AL Guidelines¶

Documentation view — the normative, auto-applied source is instructions/al-guidelines.instructions.md. If this page and the source ever diverge, the source wins.


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