ALDC - AL Development Collection for GitHub Copilot

A practical framework for building Business Central AL extensions with GitHub Copilot agents. From vibe coding to controlled engineering.

What is ALDC?

ALDC (AL Development Collection) is a framework that transforms how you develop Business Central extensions with GitHub Copilot. Instead of ad-hoc code generation, ALDC provides structured, contract-driven development with human-in-the-loop gates.

Key Features

4 Public Agents — Specialized roles for every development phase

@al-architect — Solution Architect: designs solutions, information flows, technical decisions
@al-developer — Developer: implements, debugs, quick adjustments
@al-conductor — Conductor: orchestrates TDD implementation with subagents
@al-presales — Pre-sales: estimation and scoping

3 Internal Subagents — Autonomous specialists within the conductor

al-planning-subagent — Research and context gathering
al-implement-subagent — TDD-only implementation (tests FIRST, code SECOND)
al-review-subagent — Code review against spec + architecture

11 Composable Skills — Domain knowledge loaded on demand

Required: api, copilot, debug, performance, events, permissions, testing
Recommended: migrate, pages, translate, estimation

6 Workflows — Automated processes

al-spec.create, al-build, al-pr-prepare, al-context.create, al-memory.create, al-initialize

Contracts per Requirement — Structured documentation in .github/plans/{req_name}/

{req_name}.architecture.md — Solution design (from architect)
{req_name}.spec.md — Technical blueprint (from spec.create)
{req_name}.test-plan.md — Test strategy
memory.md — Global context across sessions

How It Works

Development Flow

LOW complexity:
  al-spec.create → @al-developer

MEDIUM/HIGH complexity:
  @al-architect → al-spec.create → @al-conductor

The architect can decompose complex requirements into multiple specs, each implemented independently by the conductor.

TDD Orchestration

The conductor enforces Test-Driven Development:

Planning subagent researches context
Implement subagent creates tests FIRST (RED)
Implement subagent writes code to pass tests (GREEN)
Review subagent validates against spec + architecture
Human approves each phase (HITL gate)
Phase complete → next phase

Installation

Install from VS Code Marketplace or:

code --install-extension JavierArmesto.aldc-al-development-collection

After installation, use the Command Palette:

AL Collection: Install Toolkit to Workspace — copies framework to your project's .github/ directory
AL Collection: Update Toolkit — merges new version preserving your customizations
AL Collection: Validate Installation — verifies compliance

Quick Start

Install the extension
Open your AL project
Run: AL Collection: Install Toolkit to Workspace
Start with: @workspace use al-spec.create with your requirement
Follow the guided flow

See QUICKSTART.md for the full onboarding guide.

What's New in v3.0.0

Skills-based modularization: 11 composable skills replace 7 specialized agents
Restored TDD enforcement: al-implement-subagent with hardcoded TDD cycle
Corrected agent roles: architect = Solution Architect, spec.create = technical blueprint
Contracts per requirement: subdirectory structure .github/plans/{req_name}/
Skills evidencing: agents declare which skills they load and which patterns they applied
HITL gates enforced: mandatory stops at plan approval, each phase, and completion
Test infrastructure checks: Library Assert, Any dependency, ID range verification before writing tests

Breaking Changes from v2.x

Agents reduced from 11 to 4 public + 3 internal subagents
Agent references changed (e.g., Use al-architect mode → @al-architect)
Plans directory structure changed to per-requirement subdirectories
al-implement-subagent restored as TDD-only subagent
12 prompts absorbed into composable skills

See CHANGELOG.md for full details.

Framework Documentation

Validate Your Project

node tools/aldc-validate/index.js --config aldc.yaml

Expected result: ✅ ALDC Core v1.1 COMPLIANT

Configuration

Setting	Default	Description
`al-collection.autoInstall`	`false`	Auto-install when AL project detected
`al-collection.installPath`	`".github"`	Target directory for toolkit installation

Requirements

Visual Studio Code: 1.85.0 or higher
GitHub Copilot: Required for agent and skill features
AL Language Extension: For Business Central development

Author

Javier Armesto González Microsoft MVP (Business Central & Azure AI Services) Head of R&D & AI at VS Sistemas LinkedIn · Tech Sphere Dynamics

Support & Contributing

Report issues: GitHub Issues
Ask questions: GitHub Discussions
Star the repo if you find it useful ⭐

License

MIT — See LICENSE for details.

AL Development Collection

JavierArmestoGonzalez