fix: align task response types with MCP spec (#658)

crates/rmcp-macros/src/task_handler.rs

@@ -47,7 +47,7 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                             status: rmcp::model::TaskStatus::Working,
                             status_message: None,
                             created_at: timestamp.clone(),
-                            last_updated_at: Some(timestamp),
+                            last_updated_at: timestamp,
                             ttl: None,
                             poll_interval: None,
                         }
@@ -111,7 +111,7 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                     status: rmcp::model::TaskStatus::Working,
                     status_message: Some("Task accepted".to_string()),
                     created_at: timestamp.clone(),
-                    last_updated_at: Some(timestamp),
+                    last_updated_at: timestamp,
                     ttl: None,
                     poll_interval: None,
                 };
@@ -128,7 +128,7 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                 &self,
                 request: rmcp::model::GetTaskInfoParam,
                 _context: rmcp::service::RequestContext<rmcp::RoleServer>,
-            ) -> Result<rmcp::model::GetTaskInfoResult, McpError> {
+            ) -> Result<rmcp::model::GetTaskResult, McpError> {
                 use rmcp::task_manager::current_timestamp;
                 let task_id = request.task_id.clone();
                 let mut processor = (#processor).lock().await;
@@ -156,11 +156,11 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                         status,
                         status_message: None,
                         created_at: timestamp.clone(),
-                        last_updated_at: Some(timestamp),
+                        last_updated_at: timestamp,
                         ttl: completed_result.descriptor.ttl,
                         poll_interval: None,
                     };
-                    return Ok(rmcp::model::GetTaskInfoResult { task: Some(task) });
+                    return Ok(rmcp::model::GetTaskResult { meta: None, task });
                 }
 
                 // If not completed, check running
@@ -172,14 +172,14 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                         status: rmcp::model::TaskStatus::Working,
                         status_message: None,
                         created_at: timestamp.clone(),
-                        last_updated_at: Some(timestamp),
+                        last_updated_at: timestamp,
                         ttl: None,
                         poll_interval: None,
                     };
-                    return Ok(rmcp::model::GetTaskInfoResult { task: Some(task) });
+                    return Ok(rmcp::model::GetTaskResult { meta: None, task });
                 }
 
-                Ok(rmcp::model::GetTaskInfoResult { task: None })
+                Err(McpError::resource_not_found(format!("task not found: {}", task_id), None))
             }
         };
         item_impl.items.push(syn::parse2::<ImplItem>(get_info_fn)?);
@@ -191,7 +191,7 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                 &self,
                 request: rmcp::model::GetTaskResultParam,
                 _context: rmcp::service::RequestContext<rmcp::RoleServer>,
-            ) -> Result<rmcp::model::TaskResult, McpError> {
+            ) -> Result<rmcp::model::GetTaskPayloadResult, McpError> {
                 use std::time::Duration;
                 let task_id = request.task_id.clone();
 
@@ -207,11 +207,7 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                                         match &tool.result {
                                             Ok(call_tool) => {
                                                 let value = ::serde_json::to_value(call_tool).unwrap_or(::serde_json::Value::Null);
-                                                return Ok(rmcp::model::TaskResult {
+                                                return Ok(rmcp::model::GetTaskPayloadResult(value));
-                                                    content_type: "application/json".to_string(),
-                                                    value,
-                                                    summary: None,
-                                                });
                                             }
                                             Err(err) => return Err(McpError::internal_error(
                                                 format!("task failed: {}", err),
@@ -251,12 +247,23 @@ pub fn task_handler(attr: TokenStream, input: TokenStream) -> syn::Result<TokenS
                 &self,
                 request: rmcp::model::CancelTaskParam,
                 _context: rmcp::service::RequestContext<rmcp::RoleServer>,
-            ) -> Result<(), McpError> {
+            ) -> Result<rmcp::model::CancelTaskResult, McpError> {
+                use rmcp::task_manager::current_timestamp;
                 let task_id = request.task_id;
                 let mut processor = (#processor).lock().await;
 
                 if processor.cancel_task(&task_id) {
-                    return Ok(());
+                    let timestamp = current_timestamp();
+                    let task = rmcp::model::Task {
+                        task_id,
+                        status: rmcp::model::TaskStatus::Cancelled,
+                        status_message: None,
+                        created_at: timestamp.clone(),
+                        last_updated_at: timestamp,
+                        ttl: None,
+                        poll_interval: None,
+                    };
+                    return Ok(rmcp::model::CancelTaskResult { meta: None, task });
                 }
 
