brain

Instructions for storing lasting project knowledge in brain files, an Obsidian-based collection of notes.

In plain words
What is it for?
Recording architectural decisions, debugging lessons, plans, principles, project notes, and other information worth remembering.
Why use it?
It keeps important decisions, lessons, plans, and project details available across coding sessions.

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/poteto/noodle/brain
Any agent
npx skills add poteto/noodle --skill brain
Clone the repo
git clone --depth 1 https://github.com/poteto/noodle

Made for: Claude Code, Codex.

Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 808 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 $0.00073 $0.00808
Opus 5 $0.00036 $0.00404
Sonnet 5 $0.00015 $0.00162
Haiku 4.5 $0.00007 $0.00081

Measured 2d ago against content hash 0f214f7ba655, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

brain 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.

.agents/skills/brain/SKILL.md · 77 lines

How it starts

The opening of the file, as written. The whole thing — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Brain

Persistent memory across sessions. Obsidian vault at brain/.

The brain is the foundation of the entire workflow — every agent, skill, and session reads it. Low-quality or speculative content degrades everything downstream. Before adding anything, ask: "Does this genuinely improve how the system operates?" If the answer isn't a clear yes, don't write it.

Before Writing

Read brain/index.md first. Then read the relevant entrypoint for your topic:

  • brain/principles.md for principle updates
  • brain/plans/index.md for plan-related notes

For directories without a dedicated index file yet (brain/codebase/, brain/audits/), scan nearby files directly and edit an existing note when possible.

Structure

brain/
├── index.md              ← root entry point, links to everything
├── principles.md         ← index for principles/
├── todos.md              ← product backlog
├── vision.md             ← elevator pitch + link to architecture
├── architecture.md       ← full technical reference
├── principles/           ← engineering and design principles
├── codebase/             ← project-specific knowledge and gotchas
├── plans/                ← numbered feature plans (02-arrow-bindings/, etc.)
└── audits/               ← design and quality audits (date-prefixed filenames, e.g. 2026-02-20-quality-audit.md)

Rules:

  • One topic per file. brain/codebase/noodle-spawn-gotchas.md, not a mega-file.
  • Maintain existing index entrypoints: brain/index.md, brain/principles.md, brain/plans/index.md.
  • If you introduce a new top-level category, add an index-style entrypoint for it (links only, no inlined content).
  • brain/index.md is the root. Every brain file must be reachable from it.
  • File names: lowercase, hyphenated. worktree-gotchas.md.
  • Plan directories: prefixed with the todo ID from brain/todos.md. 02-arrow-bindings/ with overview.md and phase-N-*.md inside.

Format: [[section/file-name]]. Resolution order: same directory, then relative path, then vault root. Heading anchors ([[file#heading]]) are stripped during resolution.

Read the full file on GitHub · 77 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. 2d ago First seen · 77 lines · 73 tokens per session scan A 0f214f7ba655

Subscribe to this mod's changes

brain is a skill published in the GitHub repository poteto/noodle (267 stars, last pushed 5mo ago), licensed MIT. It adds 73 tokens to every session and 808 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 2026-08-30.

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