What is py-shiny copilot-instructions.md?

Repository guidance for GitHub Copilot, an AI coding assistant, when working on Shiny for Python, a Python framework for building interactive web applications.

Use it when generating or changing Shiny for Python code and when navigating the repository's APIs and folders.

It gives Copilot the project structure, design principles, and documentation links needed to make suggestions that fit the codebase.

How posit-dev/py-shiny configures GitHub Copilot

About the project

Shiny for Python is a Python framework for building interactive web applications and data visualizations with reactive behavior. Data scientists and Python developers use it for prototypes as well as larger applications. Its bundled agent skills provide coding agents with Shiny documentation so they can create better Shiny applications.

posit-dev/py-shiny · 1,767 stars · on GitHub · shiny.posit.co

Reuse

Borrowing it

Nothing to install: this file belongs to posit-dev/py-shiny. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/posit-dev/py-shiny/main/.github/copilot-instructions.md

Clone the repo

git clone --depth 1 https://github.com/posit-dev/py-shiny

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/posit-dev/py-shiny/copilot-instructions/github.svg)](https://agentmods.dev/instructions/posit-dev/py-shiny/copilot-instructions)

Your own site

<a href="https://agentmods.dev/instructions/posit-dev/py-shiny/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/posit-dev/py-shiny/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/posit-dev/py-shiny/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/posit-dev/py-shiny/copilot-instructions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 5,124 This file is loaded in full into every session.

When invoked 5,124 The same file — it is already loaded in full.

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.

Model	Per session	Once invoked
Fable 5.1	$0.05124	$0.05124
Opus 5.5	$0.02050	$0.02050
Sonnet 5.5	$0.01025	$0.01025
Haiku 4.5	$0.00512	$0.00512

Measured 2mo ago against content hash 97aac7b7c444, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

py-shiny 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 2mo 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 · 764 lines

How it starts

The opening of the file, as written. The whole thing — 764 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GitHub Copilot Instructions for py-shiny

This document provides GitHub Copilot with comprehensive context about the Shiny for Python repository to help generate high-quality, context-aware code and suggestions.

1. Project Overview

Shiny for Python is a framework for building fast, beautiful web applications in Python. It enables data scientists and developers to create interactive visualizations and applications quickly while remaining extensible enough to power large, mission-critical applications.

Key Principles

Reactive Programming: Automatic dependency tracking and efficient updates
Extensibility: Build simple prototypes or complex production applications
Performance: Optimized for speed and efficiency
Developer Experience: Intuitive APIs with both Express (simple) and Core (powerful) modes

Documentation

Main documentation: https://shiny.posit.co/py/
API reference: https://shiny.posit.co/py/api/
Learn more: https://shiny.posit.co/py/docs/overview.html

2. Repository Structure

py-shiny/
├── shiny/                  # Core library code
│   ├── express/           # Express API (decorator-based, simpler syntax)
│   ├── ui/                # UI components and page layouts
│   ├── render/            # Rendering functions (@render.plot, @render.table, etc.)
│   ├── reactive/          # Reactive programming primitives (@reactive.calc, @reactive.effect)
│   ├── session/           # Session management
│   ├── experimental/      # Experimental features
│   ├── api-examples/      # API documentation examples
│   └── templates/         # Project templates
├── tests/                 # Test suite
│   ├── pytest/           # Unit tests
│   └── playwright/       # End-to-end integration tests
├── examples/              # Example applications
├── docs/                  # Documentation source (Quartodoc + Quarto)
├── js/                    # JavaScript/TypeScript code
└── scripts/               # Development and build scripts

Read the full file on GitHub · 764 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.

2mo ago First seen · 764 lines · 5,124 tokens per session scan A 97aac7b7c444

Subscribe to this mod's changes

py-shiny copilot-instructions.md is an instructions file published in the GitHub repository posit-dev/py-shiny (1,767 stars, last pushed yesterday), licensed MIT. It adds 5,124 tokens to every session, about $0.0205 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 2026-08-30.

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py-shiny: Instructions file for GitHub Copilot