reminder: add sqlite storage + broker methods + dispatch

hive-c0re/src/agent_server.rs

@@ -193,10 +193,28 @@ async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) ->
             timing,
             file_path,
         } => {
-            // TODO: submit to reminder scheduler
-            // For now, return a stub response
-            AgentResponse::Err {
-                message: "remind not yet implemented".to_owned(),
+            use hive_sh4re::ReminderTiming;
+            let due_at = match timing {
+                ReminderTiming::InSeconds { seconds } => {
+                    std::time::SystemTime::now()
+                        .checked_add(std::time::Duration::from_secs(*seconds))
+                        .and_then(|t| {
+                            t.duration_since(std::time::UNIX_EPOCH)
+                                .ok()
+                                .and_then(|d| i64::try_from(d.as_secs()).ok())
+                        })
+                        .unwrap_or(0)
+                }
+                ReminderTiming::At { unix_timestamp } => *unix_timestamp,
+            };
+            match broker.store_reminder(agent, message, file_path.as_deref(), due_at) {
+                Ok(id) => {
+                    tracing::info!(%id, %agent, %due_at, "reminder scheduled");
+                    AgentResponse::Ok
+                }
+                Err(e) => AgentResponse::Err {
+                    message: format!("failed to store reminder: {e:#}"),
+                },
             }
         }
     }