Every team has conventions that generic linters don’t cover — architecture boundaries, naming patterns, testing requirements, or business-specific constraints. Custom code review rules let you encode these into automated checks.

Creating a rule in Mesrai

1. Go to Code Review Settings → Mesrai Rules
2. Click Add Rule
3. Configure:
   • Name — what the rule checks (e.g., “Service files must have tests”)
   • Scope — File-level (analyzes individual files) or PR-level (analyzes the entire PR)
   • Path — glob pattern to target specific files (e.g., src/services/**/*.ts)
   • Severity — Critical, High, Medium, or Low
   • Instructions — detailed description of what to check

What makes rules powerful

Rules can access rich context:

• Variables like fileDiff, pr_title, pr_description, pr_files_diff
• File references with @file:path/to/file.ts to compare against patterns
• MCP functions to fetch data from connected tools (Jira, repository structure, etc.)

Example: Architecture boundary rule

Name: Domain layer must not depend on infrastructure
Scope: Pull Request
Instructions: Check pr_files_diff for any import in src/domain/
that references src/infrastructure/. Reference
@file:docs/architecture.md for allowed dependencies.

Example: Test coverage rule

Name: Every service must have a test file
Scope: Pull Request
Instructions: For each file modified in src/services/,
verify a corresponding test file exists in test/services/.
Use MCP to check the repository file tree.

More ways to add rules

• Import from Rules Library — browse proven rules by language and category
• Sync from IDE tools — auto-import rules from Cursor, Copilot, Claude
• Repository rules — define rules in markdown files in your repo
• Auto-generation — Mesrai suggests rules based on your review history

For the full reference, see Mesrai Rules.