Split protocol and leaf surfaces into crates

Move the protocol runtime into unshell-protocol and remote shell leaf code into unshell-leaves so endpoint and TUI roles can compile independently without circular dependencies.

Cargo.lock

@@ -1440,11 +1440,21 @@ name = "unshell"
 version = "0.1.0"
 dependencies = [
  "chrono",
- "portable-pty",
  "rkyv",
  "static_init",
  "thiserror 2.0.18",
+ "unshell-leaves",
  "unshell-macros",
+ "unshell-protocol",
+]
+
+[[package]]
+name = "unshell-leaves"
+version = "0.1.0"
+dependencies = [
+ "portable-pty",
+ "rkyv",
+ "unshell",
 ]
 
 [[package]]
@@ -1456,6 +1466,14 @@ dependencies = [
  "syn 2.0.117",
 ]
 
+[[package]]
+name = "unshell-protocol"
+version = "0.1.0"
+dependencies = [
+ "rkyv",
+ "unshell-macros",
+]
+
 [[package]]
 name = "ush-obfuscate"
 version = "0.1.0"

Cargo.toml

@@ -5,6 +5,8 @@ members = [
     "ush-obfuscate",
     "base62",
     "unshell-macros",
+    "unshell-protocol",
+    "unshell-leaves",
     "treetest",
 ]
 resolver = "2"
@@ -27,6 +29,8 @@ quote             = "1.0.45"
 proc-macro2       = "1.0.106"
 portable-pty      = "0.9.0"
 unshell          = { path = "." }
+unshell-protocol = { path = "./unshell-protocol" }
+unshell-leaves   = { path = "./unshell-leaves" }
 # ush-obfuscate = { path = "./ush-obfuscate" }
 # base62        = { path = "./base62" }
 
@@ -50,7 +54,10 @@ chrono            = { workspace = true, optional = true }
 # ush-obfuscate     = { workspace = true }
 static_init       = { workspace = true }
 unshell-macros    = { path = "./unshell-macros" }
-portable-pty      = { workspace = true }
+unshell-protocol  = { workspace = true }
+
+[dev-dependencies]
+unshell-leaves = { workspace = true, features = ["endpoint"] }
 
 [[example]]
 name = "leaf_derive"

examples/protocol/remote_shell_endpoint.rs

@@ -4,15 +4,13 @@
 //! example over TCP, feeds inbound frames into the `ProcedureRuntime`, and flushes any resulting
 //! protocol frames back to the controller.
 
-#[path = "../../src/leaf/remote_shell/mod.rs"]
-mod remote_shell;
-
 use std::error::Error;
 use std::net::TcpStream;
 use std::sync::mpsc::RecvTimeoutError;
 use std::time::Duration;
 
 use unshell::protocol::tree::Ingress;
+use unshell_leaves::remote_shell;
 
 fn main() -> Result<(), Box<dyn Error>> {
     let mut stream = TcpStream::connect(remote_shell::LISTEN_ADDR)?;

examples/protocol/remote_shell_receive.rs

@@ -3,13 +3,11 @@
 //! This binary listens for the endpoint example, opens one remote shell session, sends a few
 //! commands, and prints returned hook data until the shell closes.
 
-#[path = "../../src/leaf/remote_shell/mod.rs"]
-mod remote_shell;
-
 use std::error::Error;
 use std::net::TcpListener;
 
 use unshell::protocol::tree::{Endpoint, EndpointOutcome, Ingress, LocalEvent};
+use unshell_leaves::remote_shell;
 
 fn main() -> Result<(), Box<dyn Error>> {
     let listener = TcpListener::bind(remote_shell::LISTEN_ADDR)?;

examples/protocol/remote_shell_single_endpoint.rs

@@ -5,13 +5,11 @@
 //! a shell process, so it is the easiest place to see how the endpoint and leaf metadata fit
 //! together.
 
