensed MIT. It adds 20 tokens to every session and 297 once invoked, about $0.0001 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 2026-09-05.

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