Languages

Cascade ships with eight built-in language profiles. Each profile bundles the conventions, tooling, and LLM guidance for that language. The pipeline reads the profile and adapts.

Built-in languages

Language	Detection	Test command
Python	pyproject.toml, setup.py, requirements.txt	pytest
TypeScript	tsconfig.json	npx vitest run
JavaScript	package.json	npx vitest run
Go	go.mod	go test ./...
Rust	Cargo.toml	cargo test
Java	pom.xml, build.gradle	mvn test
Ruby	Gemfile, Rakefile	bundle exec rspec
C#	*.csproj, *.sln	dotnet test

How detection works

When you run a Cascade command, the language is resolved in this order:

1. Explicit override in cascade.yaml (language: go)
2. CLI flag (--language rust)
3. Auto-detection from marker files in the repo root

Polyglot repos: the highest-priority profile wins. So a repo with both pyproject.toml (Python, priority 60) and go.mod (Go, priority 90) is detected as Go. If that’s wrong for your project, set language explicitly in cascade.yaml.

What each profile defines

• file_extensions: which extensions Cascade considers part of the language
• source_dir_default: where new source files go (src for Python, . for Go)
• test_dir_default: where tests go (tests for Python, . for Go inline)
• test_file_glob: how test files are named (test_*.py, *_test.go)
• test_command: what runs to validate generated code
• install_command: how to install dependencies
• type_check_command: optional type check before running tests
• detection_files: marker files that identify this language
• notes_for_llm: language-specific guidance passed to the LLM in prompts

Adding a language

A new language is one entry in src/cascade/languages.py:

KOTLIN = LanguageProfile(
    name="kotlin",
    display_name="Kotlin",
    file_extensions=(".kt", ".kts"),
    source_dir_default="src/main/kotlin",
    test_dir_default="src/test/kotlin",
    test_file_glob="*Test.kt",
    test_command=("gradle", "test"),
    install_command=("gradle", "build", "-x", "test"),
    type_check_command=None,
    formatter_command=("ktlint", "--format"),
    detection_files=("build.gradle.kts", "settings.gradle.kts"),
    detection_priority=75,
    notes_for_llm=(
        "Idiomatic Kotlin: prefer val over var, use data classes, "
        "use expressions over statements. Tests with JUnit 5 + MockK."
    ),
)

Add it to the PROFILES registry and submit a PR. That’s it.