                 // If already completed, signal it's not cancellable

crates/rmcp/src/handler/server.rs

@@ -116,15 +116,15 @@ impl<H: ServerHandler> Service<RoleServer> for H {
             ClientRequest::GetTaskInfoRequest(request) => self
                 .get_task_info(request.params, context)
                 .await
-                .map(ServerResult::GetTaskInfoResult),
+                .map(ServerResult::GetTaskResult),
             ClientRequest::GetTaskResultRequest(request) => self
                 .get_task_result(request.params, context)
                 .await
-                .map(ServerResult::TaskResult),
+                .map(ServerResult::GetTaskPayloadResult),
             ClientRequest::CancelTaskRequest(request) => self
                 .cancel_task(request.params, context)
                 .await
-                .map(ServerResult::empty),
+                .map(ServerResult::CancelTaskResult),
         }
     }
 
@@ -339,7 +339,8 @@ pub trait ServerHandler: Sized + Send + Sync + 'static {
         &self,
         request: GetTaskInfoParams,
         context: RequestContext<RoleServer>,
-    ) -> impl Future<Output = Result<GetTaskInfoResult, McpError>> + Send + '_ {
+    ) -> impl Future<Output = Result<GetTaskResult, McpError>> + Send + '_ {
+        let _ = (request, context);
         std::future::ready(Err(McpError::method_not_found::<GetTaskInfoMethod>()))
     }
 
@@ -347,7 +348,7 @@ pub trait ServerHandler: Sized + Send + Sync + 'static {
         &self,
         request: GetTaskResultParams,
         context: RequestContext<RoleServer>,
-    ) -> impl Future<Output = Result<TaskResult, McpError>> + Send + '_ {
+    ) -> impl Future<Output = Result<GetTaskPayloadResult, McpError>> + Send + '_ {
         let _ = (request, context);
         std::future::ready(Err(McpError::method_not_found::<GetTaskResultMethod>()))
     }
@@ -356,7 +357,7 @@ pub trait ServerHandler: Sized + Send + Sync + 'static {
         &self,
         request: CancelTaskParams,
         context: RequestContext<RoleServer>,
-    ) -> impl Future<Output = Result<(), McpError>> + Send + '_ {
+    ) -> impl Future<Output = Result<CancelTaskResult, McpError>> + Send + '_ {
         let _ = (request, context);
         std::future::ready(Err(McpError::method_not_found::<CancelTaskMethod>()))
     }
@@ -543,7 +544,7 @@ macro_rules! impl_server_handler_for_wrapper {
                 &self,
                 request: GetTaskInfoParams,
                 context: RequestContext<RoleServer>,
-            ) -> impl Future<Output = Result<GetTaskInfoResult, McpError>> + Send + '_ {
+            ) -> impl Future<Output = Result<GetTaskResult, McpError>> + Send + '_ {
                 (**self).get_task_info(request, context)
             }
 
@@ -551,7 +552,7 @@ macro_rules! impl_server_handler_for_wrapper {
                 &self,
                 request: GetTaskResultParams,
                 context: RequestContext<RoleServer>,
-            ) -> impl Future<Output = Result<TaskResult, McpError>> + Send + '_ {
+            ) -> impl Future<Output = Result<GetTaskPayloadResult, McpError>> + Send + '_ {
                 (**self).get_task_result(request, context)
             }
 
