coordinator: push_todo returns Result so callers can see delivery outcome

hive-c0re/src/coordinator.rs

@@ -1387,6 +1387,14 @@ impl Coordinator {
     /// delivery. An agent that's down doesn't need a todo about
     /// something it'll never see appear this way; whatever mechanism
     /// resurfaces its state on the next boot is unrelated to this path.
+    ///
+    /// Returns `Ok(())` on a successful push and `Err(reason)` — a
+    /// short human-readable string, already logged at `debug`/`warn`
+    /// by this function — on any of the silent-no-op cases below.
+    /// Most callers are pure fire-and-forget notices and ignore it
+    /// (`let _ = coord.push_todo(...).await;`); callers that track a
+    /// per-target delivery outcome (e.g. the scheduled-prompts worker's
+    /// `last_result` column) use it instead of assuming success.
     pub async fn push_todo(
         &self,
         agent: &str,
@@ -1394,15 +1402,15 @@ impl Coordinator {
         key: Option<String>,
         summary: String,
         source: Option<String>,
-    ) {
+    ) -> Result<(), String> {
         let Ok(ident) = hive_types::Ident::parse(agent) else {
             tracing::warn!(%agent, "push_todo: not a valid agent ident, skipping");
-            return;
+            return Err(format!("'{agent}' is not a valid agent ident"));
         };
         let path = hive_host_sock::agent_todo_socket(&ident);
         if !path.exists() {
             tracing::debug!(%agent, path = %path.display(), "push_todo: agent socket not present (offline?), skipping");
-            return;
+            return Err(format!("agent '{agent}' socket not present (offline?)"));
         }
         let req = hive_agent_sock::Request::UpsertTodo {
             subsystem: subsystem.to_owned(),
@@ -1419,11 +1427,13 @@ impl Coordinator {
         {
             Ok(hive_agent_sock::Response::Err { message }) => {
                 tracing::warn!(%agent, %message, "push_todo: agent rejected the todo");
+                Err(format!("agent '{agent}' rejected the todo: {message}"))
             }
             Err(e) => {
                 tracing::warn!(%agent, error = ?e, "push_todo: dial failed");
+                Err(format!("push_todo dial to '{agent}' failed: {e:#}"))
             }
-            Ok(_) => {}
+            Ok(_) => Ok(()),
         }
     }
 
@@ -1436,10 +1446,10 @@ impl Coordinator {
         key: Option<String>,
         summary: String,
         source: Option<String>,
-    ) {
+    ) -> Result<(), String> {
         let target = self.submitter_or_manager(approval_id);
         self.push_todo(&target, subsystem, key, summary, source)
-            .await;
+            .await
     }
 
     /// Push a `HelperEvent` into an arbitrary agent's inbox. Encoded