Suthahar Jegatheesan MSDEVBUILD / blog Multi-Stack Dev Build · by Suthahar
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GitHub Copilot

The 7 files Copilot reads

Most devs have never opened half of them. Here's what each one actually does — and why it matters.

What you'll learn

  • copilot-instructions.md is auto-attached to every chat request — repo-wide, no reference needed
  • instructions/*.instructions.md scopes rules per path, skills/SKILL.md loads itself when your ask matches, and agents/*.agent.md (formerly chat modes) packages personas per task
  • mcp.json and copilot-setup-steps.yml extend Copilot into real tools and give the autonomous coding agent its own preinstalled sandbox
copilot 9 steps 23 seconds —views

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Understand it one step at a time

The short runs these in order in about 23 seconds. Here they are written out — pick any step to jump the short straight to it.

1 Step 1 of 9

Be honest — how many have you opened?

Copilot reads every one of these files before it suggests a single line. Let’s open them, one by one.

Frequently asked questions

What files does GitHub Copilot actually read from a repository?
Up to seven, when a repo uses all of them: .github/copilot-instructions.md for repo-wide rules, .github/instructions/*.instructions.md for path-scoped rules via an applyTo glob, .github/skills/*/SKILL.md for self-loading agent skills, .github/agents/*.agent.md for custom agents, .github/workflows/copilot-setup-steps.yml to provision the coding agent's sandbox, .vscode/settings.json for workspace feature switches, and .vscode/mcp.json to register MCP servers.
Are GitHub Copilot chat modes the same thing as custom agents?
Yes — VS Code renamed chat modes to custom agents in 2026. Existing *.chatmode.md files still work, but the current format is *.agent.md in .github/agents, and the picker now reads "Configure Custom Agents" instead of "Configure Chat Modes."
Do GitHub Copilot prompt files still work?
They still run under the Local agent, but VS Code has deprecated *.prompt.md for Agent Host sessions in favor of Agent Skills. A SKILL.md folder bundles instructions, scripts and resources, and Copilot loads it automatically once your request matches its description — you can also still call it manually by typing /.

Free app · no app store

These are built for a phone

Every short is drawn at full portrait height, the shape a phone already is. Installed, it opens full-bleed with no address bar across the top — and the whole library reads offline.

How it works

Read deeper on GitHub Copilot

Twenty seconds gets the shape of an idea across. These go into how it behaves in production.

More shorts

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