ALchemist

Live execution and inline feedback for AL (Business Central) — like Quokka.js but for AL.

Metric	Value
Engine	AL.Runner (transpiles AL to C#, runs in-memory)
Runtime	.NET 8 SDK
Infrastructure needed	None (no Docker, no BC service tier, no SQL Server)
Execution time	Milliseconds

Features

Feature	Description
Scratch pad	Create standalone AL scratch files for quick experiments (`Ctrl+Shift+A N`)
Project-aware scratch	Add `//alchemist: project` to access workspace tables, codeunits, and enums
Run on save	Automatically execute on save with results in milliseconds
Inline Message output	`Message()` results appear as green ghost text next to the calling line
All loop values	Loop `Message()` calls show all iteration values inline (Quokka-style)
Coverage gutters	Green/gray/red dots in the gutter show which lines executed
Dimmed uncovered lines	Lines that didn't execute are visually dimmed
Inline error display	Failed assertions and errors appear as red text at the exact source line and column
Variable values on hover	Hover over any variable to see its captured value
Test Explorer	Tests appear in VS Code's Test Explorer with pass/fail/error states
Single test execution	Run individual tests from Test Explorer instead of the full suite
Coverage hover tooltips	Hover over gutter dots to see coverage status
Output panel	Formatted ALchemist output with messages, errors, and coverage summary
Status bar	Beaker icon shows idle/running/success/failure state at a glance
Auto-install	AL.Runner is downloaded automatically on first use

Prerequisites

.NET 8 SDK (AL.Runner is installed automatically)
VS Code 1.85.0 or later

Installation

From VSIX (beta):

code --install-extension alchemist-0.1.0.vsix

Or in VS Code: Ctrl+Shift+P > "Extensions: Install from VSIX..."

On first activation, ALchemist will prompt to install AL.Runner via dotnet tool install -g msdyn365bc.al.runner.

Quick Start

Open any folder in VS Code
Run ALchemist: New Scratch File (Ctrl+Shift+A N)
Write AL code in the scratch file
Save (Ctrl+S) — results appear inline

codeunit 50000 Scratch
{
    trigger OnRun()
    var
        i: Integer;
        total: Integer;
    begin
        for i := 1 to 10 do
            total += i;
        Message('Total: %1', total);   // --> Total: 55
    end;
}

For project-aware scratch files, add //alchemist: project as the first line to access workspace objects.

Architecture

  Save .al file
       |
       v
  ALchemist Extension (TypeScript)
       |
       |  spawn al-runner --output-json --capture-values [--coverage] <path>
       v
  AL.Runner (.NET CLI)
       |
       |  1. Transpile AL --> C#
       |  2. Rewrite BC types --> in-memory mocks
       |  3. Compile with Roslyn
       |  4. Execute + capture values
       |
       v
  JSON result (tests, messages, capturedValues, coverage)
       |
       v
  ALchemist renders:
    - Inline decorations (messages, errors, values)
    - Gutter icons (coverage)
    - Output panel
    - Status bar
    - Test Explorer items

Configuration

Setting	Default	Description
`alchemist.alRunnerPath`	`""`	Custom path to `al-runner` binary. Leave empty for auto-managed.
`alchemist.dotnetPath`	`""`	Custom path to `dotnet` SDK.
`alchemist.runOnSave`	`true`	Execute automatically on file save.
`alchemist.testRunOnSave`	`"current"`	Which tests to run on save: `current`, `all`, or `off`.
`alchemist.showOutputOnError`	`"onlyOnFailure"`	When to auto-focus the output panel: `always`, `never`, `onlyOnFailure`.
`alchemist.showInlineMessages`	`true`	Show `Message()`/`Error()` output inline in the editor.
`alchemist.showGutterCoverage`	`true`	Show coverage gutter indicators.
`alchemist.showCapturedValues`	`true`	Show captured variable values inline.
`alchemist.dimUncoveredLines`	`true`	Reduce opacity of lines not reached.

Commands

Command	Keybinding	Description
ALchemist: New Scratch File	`Ctrl+Shift+A N`	Create a new AL scratch file
ALchemist: Run Now	`Ctrl+Shift+A R`	Execute the current file immediately
ALchemist: Clear Results	`Ctrl+Shift+A C`	Clear all inline decorations
ALchemist: Toggle Project Context		Toggle `//alchemist: project` directive
ALchemist: Delete Scratch File		Delete the active scratch file
ALchemist: Save Scratch As...		Save scratch file to workspace
ALchemist: Stop Run		Cancel a running execution
ALchemist: Show Output		Focus the ALchemist output panel

Key Files

File	Purpose
`src/extension.ts`	Extension entry point, wires all components
`src/runner/executor.ts`	Spawns AL.Runner, collects JSON results
`src/runner/outputParser.ts`	Parses `--output-json` output and Cobertura XML
`src/runner/alRunnerManager.ts`	Auto-download, version check, path resolution
`src/editor/decorations.ts`	Inline text, gutter icons, dimming, captured values
`src/editor/hoverProvider.ts`	Coverage and variable value hover tooltips
`src/scratch/scratchManager.ts`	Scratch file lifecycle and project-aware detection
`src/testing/testDiscovery.ts`	Scans `.al` files for `[Test]` procedures
`src/testing/testController.ts`	VS Code Test Explorer integration
`src/output/outputChannel.ts`	Formatted output panel
`src/output/statusBar.ts`	Status bar indicator

Author: SShadowS License: MIT

ALchemist - AL Live Runner

SShadowS (Torben Leth)