Function zed_guidance_target 

pub fn zed_guidance_target(project_dir: &Path) -> PathBuf

The project file Zed will actually read sqz’s guidance from.

Zed uses the FIRST match in its instruction-file list, and .rules outranks AGENTS.md. So when a .rules file exists we must write there — a block appended to AGENTS.md would be invisible to Zed.