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

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

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>,
+}