-#[path = "../../src/leaf/remote_shell/mod.rs"]
-mod remote_shell;
-
 use std::error::Error;
 
 use unshell::protocol::tree::{EndpointOutcome, LocalEvent, ProtocolEndpoint};
 use unshell::protocol::{INTROSPECTION_PROCEDURE_ID, LeafIntrospection};
+use unshell_leaves::remote_shell;
 
 fn main() -> Result<(), Box<dyn Error>> {
     let mut endpoint = ProtocolEndpoint::new(

src/leaf/mod.rs

@@ -1 +0,0 @@
-pub mod remote_shell;

src/leaf/remote_shell/mod.rs

@@ -1,159 +0,0 @@
-//! Stateful remote shell leaf used by the protocol examples.
-//!
-//! # Design
-//!
-//! The leaf owns all live hook sessions explicitly in `sessions`. Each entry in
-//! that map is one `ProcedureOpen`, keyed by the caller-owned hook identity.
-//! The protocol runtime still owns packet validation and transport close state,
-//! while the procedure session owns application resources such as the spawned
-//! shell process.
-//!
-//! This keeps the storage obvious:
-//! - the leaf owns session maps
-//! - the procedure type owns one hook conversation
-//! - the runtime routes later `Data` and `Fault` packets automatically
-
-mod errors;
-mod session;
-mod transport;
-
-use std::collections::BTreeMap;
-
-use unshell::Leaf;
-use unshell::protocol::tree::{
-    Call, HookKey, Procedure, ProcedureEffect, ProcedureRuntime, ProcedureStore, ProtocolEndpoint,
-};
-
-pub use errors::ShellLeafError;
-pub use session::ProcedureOpen;
-pub use transport::LISTEN_ADDR;
-
-/// Leaf state for the remote shell example.
-///
-/// The map is explicit on purpose. Stateful procedures are easier to debug when
-/// the leaf clearly owns its live sessions instead of relying on generated hidden
-/// enums or side tables.
-#[derive(Default, Leaf)]
-#[leaf(leaf_name = "remote_shell")]
-pub struct RemoteShellLeaf {
-    sessions: BTreeMap<HookKey, ProcedureOpen>,
-}
-
-impl ProcedureStore<ProcedureOpen> for RemoteShellLeaf {
-    fn procedure_sessions(&mut self) -> &mut BTreeMap<HookKey, ProcedureOpen> {
-        &mut self.sessions
-    }
-}
-
-impl Procedure<RemoteShellLeaf> for ProcedureOpen {
-    type Error = ShellLeafError;
-    type Input = ();
-
-    fn open(_leaf: &mut RemoteShellLeaf, call: Call<Self::Input>) -> Result<Self, Self::Error> {
-        let hook_key = call.response_hook.ok_or(ShellLeafError::MissingHook)?;
-        ProcedureOpen::spawn(hook_key.return_path, hook_key.hook_id, call.procedure_id)
-    }
-
-    fn on_data(
-        _leaf: &mut RemoteShellLeaf,
-        session: &mut Self,
-        data: unshell::protocol::tree::IncomingData,
-    ) -> Result<ProcedureEffect, Self::Error> {
-        session.on_data(data)
-    }
-
-    fn on_fault(
-        _leaf: &mut RemoteShellLeaf,
-        _session: &mut Self,
-        _fault: unshell::protocol::tree::IncomingFault,
-    ) -> Result<(), Self::Error> {
-        Ok(())
-    }
-
-    fn poll(
-        _leaf: &mut RemoteShellLeaf,
-        session: &mut Self,
-    ) -> Result<ProcedureEffect, Self::Error> {
-        session.poll()
-    }
-
-    fn close(_leaf: &mut RemoteShellLeaf, mut session: Self) -> Result<(), Self::Error> {
-        session.terminate()
-    }
-}
-
-/// Returns the example endpoint path used by both shell binaries.
-pub fn agent_path() -> Vec<String> {
-    path(&["agent"])
-}
-
-/// Builds the controller endpoint used by the receiver example.
-#[allow(dead_code)]
-pub fn build_controller_endpoint() -> ProtocolEndpoint {
-    ProtocolEndpoint::new(
-        Vec::new(),
-        None,
-        vec![unshell::protocol::tree::ChildRoute::registered(agent_path())],
-        Vec::new(),
-    )
-}
-
-/// Builds the stateful shell runtime used by the endpoint example.
-#[allow(dead_code)]
-pub fn build_agent_runtime() -> ProcedureRuntime<RemoteShellLeaf, ProcedureOpen> {
-    let endpoint = ProtocolEndpoint::new(
-        agent_path(),
-        Some(Vec::new()),
-        Vec::new(),
-        vec![unshell::protocol::tree::LeafSpec {
-            name: RemoteShellLeaf::protocol_leaf_name(),
-            procedures: vec![ProcedureOpen::protocol_procedure_id()],
-        }],
-    );
-    ProcedureRuntime::new(endpoint, RemoteShellLeaf::default())
-}
-
-/// Returns the canonical leaf id used by the receiver example.
-#[allow(dead_code)]
-pub fn shell_leaf_name() -> String {
-    RemoteShellLeaf::protocol_leaf_name()
-}
-
-/// Returns the opening `procedure_id` used to create one shell session.
-#[allow(dead_code)]
-pub fn shell_open_procedure() -> String {
-    ProcedureOpen::protocol_procedure_id()
-}
-
-/// Encodes the empty opening payload used by the shell example.
-#[allow(dead_code)]
-pub fn shell_open_payload() -> Vec<u8> {
-    unshell::protocol::tree::encode_call_reply(&()).expect("unit shell open payload should encode")
-}
-
-#[allow(dead_code)]
-pub fn send_forward(
-    stream: &mut std::net::TcpStream,
-    outcome: unshell::protocol::tree::EndpointOutcome,
-) -> std::io::Result<()> {
-    transport::send_forward(stream, outcome)
-}
-
-#[allow(dead_code)]
-pub fn write_frames(
-    stream: &mut std::net::TcpStream,
-    frames: &[unshell::protocol::FrameBytes],
-) -> std::io::Result<()> {
-    transport::write_frames(stream, frames)
-}
-
-#[allow(dead_code)]
-pub fn spawn_frame_reader(
-    stream: std::net::TcpStream,
-) -> std::sync::mpsc::Receiver<std::io::Result<unshell::protocol::FrameBytes>> {
-    transport::spawn_frame_reader(stream)
-}
-
-fn path(parts: &[&str]) -> Vec<String> {
-    parts.iter().map(|part| (*part).to_owned()).collect()
-}

