spawn-instance

spawn-instance is a skill for Claude Code, Codex from aeonfun/aeon. It costs 27 tokens per session (4,195 once invoked), scanned A, original, MIT.

An agent setup workflow that clones this agent into a new GitHub repository, configures its skills, checks the setup, and registers the new agent in a fleet. A fleet is a group of managed agent instances.

In plain words
What is it for?
It helps create purpose-specific agent instances from a repository, enable their GitHub Actions, validate their configuration, and record them in the fleet.
Why use it?
It standardizes creation of new agents while keeping their secrets separate and requiring the owner to add those secrets manually.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions Claude Code.

Good fit It helps create purpose-specific agent instances from a repository, enable their GitHub Actions, validate their configuration, and record them in the fleet.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/aeonfun/aeon/spawn-instance
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 aeonfun/aeon --skill spawn-instance
Clone the repo
git clone --depth 1 https://github.com/aeonfun/aeon

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 spawn-instance

README.md
[![agentmods](https://agentmods.dev/badge/skills/aeonfun/aeon/spawn-instance.svg)](https://agentmods.dev/skills/aeonfun/aeon/spawn-instance)
Your own site
<a href="https://agentmods.dev/skills/aeonfun/aeon/spawn-instance"><img src="https://agentmods.dev/badge/skills/aeonfun/aeon/spawn-instance.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,195 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. ✓ AI security review Sonnet 5 · 6 Sept 2026 📄 Read the review Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 6 findings, up to high

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 →

  • high Prompt Injection · line 11
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
  • high Rogue Agent · line 208
    Skill modifies its own code, configuration, or behavior at runtime. Self-modification enables an agent to escalate privileges, disable safety constraints, or install persistent backdoors.
    Fix: Prevent the skill from modifying its own code, SKILL.md, or configuration files. Treat skill files as read-only at runtime.
  • high Memory Poisoning · line 230
    Skill manipulates agent memory, state, or stored context. Memory corruption can alter personality, override safety rules, or cause unpredictable behavior.
    Fix: Protect agent memory and state from modification by untrusted content. Use read-only memory for critical instructions and validate all state changes.
  • high Memory Poisoning · line 249
    Skill manipulates agent memory, state, or stored context. Memory corruption can alter personality, override safety rules, or cause unpredictable behavior.
    Fix: Protect agent memory and state from modification by untrusted content. Use read-only memory for critical instructions and validate all state changes.
  • high Tool Misuse · line 250
    Tool parameters are crafted to achieve unintended or unsafe behavior. Parameter abuse can bypass intended safety checks (e.g. shell=True, --force, dangerous glob patterns).
    Fix: Validate all tool parameters against an allowlist. Reject dangerous parameter values (shell=True, --force, -rf /) and use safe defaults.
  • medium Agent Snooping · line 117
    Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.
    Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 $0.00027 $0.04195
Opus 5 $0.00014 $0.02098
Sonnet 5 $0.00005 $0.00839
Haiku 4.5 $0.00003 $0.00419

Measured 3d ago against content hash b508a7f7794a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

spawn-instance 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 3d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/spawn-instance/SKILL.md · 374 lines

How it starts

The opening of the file, as written. The whole thing — 374 lines — stays where its author put it; the contents beside it link to each section on GitHub.

${var} — Name and purpose of the new instance. Format name: purpose, e.g. crypto-tracker: monitor DeFi protocols and token movements. If empty, notify the owner and stop with exit SPAWN_INVALID_VAR.

Today is ${today}. Create a new Aeon instance by forking this repo, configuring it for a specific purpose, validating the configuration, and registering it in the fleet.

Read memory/MEMORY.md at the start for context.

Security Model

This skill creates the repo and configuration but does NOT propagate secrets. The new instance is inert until the owner manually sets secrets (ANTHROPIC_API_KEY or CLAUDE_CODE_OAUTH_TOKEN, plus notification secrets). Each instance has its own API keys for billing isolation and blast-radius containment.

Exit Taxonomy

Every run ends with one of these status codes, written to the log and (where relevant) included in the notification:

Code Meaning
SPAWN_OK Fork created, configured, pushed, Actions enabled, registered.
SPAWN_FORK_EXISTS_RECOVERED Fork already existed but wasn't registered → configured + registered now.
SPAWN_FORK_EXISTS_REGISTERED Fork exists AND is already registered and not archived — refused, no change.
SPAWN_INVALID_VAR var was empty or couldn't be parsed into name: purpose.
SPAWN_NO_SKILLS After validation, the skill plan was empty — refused.
SPAWN_FORK_FAILED gh repo fork and the fallback forks API both failed.
SPAWN_PUSH_FAILED Fork created but push failed — fork left in place, recovery instructions emitted.
SPAWN_ACTIONS_FAILED Configuration pushed but enabling Actions failed — recovery instructions emitted.
SPAWN_API_ERROR Any other GitHub API failure not covered above.

Steps

1. Parse and validate the var

  • If ${var} is empty, log SPAWN_INVALID_VAR: empty var to memory/logs/${today}.md, notify: spawn-instance: empty var — re-run with "name: purpose", and stop.
  • Split on the first : — left is NAME_RAW, right is PURPOSE (trim whitespace). If either is empty, exit SPAWN_INVALID_VAR.
  • Derive NAME: lowercase NAME_RAW, replace non-alphanumeric runs with -, strip leading/trailing -, truncate to 40 chars. If empty after sanitization, exit SPAWN_INVALID_VAR.
  • Set REPO_NAME="aeon-${NAME}".

Read the full file on GitHub · 374 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. 3d ago First seen · 374 lines · 27 tokens per session scan E b508a7f7794a

Subscribe to this mod's changes

spawn-instance is a skill published in the GitHub repository aeonfun/aeon (716 stars, last pushed yesterday), licensed MIT. It adds 27 tokens to every session and 4,195 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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