1.2.1. Surfaces: IDE, CLI, GitHub.com, and Mobile
💡 First Principle: Each surface trades reach for context. The IDE has the richest local context (your open files); GitHub.com has the richest project context (issues, PRs, repository indexing on every plan); the CLI lives where you run commands; Mobile keeps you connected on the go.
Copilot meets developers in four broad places:
- The IDE — Visual Studio Code, Visual Studio, JetBrains IDEs, and others. This is the home turf for inline suggestions, Chat, Edit/Agent modes, and editor-level content exclusions.
- The command line (Copilot CLI) — a terminal-native agent for suggesting commands, generating and running scripts, and managing files in interactive sessions.
- GitHub.com — pull request summaries, Copilot code review, and a chat experience integrated across the platform that can draw on a repository's semantic code search index — available on every Copilot plan, including Free, since March 2025.
- GitHub Mobile — Copilot Chat on the go, including questions about a repository, a file, or specific lines of code.
A scenario the exam might pose: a reviewer wants an AI-generated summary of what a large pull request changes, without opening an IDE. That is a GitHub.com surface (PR summaries / code review), not an IDE feature. Matching the need to the surface is the whole skill.
| Surface | Best for | Key dependency |
|---|---|---|
| IDE | Writing/editing code, agentic tasks, exclusions | Supported editor + GitHub sign-in |
| Copilot CLI | Shell commands, scripts, file ops in the terminal | CLI installed + GitHub sign-in (or your own model provider) |
| GitHub.com | PR summaries, code review, repository-aware chat | Plan and policy (indexing on every plan) |
| GitHub Mobile | Quick chat, staying connected | Copilot-enabled GitHub account |
⚠️ Exam Trap: Chat availability varies by surface and editor, and some capabilities are gated by plan or by organization policy (repository indexing for Chat, by contrast, is on every plan, including Free). Don't assume every feature exists on every surface — the plan and the surface both gate availability.
Reflection Question: A developer needs to turn a plain-English request into a safe shell command without leaving the terminal. Which surface fits, and what does it need to be set up?
