Hen Language Support

Author, verify, run, inspect, and import OpenAPI-backed .hen collections directly in VS Code.

Hen Language Support combines the Rust hen CLI with a language server so Hen collections feel first-class in the editor: syntax-aware authoring, structured verification feedback, request-scoped actions, and failure inspection without leaving VS Code.

Features

Authoring

• Semantic highlighting for Hen declarations, directives, operators, response paths, and named references.
• Context-aware completions for fragment imports, request references, auth and session names, schema and scalar targets, response roots and accessors, and common snippets.
• Hover documentation for core Hen syntax plus contextual hover details for capture provenance, session reuse, richer filtered selectors, mapped dependency resolution, environment-backed interpolations, and typed schema validation with === in assertions or guards.
• Go to definition, find references, rename, document symbols, and document links for fragment imports and named Hen symbols.

Verification And Diagnostics

• Diagnostics powered by hen verify --output json plus continuous language-server import diagnostics.
• Inline [verify] ... summaries beside affected lines, with richer hover detail and quick fixes for re-running verification or jumping to executable settings.
• Executable provenance in verify feedback so it is clear whether the extension used a configured path, a workspace build, or hen from PATH.
• Low-noise live import diagnostics for missing, unreadable, cyclic, or invalid fragment imports.

Request Workflow

• Request code lenses for Run, Run + deps, Copy curl, and Preview details.
• Command palette actions to run a request or copy its curl by name from the current file.
• Explorer, editor-title, and command palette actions to import an OpenAPI JSON or YAML spec into a .hen collection with hen import.
• Request-details previews rendered as Markdown, including failure summaries, assertion diffs, transcripts, retained artifacts, trace context, and links back to request definitions.
• Request execution and details surfaces that reuse the same CLI behavior as the core hen tool instead of inventing editor-only semantics.

Editing Polish

• Hen file icons for .hen files.
• Comment support for assertion labels.
• Hen-specific bracket, quote, and block editing behavior.

Requirements

The extension uses the hen CLI for verification, OpenAPI import, request inspection, curl export, and request-details previews.

Executable resolution order:

1. hen.executablePath
2. Workspace target/debug/hen
3. Workspace target/release/hen
4. hen on PATH

If you are working inside the Hen repository, the extension will usually pick up the local workspace build automatically.

Commands

• Hen: Import OpenAPI Spec...
• Hen: Verify Current Hen File
• Hen: Clear Hen Diagnostics
• Hen: Run Hen Request...
• Hen: Copy curl for Hen Request...
• Hen: Preview Hen Request Details...

Settings

• hen.executablePath: Path to the hen executable.
• hen.verify.onOpen: Run verification when a .hen file is opened.
• hen.verify.onSave: Run verification when a .hen file is saved.
• hen.activeEnvironment: Environment name used by context hovers when explaining whether an interpolation resolves from the base declaration or an override.

Notes

• Structural correctness still comes from hen verify; the language server intentionally stays lighter weight than the Rust parser.
• Request metadata and request-picking surfaces use hen inspect --output json as the machine-readable bridge.
• The editor now prefers hover-based context for implicit provenance and environment details to keep the document surface from getting crowded.

Local Development

Install dependencies and build the extension:

npm install
npm run build

Package the extension for local install or marketplace validation:

npm run package

To test locally in VS Code, open this folder and start an Extension Development Host, or install the generated .vsix.