Hydra + OmegaConf for VS Code

A VS Code extension providing rich language support for Hydra config files and OmegaConf interpolation syntax.

Features

YAML Syntax Highlighting

Enhanced YAML highlighting for Hydra-specific constructs:

• OmegaConf interpolations: ${foo.bar}, ${oc.env:HOME}, nested ${${dynamic}}
• Hydra special keys: _target_, _recursive_, _convert_, _partial_, _args_
• Package directives: # @package _global_
• Defaults list: defaults: block with optional, override, _self_, package @ targets
• Missing values: ??? highlighted as mandatory markers
• Built-in resolvers: oc.env, oc.decode, oc.select, now, hydra, python_version, etc.
• Escaped interpolations: \${not.interpolated}

Go to and Peek Definition

Open config file definitions directly, or inspect and edit them inline with VS Code's Peek Definition command:

• Defaults list entries: - db: mysql → opens conf/db/mysql.yaml
• _target_ values: _target_: my_app.Trainer → opens the Python source file
• Interpolation paths: ${db.host} → jumps to where host is defined

Place the cursor on a defaults entry and run Peek Definition from the editor context menu or Command Palette. The standard Go to Definition and Peek Definition shortcuts work as well.

Hover Information

Hover over elements to see:

• Interpolation values: Shows the resolved value of ${...} references
• Resolver documentation: Built-in docs for oc.env, oc.select, now, etc.
• Special key docs: Explains _target_, _recursive_, etc.
• ??? markers: Explains the OmegaConf MISSING value concept
• @package directives: Documentation for package placement

Diagnostics

Real-time error and warning highlighting:

• Unclosed interpolations: Missing } in ${...} expressions
• Unresolvable references: Interpolation paths that can't be found in indexed configs
• Unknown resolvers: Hints when a resolver is not a known built-in
• Missing value markers: Warnings for ??? values that need to be set

Configuration

Setting	Default	Description
hydra.configSearchPaths	["conf", "config", "configs"]	Directories to search for Hydra config files
hydra.enableDiagnostics	true	Enable lint diagnostics for OmegaConf errors
hydra.enableHover	true	Enable hover information for interpolations

Development

# Install dependencies
npm install

# Compile
npm run compile

# Run unit tests
npm run test:unit

# Lint
npm run lint

# Package extension
npm run package

Testing

The extension has comprehensive tests covering:

• Interpolation parser: 25+ tests for ${...} parsing, nested interpolations, resolvers, edge cases
• YAML parser: 25+ tests for flattening, key path extraction, defaults list parsing
• TextMate grammar: 18+ structural tests validating completeness of all grammar patterns
• Test fixtures: Complete Hydra config workspace with realistic configs

License

Apache 2.0