subagent-fanout

A coordination pattern that assigns independent pieces of a large task to separate, fresh-context coding agents, then combines their findings.

In plain words
What is it for?
Use it for independent file edits, checks, research branches, or other work that can be split into separate units and reviewed together.
Why use it?
It keeps one agent from carrying too much unrelated material at once, which can make it lose track of details. Dependent steps remain in sequence.

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/archive228/loopkit/subagent-fanout
Any agent
npx skills add Archive228/loopkit --skill subagent-fanout
Clone the repo
git clone --depth 1 https://github.com/Archive228/loopkit

Made for: Claude Code, Codex.

Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 198 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 $0.00034 $0.00198
Opus 5 $0.00017 $0.00099
Sonnet 5 $0.00007 $0.00040
Haiku 4.5 $0.00003 $0.00020

Measured 2d ago against content hash d86d9e9ba579, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

subagent-fanout 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.

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/subagent-fanout/SKILL.md · 13 lines

What it actually says

Subagent Fan-out

One context loaded with ten jobs' worth of material is the exact shape that triggers context rot. Ten small contexts don't.

  • Spawn one subagent per independent unit (one file, one source, one check). Each gets a fresh context window.
  • An orchestrator synthesizes their results — it never does the per-unit work itself.
  • Give each worker a tight role and only the input it needs.
  • Use ONLY when the pieces are genuinely independent. Sequential dependencies stay in one chain. Fan-out for breadth (research, multi-file edits, multi-source verification). Keep it serial when step N needs step N-1's output.
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 · 13 lines · 34 tokens per session scan A d86d9e9ba579

Subscribe to this mod's changes

subagent-fanout is a skill published in the GitHub repository Archive228/loopkit (753 stars, last pushed 1mo ago), licensed MIT. It adds 34 tokens to every session and 198 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 2026-08-30.

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