myelin copilot-instructions.md

myelin copilot-instructions.md is an instructions file for GitHub Copilot from et-do/myelin. It costs 401 tokens per session, scanned A, original, MIT.

Instructions for using Myelin, a long-term memory system connected through MCP tools, to recall project context and store decisions, bug fixes, conventions, and completed work.

In plain words
What is it for?
Use them at the start of a task to recall relevant context and after meaningful decisions or fixes to record what happened and why.
Why use it?
They reduce repeated discovery and help preserve important project knowledge between tasks.

Instructions file for GitHub Copilot

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 instructions/et-do/myelin/copilot-instructions
Clone the repo
git clone --depth 1 https://github.com/et-do/myelin

Made for: GitHub Copilot.

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 myelin copilot-instructions.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/et-do/myelin/copilot-instructions.svg)](https://agentmods.dev/instructions/et-do/myelin/copilot-instructions)
Your own site
<a href="https://agentmods.dev/instructions/et-do/myelin/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/et-do/myelin/copilot-instructions.svg" alt="Measured on agentmods" height="20"></a>
Per session 401 This file is loaded in full into every session.
When invoked 401 The same file — it is already loaded in full.
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 $0.00401 $0.00401
Opus 5 $0.00200 $0.00200
Sonnet 5 $0.00080 $0.00080
Haiku 4.5 $0.00040 $0.00040

Measured 4d ago against content hash 6702d570f2c9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

myelin copilot-instructions.md 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 4d 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.

.github/copilot-instructions.md · 34 lines

What it actually says

Copilot Instructions

Memory

You have access to a long-term memory system (Myelin) via MCP tools.

When to Recall

  • At the START of every task, recall relevant context about the current project, file, or problem domain.
  • Before making architectural decisions, recall past decisions and their rationale.
  • When debugging, recall similar past issues and their resolutions.

When to Store

  • After making significant decisions — record WHAT was decided and WHY.
  • After resolving non-trivial bugs — record the symptoms, root cause, and fix.
  • When discovering project conventions, patterns, or gotchas.
  • After completing a meaningful feature — summarize the approach and trade-offs.

How to Store Effectively

  • Always include project metadata (e.g., project="myelin").
  • Use scope to organize by domain (e.g., scope="auth", scope="database").
  • Use tags for cross-cutting concerns (e.g., tags="performance,optimization").
  • Use memory_type when it's clear: "semantic" for decisions/facts, "procedural" for how-to, "episodic" for events, "prospective" for plans.
  • Be specific. "We use JWT RS256 because asymmetric keys let the API gateway verify without the signing secret" is better than "We use JWT."

Maintenance

  • After extended sessions (10+ stores), run consolidate to build the semantic network — it improves recall by linking related entities.
  • Consolidation auto-triggers every 50 stores, but running it manually after a burst of activity gives immediate benefit.
  • Periodically run decay_sweep to prune stale memories (90+ days idle, <2 accesses).

What NOT to Store

  • Trivial or ephemeral information (typo fixes, one-off commands).
  • Exact code blocks — store the reasoning, not the implementation.
  • Anything sensitive (secrets, credentials, PII).
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. 4d ago First seen · 34 lines · 401 tokens per session scan A 6702d570f2c9

Subscribe to this mod's changes

myelin copilot-instructions.md is an instructions file published in the GitHub repository et-do/myelin (9 stars, last pushed 4mo ago), licensed MIT. It adds 401 tokens to every session, about $0.0020 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.

Related

Other instructions, from other repositories