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AL Guidelines
File al-guidelines.instructions.md
Applies to **/*.al, **/*.json
Activation Always active
Role Master hub

Purpose

Master integration hub that references all other instruction files. Establishes the core AL development philosophy: event-driven programming, extension-only development, and AI-optimized coding rules for Business Central.

Core principles

Principle Rule
Event-driven Never modify standard objects; use events
AL-Go structure Separate App and Test projects
Feature-based folders src/feature/subfeature/, not by object type
Performance first Filter early, use SetLoadFields, temporary tables
Test on demand Only generate tests when explicitly requested

Context loading

This file acts as the entry point — Copilot reads it first and loads the referenced domain-specific guidelines:

  • al-code-style — Formatting and structure
  • al-naming-conventions — Naming patterns
  • al-performance — Optimization
  • al-error-handling — Error patterns and telemetry
  • al-events — Event-driven development
  • al-testing — Test implementation

Key rules summary

Area Convention
File naming <ObjectName>.<ObjectType>.al
Code style 2-space indent, PascalCase, 120 char lines
Folders src/feature/subfeature/
AI behavior Concise, actionable, with AL method references

Source: instructions/al-guidelines.instructions.md