fix: remove redundant system reminder wrappers

crates/worker/src/feature/builtin/task/mod.rs

@@ -312,8 +312,7 @@ mod tests {
         let SystemItem::TaskReminder { body, .. } = &queued[0] else {
             panic!("unexpected system item: {:?}", queued[0]);
         };
-        assert_eq!(body.matches("<system-reminder>").count(), 1);
-        assert_eq!(body.matches("</system-reminder>").count(), 1);
+        assert!(body.starts_with("Current session steps are listed below."));
         assert!(body.contains("taskid 1"));
         assert!(body.contains("pending"));
         assert!(body.contains("keep going"));
@@ -338,19 +337,17 @@ mod tests {
             panic!("unexpected system item: {:?}", queued[0]);
         };
         assert_eq!(*source, SystemReminderSource::TaskInactivity);
-        assert_eq!(body.matches("<system-reminder>").count(), 1);
-        assert_eq!(body.matches("</system-reminder>").count(), 1);
+        assert!(body.starts_with("Current session steps are listed below."));
         assert!(body.contains("typed"));
     }
 
     #[test]
-    fn render_task_reminder_body_is_unwrapped_for_system_reminder_helper() {
+    fn render_task_reminder_body_is_plain_system_text() {
         let feature = TaskFeature::new();
         let task = feature.task_store().create("body".into(), String::new());
         let body = render_task_reminder_body(&[task]);
 
-        assert!(!body.contains("<system-reminder>"));
-        assert!(!body.contains("</system-reminder>"));
+        assert!(body.starts_with("Current session steps are listed below."));
         assert!(body.contains("TaskUpdate"));
         assert!(body.contains("taskid 1"));
     }

crates/worker/src/hook.rs

@@ -176,9 +176,7 @@ impl SystemItemAppendHandle {
 
     /// Queue a task-inactivity reminder for durable model-visible append.
     ///
-    /// The body should be the unwrapped reminder text; the host-side
-    /// `SystemReminder` renderer wraps it exactly once in `<system-reminder>`
-    /// tags before commit.
+    /// The body is committed verbatim as the typed item's system-message text.
     pub fn append_task_reminder(&self, body: impl Into<String>) {
         let item = SystemReminder::task_inactivity(body).into_system_item();
         self.pending
@@ -452,8 +450,7 @@ mod tests {
         assert_eq!(queued.len(), 1);
         match &queued[0] {
             SystemItem::TaskReminder { body, .. } => {
-                assert_eq!(body.matches("<system-reminder>").count(), 1);
-                assert!(body.contains("remember tasks"));
+                assert_eq!(body, "remember tasks");
             }
             other => panic!("unexpected system item: {other:?}"),
         }

crates/worker/src/ipc/notify_buffer.rs

@@ -12,8 +12,8 @@
 //!
 //! This is the **single lane** for "system messages produced by Worker
 //! state that should land in the next LLM request": Notify,
-//! agent-visible WorkerEvent variants, and any future `<system-reminder>`
-//! injection all ride this queue.
+//! agent-visible WorkerEvent variants, and any future typed system reminder
+//! insertion all ride this queue.
 //! Per `tickets/notify-history-persist.md` and `AGENTS.md` (LLM
 //! context の加工原則), there is **no** "transient, history-skipping"
 //! lane — everything injected into a request is also committed to