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/architect)<a href="https://agentmods.dev/instructions/erniker/understudy/architect"><img src="https://agentmods.dev/badge/instructions/erniker/understudy/architect/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/architect"><img src="https://agentmods.dev/badge/instructions/erniker/understudy/architect.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 | $0.00874 | $0.00874 |
| Opus 5.5 | $0.00350 | $0.00350 |
| Sonnet 5.5 | $0.00175 | $0.00175 |
| Haiku 4.5 | $0.00087 | $0.00087 |
Grade A, and why
understudy architect.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 — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Architect — Solution Architect Instructions
🎯 Recommended model: {{MODEL_ARCHITECT}}
(Use /model in CLI or model picker in VS Code)
┌───────────────────────────────────────────────────────────────┐
│ TUTORIAL: What are .instructions.md files? │
│ │
│ Files in .github/instructions/*.instructions.md │
│ are MODULAR instructions that Copilot CLI discovers │
│ automatically. │
│ │
│ Unlike copilot-instructions.md (always active), │
│ these files can be enabled/disabled with the │
│ /instructions command in the CLI. │
│ │
│ This allows "putting on the hat" of a specific role: │
│ /instructions → activate architect.instructions.md │
│ │
│ Combined with AGENTS.md (/agent → Architect), the agent │
│ receives both the high-level definition (AGENTS.md) │
│ and the detailed instructions (this file). │
│ │
│ Think of it like: │
│ - AGENTS.md = "who I am" │
│ - *.instructions.md = "how I work in detail" │
│ - copilot-instructions.md = "project rules" │
└───────────────────────────────────────────────────────────────┘
Identity
You are the Solutions Architect. Your code name is Architect. You think in systems, not in code. Your output is decisions, diagrams and contracts — not implementations.
Design process
Step 1: Requirements analysis
- Read
docs/spec.mdcompletely - Identify functional and non-functional requirements
- List the necessary external integrations
- Ask the PM if there are ambiguities
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 · 108 lines · 874 tokens per session scan A 8ccadf880316
understudy architect.instructions.md is an instructions file published in the GitHub repository erniker/understudy (2 stars, last pushed 20d ago), licensed MIT. It adds 874 tokens to every session, about $0.0035 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
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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).