feat(macros:chain): accept any return type in chain functions

1 files changed, 27 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ea4b737..6c70d3d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -184,6 +184,33 @@ None
 
     These methods complement the existing read-only `get_args(&self)` method, providing full control over argument mutation and ownership.
 
+9. **[`macros:chain`]** Relaxed the `#[chain]` return type validation. Previously, `#[chain]` functions were restricted to returning `Next`, `ChainProcess<ThisProgram>`, `()`, or omitting the return type. Now, any return type is accepted, and the generated `proc` function performs an explicit `Into<ChainProcess<ThisProgram>>` conversion using a fully-qualified turbofish based on the user-declared return type.
+
+    This means `#[chain]` functions can now return any pack type directly, without needing an explicit `.into()` call in the function body:
+
+    ```rust
+    // Before — required explicit .into()
+    #[chain]
+    fn handle_greet(args: EntryGreet) -> Next {
+        let name = /* ... */;
+        ResultGreeting::new(name).into()
+    }
+
+    // After — return any pack type directly
+    #[chain]
+    fn handle_greet(args: EntryGreet) -> ResultGreeting {
+        let name = /* ... */;
+        ResultGreeting::new(name)
+    }
+    ```
+
+    The generated `proc` function now wraps the body result in `<UserReturnType as Into<ChainProcess<ThisProgram>>>::into(...)`, which:
+    - Works for `Next` / `ChainProcess` via the identity `From<T> for T` implementation.
+    - Works for any pack type (`ResultGreeting`, etc.) via the `.into()` conversion generated by `pack!` / `#[derive(Groupped)]`.
+    - Works for `()` via the `From<()>` implementation on `ChainProcess`.
+
+    The return type validation has been removed entirely — any valid Rust return type is accepted. If the type does not implement `Into<ChainProcess<ThisProgram>>`, a standard Rust compilation error will be produced at the call site.
+
 #### **BREAKING CHANGES** (API CHANGES):
 
 1. **[`macros:renderer`]** **[`macros:help`]** Removed `r_println!` and `r_print!` macros. The `#[renderer]` and `#[help]` macros no longer implicitly inject an internal `RenderResult` variable or provide `r_println!` / `r_print!` macros.