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AI IDE Comparison: Rules & Configuration

A detailed comparison of how the top AI coding IDEs handle rule configuration, context management, and customization.

Feature Matrix

Feature Cursor Windsurf GitHub Copilot Claude Code Cline Codex Zed AI Gemini CLI Aider Continue.dev
Config file .cursor/rules/*.mdc .windsurfrules .github/copilot-instructions.md CLAUDE.md .clinerules AGENTS.md .rules GEMINI.md conventions.md .continue/rules/*.md
Multi-file support ✅ (.mdc per rule) ❌ (single file) ✅ (.instructions.md) ✅ (.claude/rules/) ✅ (.clinerules/) ✅ (dir-based) ❌ (single file) ✅ (dir-based) ❌ (single file) ✅ (rules per topic)
Glob/path filtering ✅ (globs in YAML) ❌ ✅ (applyTo) ❌ (directory-based) ✅ (YAML frontmatter) ❌ ❌ ❌ ❌ ✅ (YAML globs)
Global rules ✅ (User Rules) ✅ (global_rules.md) ✅ (VS Code settings) ✅ (~/.claude/CLAUDE.md) ✅ (VS Code settings) ✅ (~/.codex/AGENTS.md) ❌ ❌ ✅ (~/.aider.conf.yml) ✅ (~/.continue/)
AGENTS.md support ✅ native ❌ (manual) ✅ (detected) ❌ (manual) ✅ (reads it) ✅ native ✅ native ✅ native ✅ native ❌
Hierarchy levels User > Project > Rule Global > Project Repo > Directory User > Project > Dir Global > Workspace Global > Project > Dir Project only Project > Dir Global > Project Global > Project > Rule
Format YAML frontmatter + MD Plain Markdown YAML frontmatter + MD Plain Markdown Plain MD / YAML+MD Plain Markdown Plain Markdown Plain Markdown Plain Markdown YAML frontmatter + MD
Max recommended size ~500 tokens per .mdc ~6000 chars global No hard limit No hard limit No hard limit 32 KiB default No hard limit No hard limit No hard limit No hard limit
Legacy file .cursorrules - - - - - - - - -

How Each IDE Loads Rules

Cursor

  1. User Rules: Set in Cursor Settings → General → "Rules for AI"
  2. Project Rules (.mdc): Loaded from .cursor/rules/ directory
    • alwaysApply: true → Always included in context
    • globs: ["*.tsx"] → Auto-activated when matching files are open
    • No flags → Only when explicitly @-mentioned
  3. Legacy (.cursorrules): Single file in project root, always loaded
  4. AGENTS.md: Read natively from project root

Loading order: User Rules → .cursorrules → .cursor/rules/*.mdc (filtered by context)

Windsurf

  1. Global Rules: Configured in Windsurf Settings → AI Settings → Global Rules
    • Applied to ALL projects (max ~6000 characters)
  2. Project Rules (.windsurfrules): Single file in project root
    • Always loaded for the project
    • Plain Markdown format

Loading order: Global Rules → .windsurfrules

GitHub Copilot

  1. Repository Instructions: .github/copilot-instructions.md (always active)
  2. Path-specific: .github/instructions/*.instructions.md with applyTo frontmatter
  3. AGENTS.md: Detected and read from project root
  4. VS Code Settings: github.copilot.chat.codeGeneration.instructions in settings.json

Loading order: VS Code Settings → Repository Instructions → Path-specific (filtered)

Claude Code

  1. User-global: ~/.claude/CLAUDE.md (personal rules across all projects)
  2. Project root: ./CLAUDE.md (project-level rules)
  3. Modular rules: ./.claude/rules/*.md (topic-specific rules)
  4. Directory-specific: ./subfolder/CLAUDE.md (scoped overrides)

Loading order: User-global → Project CLAUDE.md → .claude/rules/ → Directory CLAUDE.md

Key behavior: CLAUDE.md content is treated as immutable system rules with higher priority than user chat input.

Cline

  1. VS Code Settings: Global rules in Cline extension settings
  2. Single file: .clinerules in project root
  3. Multi-file: .clinerules/ folder with numbered Markdown files
  4. Cross-tool: Also reads .cursorrules, CLAUDE.md, .windsurfrules, AGENTS.md

Loading order: VS Code Settings → .clinerules(/) → Cross-tool files (if present)

OpenAI Codex

  1. Global scope: ~/.codex/AGENTS.override.md → ~/.codex/AGENTS.md
  2. Project scope: AGENTS.md from Git root down to current working directory
  3. Override: AGENTS.override.md takes precedence at each level
  4. Config: ~/.codex/config.toml for discovery settings

Loading order: Global AGENTS.md → Project root AGENTS.md → Subdirectory AGENTS.md (concatenated)

Zed AI

  1. Project Rules: Scans project root for rule files in priority order
    • .rules → .cursorrules → .windsurfrules → .clinerules → .github/copilot-instructions.md → AGENTS.md → CLAUDE.md → GEMINI.md
  2. First match wins — only one file is loaded

Loading order: First file found in priority scan order

Key behavior: Zed is the most format-compatible editor, recognizing 8+ rule file formats natively. No proprietary config format needed.

