extension-creator

extension-creator is a skill for Claude Code, Codex from hotovo/aider-desk. It costs 44 tokens per session (5,544 once invoked), scanned A, original, Apache-2.0.

A guide for building AiderDesk extensions, which are add-ons that can add commands, tools, agents, modes, or event handlers to the app.

In plain words
What is it for?
Use it when creating a new AiderDesk extension or implementing extension commands, tools, agents, modes, or event handlers.
Why use it?
It explains the required extension structure, metadata, interface methods, installation location, and documentation so a new add-on can be set up consistently.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for aider. Also seen: built for aider.

Good fit Use it when creating a new AiderDesk extension or implementing extension commands, tools, agents, modes, or event handlers.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/hotovo/aider-desk/extension-creator
About the project

AiderDesk is an open-source desktop platform that coordinates AI-assisted software development around the Aider coding tool, letting engineers inspect and control proposed changes. It is for professional developers who want AI help while retaining their existing editor, terminal, and Git workflow. Catalogue add-ons extend its controlled development workflow.

hotovo/aider-desk · 1,423 stars · on GitHub · aiderdesk.hotovo.com

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 hotovo/aider-desk --skill extension-creator
Clone the repo
git clone --depth 1 https://github.com/hotovo/aider-desk

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 extension-creator

README.md
[![agentmods](https://agentmods.dev/badge/skills/hotovo/aider-desk/extension-creator/github.svg)](https://agentmods.dev/skills/hotovo/aider-desk/extension-creator)
Your own site
<a href="https://agentmods.dev/skills/hotovo/aider-desk/extension-creator"><img src="https://agentmods.dev/badge/skills/hotovo/aider-desk/extension-creator/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 extension-creator

Your own site · 80×15
<a href="https://agentmods.dev/skills/hotovo/aider-desk/extension-creator"><img src="https://agentmods.dev/badge/skills/hotovo/aider-desk/extension-creator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,544 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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: 4 findings, up to medium

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 →

  • medium Rogue Agent · line 3
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
  • medium Rogue Agent · line 169
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
  • medium Rogue Agent · line 175
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
  • low Excessive Agency · line 8
    Skill's behavior or capabilities extend beyond its stated purpose. Scope creep allows an agent to perform actions unrelated to its documented functionality, increasing the attack surface.
    Fix: Limit the skill's scope to its documented purpose. Remove instructions that enable the agent to perform actions outside its stated functionality.
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 $0.00044 $0.05544
Opus 5 $0.00022 $0.02772
Sonnet 5 $0.00009 $0.01109
Haiku 4.5 $0.00004 $0.00554

Measured 12d ago against content hash dd39be30b7ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

extension-creator scanned grade A with 1 finding 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 12d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (assets/scripts/validate-extension-ui.mjs), 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

**Pattern:** Node.js built-in modules (`fs`, `path`, `child_process`, `os`, etc.) are available in extensions.
resources/skills/extension-creator/SKILL.md · 503 lines

How it starts

The opening of the file, as written. The whole thing — 503 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Extension Creator

Create AiderDesk extensions that extend functionality through events, commands, tools, agents, and modes.

When to Use

Use this skill when:

  • Building a new AiderDesk extension
  • Creating extension commands, tools, or event handlers
  • Implementing the Extension interface
  • Setting up extension metadata and documentation

Do not use when:

  • Simply activating an existing extension
  • Making general code changes unrelated to extensions
  • Running tests or builds

Rules

Rule: Choose installation target first

When: Starting extension creation

Then: Ask the user where to install the extension

If: Working inside the AiderDesk project (the current project is the aider-desk repository)

Then: Offer three options:

  1. Current Project — Install to .aider-desk/extensions/ in the current project (project-scoped)
  2. Global — Install to ~/.aider-desk/extensions/ (available in all projects)
  3. In-Repo — Create inside packages/extensions/extensions/ (ships with AiderDesk app)

If: Working outside the AiderDesk project

Then: Offer two options:

  1. Current Project — Install to .aider-desk/extensions/ in the current project (project-scoped)
  2. Global — Install to ~/.aider-desk/extensions/ (available in all projects)

Must: Wait for user's choice before proceeding. The chosen target determines the entire workflow.

Reference: references/install-targets.md for full details on each target.

Rule: Follow the correct flow for the chosen target

When: User has chosen an installation target

If: Target is Current Project or Global

Then: Follow the Project / Global Flow:

  1. Determine extension type (single-file or folder)
  2. Create extension file(s) in the target directory (.aider-desk/extensions/ or ~/.aider-desk/extensions/)
  3. Implement Extension interface methods
  4. Export metadata and default class
  5. Verify the extension loads (auto-discovered, no registry needed)

Read the full file on GitHub · 503 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. 12d ago First seen · 503 lines · 44 tokens per session scan A dd39be30b7ef

Subscribe to this mod's changes

extension-creator is a skill published in the GitHub repository hotovo/aider-desk (1,423 stars, last pushed today), licensed Apache-2.0. It adds 44 tokens to every session and 5,544 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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