GitHub Copilot Advanced Tips 2026: 8 Powerful Features 90% of People Don't Use

GitHub Copilot is no longer just a "press Tab to accept" line-level tool—it's now a complete system of completions + chat + multi-file editing + autonomous agents. Yet most people still use only 20% of its capabilities. The 8 features below are ordered from "immediately usable" to "game-changing workflow", all based on VS Code (JetBrains equivalents exist for most).

Feature 1: Inline Chat (Cmd+I) + Slash Commands

Without switching to the sidebar, press Cmd+I (Win: Ctrl+I) at the cursor to invoke inline chat:

text
/doc      Generate documentation comments for the selected function
/explain  Explain the selected code
/fix      Fix issues in the selected code
/tests    Generate tests (including edge cases)
/optimize Performance optimization suggestions

Practical tip: Select a complex function → Cmd+I → /tests → directly generate Jest/Pytest test cases. The value of inline mode is that changes appear as a diff in place—accept or reject with one click, without breaking flow.

Feature 2: Repository-Level Custom Instructions (Most Underrated Feature)

Create .github/copilot-instructions.md in your repo, and all Chat/Agent requests will automatically follow it:

markdown
Project Conventions
TypeScript strict mode; functional components, no class components
Async always uses async/await; test framework is Vitest (not Jest)
Naming: camelCase for variables, UPPER_SNAKE for constants
Style
Functions no longer than 30 lines; prefer self-explanatory names over comments

Configure once, then say "write a user registration function" and it follows the spec. Put this file in version control—it's like tuning Copilot for everyone on the team. This is the single highest-leverage factor for generation quality (see prompt sensitivity for the principle: explicit rules in context drastically reduce output variance).

Feature 3: Context Variables—#file, @workspace

Chat quality depends on the context you feed:

#file:src/auth/login.ts pulls the specified file into context

@workspace How is authentication implemented in this project? makes Copilot search the entire repo to answer—the first tool for reading unfamiliar codebases

@terminal explains terminal errors, #selection targets only the selection

Practical combo: @workspace Where is the payment callback handled? → find the file → #file:... Add idempotency to this callback.

Feature 4: Copilot Edits / Multi-File Editing

Sidebar Edits mode (or the predecessor to Agent mode): describe a cross-file change like "convert UserService's callback style to async/await and update all callers synchronously"—it lists affected files, shows diffs one by one, and you accept/reject per file. Refactoring tasks upgrade from "Cmd+I per file" to "one sentence batch".

Feature 5: Agent Mode—Give Tasks, Not Instructions

In Agent mode, Copilot plans autonomously: reads files, modifies code, runs terminal commands, checks errors, fixes itself, loops until the task is done. Ideal for: writing a new endpoint with tests, fixing a bug with a full error stack, adding test coverage to an old module.

The key to using it well—same as all coding agents—is to state the acceptance criteria fully in the first sentence ("Add pagination to /api/orders with query params page/limit, include Vitest tests, and run npm test to pass"). Open-ended descriptions + multiple rounds of correction = slower and more expensive. For a horizontal comparison of agent-like tools, see Cursor vs Copilot and Windsurf vs Devin vs SWE-agent.

Feature 6: Hidden Completion Operations

Alt+] / Alt+[: Cycle through multiple completion candidates (many don't know there's more than one)

Cmd+→: Accept completion word by word (use only the first half without accepting all)

Comment-driven: Write // Use binary search to find insertion position in sorted array, handle duplicates then press Enter—much more accurate than typing halfway and waiting for guesses

When completions are distracting, disable line-level completions per language (in settings github.copilot.enable toggle per language), keeping only Chat/Edits

Feature 7: Copilot Code Review

Request a Copilot review on a PR page (or run review on staged changes in VS Code): it checks for logic issues, missed edge cases, security concerns first—humans only review architectural issues the machine can't spot. Combine with .github/copilot-instructions.md to specify review focus areas for the project, significantly reducing false positives.

Feature 8: Copilot CLI—Copilot in the Terminal

bash
gh copilot suggest "Find all files under src that reference lodash and count occurrences"
gh copilot explain "tar -xzvf archive.tar.gz -C /tmp"

Never memorize shell incantations again. suggest gives a command, you can ask follow-ups to modify it, and only execute when confirmed—safer than pasting StackOverflow commands directly.

Comprehensive Mindset

Context > Wording: Feed the right context via #file/@workspace/instructions—it's more effective than rephrasing ten times

Accept in Small Steps: Review diffs one by one for multi-file changes; Copilot's mistakes are "confidently wrong"

Model Selection: Chat/Agent supports switching underlying models—use the strongest for refactoring and multi-file tasks, keep default for completions (speed first)—see model library for coding capability comparisons

FAQ

Q: Copilot vs Cursor? Copilot wins on multi-IDE support (VS Code/JetBrains/Neovim), enterprise compliance (IP indemnity), and deep GitHub ecosystem integration; Cursor is an AI-native editor with more aggressive Composer/context experiences. See full comparison.

Q: What does the free tier offer? Limited completions + Chat with quotas, enough for light use; heavy development should go for the paid tier—the efficiency gains from Agent/Edits pay back the cost in a day.

Q: Is company code safe? Business/Enterprise tiers do not use your code for model training by default, and code reference filtering can be enabled; teams with high compliance requirements should start with these tiers.

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*Last updated: June 2026. Features evolve rapidly; refer to official GitHub documentation.*