glob-pattern-library

name	glob-pattern-library
description	Reference library of glob patterns for GitHub Copilot instruction files. Use when writing applyTo patterns in .instructions.md files, or when debugging why instructions apply to wrong files. Covers common patterns by ecosystem, exclusions, and anti-patterns.

Glob Pattern Library

Tested glob patterns for applyTo fields in .instructions.md files.

Pattern Syntax Quick Reference

Syntax	Meaning	Example
*	Any characters in one segment	*.ts matches app.ts
**	Any number of path segments	**/*.ts matches src/app.ts
?	Single character	?.ts matches a.ts
{a,b}	Alternatives (MUST quote in YAML)	"**/*.{ts,tsx}"
[abc]	Character class	[Rr]eadme.md
!	Negation (when supported)	!**/node_modules/**

YAML quoting rule: Patterns containing {, }, [, ], #, or : MUST be quoted.

Patterns by Ecosystem

JavaScript / TypeScript

Purpose	Pattern
All TypeScript	"**/*.{ts,tsx}"
All JavaScript	"**/*.{js,jsx}"
All JS/TS	"**/*.{js,jsx,ts,tsx}"
Test files (Jest/Vitest)	"**/*.{test,spec}.{ts,tsx,js,jsx}"
Test directories	"**/__tests__/**"
React components	"**/components/**/*.{tsx,jsx}"
Next.js pages	"**/app/**/page.{ts,tsx}"
Next.js API routes	"**/app/api/**/*.ts"
Config files	"*.config.{ts,js,mjs,cjs}"
Package manifests	"**/package.json"

Python

Purpose	Pattern
All Python	**/*.py
Test files	"**/test_*.py"
Test files (pytest)	"**/*_test.py"
Django views	"**/views.py"
Django models	"**/models.py"
FastAPI routes	"**/routers/**/*.py"
Config	"**/{settings,config}.py"
Requirements	"**/requirements*.txt"

Go

Purpose	Pattern
All Go	**/*.go
Test files	**/*_test.go
Go modules	**/go.{mod,sum}

Rust

Purpose	Pattern
All Rust	**/*.rs
Cargo config	**/Cargo.toml

C# / .NET

Purpose	Pattern
All C#	**/*.cs
Test projects	"**/*.Tests/**/*.cs"
Project files	"**/*.{csproj,sln}"
Razor views	"**/*.{cshtml,razor}"

Java / Kotlin

Purpose	Pattern
All Java	**/*.java
All Kotlin	"**/*.{kt,kts}"
Test files	"**/src/test/**/*.java"
Build config	"**/{build.gradle,pom.xml}"

Infrastructure & DevOps

Purpose	Pattern
Terraform	**/*.tf
Bicep	**/*.bicep
Docker	"**/Dockerfile*"
Docker Compose	"**/docker-compose*.{yml,yaml}"
Kubernetes	"**/k8s/**/*.{yml,yaml}"
GitHub Actions	".github/workflows/**/*.{yml,yaml}"
CI configs	"**/.{github,gitlab-ci,circleci}/**"

Documentation & Config

Purpose	Pattern
All Markdown	**/*.md
All YAML	"**/*.{yml,yaml}"
All JSON	**/*.json
All TOML	**/*.toml
Environment files	"**/.env*"
Editor config	"**/.{editorconfig,prettierrc,eslintrc}*"

Copilot Configuration Files

Purpose	Pattern
Agent definitions	"**/*.agent.md"
Instruction files	"**/*.instructions.md"
Prompt files	"**/*.prompt.md"
Skill files	"**/.github/skills/**/SKILL.md"
Skills (any location)	"**/SKILL.md"
Hooks config	"**/hooks.json"
Copilot instructions	"**/copilot-instructions.md"

Anti-Patterns (Avoid These)

Bad Pattern	Problem	Better Pattern
**/*	Matches ALL files	Use specific extensions
*.ts	Only matches root directory	**/*.ts for recursive
**/*.{ts,tsx,js,jsx,json,md,css,html}	Too broad, many unrelated files	Split into separate instruction files
src/**	Matches everything in src/	src/**/*.ts for specific types
test/**	May miss colocated tests	"**/*.{test,spec}.*" catches both
**/*.test.ts	Misses .spec.ts files	"**/*.{test,spec}.ts"
Unquoted **/*.{a,b}	YAML parse error	"**/*.{a,b}" (quote it)

Pattern Composition Tips

1. One instruction per concern: Create separate instruction files for testing vs implementation code
2. Specificity wins: src/api/**/*.ts is better than **/*.ts when instructions only apply to API code
3. Test pattern matching: Run find . -path './pattern' or ls pattern to verify matches
4. Consider exclusions: Use excludeAgent in frontmatter rather than complex negative globs
5. Document intent: Add description to explain what the pattern targets and why