Merge pull request #584 from posit-dev/feature/jep65-feature-flag

Move protocol version to Amalthea and add feature flag

crates/amalthea/src/socket/shell.rs

@@ -42,6 +42,7 @@ use crate::wire::jupyter_message::JupyterMessage;
 use crate::wire::jupyter_message::Message;
 use crate::wire::jupyter_message::ProtocolMessage;
 use crate::wire::jupyter_message::Status;
+use crate::wire::kernel_info_full_reply;
 use crate::wire::originator::Originator;
 use crate::wire::status::ExecutionState;
 use crate::wire::status::KernelStatus;
@@ -128,6 +129,7 @@ impl Shell {
         match msg {
             Message::KernelInfoRequest(req) => self.handle_request(req.clone(), |msg| {
                 block_on(shell_handler.handle_info_request(msg))
+                    .map(kernel_info_full_reply::KernelInfoReply::from)
             }),
             Message::IsCompleteRequest(req) => self.handle_request(req, |msg| {
                 block_on(shell_handler.handle_is_complete_request(msg))

crates/amalthea/src/wire/jupyter_message.rs

@@ -11,6 +11,7 @@ use serde::Serialize;
 use super::display_data::DisplayData;
 use super::handshake_reply::HandshakeReply;
 use super::handshake_request::HandshakeRequest;
+use super::kernel_info_full_reply::KernelInfoReply;
 use super::stream::StreamOutput;
 use super::update_display_data::UpdateDisplayData;
 use super::welcome::Welcome;
@@ -43,7 +44,6 @@ use crate::wire::interrupt_reply::InterruptReply;
 use crate::wire::interrupt_request::InterruptRequest;
 use crate::wire::is_complete_reply::IsCompleteReply;
 use crate::wire::is_complete_request::IsCompleteRequest;
-use crate::wire::kernel_info_reply::KernelInfoReply;
 use crate::wire::kernel_info_request::KernelInfoRequest;
 use crate::wire::originator::Originator;
 use crate::wire::shutdown_request::ShutdownRequest;

crates/amalthea/src/wire/kernel_info_full_reply.rs

@@ -0,0 +1,69 @@
+/*
+ * kernel_info_full_reply.rs
+ *
+ * Copyright (C) 2024 Posit Software, PBC. All rights reserved.
+ *
+ */
+
+use serde::Deserialize;
+use serde::Serialize;
+
+use crate::wire::help_link::HelpLink;
+use crate::wire::jupyter_message::MessageType;
+use crate::wire::jupyter_message::Status;
+use crate::wire::kernel_info_reply;
+use crate::wire::language_info::LanguageInfo;
+
+/// Complete version of `kernel_info_reply`
+///
+/// Private to Amalthea. Includes fields owned by Amalthea such as the protocol
+/// version and feature flags.
+///
+/// Kernel authors should use [kernel_info_reply::KernelInfoReply] instead.
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct KernelInfoReply {
+    /// Version of messaging protocol
+    pub protocol_version: String,
+
+    /// List of feature flags supported by the kernel. See JEP 92.
+    pub supported_features: Vec<String>,
+
+    /// The execution status ("ok" or "error")
+    pub status: Status,
+
+    /// Information about the language the kernel supports
+    pub language_info: LanguageInfo,
+
+    /// A startup banner
+    pub banner: String,
+
+    /// Whether debugging is supported
+    pub debugger: bool,
+
+    /// A list of help links
+    pub help_links: Vec<HelpLink>,
+}
+
+impl MessageType for KernelInfoReply {
+    fn message_type() -> String {
+        String::from("kernel_info_reply")
+    }
+}
+
+/// Adds Amalthea fields to partial [kernel_info_reply::KernelInfoReply].
+impl From<kernel_info_reply::KernelInfoReply> for KernelInfoReply {
+    fn from(value: kernel_info_reply::KernelInfoReply) -> Self {
+        Self {
+            // These fields are set by Amalthea
+            protocol_version: String::from("5.4"),
+            supported_features: vec![String::from("iopub_welcome")],
+
+            // These fields are set by the Amalthea user
+            status: value.status,
+            language_info: value.language_info,
+            banner: value.banner,
+            debugger: value.debugger,
+            help_links: value.help_links,
+        }
+    }
+}

crates/amalthea/src/wire/kernel_info_reply.rs

@@ -1,27 +1,26 @@
 /*
  * kernel_info_reply.rs
  *
- * Copyright (C) 2022 Posit Software, PBC. All rights reserved.
+ * Copyright (C) 2022-2024 Posit Software, PBC. All rights reserved.
  *
  */
 
 use serde::Deserialize;
 use serde::Serialize;
 
 use crate::wire::help_link::HelpLink;
-use crate::wire::jupyter_message::MessageType;
 use crate::wire::jupyter_message::Status;
 use crate::wire::language_info::LanguageInfo;
 
-/// Represents a reply to a kernel_info_request
+/// Represents a reply to a `kernel_info_request`
+///
+/// When implementing a kernel, use this struct. Amalthea is in charge of
+/// providing the `protocol_version` to complete the reply.
 #[derive(Debug, Serialize, Deserialize, Clone)]
 pub struct KernelInfoReply {
     /// The execution status ("ok" or "error")
     pub status: Status,
 
-    /// Version of messaging protocol
-    pub protocol_version: String,
-
     /// Information about the language the kernel supports
     pub language_info: LanguageInfo,
 
@@ -34,9 +33,3 @@ pub struct KernelInfoReply {
     /// A list of help links
     pub help_links: Vec<HelpLink>,
 }
-
-impl MessageType for KernelInfoReply {
-    fn message_type() -> String {
-        String::from("kernel_info_reply")
-    }
-}

crates/amalthea/src/wire/mod.rs

@@ -34,6 +34,7 @@ pub mod interrupt_request;
 pub mod is_complete_reply;
 pub mod is_complete_request;
 pub mod jupyter_message;
+pub mod kernel_info_full_reply;
 pub mod kernel_info_reply;
 pub mod kernel_info_request;
 pub mod language_info;

crates/amalthea/tests/client.rs

@@ -38,6 +38,8 @@ fn test_amalthea_kernel_info() {
         frontend.recv_shell(),
         Message::KernelInfoReply(reply) => {
             assert_eq!(reply.content.language_info.name, "Test");
+            assert_eq!(reply.content.protocol_version, "5.4");
+            assert!(reply.content.supported_features.contains(&String::from("iopub_welcome")));
         }
     );
 

crates/amalthea/tests/shell/mod.rs

@@ -102,7 +102,6 @@ impl ShellHandler for Shell {
             status: Status::Ok,
             banner: format!("Amalthea Echo {}", env!("CARGO_PKG_VERSION")),
             debugger: false,
-            protocol_version: String::from("5.0"),
             help_links: Vec::new(),
             language_info: info,
         })

crates/ark/src/shell.rs

@@ -168,7 +168,6 @@ impl ShellHandler for Shell {
             status: Status::Ok,
             banner: kernel_info.banner.clone(),
             debugger: false,
-            protocol_version: String::from("5.3"),
             help_links: Vec::new(),
             language_info: info,
         })

crates/echo/src/shell.rs

@@ -77,7 +77,6 @@ impl ShellHandler for Shell {
             status: Status::Ok,
             banner: format!("Amalthea Echo {}", env!("CARGO_PKG_VERSION")),
             debugger: false,
-            protocol_version: String::from("5.0"),
             help_links: Vec::new(),
             language_info: info,
         })