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.
git clone --depth 1 https://github.com/erniker/understudyWrote 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.
[](https://agentmods.dev/instructions/erniker/understudy/copilot-instructions)<a href="https://agentmods.dev/instructions/erniker/understudy/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/erniker/understudy/copilot-instructions/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.
<a href="https://agentmods.dev/instructions/erniker/understudy/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/erniker/understudy/copilot-instructions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.01535 | $0.01535 |
| Opus 5.5 | $0.00614 | $0.00614 |
| Sonnet 5.5 | $0.00307 | $0.00307 |
| Haiku 4.5 | $0.00153 | $0.00153 |
Grade A, and why
understudy 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Copilot Project Instructions — {{PROJECT_NAME}}
┌─────────────────────────────────────────────────────────────┐
│ TUTORIAL: What is .github/copilot-instructions.md? │
│ │
│ This file is LOADED AUTOMATICALLY by Copilot CLI │
│ every time you open a session in this repository. │
│ You don't need to run /agent or /instructions for it │
│ to apply — it is always active. │
│ │
│ Use it to: │
│ - Give general project context to ALL agents │
│ - Define global rules that apply regardless of role │
│ - Establish project conventions │
│ - Indicate where to find key documentation │
│ │
│ Difference from AGENTS.md: │
│ - copilot-instructions.md = global context, always on │
│ - AGENTS.md = selectable roles via /agent │
│ │
│ Difference from .github/instructions/*.instructions.md: │
│ - copilot-instructions.md = applies to ALL │
│ - *.instructions.md = modular, toggleable instructions │
│ via /instructions │
└─────────────────────────────────────────────────────────────┘
Project
- Name: {{PROJECT_NAME}}
- Description: {{PROJECT_DESCRIPTION}}
- Main stack: {{TECH_STACK}}
- Repository: {{REPOSITORY_URL}}
- Project Manager: {{TEAM_LEAD}}
Team context
This project uses the Understudy system: a team of specialized AI agents.
Each agent has a defined role in AGENTS.md and detailed instructions in
.github/instructions/<role>.instructions.md.
Available roles:
- Architect — Solution design and architectural decisions
- Backend — API, service and business logic implementation
- Frontend — User interfaces and experience
- DevOps — Infrastructure, CI/CD and operations
- Security — Security integrated throughout the cycle
- QA — Testing and software quality (.NET, Node.js, Python)
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.
- 1mo ago First seen · 164 lines · 1,535 tokens per session scan C 6be949502e49
understudy copilot-instructions.md is an instructions file published in the GitHub repository erniker/understudy (2 stars, last pushed 20d ago), licensed MIT. It adds 1,535 tokens to every session, about $0.0061 per session on Opus 5.5. 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.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).