idml

A tool for unpacking Adobe InDesign Markup Language files, editing their XML, and packing them back into valid .idml files. IDML is a ZIP-based format that stores an InDesign document as XML.

In plain words
What is it for?
Use it to edit text, styles, colors, spreads, and links in IDML files, or convert an IDML package into editable XML and back.
Why use it?
It lets you inspect, compare, and change document contents without having Adobe InDesign installed, while preserving the packaging rules InDesign expects.

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/mindboard/indesign-extendscript-plugins/idml
Any agent
npx skills add mindboard/indesign-extendscript-plugins --skill idml
Clone the repo
git clone --depth 1 https://github.com/mindboard/indesign-extendscript-plugins

Made for: Claude Code, Codex.

Per session 81 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,590 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 $0.00081 $0.02590
Opus 5 $0.00041 $0.01295
Sonnet 5 $0.00016 $0.00518
Haiku 4.5 $0.00008 $0.00259

Measured 2d ago against content hash 3a8d5998ec70, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

idml 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/idmlutil.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/idml/SKILL.md · 190 lines

How it starts

The opening of the file, as written. The whole thing — 190 lines — stays where its author put it; the contents beside it link to each section on GitHub.

IDML Unpack / Pack (XML editing)

An IDML (.idml) file is Adobe InDesign Markup — a ZIP package of XML files (an OCF container, the same family as EPUB). Unpacking it gives you a tree of human- and AI-readable XML you can read, diff, and edit directly, then pack back into a valid .idml that InDesign opens.

This skill uses Python 3 (stdlib only) — no pip install, nothing to set up. Python is the right tool here: it's already on macOS, and editing the unpacked XML is exactly what Claude is good at. The companion script is scripts/idmlutil.py.

Sibling skill: indd drives a live InDesign app via ExtendScript. Use idml (this one) when you want to manipulate the file's XML offline without launching InDesign; use indd when you need InDesign to render, export (PDF/PNG), or convert IDML↔INDD.

The one rule that makes an IDML valid

A plain zip -r out.idml folder/ produces a file InDesign rejects. The package must contain a mimetype entry that is:

  1. the first entry in the archive, and
  2. STORED (uncompressed), holding exactly application/vnd.adobe.indesign-idml-package.

InDesign reads those magic bytes from a fixed offset, so order and compression matter. idmlutil.py pack does this for you (every other file is DEFLATED). Always repack with this script, never with a generic zip command.

How to run it

# Extract an .idml into a folder of XML (default folder: ./workspace)
python3 skills/idml/scripts/idmlutil.py unpack /abs/path/in.idml /abs/path/out_dir

# Repack a folder back into a valid .idml (default folder: ./workspace)
python3 skills/idml/scripts/idmlutil.py pack /abs/path/out.idml /abs/path/src_dir
  • The 3rd argument (folder) is optional and defaults to ./workspace.
  • unpack clears the destination folder first, so each extraction is clean.
  • pack reads the mimetype from the source folder if present, otherwise writes the standard constant; it skips .DS_Store.
  • Prefer absolute paths.

Read the full file on GitHub · 190 lines

Files

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.

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. 2d ago First seen · 190 lines · 81 tokens per session scan A 3a8d5998ec70

Subscribe to this mod's changes

idml is a skill published in the GitHub repository mindboard/indesign-extendscript-plugins (4 stars, last pushed 10d ago), licensed MIT. It adds 81 tokens to every session and 2,590 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 2026-08-31.