src/lib.rs

@@ -18,7 +18,10 @@ pub extern crate alloc;
 extern crate self as unshell;
 
 pub mod logger;
-pub mod protocol;
+
+/// Re-export the protocol crate behind the historical `unshell::protocol` path so
+/// proc-macro output and downstream code do not need a second migration.
+pub use unshell_protocol as protocol;
 
 pub use unshell_macros::{Leaf, Procedure, procedures};
 

unshell-leaves/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "unshell-leaves"
+version.workspace = true
+edition.workspace = true
+description = "Application-layer UnShell leaves and client surfaces"
+
+[features]
+default = []
+endpoint = ["dep:portable-pty"]
+tui = []
+
+[dependencies]
+rkyv = { workspace = true }
+portable-pty = { workspace = true, optional = true }
+unshell = { workspace = true }
+
+[lints.rust]
+elided_lifetimes_in_paths = "warn"
+future_incompatible = { level = "warn", priority = -1 }
+nonstandard_style = { level = "warn", priority = -1 }
+rust_2018_idioms = { level = "warn", priority = -1 }
+rust_2021_prelude_collisions = "warn"
+semicolon_in_expressions_from_macros = "warn"
+unsafe_op_in_unsafe_fn = "warn"
+unused_import_braces = "warn"
+unused_lifetimes = "warn"
+trivial_casts = "allow"
+missing_docs = "warn"

