Concepts overview

Sunset has four user-visible concepts:

Concept	Meaning
Source file	A file whose extension maps to one of the registered tree-sitter grammars.
Parse result	A tree and source bytes produced for one file. The public Go API exposes this as `FileResult`.
Generated document	Markdown containing frontmatter and either a summary or full CST body.
Incremental state	SHA-256 hashes and metadata stored in `.sunset/cache/cache.json`.

The CLI engine connects them in this order:

project root -> scanner -> language registry -> parser -> output renderer
                   |                                      |
                   +------------ cache -------------------+

The scanner and engine are internal implementation details. The pkg/sunset package is the stable public Go surface for parsing one file, inspecting its tree, and listing languages. The Markdown schema is implemented by internal/output and is observable, but its internal Go structs are not public API.

Language identity

Language detection is case-insensitive and uses the file extension. Go uses .go; JavaScript uses .js and .jsx; TypeScript uses .ts and .tsx; and Python uses .py. An unsupported or extensionless file returns an unsupported language error from the parser path.

Language identity​

Language identity