feat(task): add task support (SEP-1686) (#536)

Signed-off-by: jokemanfire <hu.dingyang@zte.com.cn>

crates/rmcp/src/model/capabilities.rs

@@ -40,6 +40,25 @@ pub struct RootsCapabilities {
     pub list_changed: Option<bool>,
 }
 
+/// Task capability negotiation for SEP-1686.
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TasksCapability {
+    /// Map of request category (e.g. "tools.call") to a boolean indicating support.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub requests: Option<TaskRequestMap>,
+    /// Whether the receiver supports `tasks/list`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub list: Option<bool>,
+    /// Whether the receiver supports `tasks/cancel`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub cancel: Option<bool>,
+}
+
+/// A convenience alias for describing per-request task support.
+pub type TaskRequestMap = BTreeMap<String, bool>;
+
 /// Capability for handling elicitation requests from servers.
 ///
 /// Elicitation allows servers to request interactive input from users during tool execution.
@@ -78,6 +97,8 @@ pub struct ClientCapabilities {
     /// Capability to handle elicitation requests from servers for interactive user input
     #[serde(skip_serializing_if = "Option::is_none")]
     pub elicitation: Option<ElicitationCapability>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tasks: Option<TasksCapability>,
 }
 
 ///
@@ -109,6 +130,8 @@ pub struct ServerCapabilities {
     pub resources: Option<ResourcesCapability>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub tools: Option<ToolsCapability>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tasks: Option<TasksCapability>,
 }
 
 macro_rules! builder {
@@ -223,12 +246,13 @@ builder! {
         completions: JsonObject,
         prompts: PromptsCapability,
         resources: ResourcesCapability,
-        tools: ToolsCapability
+        tools: ToolsCapability,
+        tasks: TasksCapability
     }
 }
 
-impl<const E: bool, const L: bool, const C: bool, const P: bool, const R: bool>
-    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, L, C, P, R, true>>
+impl<const E: bool, const L: bool, const C: bool, const P: bool, const R: bool, const TASKS: bool>
+    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, L, C, P, R, true, TASKS>>
 {
     pub fn enable_tool_list_changed(mut self) -> Self {
         if let Some(c) = self.tools.as_mut() {
@@ -238,8 +262,8 @@ impl<const E: bool, const L: bool, const C: bool, const P: bool, const R: bool>
     }
 }
 
-impl<const E: bool, const L: bool, const C: bool, const R: bool, const T: bool>
-    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, L, C, true, R, T>>
+impl<const E: bool, const L: bool, const C: bool, const R: bool, const T: bool, const TASKS: bool>
+    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, L, C, true, R, T, TASKS>>
 {
     pub fn enable_prompts_list_changed(mut self) -> Self {
         if let Some(c) = self.prompts.as_mut() {
@@ -249,8 +273,8 @@ impl<const E: bool, const L: bool, const C: bool, const R: bool, const T: bool>
     }
 }
 
-impl<const E: bool, const L: bool, const C: bool, const P: bool, const T: bool>
-    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, L, C, P, true, T>>
+impl<const E: bool, const L: bool, const C: bool, const P: bool, const T: bool, const TASKS: bool>
+    ServerCapabilitiesBuilder<ServerCapabilitiesBuilderState<E, L, C, P, true, T, TASKS>>
 {
     pub fn enable_resources_list_changed(mut self) -> Self {
         if let Some(c) = self.resources.as_mut() {
@@ -273,11 +297,12 @@ builder! {
         roots: RootsCapabilities,
         sampling: JsonObject,
         elicitation: ElicitationCapability,
+        tasks: TasksCapability,
     }
 }
 
-impl<const E: bool, const S: bool>
-    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, true, S>>
+impl<const E: bool, const S: bool, const EL: bool, const TASKS: bool>
+    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, true, S, EL, TASKS>>
 {
     pub fn enable_roots_list_changed(mut self) -> Self {
         if let Some(c) = self.roots.as_mut() {
@@ -288,8 +313,8 @@ impl<const E: bool, const S: bool>
 }
 
 #[cfg(feature = "elicitation")]
-impl<const E: bool, const R: bool, const S: bool>
-    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, R, S, true>>
+impl<const E: bool, const R: bool, const S: bool, const TASKS: bool>
+    ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, R, S, true, TASKS>>
 {
     /// Enable JSON Schema validation for elicitation responses.
     /// When enabled, the client will validate user input against the requested_schema

crates/rmcp/src/model/meta.rs

@@ -107,6 +107,10 @@ variant_extension! {
         CallToolRequest
         ListToolsRequest
         CustomRequest
+        GetTaskInfoRequest
+        ListTasksRequest
+        GetTaskResultRequest
+        CancelTaskRequest
     }
 }
 

crates/rmcp/src/model/task.rs

@@ -0,0 +1,79 @@
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+/// Canonical task lifecycle status as defined by SEP-1686.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub enum TaskStatus {
+    /// The receiver accepted the request and is currently working on it.
+    #[default]
+    Working,
+    /// The receiver requires additional input before work can continue.
+    InputRequired,
+    /// The underlying operation completed successfully and the result is ready.
+    Completed,
+    /// The underlying operation failed and will not continue.
+    Failed,
+    /// The task was cancelled and will not continue processing.
+    Cancelled,
+}
+
+/// Final result for a succeeded task (returned from `tasks/result`).
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskResult {
+    /// MIME type or custom content-type identifier.
+    pub content_type: String,
+    /// The actual result payload, matching the underlying request's schema.
+    pub value: Value,
+    /// Optional short summary for UI surfaces.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub summary: Option<String>,
+}
+
+/// Primary Task object that surfaces metadata during the task lifecycle.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct Task {
+    /// Unique task identifier generated by the receiver.
+    pub task_id: String,
+    /// Current lifecycle status (see [`TaskStatus`]).
+    pub status: TaskStatus,
+    /// Optional human-readable status message for UI surfaces.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub status_message: Option<String>,
+    /// ISO-8601 creation timestamp.
+    pub created_at: String,
+    /// ISO-8601 timestamp for the most recent status change.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub last_updated_at: Option<String>,
+    /// Retention window in milliseconds that the receiver agreed to honor.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub ttl: Option<u64>,
+    /// Suggested polling interval (milliseconds).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub poll_interval: Option<u64>,
+}
+
+/// Wrapper returned by task-augmented requests (CreateTaskResult in SEP-1686).
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct CreateTaskResult {
+    pub task: Task,
+}
+
+/// Paginated list of tasks
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct TaskList {
+    pub tasks: Vec<Task>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub next_cursor: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub total: Option<u64>,
+}