unshell-leaves/src/lib.rs

@@ -0,0 +1,79 @@
+//! Application-layer leaves and user-facing surfaces built on top of the UnShell
+//! protocol runtime.
+//!
+//! Each leaf module always exports its shared protocol-facing types. Role-specific
+//! implementations are selected with the crate-wide `endpoint` and `tui`
+//! features, and can optionally be re-exported behind one stable alias.
+
+use unshell::protocol::DataMessage;
+
+/// Re-exports one role-specific type behind a stable public alias.
+///
+/// This keeps consumers on a single name such as `RemoteShell` while still
+/// compiling only the role implementation needed by the current binary.
+#[macro_export]
+macro_rules! role_leaf {
+    (
+        $(#[$meta:meta])*
+        $vis:vis type $alias:ident {
+            endpoint => $endpoint:path,
+            tui => $tui:path $(,)?
+        }
+    ) => {
+        #[cfg(all(feature = "endpoint", feature = "tui"))]
+        compile_error!(concat!(
+            "`",
+            stringify!($alias),
+            "` can only alias one concrete role at a time; enable either `endpoint` or `tui`, not both"
+        ));
+
+        #[cfg(feature = "endpoint")]
+        $(#[$meta])*
+        $vis type $alias = $endpoint;
+
+        #[cfg(all(not(feature = "endpoint"), feature = "tui"))]
+        $(#[$meta])*
+        $vis type $alias = $tui;
+    };
+}
+
+/// Minimal leaf-specific TUI contract.
+///
+/// The initial implementation intentionally stays transport-agnostic. A CLI can
+/// feed validated protocol `DataMessage` values into a leaf TUI and ask it for a
+/// textual frame without depending on a specific rendering crate yet.
+pub trait LeafTui {
+    /// Returns the canonical protocol leaf name this UI understands.
+    fn leaf_name(&self) -> String;
+
+    /// Applies one inbound hook payload to the local UI state.
+    fn handle_data(&mut self, message: &DataMessage) -> Result<(), TuiError>;
+
+    /// Produces the current textual frame for the leaf.
+    fn render(&self) -> String;
+}
+
+/// Lightweight error used by the leaf TUI surface.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct TuiError {
+    message: String,
+}
+
+impl TuiError {
+    /// Creates one UI-surface error from owned text.
+    pub fn new(message: impl Into<String>) -> Self {
+        Self {
+            message: message.into(),
+        }
+    }
+}
+
+impl core::fmt::Display for TuiError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.write_str(&self.message)
+    }
+}
+
+impl core::error::Error for TuiError {}
+
+pub mod remote_shell;

unshell-leaves/src/remote_shell/endpoint.rs

@@ -0,0 +1,96 @@
+//! PTY-backed endpoint implementation for the remote shell leaf.
+
+mod errors;
+mod session;
+mod transport;
+
+use std::collections::BTreeMap;
+
+use unshell::Leaf;
+use unshell::protocol::tree::{
+    Call, HookKey, Procedure, ProcedureEffect, ProcedureRuntime, ProcedureStore, ProtocolEndpoint,
+};
+
+pub use errors::ShellLeafError;
+pub use session::ProcedureOpen;
+pub use transport::{LISTEN_ADDR, send_forward, spawn_frame_reader, write_frames};
+
+use super::{OpenRequest, agent_path};
+
+/// Leaf state for the remote shell endpoint runtime.
+///
+/// The endpoint keeps each live shell session in an explicit map keyed by the
+/// caller-owned hook identity. That makes ownership and cleanup of hook-backed
+/// shell processes easy to inspect during debugging.
+#[derive(Default, Leaf)]
+#[leaf(leaf_name = "remote_shell")]
+pub struct RemoteShellEndpoint {
+    sessions: BTreeMap<HookKey, ProcedureOpen>,
+}
+
+impl ProcedureStore<ProcedureOpen> for RemoteShellEndpoint {
+    fn procedure_sessions(&mut self) -> &mut BTreeMap<HookKey, ProcedureOpen> {
+        &mut self.sessions
+    }
+}
+
+impl Procedure<RemoteShellEndpoint> for ProcedureOpen {
+    type Error = ShellLeafError;
+    type Input = OpenRequest;
+
+    fn open(_leaf: &mut RemoteShellEndpoint, call: Call<Self::Input>) -> Result<Self, Self::Error> {
+        let hook_key = call.response_hook.ok_or(ShellLeafError::MissingHook)?;
+        ProcedureOpen::spawn(hook_key.return_path, hook_key.hook_id, call.procedure_id)
+    }
+
+    fn on_data(
+        _leaf: &mut RemoteShellEndpoint,
+        session: &mut Self,
+        data: unshell::protocol::tree::IncomingData,
+    ) -> Result<ProcedureEffect, Self::Error> {
+        session.on_data(data)
+    }
+
+    fn on_fault(
+        _leaf: &mut RemoteShellEndpoint,
+        _session: &mut Self,
+        _fault: unshell::protocol::tree::IncomingFault,
+    ) -> Result<(), Self::Error> {
+        Ok(())
+    }
+
+    fn poll(
+        _leaf: &mut RemoteShellEndpoint,
+        session: &mut Self,
+    ) -> Result<ProcedureEffect, Self::Error> {
+        session.poll()
+    }
+
+    fn close(_leaf: &mut RemoteShellEndpoint, mut session: Self) -> Result<(), Self::Error> {
+        session.terminate()
+    }
+}
+
+/// Builds the controller endpoint used by the receiver example.
+pub fn build_controller_endpoint() -> ProtocolEndpoint {
+    ProtocolEndpoint::new(
+        Vec::new(),
+        None,
+        vec![unshell::protocol::tree::ChildRoute::registered(agent_path())],
+        Vec::new(),
+    )
+}
+
+/// Builds the stateful shell runtime used by the endpoint example.
+pub fn build_agent_runtime() -> ProcedureRuntime<RemoteShellEndpoint, ProcedureOpen> {
+    let endpoint = ProtocolEndpoint::new(
+        agent_path(),
+        Some(Vec::new()),
+        Vec::new(),
+        vec![unshell::protocol::tree::LeafSpec {
+            name: RemoteShellEndpoint::protocol_leaf_name(),
+            procedures: vec![ProcedureOpen::protocol_procedure_id()],
+        }],
+    );
+    ProcedureRuntime::new(endpoint, RemoteShellEndpoint::default())
+}

