5 files changed, 42 insertions, 41 deletions

diff --git a/mingling_core/src/program/collection.rs b/mingling_core/src/program/collection.rs
index d5aab4b..14705ac 100644
--- a/mingling_core/src/program/collection.rs
+++ b/mingling_core/src/program/collection.rs
@@ -4,7 +4,7 @@ use std::pin::Pin;
 #[cfg(feature = "dispatch_tree")]
 use crate::Dispatcher;
 
-use crate::{AnyOutput, ChainProcess, Groupped, RenderResult};
+use crate::{AnyOutput, ChainProcess, Grouped, RenderResult};
 
 #[cfg(feature = "structural_renderer")]
 use crate::{StructuralRendererSetting, error::StructuralRendererSerializeError};
@@ -21,9 +21,17 @@ pub use mock::*;
 pub trait ProgramCollect {
     /// Enum type representing internal IDs for the program
     type Enum;
-    type ErrorDispatcherNotFound: Groupped<Self::Enum>;
-    type ErrorRendererNotFound: Groupped<Self::Enum>;
-    type ResultEmpty: Groupped<Self::Enum>;
+    /// Error type when a dispatcher is not found for the given member
+    type ErrorDispatcherNotFound: Grouped<Self::Enum>;
+
+    /// Error type when a renderer is not found for the given member
+    type ErrorRendererNotFound: Grouped<Self::Enum>;
+
+    /// Result type for an empty chain result
+    ///
+    /// When the `extra_macros` feature is enabled,
+    /// you can use the `empty_result!()` macro to create this
+    type ResultEmpty: Grouped<Self::Enum>;
 
     /// Use a prefix tree to quickly match arguments and dispatch to an Entry
     #[cfg(feature = "dispatch_tree")]
diff --git a/mingling_core/src/program/collection/mock.rs b/mingling_core/src/program/collection/mock.rs
index 9b2e7af..dbe4789 100644
--- a/mingling_core/src/program/collection/mock.rs
+++ b/mingling_core/src/program/collection/mock.rs
@@ -4,7 +4,7 @@ use std::pin::Pin;
 #[cfg(feature = "dispatch_tree")]
 use crate::Dispatcher;
 
-use crate::{AnyOutput, ChainProcess, Groupped, ProgramCollect, RenderResult};
+use crate::{AnyOutput, ChainProcess, Grouped, ProgramCollect, RenderResult};
 
 #[cfg(feature = "structural_renderer")]
 use crate::{StructuralRendererSetting, error::StructuralRendererSerializeError};
@@ -23,9 +23,12 @@ pub enum MockProgramCollect {
     Bar,
 }
 
-impl Groupped<MockProgramCollect> for MockProgramCollect {
+/// SAFETY: This is a mock type used only for temporary testing.
+/// It will never actually enter the macro system.
+/// The internal `panic!` ensures that `member_id` will never be executed.
+unsafe impl Grouped<MockProgramCollect> for MockProgramCollect {
     fn member_id() -> MockProgramCollect {
-        MockProgramCollect::Foo
+        panic!("Attempting to read an unsafe enum type");
     }
 }
 
diff --git a/mingling_core/src/program/hook.rs b/mingling_core/src/program/hook.rs
index 56d8e0e..7d94a21 100644
--- a/mingling_core/src/program/hook.rs
+++ b/mingling_core/src/program/hook.rs
@@ -144,8 +144,9 @@ where
 {
     /// Adds a typed hook to the program. The hook will be called at the appropriate
     /// lifecycle events.
-    pub fn with_hook(&mut self, hook: ProgramHook<C>) {
+    pub fn with_hook(&mut self, hook: ProgramHook<C>) -> &mut Self {
         self.hooks.push(hook);
+        self
     }
 
     pub(crate) fn run_hook_on_begin(&self, info: HookBeginInfo) {
@@ -678,7 +679,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::Groupped;
+    use crate::Grouped;
     use std::sync::atomic::{AtomicBool, Ordering};
 
     #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -694,7 +695,17 @@ mod tests {
         }
     }
 
-    impl Groupped<MockHookEnum> for MockHookEnum {
+    /// SAFETY:
+    ///
+    /// This implementation is only for testing purposes to satisfy trait bounds.
+    /// Since this code only constructs `AnyOutput` and calls methods like
+    /// `downcast`, `is`, `restore`, `route_chain`, and `route_renderer` —
+    /// none of which involve `ProgramCollect::do_chain` or
+    /// `ProgramCollect::render` — the type/member_id correspondence is
+    /// never exploited in an unsafe way here.
+    /// The caller must ensure that the associated `member_id` correctly
+    /// corresponds to the type's role in the group.
+    unsafe impl Grouped<MockHookEnum> for MockHookEnum {
         fn member_id() -> MockHookEnum {
             MockHookEnum::A
         }
diff --git a/mingling_core/src/program/once_exec.rs b/mingling_core/src/program/once_exec.rs
index 9d6f1e4..a846d04 100644
--- a/mingling_core/src/program/once_exec.rs
+++ b/mingling_core/src/program/once_exec.rs
@@ -79,23 +79,12 @@ where
         };
 
         // Read exit code
-        let exit_code = result.exit_code;
-
         // Render result
-        if stdout_setting.render_output && !result.is_empty() {
-            print!("{result}");
-
-            if let Err(e) = std::io::Write::flush(&mut std::io::stdout())
-                && stdout_setting.error_output
-            {
-                eprintln!("{e}");
-                1
-            } else {
-                exit_code
-            }
-        } else {
-            exit_code
+        if stdout_setting.render_output {
+            result.std_print();
         }
+
+        result.exit_code
     }
 
     /// Run the command line program, then exit
@@ -217,23 +206,12 @@ where
         };
 
         // Read exit code
-        let exit_code = result.exit_code;
-
         // Render result
-        if stdout_setting.render_output && !result.is_empty() {
-            print!("{result}");
-
-            if let Err(e) = std::io::Write::flush(&mut std::io::stdout())
-                && stdout_setting.error_output
-            {
-                eprintln!("{e}");
-                1
-            } else {
-                exit_code
-            }
-        } else {
-            exit_code
+        if stdout_setting.render_output {
+            result.std_print();
         }
+
+        result.exit_code
     }
 
     /// Run the command line program, then exit
diff --git a/mingling_core/src/program/setup.rs b/mingling_core/src/program/setup.rs
index 838c29a..a8ff114 100644
--- a/mingling_core/src/program/setup.rs
+++ b/mingling_core/src/program/setup.rs
@@ -29,8 +29,9 @@ where
     C: ProgramCollect<Enum = C>,
 {
     /// Load and execute init logic
-    pub fn with_setup<S: ProgramSetup<C> + 'static>(&mut self, setup: S) {
+    pub fn with_setup<S: ProgramSetup<C> + 'static>(&mut self, setup: S) -> &mut Self {
         S::setup(setup, self);
+        self
     }
 }