Library evolution mode: which types need @frozen to keep ABI stability across framework updates

I'm maintaining a small Swift framework consumed by an application that must be updatable without recompiling or restarting dependent clients. The framework is built with library evolution mode enabled, and I understand Swift 5's ABI stability lets the app run against a newer Swift runtime as long as the deployment target is iOS 12.2 / macOS 10.14.4 or later.

What I can't resolve is the resilience boundary for my own public types. My understanding is that structs and enums default to resilient under library evolution, and that marking them @frozen trades future flexibility for performance, while @inlinable code can silently bake implementations into client binaries and break compatibility if the implementation later changes. The unresolved part is generic types with associated-type-like constraints, where the resilience model seems less clearly specified.

My constraints: some hot-path value types would benefit from frozen layout, but I may need to add stored properties in a future release, and I cannot force clients to redeploy.

Given that, my questions are:

• Which public type shapes actually require @frozen (or must avoid it) to guarantee binary compatibility across framework updates?
• Is there a documented way to verify, beyond otool -L and runtime testing, that a given public API surface is ABI-safe before shipping?
• Are generic types with associated-type constraints currently a manual-annotation case, or is there a finalized default rule I can rely on?