Describe software systems by what they mean.

Declarative Capability Language (DCL) is a language for modelling software systems through capabilities, intents, outcomes, rules, effects, events, policies, lifecycles, and contexts. This extension brings DCL authoring, compiler-backed feedback, semantic navigation, and architecture graphs into VS Code.

Website: https://russelleast.github.io/Capability-Language/
Documentation: https://russelleast.github.io/Capability-Language/docs
Examples: https://russelleast.github.io/Capability-Language/examples
GitHub repository: https://github.com/russelleast/Capability-Language
Issues: https://github.com/russelleast/Capability-Language/issues

Version

Extension version: 1.1.0
Supported DCL language versions: 1.0, 1.1

The extension is available on the VS Code Marketplace and can also be downloaded from the DCL website. It bundles DCL Compiler 1.1.0 and provides version-aware diagnostics, completion, hover, highlighting, summaries, and graphs for DCL Language 1.0 and 1.1.

Screenshots

DCL authoring with syntax highlighting, hover help, and compiler diagnostics:

DCL authoring

DCL Explorer for contexts, capabilities, and events:

DCL Explorer

Graph Workspace with Architecture Overview:

DCL Architecture Overview

Event Flow and Lifecycle graph views:

DCL Event Flow or Lifecycle Graph

Features

Authoring

Syntax highlighting for .dcl files
Snippets for common DCL declarations
Hover help for core DCL concepts
Compiler-backed formatting
Compiler-backed diagnostics in VS Code Problems

DCL Explorer Activity Bar view
Outline view support through the bundled language server
Workspace Symbols
Go To Definition
Find References
Source-to-graph and graph-to-source navigation where compiler source locations are available

Architecture Visualisation

Architecture Overview
Capability Graph
Capability Map
Capability Influence Graph
Cause and Effect Graph
Lifecycle Graph
Event Flow Graph
Context Map
SVG and PNG graph export

The Capability Map shows declared capabilities grouped by DCL context. It is a business responsibility map, not an implementation, dependency, runtime, service, or infrastructure diagram. Contexts are shown as labelled containers, capabilities are shown as tiles, and badges indicate available semantic metadata such as lifecycle, effects, events, policies, and compiler analysis warnings.

The Capability Influence Graph shows explicit compiler-derived semantic influence between capabilities. It does not show all dependencies, shared ownership, similarity, or implementation coupling. Thicker arrows indicate stronger explicit semantic influence from compiler-derived evidence such as lifecycle supervision, event-triggered transitions, effect targets, policy constraints, explicit capability references, or concrete context dependency references. It does not infer influence from naming, folder layout, shared actors, or context proximity.

The cause-and-effect graph shows how intents, rules, policies, effects and outcomes are causally connected. Entry edges such as intent starts capability are shown for orientation, but outcomes, events, and lifecycle movement are only connected when causation is explicit in source or compiler IR.

Language Intelligence

Bundled DCL compiler
Bundled DCL language server
Semantic source index for compiler-backed navigation
Semantic summary for Explorer and graph views

Quick Start

Install the DCL extension in VS Code.
Open a folder containing .dcl files.
Open a .dcl file.
Run DCL: Compile Workspace from the Command Palette.
Open the DCL Explorer from the Activity Bar.
Run DCL: Open Graph Workspace to explore architecture graphs.

Commands

DCL: Compile Workspace
DCL: Compile Current File
DCL: Open Graph Workspace
DCL: Show Architecture Overview
DCL: Show Capability Graph
DCL: Show Capability Map
DCL: Show Capability Influence Graph
DCL: Show Cause and Effect Graph
DCL: Show Lifecycle Graph
DCL: Show Event Flow Graph
DCL: Show Context Map
DCL: Navigate Symbol
DCL: Find Related Elements
DCL: Show Compiler Info
DCL: Show Language Server Status
DCL: Export Current Graph

Settings

dcl.compileOnSaveMode

Controls compile-on-save for .dcl files. The default is workspace.

workspace: compile all workspace .dcl files together
file: compile only the saved .dcl file
off: disable compile-on-save

dcl.compilerPath

Optional path to a custom DCL compiler executable. Leave empty to use the bundled compiler for supported platforms, falling back to dcl on PATH.

dcl.languageServer.enabled

Enables the bundled DCL language server for compiler-backed diagnostics, document symbols, workspace symbols, definition navigation, and find references. Disabled by default.

dcl.languageServer.path

Optional path to a custom dcl-lsp executable. Leave empty to use the bundled language server for supported platforms, falling back to dcl-lsp on PATH.

dcl.languageServer.trace

Controls language server protocol logging. Use off for normal use, or messages / verbose when debugging language server traffic.

dcl.graph.followSourceSelection

When enabled, moving the cursor inside compiler-known DCL semantic items focuses the matching node in the open Graph Workspace.

dcl.graph.autoRevealFromSource

When enabled, source cursor movement can reveal the Graph Workspace from a DCL editor. Disabled by default.

Bundled Compiler And Language Server

The extension includes the DCL compiler and DCL language server for supported macOS, Linux, and Windows platforms.

Use dcl.compilerPath or dcl.languageServer.path only when you need to run a custom local build or a separately installed executable.

Known Limitations

DCL v1.0 defines the stable language core; advanced tooling and compiler analysis may continue to evolve.
Graphs and navigation use compiler-provided semantic data; unavailable relationships are not inferred by the extension.