Function plan 

pub fn plan(
    manifest_path: &Path,
    migrations_dir: &Path,
) -> Result<PlanOutcome, Vec<DoctorFailure>>

fz plan: describes what the manifest would change, and nothing else. Read-only by construction — nothing here touches the disk beyond reading its inputs.

Errors

Coded failures when the manifest cannot be read or resolved, or the lockfile or deploy record cannot be parsed.