@@ -559,7 +560,7 @@ macro_rules! impl_server_handler_for_wrapper {
                 &self,
                 request: CancelTaskParams,
                 context: RequestContext<RoleServer>,
-            ) -> impl Future<Output = Result<(), McpError>> + Send + '_ {
+            ) -> impl Future<Output = Result<CancelTaskResult, McpError>> + Send + '_ {
                 (**self).cancel_task(request, context)
             }
         }

crates/rmcp/src/model.rs

@@ -2537,14 +2537,9 @@ impl RequestParamsMeta for CancelTaskParams {
 /// Deprecated: Use [`CancelTaskParams`] instead (SEP-1319 compliance).
 #[deprecated(since = "0.13.0", note = "Use CancelTaskParams instead")]
 pub type CancelTaskParam = CancelTaskParams;
-#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
+/// Deprecated: Use [`GetTaskResult`] instead (spec alignment).
-#[serde(rename_all = "camelCase")]
+#[deprecated(since = "0.15.0", note = "Use GetTaskResult instead")]
-#[serde(deny_unknown_fields)]
+pub type GetTaskInfoResult = GetTaskResult;
-#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
-pub struct GetTaskInfoResult {
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub task: Option<crate::model::Task>,
-}
 
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
 #[serde(rename_all = "camelCase")]
@@ -2720,9 +2715,10 @@ ts_union!(
     | EmptyResult
     | CreateTaskResult
     | ListTasksResult
-    | GetTaskInfoResult
+    | GetTaskResult
-    | TaskResult
+    | CancelTaskResult
     | CustomResult
+    | GetTaskPayloadResult
     ;
 );
 

crates/rmcp/src/model/task.rs

@@ -1,6 +1,8 @@
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
+use super::Meta;
+
 /// Canonical task lifecycle status as defined by SEP-1686.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
 #[serde(rename_all = "snake_case")]
@@ -19,21 +21,10 @@ pub enum TaskStatus {
     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.
+///
+/// Per spec, `lastUpdatedAt` and `ttl` are required fields.
+/// `ttl` is nullable (`null` means unlimited retention).
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
 #[serde(rename_all = "camelCase")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
@@ -48,10 +39,9 @@ pub struct Task {
     /// 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: String,
-    pub last_updated_at: Option<String>,
     /// Retention window in milliseconds that the receiver agreed to honor.
-    #[serde(skip_serializing_if = "Option::is_none")]
+    /// `None` (serialized as `null`) means unlimited retention.
     pub ttl: Option<u64>,
     /// Suggested polling interval (milliseconds).
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -66,6 +56,43 @@ pub struct CreateTaskResult {
     pub task: Task,
 }
 
+/// Response to a `tasks/get` request.
+///
+/// Per spec, `GetTaskResult = allOf[Result, Task]` — the Task fields are
+/// flattened at the top level, not nested under a `task` key.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct GetTaskResult {
+    #[serde(rename = "_meta", default, skip_serializing_if = "Option::is_none")]
+    pub meta: Option<Meta>,
+    #[serde(flatten)]
+    pub task: Task,
+}
+
+/// Response to a `tasks/result` request.
+///
+/// Per spec, the result structure matches the original request type
+/// (e.g., `CallToolResult` for `tools/call`). This is represented as
+/// an open object. The payload is the original request's result
+/// serialized as a JSON value.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct GetTaskPayloadResult(pub Value);
+
+/// Response to a `tasks/cancel` request.
+///
+/// Per spec, `CancelTaskResult = allOf[Result, Task]` — same shape as `GetTaskResult`.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub struct CancelTaskResult {
+    #[serde(rename = "_meta", default, skip_serializing_if = "Option::is_none")]
+    pub meta: Option<Meta>,
+    #[serde(flatten)]
+    pub task: Task,
+}
+
 /// Paginated list of tasks
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]

crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema.json

@@ -407,6 +407,70 @@
         "content"
       ]
     },
+    "CancelTaskResult": {
+      "description": "Response to a `tasks/cancel` request.\n\nPer spec, `CancelTaskResult = allOf[Result, Task]` — same shape as `GetTaskResult`.",
+      "type": "object",
+      "properties": {
+        "_meta": {
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": true
+        },
+        "createdAt": {
+          "description": "ISO-8601 creation timestamp.",
+          "type": "string"
+        },
+        "lastUpdatedAt": {
+          "description": "ISO-8601 timestamp for the most recent status change.",
+          "type": "string"
+        },
+        "pollInterval": {
+          "description": "Suggested polling interval (milliseconds).",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
+        },
+        "status": {
+          "description": "Current lifecycle status (see [`TaskStatus`]).",
+          "allOf": [
+            {
+              "$ref": "#/definitions/TaskStatus"
+            }
+          ]
+        },
+        "statusMessage": {
+          "description": "Optional human-readable status message for UI surfaces.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "taskId": {
+          "description": "Unique task identifier generated by the receiver.",
+          "type": "string"
+        },
+        "ttl": {
+          "description": "Retention window in milliseconds that the receiver agreed to honor.\n`None` (serialized as `null`) means unlimited retention.",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
+        }
+      },
+      "required": [
+        "taskId",
+        "status",
+        "createdAt",
+        "lastUpdatedAt"
+      ]
+    },
     "CancelledNotificationMethod": {
       "type": "string",
       "format": "const",
@@ -937,21 +1001,72 @@
         "messages"
       ]
     },
-    "GetTaskInfoResult": {
+    "GetTaskPayloadResult": {
+      "description": "Response to a `tasks/result` request.\n\nPer spec, the result structure matches the original request type\n(e.g., `CallToolResult` for `tools/call`). This is represented as\nan open object. The payload is the original request's result\nserialized as a JSON value."
+    },
+    "GetTaskResult": {
+      "description": "Response to a `tasks/get` request.\n\nPer spec, `GetTaskResult = allOf[Result, Task]` — the Task fields are\nflattened at the top level, not nested under a `task` key.",
       "type": "object",
       "properties": {
-        "task": {
+        "_meta": {
-          "anyOf": [
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": true
+        },
+        "createdAt": {
+          "description": "ISO-8601 creation timestamp.",
+          "type": "string"
+        },
+        "lastUpdatedAt": {
+          "description": "ISO-8601 timestamp for the most recent status change.",
+          "type": "string"
+        },
+        "pollInterval": {
+          "description": "Suggested polling interval (milliseconds).",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
+        },
+        "status": {
+          "description": "Current lifecycle status (see [`TaskStatus`]).",
+          "allOf": [
             {
-              "$ref": "#/definitions/Task"
+              "$ref": "#/definitions/TaskStatus"
-            },
-            {
-              "type": "null"
             }
           ]
+        },
+        "statusMessage": {
+          "description": "Optional human-readable status message for UI surfaces.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "taskId": {
+          "description": "Unique task identifier generated by the receiver.",
+          "type": "string"
+        },
+        "ttl": {
+          "description": "Retention window in milliseconds that the receiver agreed to honor.\n`None` (serialized as `null`) means unlimited retention.",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
         }
       },
-      "additionalProperties": false
+      "required": [
+        "taskId",
+        "status",
+        "createdAt",
+        "lastUpdatedAt"
+      ]
     },
     "Icon": {
       "description": "A URL pointing to an icon resource or a base64-encoded data URI.\n\nClients that support rendering icons MUST support at least the following MIME types:\n- image/png - PNG images (safe, universal compatibility)\n- image/jpeg (and image/jpg) - JPEG images (safe, universal compatibility)\n\nClients that support rendering icons SHOULD also support:\n- image/svg+xml - SVG images (scalable but requires security precautions)\n- image/webp - WebP images (modern, efficient format)",
@@ -2701,13 +2816,16 @@
           "$ref": "#/definitions/ListTasksResult"
         },
         {
-          "$ref": "#/definitions/GetTaskInfoResult"
+          "$ref": "#/definitions/GetTaskResult"
         },
         {
-          "$ref": "#/definitions/TaskResult"
+          "$ref": "#/definitions/CancelTaskResult"
         },
         {
           "$ref": "#/definitions/CustomResult"
+        },
+        {
+          "$ref": "#/definitions/GetTaskPayloadResult"
         }
       ]
     },
@@ -2813,7 +2931,7 @@
       "const": "string"
     },
     "Task": {
-      "description": "Primary Task object that surfaces metadata during the task lifecycle.",
+      "description": "Primary Task object that surfaces metadata during the task lifecycle.\n\nPer spec, `lastUpdatedAt` and `ttl` are required fields.\n`ttl` is nullable (`null` means unlimited retention).",
       "type": "object",
       "properties": {
         "createdAt": {
@@ -2822,10 +2940,7 @@
         },
         "lastUpdatedAt": {
           "description": "ISO-8601 timestamp for the most recent status change.",
-          "type": [
+          "type": "string"
-            "string",
-            "null"
-          ]
         },
         "pollInterval": {
           "description": "Suggested polling interval (milliseconds).",
@@ -2856,7 +2971,7 @@
           "type": "string"
         },
         "ttl": {
-          "description": "Retention window in milliseconds that the receiver agreed to honor.",
+          "description": "Retention window in milliseconds that the receiver agreed to honor.\n`None` (serialized as `null`) means unlimited retention.",
           "type": [
             "integer",
             "null"
@@ -2868,7 +2983,8 @@
       "required": [
         "taskId",
         "status",
-        "createdAt"
+        "createdAt",
+        "lastUpdatedAt"
       ]
     },
     "TaskRequestsCapability": {
@@ -2907,30 +3023,6 @@
         }
       }
     },
-    "TaskResult": {
-      "description": "Final result for a succeeded task (returned from `tasks/result`).",
-      "type": "object",
-      "properties": {
-        "contentType": {
-          "description": "MIME type or custom content-type identifier.",
-          "type": "string"
-        },
-        "summary": {
-          "description": "Optional short summary for UI surfaces.",
-          "type": [
-            "string",
-            "null"
-          ]
-        },
-        "value": {
-          "description": "The actual result payload, matching the underlying request's schema."
-        }
-      },
-      "required": [
-        "contentType",
-        "value"
-      ]
-    },
     "TaskStatus": {
       "description": "Canonical task lifecycle status as defined by SEP-1686.",
       "oneOf": [

crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema_current.json

@@ -407,6 +407,70 @@
         "content"
       ]
     },
+    "CancelTaskResult": {
+      "description": "Response to a `tasks/cancel` request.\n\nPer spec, `CancelTaskResult = allOf[Result, Task]` — same shape as `GetTaskResult`.",
+      "type": "object",
+      "properties": {
+        "_meta": {
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": true
+        },
+        "createdAt": {
+          "description": "ISO-8601 creation timestamp.",
+          "type": "string"
+        },
+        "lastUpdatedAt": {
+          "description": "ISO-8601 timestamp for the most recent status change.",
+          "type": "string"
+        },
+        "pollInterval": {
+          "description": "Suggested polling interval (milliseconds).",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
+        },
+        "status": {
+          "description": "Current lifecycle status (see [`TaskStatus`]).",
+          "allOf": [
+            {
+              "$ref": "#/definitions/TaskStatus"
+            }
+          ]
+        },
+        "statusMessage": {
+          "description": "Optional human-readable status message for UI surfaces.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "taskId": {
+          "description": "Unique task identifier generated by the receiver.",
+          "type": "string"
+        },
+        "ttl": {
+          "description": "Retention window in milliseconds that the receiver agreed to honor.\n`None` (serialized as `null`) means unlimited retention.",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
+        }
+      },
+      "required": [
+        "taskId",
+        "status",
+        "createdAt",
+        "lastUpdatedAt"
+      ]
+    },
     "CancelledNotificationMethod": {
       "type": "string",
       "format": "const",
@@ -937,21 +1001,72 @@
         "messages"
       ]
     },
-    "GetTaskInfoResult": {
+    "GetTaskPayloadResult": {
+      "description": "Response to a `tasks/result` request.\n\nPer spec, the result structure matches the original request type\n(e.g., `CallToolResult` for `tools/call`). This is represented as\nan open object. The payload is the original request's result\nserialized as a JSON value."
+    },
+    "GetTaskResult": {
+      "description": "Response to a `tasks/get` request.\n\nPer spec, `GetTaskResult = allOf[Result, Task]` — the Task fields are\nflattened at the top level, not nested under a `task` key.",
       "type": "object",
       "properties": {
-        "task": {
+        "_meta": {
-          "anyOf": [
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": true
+        },
+        "createdAt": {
+          "description": "ISO-8601 creation timestamp.",
+          "type": "string"
+        },
+        "lastUpdatedAt": {
+          "description": "ISO-8601 timestamp for the most recent status change.",
+          "type": "string"
+        },
+        "pollInterval": {
+          "description": "Suggested polling interval (milliseconds).",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
+        },
+        "status": {
+          "description": "Current lifecycle status (see [`TaskStatus`]).",
+          "allOf": [
             {
-              "$ref": "#/definitions/Task"
+              "$ref": "#/definitions/TaskStatus"
-            },
-            {
-              "type": "null"
             }
           ]
+        },
+        "statusMessage": {
+          "description": "Optional human-readable status message for UI surfaces.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "taskId": {
+          "description": "Unique task identifier generated by the receiver.",
+          "type": "string"
+        },
+        "ttl": {