unshell-leaves/src/remote_shell/endpoint/errors.rs

@@ -1,9 +1,12 @@
 use std::fmt;
 use std::io;
 
+/// Error produced by the remote shell endpoint implementation.
 #[derive(Debug)]
 pub enum ShellLeafError {
+    /// Underlying PTY or I/O failure.
     Io(io::Error),
+    /// Shell open requires a response hook so the session can stream bytes back.
     MissingHook,
 }
 

unshell-leaves/src/remote_shell/endpoint/session.rs

@@ -1,13 +1,9 @@
 //! Per-hook remote shell session lifecycle.
 //!
-//! A session opens one PTY-backed shell process and then translates protocol hook
+//! A session opens one PTY-backed shell process and translates protocol hook
-//! traffic into stdin writes and stdout/stderr chunks. The close model is
+//! traffic into stdin writes and stdout or stderr chunks. Close is intentionally
-//! intentionally two-sided:
+//! two-sided: the peer signals input completion with `end_hook`, while the local
-//! - peer end: the caller sets `end_hook`, so no more stdin is accepted
+//! side closes only after the child exits and the PTY reader drains.
-//! - local end: the shell process exits and the PTY reader drains completely
-//!
-//! Only after both conditions are observed does the session emit its final empty
-//! `end_hook` packet back through the protocol runtime.
 
 use std::io::{self, Read, Write};
 use std::process::Command;
@@ -15,18 +11,18 @@ use std::sync::mpsc::{self, Receiver, SyncSender, TryRecvError};
 use std::thread;
 
 use portable_pty::{CommandBuilder, ExitStatus, PtySize, native_pty_system};
+use unshell::Procedure;
 use unshell::protocol::tree::{IncomingData, OutgoingData, ProcedureEffect};
 
-use unshell::Procedure;
+use super::RemoteShellEndpoint;
-
 use super::errors::ShellLeafError;
 
 /// Per-hook shell session created by the `open` procedure.
 ///
-/// The procedure type is also the stored session type. This keeps the mapping
+/// The procedure type is also the stored session type so the mapping between
-/// between protocol procedure and hook state direct and easy to inspect.
+/// one opening procedure and one live hook remains direct and visible.
 #[derive(Procedure)]
-#[procedure(leaf = RemoteShellLeaf, name = "open")]
+#[procedure(leaf = RemoteShellEndpoint, name = "open")]
 pub struct ProcedureOpen {
     /// Spawned PTY child process.
     pub(super) child: Box<dyn portable_pty::Child + Send>,
@@ -56,8 +52,6 @@ enum OutputEvent {
     ReaderClosed,
 }
 
-use super::RemoteShellLeaf;
-
 impl ProcedureOpen {
     pub(super) fn spawn(
         return_path: Vec<String>,
@@ -173,9 +167,7 @@ impl ProcedureOpen {
         }
 
         // Peer end means no more stdin from the caller. Keep the process alive so
-        // any buffered PTY output can drain through the normal poll path. On Unix
+        // buffered PTY output can drain through the normal poll path.
-        // we also send SIGHUP so an interactive shell treats this like terminal
-        // hangup instead of waiting forever on the still-open PTY master.
         self.stdin_tx.take();
         self.signal_process_group("-HUP");
         Ok(ProcedureEffect::default())

unshell-leaves/src/remote_shell/endpoint/transport.rs

@@ -6,10 +6,11 @@ use std::thread;
 use unshell::protocol::FrameBytes;
 use unshell::protocol::tree::EndpointOutcome;
 