Google Gemini CLI

  1. Project root: ./GEMINI.md (primary configuration)
  2. Directory-specific: ./subfolder/GEMINI.md (scoped instructions)
  3. Fallback: AGENTS.md (also supported)

Loading order: Project GEMINI.md → Subdirectory GEMINI.md (hierarchical)

Key behavior: Similar to Claude Code's CLAUDE.md model — hierarchical plain Markdown files scoped by directory.

Aider

  1. Global config: ~/.aider.conf.yml (model, auto-commit, lint/test commands)
  2. Project conventions: .aider/conventions.md or conventions.md in project root
  3. AGENTS.md: Read natively from project root
  4. Ad-hoc context: --read flag to pass any file as read-only context

Loading order: Global config → Project conventions → AGENTS.md → --read files

Key behavior: CLI-based pair programming tool. Supports multiple LLM backends. Auto-commits changes by default.

Continue.dev

  1. Global config: ~/.continue/ directory with model configuration
  2. Project rules: .continue/rules/*.md with YAML frontmatter
    • alwaysApply: true → Always included in context
    • globs: ["*.tsx"] → Auto-activated for matching files
    • regex: "TODO|FIXME" → Activated by content patterns
  3. Model config: .continuerc.json in project root

Loading order: Global config → Project rules (filtered by type/glob/regex)

Key behavior: Open-source IDE extension for VS Code and JetBrains. Rule format similar to Cursor's .mdc files with YAML frontmatter.

Cross-IDE Compatibility

Which IDE reads which file natively?

File Cursor Windsurf Copilot Claude Code Cline Codex Zed AI Gemini CLI Aider Continue
AGENTS.md ✅ ❌ ✅ ❌ ✅ ✅ ✅ ✅ ✅ ❌
.cursorrules ✅ ❌ ❌ ❌ ✅ ❌ ✅ ❌ ❌ ❌
.windsurfrules ❌ ✅ ❌ ❌ ✅ ❌ ✅ ❌ ❌ ❌
CLAUDE.md ❌ ❌ ❌ ✅ ✅ ❌ ✅ ❌ ❌ ❌
GEMINI.md ❌ ❌ ❌ ❌ ❌ ❌ ✅ ✅ ❌ ❌
.clinerules ❌ ❌ ❌ ❌ ✅ ❌ ✅ ❌ ❌ ❌
.rules ❌ ❌ ❌ ❌ ❌ ❌ ✅ ❌ ❌ ❌
.github/copilot-instructions.md ❌ ❌ ✅ ❌ ❌ ❌ ✅ ❌ ❌ ❌
.cursor/rules/*.mdc ✅ ❌ ❌ ❌ ❌ ❌ ❌ ❌ ❌ ❌
.claude/rules/*.md ❌ ❌ ❌ ✅ ❌ ❌ ❌ ❌ ❌ ❌
.continue/rules/*.md ❌ ❌ ❌ ❌ ❌ ❌ ❌ ❌ ❌ ✅
conventions.md ❌ ❌ ❌ ❌ ❌ ❌ ❌ ❌ ✅ ❌

Key insight: Zed AI is the most format-compatible editor, reading 8+ rule file formats natively. Using AGENTS.md gives you the broadest native support (Cursor, Copilot, Cline, Codex, Zed AI, Gemini CLI, Aider).

Recommendations

For Solo Developers

  • Using one IDE: Use that IDE's native format for full feature support
  • Switching between IDEs: Use AGENTS.md with symlinks

For Teams (Mixed IDEs)

  • Best approach: Maintain AGENTS.md as source of truth + symlinks
  • Advanced: AGENTS.md for universal rules + IDE-specific files for advanced features

For Open Source Projects

  • Must have: AGENTS.md (broadest compatibility)
  • Nice to have: .github/copilot-instructions.md (GitHub integration)
  • Optional: .cursor/rules/ for Cursor-specific features

By Project Complexity

  • Simple projects: Single AGENTS.md file is sufficient
  • Medium projects: AGENTS.md + one IDE-specific config
  • Complex monorepos: Hierarchical AGENTS.md + IDE-specific modular rules

See also: Migration Guide for step-by-step migration instructions between IDEs.