/arc:rules

Apply standards

—What it does

Rules copies Arc's coding standards to your project's .ruler/ directory: TypeScript patterns, React conventions, Next.js best practices, Tailwind usage, testing strategies, and UI design guidelines. Every Arc skill reads from .ruler/ when generating or reviewing code—so the AI follows your project's standards, not generic ones.

—Why it exists

Without shared standards, every AI-generated file is inconsistent. Rules puts the playbook in one place that all AI tools can read. Combined with Ruler (optional), these standards propagate to Copilot, Cursor, and other agents—so your whole toolchain follows the same conventions.

—Design decisions

  • —Copy, not symlink. Projects can customize rules for their needs.
  • —Backup on update. Your customizations are never lost.
  • —Optional Ruler integration. Distributes rules to Copilot, Cursor, and other agents.

Source document


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Apply Arc's coding standards to the current project.

Step 1: Check for existing rules

Use Glob tool: .ruler/*.md

If .ruler/ does not exist: Go to Step 2 (Fresh Install)

If .ruler/ exists: Go to Step 3 (Update Flow)

Step 2: Fresh Install

Resolve the Arc install root from this skill's location and refer to it as ${ARC_ROOT} for the rest of this workflow.

Copy all rules from Arc to the project:

cp -r "${ARC_ROOT}/rules/" .ruler/

Tell the user:

Rules copied to .ruler/

Files added:
- stack.md, api.md, ai-sdk.md, cli.md, code-style.md, env.md, git.md, integrations.md, tooling.md
- nextjs.md, react.md, tailwind.md, testing.md
- turborepo.md, typescript.md, versions.md
- interface/ (animation, design, forms, interactions, layout, performance, typography)

Go to Step 4 (Offer Ruler)

Step 3: Update Flow

Existing .ruler/ found. Ask the user:

AskUserQuestion:
  question: "Found existing .ruler/ in this project. Update with Arc's latest rules? This will backup current rules and overwrite with Arc's latest. You can review changes with `git diff .ruler/` after."
  header: "Update Rules"
  options:
    - label: "Update rules"
      description: "Backup current rules to .ruler.backup-TIMESTAMP/ and overwrite with Arc's latest"
    - label: "Keep existing"
      description: "Keep your current rules unchanged"

If user picks "Update rules":

# Create backup
cp -r .ruler/ ".ruler.backup-$(date +%Y%m%d-%H%M%S)/"

# Copy fresh rules
rm -rf .ruler/
cp -r "${ARC_ROOT}/rules/" .ruler/

Tell the user:

Rules updated. Backup saved to .ruler.backup-YYYYMMDD-HHMMSS/

Review changes with: git diff .ruler/

Go to Step 4 (Offer Ruler)

If user picks "Keep existing":

Keeping existing rules. You can manually compare with Arc's rules at:
${ARC_ROOT}/rules/

Done.

Step 4: Offer Ruler

Ask the user:

AskUserQuestion:
  question: "Want to distribute rules to other AI agents (Copilot, Cursor, etc.) via Ruler?"
  header: "Distribute Rules"
  options:
    - label: "Run ruler apply"
      description: "Run npx ruler apply to distribute rules to other AI tools"
    - label: "Skip"
      description: "Keep rules in .ruler/ only, distribute later if needed"

If user picks "Run ruler apply":

npx ruler apply

If ruler is not installed (command fails):

Ruler not found. Rules are in .ruler/ and ready for use.

To distribute to other AI agents, install ruler:
  npm install -g ruler

Then run:
  npx ruler apply

If user picks "Skip":

Rules are ready in .ruler/. Run `npx ruler apply` later if you want to distribute to other agents.

Step 5: Suggest Linear (for complex projects)

After rules are set up, check project complexity:

# Count source files
find . -type f \( -name "*.ts" -o -name "*.tsx" -o -name "*.js" -o -name "*.jsx" \) | grep -v node_modules | wc -l

If >50 files or monorepo detected:

This looks like a complex project. Consider setting up Linear MCP for issue tracking:

1. Add to .mcp.json:
   {
     "mcpServers": {
       "linear": {
         "command": "npx",
         "args": ["-y", "@anthropic/linear-mcp"]
       }
     }
   }

2. Arc will then:
   - Query active issues in /arc:suggest
   - Create issues from /arc:audit findings
   - Link work to issues for context

See .ruler/tooling.md for details.

If small project: Skip this suggestion.

Done.

<notes> - Rules are copied, not symlinked, so projects can customize - Backup ensures user customizations are never lost - Ruler is optional — Arc works without it - After copying, rules are immediately available to Arc skills that read from `.ruler/` </notes>