Function plan_sync 

pub(crate) fn plan_sync<P: AsRef<Path>>(
    fs: &FileSystem,
    root: P,
    profile: Option<&str>,
    profile_suffix: Option<&str>,
    variables: &BTreeMap<String, String>,
) -> Result<Project, ProjectError>

Compile a project root into a planned deployment representation.

Behaviorally, this function:

• discovers project-owned objects and mod statements
• reuses any valid persisted object artifacts for the active compile context
• recompiles cache misses in parallel
• assembles the current typed project and lowers it into a planned project

The returned plan is defined by the project sources, the active profile configuration, and the compile-time variable bindings. Cached artifacts may accelerate evaluation, but they do not change the result.