Copilot instructions
Two layers: one always-on repo file, plus optional glob-scoped instruction files. Lives under .github/ rather than the repo root, which is the tell that it is aimed at the GitHub platform surface as much as the editor.
What the corpus measured
2026-08-03Repositories
126
2026-08-03Adopting repositories, not files.Share of corpus
18.1%
2026-08-03Of every repository RuleStack indexes.Median length
417w
2026-08-0390th percentile 1,329 words.Median quality
60
2026-08-0341.8% name a command; 48.2% contain code.Repositories carrying Copilot instructions, 2026-08-01 to 2026-08-03
Real Copilot instructions files
| Repository | Format | Stack | Covers | Score | Changed |
|---|---|---|---|---|---|
| pytorch/pytorch.github/copilot-instructions.md · 102k | Copilot instructions | setupbuildteststyle+5 | 100/100 | 3 days ago | |
| louislam/uptime-kuma.github/copilot-instructions.md · 90k | Copilot instructions | setupbuildtestlint-format+9 | 100/100 | 3 days ago | |
| chihebnabil/lovable-boilerplate.github/instructions/global.instructions.md · 63 | Copilot instructions | buildlint-formatstylearch+4 | 100/100 | 3 days ago | |
| dotnet/roslyn.github/instructions/Compiler.instructions.md · 21k | Copilot instructions | buildteststylearch+3 | 99/100 | 3 days ago | |
| rtk-ai/rtk.github/copilot-instructions.md · 74k | Copilot instructions | buildtestlint-formatstyle+2 | 97/100 | 3 days ago | |
| hiyouga/LlamaFactory.github/copilot-instructions.md · 74k | Copilot instructions | setupbuildtestlint-format+5 | 97/100 | 2 days ago | |
| JCodesMore/ai-website-cloner-template.github/copilot-instructions.md · 31k | Copilot instructions | buildlint-formatstylearch+3 | 97/100 | 2 days ago | |
| bagisto/bagisto.github/copilot-instructions.md · 28k | Copilot instructions | setupbuildteststyle+5 | 97/100 | 3 days ago | |
| dotnet/roslyn.github/copilot-instructions.md · 21k | Copilot instructions | buildteststylearch+3 | 97/100 | 3 days ago |
What it asserts
2026-08-01Read from the format’s own documentation and checked by hand. Capabilities are asserted; adoption is measured.
- File
- .github/copilot-instructions.md
- When it applies
- copilot-instructions.md is always in scope. Additional .github/instructions/*.instructions.md files load when their applyTo glob matches the open file.
- Size limits
- None documented
- Tools that read it
- GitHub CopilotCopilot coding agentVS Code
Capabilities
- Read by more than one tool
- Frontmatter
- Glob targeting
- Imports other files
- Nested / per-directory
- Multiple files
- User-level scope
Strengths
- Reaches Copilot across the editor, github.com and the coding agent from one file
- applyTo globs give per-path targeting without leaving the .github convention
Weaknesses
- Copilot-only
- No imports; shared text is copied between instruction files
- Buried under .github/, so contributors discover it less often than a root file
Measured — counted from real repositories, nightlyAsserted — read from the vendor docs, dated
Repositories that carry Copilot instructions and something else
Counted pairwise across the whole corpus. The percentage is of repositories carrying Copilot instructions — the number a “Copilot instructions vs …” search is really asking for.
+ AGENTS.md
58.7%
2026-08-0374 repos carry both18.7% the other way
+ CLAUDE.md37.3%
2026-08-0347 repos carry both19.0% the other way
+ Cursor rules23.0%
2026-08-0329 repos carry both16.2% the other way
+ Cline rules15.9%
2026-08-0320 repos carry both25.3% the other way
+ GEMINI.md11.1%
2026-08-0314 repos carry both42.4% the other way
+ Windsurf rules9.5%
2026-08-0312 repos carry both85.7% the other way
+ .cursorrules4.0%
2026-08-035 repos carry both18.5% the other way
