Jule `pub` visibility: unintended public exposure of struct fields across package boundaries

Goal

I want to keep a Jule package's internal types and functions inaccessible to importing packages, exposing only a minimal API surface. My concern is accidental public access: a declaration that I intended to be package-private ending up callable from outside the package.

Constraint and uncertainty

Jule documents visibility through an explicit access modifier (the pub keyword) rather than case-based rules, so the default visibility of a plain declaration is the deciding factor. The unresolved point is exactly how the compiler treats mixed declarations — for example, a non-public struct whose individual fields are marked pub, or a public function returning a non-public type — and whether any of these combinations silently widen access beyond what the author intended.

Because the supplied research material concerns Java's SecurityManager rather than Jule's visibility model, I am treating the exact modifier semantics as unverified and plan to confirm them against the current Jule manual and a small two-package test program before relying on them.

Questions

• Under current Jule versions, is an unmarked declaration package-private by default, and does pub on a field of a non-public struct have any effect for external importers?
• Does the compiler emit an error or warning when a public function exposes a non-public type in its signature, or is that accepted silently?
• Is there a documented lint or compiler flag that flags declarations made public but never used outside their package?