Function detect_language_python_first 

pub fn detect_language_python_first(repo_root: &Path) -> Result<DslLanguage>

Like detect_language but prefers Python when both are present.

Used by the machine-facing hm pipelines / hm render commands that the backend shells out to: the Python path is the fully-supported one (the discovery envelope is Python-only today), so a repo carrying both a .py and a redundant .ts resolves to Python rather than the unsupported TS registry. hm run keeps the TypeScript-preferring detect_language.

Errors

• The .hm/ directory does not exist.
• No .py or .ts files are found inside .hm/.