RuleStack
Counted 08:17 UTC

Real files, at real paths, counted every night

RuleStack
Real files, at real paths, counted every nightCounted 08:17 UTCDiff two files
7,205instruction files1,198repositories visited4,189rows written36files changed8formats20section tags85stacksCounted 13 September 2026
AGENTS.md617 repos, 60.4%CLAUDE.md359 repos, 35.2%.cursor/rules/*.mdc310 repos, 30.4%.github/copilot-instructions.md190 repos, 18.6%.clinerules188 repos, 18.4%GEMINI.md48 repos, 4.7%.windsurf/rules/*.md38 repos, 3.7%.cursorrules36 repos, 3.5%

.cursor/rules/*.mdc is in 310 repositories. The median one runs 277 words.

The most expressive format here. Many small .mdc files, each with frontmatter declaring when it should load, so a rule about migrations only enters context when a migration is open. Costs the most to maintain and only one editor reads it.

CursorCursorvendorSince 2025-02-01All 2,162 indexed files
Measured

What the nightly counted in real repositories

Counted 13 September 2026
Repositories carrying it310 30.4% of the corpus
Files that write down a command28.8%
Files carrying a code block60.0%
Every night counted

Repositories carrying Cursor rules, one column a night

24 nights stored
2026-08-01171 to 310 repositories2026-09-13
Asserted

What the documentation says this file can express

Read 2 August 2026
File.cursor/rules/*.mdc
OwnerCursor
Tools that read itCursor only
Glob targetingYes
ImportsYes
FrontmatterYes
Nested filesYes
User scopeNo

Read from the format’s own documentation and checked by hand. Capabilities are asserted; adoption is measured.

Four modes set in frontmatter: Always Apply (every chat session), Apply Intelligently (the agent picks it by description), Apply to Specific Files (globs match the edited file), and Apply Manually (@-mentioned). Rules must carry the .mdc extension, a plain .md file in .cursor/rules is ignored.

CursorCursor
What it does well
Glob-scoped activation, the only widely-used format that keeps unrelated rules out of context
Description-based activation lets the agent pull a rule in on demand
Many small files are easier to review in a PR than one growing document
What it cannot do
Cursor-only
Frontmatter is a schema, and a malformed .mdc silently stops applying
Fragmentation: rules spread over many files are easy to duplicate and contradict
Counted pairwise

Repositories that carry Cursor rules and something else

Counted 13 September 2026

The percentage is of repositories carrying Cursor rules, which is the number a “Cursor rules versus something” search is really asking for.

AGENTS.md51.3%159 carry both, 25.8% the other wayCLAUDE.md40.6%126 carry both, 35.1% the other wayCopilot instructions17.4%54 carry both, 28.4% the other wayCline rules11.3%35 carry both, 18.6% the other wayWindsurf rules10.3%32 carry both, 84.2% the other wayGEMINI.md7.4%23 carry both, 47.9% the other way.cursorrules6.8%21 carry both, 58.3% the other way
The files

2,162 Cursor rules files match in the corpus. These score highest.

All 2,162
NoRepository and pathCoversScoreChanged
001HTMLColorlibHQ/gentelella.cursor/rules/project.mdc100 /10013 days ago002Gohiromaily/go-crypto-wallet.cursor/rules/typescript.mdc100 /1001 month ago003TypeScriptTechSquidTV/Hermes.cursor/rules/10-hermes-api.mdc100 /1001 month ago004TypeScriptdeifos/clipmira-subtitles.cursor/rules/frontend.mdc99 /1001 month ago005TypeScriptdodgecfr/combatfilms-webapp.cursor/rules/frontend.mdc99 /1001 month ago006TypeScriptmarkstev/mark-starter.cursor/rules/frontend.mdc99 /1001 month ago007TypeScriptAllymahmoud/case-intake-platform.cursor/rules/frontend.mdc99 /1001 month ago008Pythonlangflow-ai/langflow.cursor/rules/docs_development.mdc97 /1001 month ago009Shellbybren-llc/safe-agentic-workflow.cursor/rules/10-backend-python.mdc97 /10029 days ago010TypeScriptTechSquidTV/Hermes.cursor/rules/20-hermes-api-tests.mdc97 /1001 month ago011TypeScriptskillrecordings/egghead-next.cursor/rules/project-update-user-rules.mdc96 /1001 month ago012TypeScriptskillrecordings/egghead-next.cursor/rules/project-update-rules.mdc96 /1001 month ago
The ten best, annotated