+/// TCP listen address used by the remote shell examples.
 pub const LISTEN_ADDR: &str = "127.0.0.1:4444";
 const MAX_FRAME_BYTES: usize = 1024 * 1024;
 
-#[allow(dead_code)]
+/// Writes the forwarded frame produced by one endpoint outcome.
 pub fn send_forward(stream: &mut TcpStream, outcome: EndpointOutcome) -> io::Result<()> {
     match outcome {
         EndpointOutcome::Forward { frame, .. } => write_frames(stream, &[frame]),
@@ -17,6 +18,7 @@ pub fn send_forward(stream: &mut TcpStream, outcome: EndpointOutcome) -> io::Res
     }
 }
 
+/// Writes one or more framed packets onto the example TCP stream.
 pub fn write_frames(stream: &mut TcpStream, frames: &[FrameBytes]) -> io::Result<()> {
     for frame in frames {
         let frame_len = u32::try_from(frame.len()).map_err(|_| {
@@ -29,6 +31,7 @@ pub fn write_frames(stream: &mut TcpStream, frames: &[FrameBytes]) -> io::Result
     Ok(())
 }
 
+/// Spawns the example frame reader that lifts prefixed frames off the TCP stream.
 pub fn spawn_frame_reader(mut stream: TcpStream) -> Receiver<io::Result<FrameBytes>> {
     let (tx, rx) = mpsc::sync_channel(64);
 
@@ -65,10 +68,7 @@ fn read_frame(stream: &mut TcpStream) -> io::Result<Option<FrameBytes>> {
         ));
     }
     let mut bytes = vec![0u8; frame_len];
-    match stream.read_exact(&mut bytes) {
+    stream.read_exact(&mut bytes)?;
-        Ok(()) => {}
-        Err(error) => return Err(error),
-    }
 
     let mut frame = FrameBytes::with_capacity(bytes.len());
     frame.extend_from_slice(&bytes);

unshell-leaves/src/remote_shell/mod.rs

@@ -0,0 +1,92 @@
+//! Remote shell leaf and its user-facing surfaces.
+//!
+//! The module always exports the protocol contract for the leaf. Role-specific
+//! implementations live behind crate-wide features:
+//! - `endpoint` builds the PTY-backed runtime leaf
+//! - `tui` builds a placeholder client-side TUI surface
+
+use rkyv::{Archive, Deserialize, Serialize};
+
+#[cfg(feature = "endpoint")]
+mod endpoint;
+#[cfg(feature = "tui")]
+mod tui;
+
+#[cfg(feature = "endpoint")]
+pub use endpoint::{
+    LISTEN_ADDR, RemoteShellEndpoint, ShellLeafError, build_agent_runtime,
+    build_controller_endpoint, send_forward, spawn_frame_reader, write_frames,
+};
+#[cfg(feature = "tui")]
+pub use tui::RemoteShellTui;
+
+use unshell::protocol::tree::encode_call_reply;
+
+/// Open-request payload for the remote shell leaf.
+///
+/// The shell currently needs no structured arguments, but a named payload type is
+/// easier for downstream code to discover than a bare `()`.
+#[derive(Archive, Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq)]
+pub struct OpenRequest;
+
+crate::role_leaf! {
+    /// Feature-selected remote shell surface.
+    pub type RemoteShell {
+        endpoint => endpoint::RemoteShellEndpoint,
+        tui => tui::RemoteShellTui,
+    }
+}
+
+/// Returns the example endpoint path used by the remote shell samples.
+pub fn agent_path() -> Vec<String> {
+    path(&["agent"])
+}
+
+/// Returns the canonical leaf id used by endpoint and TUI code.
+#[cfg(feature = "endpoint")]
+pub fn shell_leaf_name() -> String {
+    RemoteShellEndpoint::protocol_leaf_name()
+}
+
+/// Returns the canonical opening `procedure_id` for the shell leaf.
+#[cfg(feature = "endpoint")]
+pub fn shell_open_procedure() -> String {
+    endpoint::ProcedureOpen::protocol_procedure_id()
+}
+
+/// Encodes the empty open-request payload used by the shell example.
+#[cfg(all(not(feature = "endpoint"), feature = "tui"))]
+pub fn shell_leaf_name() -> String {
+    RemoteShellTui::protocol_leaf_name()
+}
+
+/// Returns the canonical opening `procedure_id` for the shell leaf.
+#[cfg(all(not(feature = "endpoint"), feature = "tui"))]
+pub fn shell_open_procedure() -> String {
+    let mut procedure_id = shell_leaf_name();
+    procedure_id.push_str(".open");
+    procedure_id
+}
+
+/// Encodes the empty open-request payload used by the shell example.
+#[cfg(not(any(feature = "endpoint", feature = "tui")))]
+pub fn shell_leaf_name() -> String {
+    String::from("remote_shell")
+}
+
+/// Returns the canonical opening `procedure_id` for the shell leaf.
+#[cfg(not(any(feature = "endpoint", feature = "tui")))]
+pub fn shell_open_procedure() -> String {
+    let mut procedure_id = shell_leaf_name();
+    procedure_id.push_str(".open");
+    procedure_id
+}
+
+/// Encodes the empty open-request payload used by the shell example.
+pub fn shell_open_payload() -> Vec<u8> {
+    encode_call_reply(&OpenRequest).expect("remote shell open payload should encode")
+}
+
+fn path(parts: &[&str]) -> Vec<String> {
+    parts.iter().map(|part| (*part).to_owned()).collect()
+}

