fix reminder tool issues: error on time overflow, optimize scheduler query

hive-c0re/src/broker.rs

@@ -253,6 +253,25 @@ impl Broker {
             .context("query reminders")
     }
 
+    /// Get all due reminders across all agents in a single query.
+    /// Returns a vec of (agent, id, message, file_path) tuples.
+    pub fn get_all_due_reminders(&self) -> Result<Vec<(String, i64, String, Option<String>)>> {
+        let conn = self.conn.lock().unwrap();
+        let mut stmt = conn.prepare(
+            "SELECT agent, id, message, file_path FROM reminders WHERE due_at <= ?1 AND sent_at IS NULL ORDER BY agent, due_at ASC"
+        )?;
+        let rows = stmt.query_map(params![now_unix()], |row| {
+            Ok((
+                row.get::<_, String>(0)?,
+                row.get::<_, i64>(1)?,
+                row.get::<_, String>(2)?,
+                row.get::<_, Option<String>>(3)?,
+            ))
+        })?;
+        rows.collect::<rusqlite::Result<Vec<_>>>()
+            .context("query all due reminders")
+    }
+
     /// Mark a reminder as sent (delivered).
     pub fn mark_reminder_sent(&self, id: i64) -> Result<()> {
         let conn = self.conn.lock().unwrap();