feat(unstable): Add initial support for listing sessions

Cargo.toml

@@ -27,7 +27,7 @@ tokio = { version = "1.48", features = ["full"] }
 tokio-util = { version = "0.7", features = ["compat"] }
 
 # Protocol
-agent-client-protocol-schema = { version = "0.10.0" }
+agent-client-protocol-schema = { version = "=0.10.4" }
 
 # Serialization
 serde = { version = "1.0", features = ["derive", "rc"] }

examples/agent.rs

@@ -73,7 +73,7 @@ impl acp::Agent for ExampleAgent {
         Ok(acp::NewSessionResponse {
             session_id: acp::SessionId(session_id.to_string().into()),
             modes: None,
-            #[cfg(feature = "unstable")]
+            #[cfg(feature = "unstable_session_model")]
             models: None,
             meta: None,
         })
@@ -86,7 +86,7 @@ impl acp::Agent for ExampleAgent {
         log::info!("Received load session request {arguments:?}");
         Ok(acp::LoadSessionResponse {
             modes: None,
-            #[cfg(feature = "unstable")]
+            #[cfg(feature = "unstable_session_model")]
             models: None,
             meta: None,
         })
@@ -133,7 +133,7 @@ impl acp::Agent for ExampleAgent {
         Ok(acp::SetSessionModeResponse::default())
     }
 
-    #[cfg(feature = "unstable")]
+    #[cfg(feature = "unstable_session_model")]
     async fn set_session_model(
         &self,
         args: acp::SetSessionModelRequest,
@@ -142,6 +142,15 @@ impl acp::Agent for ExampleAgent {
         Ok(acp::SetSessionModelResponse::default())
     }
 
+    #[cfg(feature = "unstable_session_list")]
+    async fn list_sessions(
+        &self,
+        args: acp::ListSessionsRequest,
+    ) -> Result<acp::ListSessionsResponse, acp::Error> {
+        log::info!("Received list sessions request {args:?}");
+        Ok(acp::ListSessionsResponse::new(vec![]))
+    }
+
     async fn ext_method(&self, args: acp::ExtRequest) -> Result<acp::ExtResponse, acp::Error> {
         log::info!(
             "Received extension method call: method={}, params={:?}",

src/agent-client-protocol/Cargo.toml

@@ -13,7 +13,22 @@ keywords = ["agent", "client", "protocol", "ai", "editor"]
 categories = ["development-tools", "api-bindings"]
 
 [features]
-unstable = ["agent-client-protocol-schema/unstable"]
+unstable = [
+    "unstable_cancel_request",
+    "unstable_session_config_options",
+    "unstable_session_fork",
+    "unstable_session_info_update",
+    "unstable_session_list",
+    "unstable_session_model",
+    "unstable_session_resume",
+]
+unstable_cancel_request = ["agent-client-protocol-schema/unstable_cancel_request"]
+unstable_session_config_options = ["agent-client-protocol-schema/unstable_session_config_options"]
+unstable_session_fork = ["agent-client-protocol-schema/unstable_session_fork"]
+unstable_session_info_update = ["agent-client-protocol-schema/unstable_session_info_update"]
+unstable_session_list = ["agent-client-protocol-schema/unstable_session_list"]
+unstable_session_model = ["agent-client-protocol-schema/unstable_session_model"]
+unstable_session_resume = ["agent-client-protocol-schema/unstable_session_resume"]
 
 [dependencies]
 agent-client-protocol-schema.workspace = true

src/agent-client-protocol/src/agent.rs

@@ -6,7 +6,9 @@ use agent_client_protocol_schema::{
     LoadSessionResponse, NewSessionRequest, NewSessionResponse, PromptRequest, PromptResponse,
     Result, SetSessionModeRequest, SetSessionModeResponse,
 };
-#[cfg(feature = "unstable")]
+#[cfg(feature = "unstable_session_list")]
+use agent_client_protocol_schema::{ListSessionsRequest, ListSessionsResponse};
+#[cfg(feature = "unstable_session_model")]
 use agent_client_protocol_schema::{SetSessionModelRequest, SetSessionModelResponse};
 use serde_json::value::RawValue;
 
@@ -118,14 +120,26 @@ pub trait Agent {
     /// This capability is not part of the spec yet, and may be removed or changed at any point.
     ///
     /// Select a model for a given session.
-    #[cfg(feature = "unstable")]
+    #[cfg(feature = "unstable_session_model")]
     async fn set_session_model(
         &self,
         _args: SetSessionModelRequest,
     ) -> Result<SetSessionModelResponse> {
         Err(Error::method_not_found())
     }
 