unshell-leaves/src/remote_shell/tui.rs

@@ -0,0 +1,43 @@
+//! Placeholder client-side TUI surface for the remote shell leaf.
+//!
+//! The first application-layer consumer will be a CLI and later a full GUI. This
+//! stub keeps the leaf-specific interpretation point in place without forcing a
+//! rendering-library decision yet.
+
+use std::string::String;
+use std::vec::Vec;
+
+use unshell::Leaf;
+use unshell::protocol::DataMessage;
+
+use crate::{LeafTui, TuiError};
+
+/// Stub TUI surface for the remote shell leaf.
+#[derive(Default, Leaf)]
+#[leaf(leaf_name = "remote_shell")]
+pub struct RemoteShellTui {
+    transcript: Vec<u8>,
+}
+
+impl RemoteShellTui {
+    /// Returns a short explanation of the current stub status.
+    pub fn status_line(&self) -> &'static str {
+        "remote shell TUI stub: rendering is placeholder-only for now"
+    }
+}
+
+impl LeafTui for RemoteShellTui {
+    fn leaf_name(&self) -> String {
+        Self::protocol_leaf_name()
+    }
+
+    fn handle_data(&mut self, message: &DataMessage) -> Result<(), TuiError> {
+        self.transcript.extend_from_slice(&message.data);
+        Ok(())
+    }
+
+    fn render(&self) -> String {
+        let body = String::from_utf8_lossy(&self.transcript);
+        format!("{}\n\n{}", self.status_line(), body)
+    }
+}

unshell-protocol/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "unshell-protocol"
+version.workspace = true
+edition.workspace = true
+description = "Wire protocol, framing, validation, and endpoint runtime for UnShell"
+
+[lib]
+doctest = false
+
+[dependencies]
+rkyv = { workspace = true }
+unshell-macros = { path = "../unshell-macros" }
+
+[lints.rust]
+elided_lifetimes_in_paths = "warn"
+future_incompatible = { level = "warn", priority = -1 }
+nonstandard_style = { level = "warn", priority = -1 }
+rust_2018_idioms = { level = "warn", priority = -1 }
+rust_2021_prelude_collisions = "warn"
+semicolon_in_expressions_from_macros = "warn"
+unsafe_op_in_unsafe_fn = "warn"
+unused_import_braces = "warn"
+unused_lifetimes = "warn"
+trivial_casts = "allow"
+missing_docs = "warn"

unshell-protocol/src/lib.rs

@@ -0,0 +1,20 @@
+//! # UnShell Protocol
+//!
+//! The protocol crate owns the wire types, framing, validation helpers, and the
+//! small tree runtime used by endpoint implementations.
+
+#![no_std]
+
+pub extern crate alloc;
+#[allow(unused_extern_crates)]
+extern crate self as unshell;
+
+/// Keep the historical nested path so existing imports and proc-macro output can
+/// continue to target `unshell::protocol::...` while the implementation lives in
+/// its own crate.
+pub mod protocol;
+
+pub use protocol::*;
+
+#[cfg(test)]
+pub use unshell_macros::{Leaf, Procedure, procedures};