Store session state directly

LEAF_MACRO_INTERFACE.md

@@ -41,7 +41,7 @@ unshell_leaf! {
             authors: unshell::alloc::vec!["ASTATIN3"],
         },
         sessions {
-            pty: PtySession,
+            pty: PtySessionState,
         }
         procedures {}
     }
@@ -59,10 +59,14 @@ The example above expands to the equivalent of:
 pub struct FakePtyLeaf {
     state: FakePtyState,
     outbox: LeafOutbox,
-    pty: SessionFamily<<PtySession as Session<FakePtyState>>::State>,
+    pty: SessionFamily<PtySessionState>,
 }
 ```
 
+Session types are the per-hook state values themselves. There is no separate
+zero-sized handler struct; a type like `PtySessionState` implements `Session` and is
+stored directly in the generated `SessionFamily`.
+
 The wrapper implements:
 
 - `new(state)`
@@ -149,13 +153,12 @@ Ratatui rendering is a plain feature-gated pass:
 leaf.render_ratatui(frame, area, &mut interface);
 ```
 
-Session rendering is an associated function because session families are type-level
+Session rendering is an associated function on the stored session state type:
-contracts, not stored objects:
 
 ```rust
 fn render_ratatui(
     leaf: &LeafState,
-    session: &Self::State,
+    session: &Self,
     view: &mut SessionView,
     frame: &mut ratatui::Frame<'_>,
     area: ratatui::layout::Rect,

src/protocol/leaf_template.rs

@@ -17,9 +17,7 @@ macro_rules! unshell_leaf {
             state: $State,
             outbox: $crate::protocol::LeafOutbox,
             $(
-                $session_field: $crate::protocol::SessionFamily<
+                $session_field: $crate::protocol::SessionFamily<$Session>,
-                    <$Session as $crate::protocol::Session<$State>>::State,
-                >,
             )*
         }
 

src/protocol/runtime.rs

@@ -91,7 +91,7 @@ pub fn dispatch_session<L, S>(
     endpoint: &Endpoint,
     leaf_id: u32,
     leaf: &mut L,
-    family: &mut SessionFamily<S::State>,
+    family: &mut SessionFamily<S>,
     packet: Packet,
     outbox: &mut LeafOutbox,
     interface: &mut Option<&mut InterfaceStore>,
@@ -215,7 +215,7 @@ pub fn dispatch_session<L, S>(
 pub fn update_session_family<L, S>(
     leaf_id: u32,
     leaf: &mut L,
-    family: &mut SessionFamily<S::State>,
+    family: &mut SessionFamily<S>,
     interface: &mut Option<&mut InterfaceStore>,
 ) where
     S: Session<L>,
@@ -338,7 +338,7 @@ pub fn flush_leaf_outbox(
 pub fn flush_session_family<L, S>(
     endpoint: &mut Endpoint,
     leaf_id: u32,
-    family: &mut SessionFamily<S::State>,
+    family: &mut SessionFamily<S>,
     interface: &mut Option<&mut InterfaceStore>,
 ) where
     S: Session<L>,

src/protocol/session.rs

@@ -9,26 +9,25 @@ use crate::interface::SessionView;
 ///
 /// A session family maps one outer `procedure_id` to many live hook instances. The
 /// generated leaf owns packet grouping, retry-safe output flushing, and final cleanup;
-/// the session implementation owns only application behavior.
+/// the session value owns one hook's application behavior and mutable state.
 ///
 /// # Example
 ///
 /// ```rust,ignore
-/// impl Session<MyLeafState> for MySession {
+/// impl Session<MyLeafState> for MySessionState {
 ///     const PROCEDURE_ID: u32 = 7;
-///     type State = MySessionState;
 ///
 ///     fn init(
 ///         leaf: &mut MyLeafState,
 ///         packet: Packet,
 ///         ctx: &mut SessionInit,
-///     ) -> Result<Self::State, SessionInitError> {
+///     ) -> Result<Self, SessionInitError> {
 ///         Ok(MySessionState::from_open(leaf, packet, ctx))
 ///     }
 ///
 ///     fn update(
 ///         leaf: &mut MyLeafState,
-///         session: &mut Self::State,
+///         session: &mut Self,
 ///         incoming: &mut PacketQueue,
 ///         ctx: &mut SessionCtx<'_>,
 ///     ) -> SessionStatus {
@@ -39,23 +38,16 @@ use crate::interface::SessionView;
 ///     }
 /// }
 /// ```
-pub trait Session<L> {
+pub trait Session<L>: Sized {
     /// Outer packet procedure id used by every packet in this session family.
     const PROCEDURE_ID: u32;
 
-    /// Application state stored for one live hook.
+    /// Creates one session value from a packet whose hook has no active session.
-    type State;
-
-    /// Creates one session state from a packet whose hook has no active session.
     ///
     /// The generated runtime derives all response routing from hook state. Session
     /// initialization therefore returns only application state or a protocol-level
     /// rejection; it never stores or receives a caller reply path.
-    fn init(
+    fn init(leaf: &mut L, packet: Packet, ctx: &mut SessionInit) -> Result<Self, SessionInitError>;
-        leaf: &mut L,
-        packet: Packet,
-        ctx: &mut SessionInit,
-    ) -> Result<Self::State, SessionInitError>;
 
     /// Advances one active hook session.
     ///
@@ -65,7 +57,7 @@ pub trait Session<L> {
     /// generated retry rules.
     fn update(
         leaf: &mut L,
-        session: &mut Self::State,
+        session: &mut Self,
         incoming: &mut PacketQueue,
         ctx: &mut SessionCtx<'_>,
     ) -> SessionStatus;
@@ -73,7 +65,7 @@ pub trait Session<L> {
     #[cfg(feature = "interface_ratatui")]
     fn render_ratatui(
         _: &L,
-        _: &Self::State,
+        _: &Self,
         _: &mut SessionView,
         _: &mut ratatui::Frame<'_>,
         _: ratatui::layout::Rect,