+          "description": "Retention window in milliseconds that the receiver agreed to honor.\n`None` (serialized as `null`) means unlimited retention.",
+          "type": [
+            "integer",
+            "null"
+          ],
+          "format": "uint64",
+          "minimum": 0
         }
       },
-      "additionalProperties": false
+      "required": [
+        "taskId",
+        "status",
+        "createdAt",
+        "lastUpdatedAt"
+      ]
     },
     "Icon": {
       "description": "A URL pointing to an icon resource or a base64-encoded data URI.\n\nClients that support rendering icons MUST support at least the following MIME types:\n- image/png - PNG images (safe, universal compatibility)\n- image/jpeg (and image/jpg) - JPEG images (safe, universal compatibility)\n\nClients that support rendering icons SHOULD also support:\n- image/svg+xml - SVG images (scalable but requires security precautions)\n- image/webp - WebP images (modern, efficient format)",
@@ -2701,13 +2816,16 @@
           "$ref": "#/definitions/ListTasksResult"
         },
         {
-          "$ref": "#/definitions/GetTaskInfoResult"
+          "$ref": "#/definitions/GetTaskResult"
         },
         {
-          "$ref": "#/definitions/TaskResult"
+          "$ref": "#/definitions/CancelTaskResult"
         },
         {
           "$ref": "#/definitions/CustomResult"
+        },
+        {
+          "$ref": "#/definitions/GetTaskPayloadResult"
         }
       ]
     },
@@ -2813,7 +2931,7 @@
       "const": "string"
     },
     "Task": {
-      "description": "Primary Task object that surfaces metadata during the task lifecycle.",
+      "description": "Primary Task object that surfaces metadata during the task lifecycle.\n\nPer spec, `lastUpdatedAt` and `ttl` are required fields.\n`ttl` is nullable (`null` means unlimited retention).",
       "type": "object",
       "properties": {
         "createdAt": {
@@ -2822,10 +2940,7 @@
         },
         "lastUpdatedAt": {
           "description": "ISO-8601 timestamp for the most recent status change.",
-          "type": [
+          "type": "string"
-            "string",
-            "null"
-          ]
         },
         "pollInterval": {
           "description": "Suggested polling interval (milliseconds).",
@@ -2856,7 +2971,7 @@
           "type": "string"
         },
         "ttl": {
-          "description": "Retention window in milliseconds that the receiver agreed to honor.",
+          "description": "Retention window in milliseconds that the receiver agreed to honor.\n`None` (serialized as `null`) means unlimited retention.",
           "type": [
             "integer",
             "null"
@@ -2868,7 +2983,8 @@
       "required": [
         "taskId",
         "status",
-        "createdAt"
+        "createdAt",
+        "lastUpdatedAt"
       ]
     },
     "TaskRequestsCapability": {
@@ -2907,30 +3023,6 @@
         }
       }
     },
-    "TaskResult": {
-      "description": "Final result for a succeeded task (returned from `tasks/result`).",
-      "type": "object",
-      "properties": {
-        "contentType": {
-          "description": "MIME type or custom content-type identifier.",
-          "type": "string"
-        },
-        "summary": {
-          "description": "Optional short summary for UI surfaces.",
-          "type": [
-            "string",
-            "null"
-          ]
-        },
-        "value": {
-          "description": "The actual result payload, matching the underlying request's schema."
-        }
-      },
-      "required": [
-        "contentType",
-        "value"
-      ]
-    },
     "TaskStatus": {
       "description": "Canonical task lifecycle status as defined by SEP-1686.",
       "oneOf": [