+    /// **UNSTABLE**
+    ///
+    /// This capability is not part of the spec yet, and may be removed or changed at any point.
+    ///
+    /// Lists existing sessions known to the agent.
+    ///
+    /// Only available if the Agent supports the `sessionCapabilities.list` capability.
+    #[cfg(feature = "unstable_session_list")]
+    async fn list_sessions(&self, _args: ListSessionsRequest) -> Result<ListSessionsResponse> {
+        Err(Error::method_not_found())
+    }
+
     /// Handles extension method requests from the client.
     ///
     /// Extension methods provide a way to add custom functionality while maintaining
@@ -173,13 +187,17 @@ impl<T: Agent> Agent for Rc<T> {
     async fn cancel(&self, args: CancelNotification) -> Result<()> {
         self.as_ref().cancel(args).await
     }
-    #[cfg(feature = "unstable")]
+    #[cfg(feature = "unstable_session_model")]
     async fn set_session_model(
         &self,
         args: SetSessionModelRequest,
     ) -> Result<SetSessionModelResponse> {
         self.as_ref().set_session_model(args).await
     }
+    #[cfg(feature = "unstable_session_list")]
+    async fn list_sessions(&self, args: ListSessionsRequest) -> Result<ListSessionsResponse> {
+        self.as_ref().list_sessions(args).await
+    }
     async fn ext_method(&self, args: ExtRequest) -> Result<ExtResponse> {
         self.as_ref().ext_method(args).await
     }
@@ -214,13 +232,17 @@ impl<T: Agent> Agent for Arc<T> {
     async fn cancel(&self, args: CancelNotification) -> Result<()> {
         self.as_ref().cancel(args).await
     }
-    #[cfg(feature = "unstable")]
+    #[cfg(feature = "unstable_session_model")]
     async fn set_session_model(
         &self,
         args: SetSessionModelRequest,
     ) -> Result<SetSessionModelResponse> {
         self.as_ref().set_session_model(args).await
     }
+    #[cfg(feature = "unstable_session_list")]
+    async fn list_sessions(&self, args: ListSessionsRequest) -> Result<ListSessionsResponse> {
+        self.as_ref().list_sessions(args).await
+    }
     async fn ext_method(&self, args: ExtRequest) -> Result<ExtResponse> {
         self.as_ref().ext_method(args).await
     }

src/agent-client-protocol/src/lib.rs

@@ -142,7 +142,7 @@ impl Agent for ClientSideConnection {
         )
     }
 
-    #[cfg(feature = "unstable")]
+    #[cfg(feature = "unstable_session_model")]
     async fn set_session_model(
         &self,
         args: SetSessionModelRequest,
@@ -155,6 +155,16 @@ impl Agent for ClientSideConnection {
             .await
     }
 
+    #[cfg(feature = "unstable_session_list")]
+    async fn list_sessions(&self, args: ListSessionsRequest) -> Result<ListSessionsResponse> {
+        self.conn
+            .request(
+                AGENT_METHOD_NAMES.session_list,
+                Some(ClientRequest::ListSessionsRequest(args)),
+            )
+            .await
+    }
+
     async fn ext_method(&self, args: ExtRequest) -> Result<ExtResponse> {
         self.conn
             .request(
@@ -514,10 +524,14 @@ impl Side for AgentSide {
             m if m == AGENT_METHOD_NAMES.session_set_mode => serde_json::from_str(params.get())
                 .map(ClientRequest::SetSessionModeRequest)
                 .map_err(Into::into),
-            #[cfg(feature = "unstable")]
+            #[cfg(feature = "unstable_session_model")]
             m if m == AGENT_METHOD_NAMES.session_set_model => serde_json::from_str(params.get())
                 .map(ClientRequest::SetSessionModelRequest)
                 .map_err(Into::into),
+            #[cfg(feature = "unstable_session_list")]
+            m if m == AGENT_METHOD_NAMES.session_list => serde_json::from_str(params.get())
+                .map(ClientRequest::ListSessionsRequest)
+                .map_err(Into::into),
             m if m == AGENT_METHOD_NAMES.session_prompt => serde_json::from_str(params.get())
                 .map(ClientRequest::PromptRequest)
                 .map_err(Into::into),
@@ -582,11 +596,16 @@ impl<T: Agent> MessageHandler<AgentSide> for T {
                 let response = self.set_session_mode(args).await?;
                 Ok(AgentResponse::SetSessionModeResponse(response))
             }
-            #[cfg(feature = "unstable")]
+            #[cfg(feature = "unstable_session_model")]
             ClientRequest::SetSessionModelRequest(args) => {
                 let response = self.set_session_model(args).await?;
                 Ok(AgentResponse::SetSessionModelResponse(response))
             }
+            #[cfg(feature = "unstable_session_list")]
+            ClientRequest::ListSessionsRequest(args) => {
+                let response = self.list_sessions(args).await?;
+                Ok(AgentResponse::ListSessionsResponse(response))
+            }
             ClientRequest::ExtMethodRequest(args) => {
                 let response = self.ext_method(args).await?;
                 Ok(AgentResponse::ExtMethodResponse(response))

src/agent-client-protocol/src/rpc_tests.rs

@@ -196,7 +196,7 @@ impl Agent for TestAgent {
         Ok(())
     }
 
-    #[cfg(feature = "unstable")]
+    #[cfg(feature = "unstable_session_model")]
     async fn set_session_model(
         &self,
         args: agent_client_protocol_schema::SetSessionModelRequest,
@@ -205,6 +205,16 @@ impl Agent for TestAgent {
         Ok(agent_client_protocol_schema::SetSessionModelResponse::default())
     }
 
+    #[cfg(feature = "unstable_session_list")]
+    async fn list_sessions(
+        &self,
+        _args: agent_client_protocol_schema::ListSessionsRequest,
+    ) -> Result<agent_client_protocol_schema::ListSessionsResponse> {
+        Ok(agent_client_protocol_schema::ListSessionsResponse::new(
+            vec![],
+        ))
+    }
+
     async fn ext_method(&self, args: ExtRequest) -> Result<ExtResponse> {
         dbg!();
         match dbg!(args.method.as_ref()) {