Declarative Capability Language (DCL)

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: 1.0.6
• DCL language version: 1.0

The extension is available on the VS Code Marketplace and can also be downloaded from the DCL website. DCL v1.0 defines the stable core language; editor tooling and ecosystem integrations continue to evolve around it.

Screenshots

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

DCL Explorer for contexts, capabilities, and events:

Graph Workspace with Architecture Overview:

Event Flow and Lifecycle graph views:

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

Navigation

• 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

1. Install the DCL extension in VS Code.
2. Open a folder containing .dcl files.
3. Open a .dcl file.
4. Run DCL: Compile Workspace from the Command Palette.
5. Open the DCL Explorer from the Activity Bar.
6. 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.

Feedback And Issues

Please report issues at https://github.com/russelleast/Capability-Language/issues.

License

Apache-2.0