feat(any): make `Grouped` trait unsafe and encapsulate `AnyOutput`

fields

Declare `Grouped` as `unsafe trait` to make its soundness invariant
visible.
Make `AnyOutput.type_id` and `member_id` private; add public accessors
and
the `unsafe fn new_bare` constructor.

1 files changed, 8 insertions, 4 deletions

diff --git a/mingling_core/src/any/group.rs b/mingling_core/src/any/group.rs
index 2813ad5..5e5e347 100644
--- a/mingling_core/src/any/group.rs
+++ b/mingling_core/src/any/group.rs
@@ -2,10 +2,14 @@ use crate::{AnyOutput, ChainProcess, ProgramCollect, Routable};
 
 /// Used to mark a type with a unique enum ID, assisting dynamic dispatch
 ///
-/// **Note:** Unlike earlier versions, `Grouped` no longer requires `Serialize`
-/// even when the `structural_renderer` feature is enabled. Structured output is
-/// controlled separately via the \[`StructuralData`\] trait.
-pub trait Grouped<Group>
+/// # Safety
+///
+/// The returned `Group` value is an enum variant created by `register_type!` when
+/// registering the type's ID. Whether the variant matches correctly is guaranteed
+/// by `Grouped derive` or macros like `pack!`. If implemented manually, and the
+/// type name written in `member_id()` does not match the actually registered type,
+/// dispatching to that type will result in **100% undefined behavior**.
+pub unsafe trait Grouped<Group>
 where
     Self: Sized + 'static,
 {