vscode-copilot-chat copilot-instructions.md

Project instructions for GitHub Copilot Chat, a Visual Studio Code extension that provides conversational coding help, inline editing, code completions, and multi-step coding tasks.

In plain words
What is it for?
Implementing or reviewing features in the Copilot Chat extension, including chat, agent mode, inline editing, prompts, and language-model integrations.
Why use it?
They give the coding agent an overview of the extension's architecture, technologies, and validation expectations before it changes the code.

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/microsoft/vscode-copilot-chat/copilot-instructions
Clone the repo
git clone --depth 1 https://github.com/microsoft/vscode-copilot-chat

Made for: GitHub Copilot.

Per session 3,970 This file is loaded in full into every session.
When invoked 3,970 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 $0.03970 $0.03970
Opus 5 $0.01985 $0.01985
Sonnet 5 $0.00794 $0.00794
Haiku 4.5 $0.00397 $0.00397

Measured 2d ago against content hash 572dbaecc398, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

vscode-copilot-chat 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 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.

.github/copilot-instructions.md · 353 lines

How it starts

The opening of the file, as written. The whole thing — 353 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GitHub Copilot Chat Extension - Copilot Instructions

Project Overview

This is the GitHub Copilot Chat extension for Visual Studio Code - a VS Code extension that provides conversational AI assistance, a coding agent with many tools, inline editing capabilities, and advanced AI-powered features for VS Code.

Key Features

  • Chat Interface: Conversational AI assistance with chat participants, variables, and slash commands
  • Inline Chat: AI-powered editing directly in the editor with Ctrl+I
  • Agent Mode: Multi-step autonomous coding tasks
  • Edit Mode: Natural language to code
  • Inline Suggestions: Next edit suggestions and inline completions
  • Language Model Integration: Support for multiple AI models (GPT-4, Claude, Gemini, etc.)
  • Context-Aware: Workspace understanding, semantic search, and code analysis

Tech Stack

  • TypeScript: Primary language (follows VS Code coding standards)
  • TSX: Prompts are built using the @vscode/prompt-tsx library
  • Node.js: Runtime for extension host and language server features
  • WebAssembly: For performance-critical parsing and tokenization
  • VS Code Extension API: Extensive use of proposed APIs for chat, language models, and editing
  • ESBuild: Bundling and compilation
  • Vitest: Unit testing framework
  • Python: For notebooks integration and ML evaluation scripts

Validating changes

You MUST check compilation output before running ANY script or declaring work complete!

  1. ALWAYS check the start-watch-tasks watch task output for compilation errors
  2. NEVER use the compile task as a way to check if everything is working properly
  3. FIX all compilation errors before moving forward

TypeScript compilation steps

  • Monitor the start-watch-tasks task outputs for real-time compilation errors as you make changes
  • This task runs npm: watch:tsc-extension,npm: watch:tsc-extension-web, npm: watch:tsc-simulation-workbench, and npm: watch:esbuild to incrementally compile the project
  • Start the task if it's not already running in the background

Read the full file on GitHub · 353 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 · 353 lines · 3,970 tokens per session scan A 572dbaecc398

Subscribe to this mod's changes

vscode-copilot-chat copilot-instructions.md is an instructions file published in the GitHub repository microsoft/vscode-copilot-chat (9,973 stars, last pushed 3mo ago), licensed MIT. It adds 3,970 tokens to every session, about $0.0198 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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