go4

go4 is a skill for Claude Code, Codex from jlldavies/go4-llm-design-patterns. It costs 141 tokens per session (2,064 once invoked), scanned A, original, MIT.

A guide to designing systems that use large language models (LLMs), including agents, retrieval, prompts, tool calls, memory, evaluation, and safety controls. It contains reusable design patterns and guidance on balancing token use, cost, and response time.

In plain words
What is it for?
Use it when planning or debugging an LLM feature such as an agent loop, retrieval system, multi-agent workflow, tool integration, context management, evaluation setup, or production safeguards.
Why use it?
It helps you choose an architecture based on scale, error cost, latency, budget, and model limits instead of relying on guesses.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents; positional $N argument; mentions Claude Code.

Good fit Use it when planning or debugging an LLM feature such as an agent loop, retrieval system, multi-agent workflow, tool integration, context management, evaluation setup, or production safeguards.

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Install with agentmods
npx agentmods add skills/jlldavies/go4-llm-design-patterns/go4
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 jlldavies/go4-llm-design-patterns --skill go4
Clone the repo
git clone --depth 1 https://github.com/jlldavies/go4-llm-design-patterns

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 go4

README.md
[![agentmods](https://agentmods.dev/badge/skills/jlldavies/go4-llm-design-patterns/go4/github.svg)](https://agentmods.dev/skills/jlldavies/go4-llm-design-patterns/go4)
Your own site
<a href="https://agentmods.dev/skills/jlldavies/go4-llm-design-patterns/go4"><img src="https://agentmods.dev/badge/skills/jlldavies/go4-llm-design-patterns/go4/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 go4

Your own site · 80×15
<a href="https://agentmods.dev/skills/jlldavies/go4-llm-design-patterns/go4"><img src="https://agentmods.dev/badge/skills/jlldavies/go4-llm-design-patterns/go4.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 141 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,064 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.
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 $0.00141 $0.02064
Opus 5 $0.00071 $0.01032
Sonnet 5 $0.00028 $0.00413
Haiku 4.5 $0.00014 $0.00206

Measured 9d ago against content hash 6dd017756dcd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

go4 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 9d 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/go4/SKILL.md · 128 lines

How it starts

The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GO4 — LLM engineering design patterns

94 patterns across seven categories, grounded in transformer mechanics. Two jobs: pick the right pattern, and get its token economics right — cost is not a fixed tier, it's a function of how the system is used, and the choice compounds over every call. Don't read the whole catalog — the value is the decision guides and the conflict graph.

Resolve the catalog root

GO4 = $GO4_ROOT if set → else ../../ from this skill file → else ask. Verify: ls $GO4/patterns/CONFLICTS.md.

Before a big build — ask, then isolate

  • Ask before you plan. Regime (Step 2) and pattern choice turn on facts usually in the user's head: scale / call frequency (once? thousands/day? millions?), cost of being wrong (reversible, or irreversible and expensive to redo?), latency / budget / model limits. If a substantial build hinges on numbers you'd otherwise guess, ask first — a plan for the wrong regime is worse than one question. Skip it for small or fully-specified tasks; don't interrogate.
  • Then isolate. For a substantial or risky build, recommend the work happen in an isolated fork (git worktree/branch, not base) so it can be merged or cleanly reverted. The fork-and-revert mechanics are fiddly — use superpowers:using-git-worktrees rather than hand-rolling git — and flag the merge-or-revert decision up front so work isn't stranded.

Step 1 — Classify (most designs touch two or three)

Category Governs Reach for it when
Signal Prompt shaping Output format, personas, constraints, few-shot
Knowledge Context engineering RAG, retrieval, memory, compression, long context
Reasoning Thinking structure CoT, ReAct, tool loops, self-consistency, reflection
Orchestration Multi-agent coordination Pipelines, routing, parallelism, subagents, hierarchies
Reliability Production safety Bounds, logging, evals, human oversight, injection defence
Integration Tool use Function calling, MCP, CLI, agent-to-agent delegation
Humanizers Cross-session continuity Identity, persistent memory, self-improvement

Read the full file on GitHub · 128 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. 9d ago First seen · 128 lines · 141 tokens per session scan A 6dd017756dcd

Subscribe to this mod's changes

go4 is a skill published in the GitHub repository jlldavies/go4-llm-design-patterns (2 stars, last pushed 25d ago), licensed MIT. It adds 141 tokens to every session and 2,064 once invoked, about $0.0007 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.