1 files changed, 33 insertions, 8 deletions

diff --git a/crates/dinggerd/src/watcher.rs b/crates/dinggerd/src/watcher.rs
index aee8d5e..9bad1fe 100644
--- a/crates/dinggerd/src/watcher.rs
+++ b/crates/dinggerd/src/watcher.rs
@@ -29,6 +29,7 @@
 //! - `@dingger_draft` the draft in the agent's input box, as one line
 //! - `@dingger_cost`  what the agent's session spent today (see `cost`)
 //! - `@dingger_context` how full its context window is, in whole percent
+//! - `@dingger_error`  why its run failed, while it is done (unseen)
 
 use std::collections::HashMap;
 
@@ -375,7 +376,15 @@ impl Watcher {
             // Apply every observation in order: a turn that started and
             // finished between two ticks is still a completion.
             let mut alerts = Vec::new();
+            // Why its last run failed: kept while it is done.
+            let mut error = pane.written_error.clone();
             for observed in observations {
+                if observed.state != AgentState::Idle {
+                    error.clear();
+                }
+                if observed.failed {
+                    error = hooks::error(&pane.pane_id).unwrap_or_else(|| "error".into());
+                }
                 let mut next = advance(track, observed.state, pane.attended, acked, now);
                 // A cancelled run did not finish: idle, as if seen.
                 if observed.cancelled && next.state == AgentState::Idle {
@@ -392,7 +401,12 @@ impl Watcher {
                     // Notify on transitions observed by this process, not
                     // when resuming from options written before a restart.
                     if !restored && !observed.cancelled {
-                        alerts.extend(notification_kind_for_transition(track.state, next.state));
+                        alerts.extend(notification_kind_for_transition(track.state, next.state).map(|kind| {
+                            match kind {
+                                NotificationKind::Finished if observed.failed => NotificationKind::Failed,
+                                kind => kind,
+                            }
+                        }));
                     }
                 }
                 track = next;
@@ -408,14 +422,18 @@ impl Watcher {
                 track = next;
             }
             self.tracks.insert(pane.pane_id.clone(), track);
+            // Seen, a new run, or gone: the failure is no longer news.
+            if track.status() != Status::Done {
+                error.clear();
+            }
 
             // Update what the user sees first, then alert.
             if acked {
                 let _ = tmux::unset_pane_option(&pane.pane_id, "@dingger_ack");
             }
-            self.write_pane_options(pane, track);
+            self.write_pane_options(pane, track, &error);
             for kind in alerts {
-                self.notify(pane, kind);
+                self.notify(pane, kind, &error);
             }
         }
 
@@ -465,7 +483,7 @@ impl Watcher {
     /// Write the pane's options that changed, in one tmux command list:
     /// tmux applies it as a unit, so a daemon killed mid-write never leaves
     /// a display state that disagrees with the hook state it came from.
-    fn write_pane_options(&self, pane: &tmux::Pane, track: PaneTrack) {
+    fn write_pane_options(&self, pane: &tmux::Pane, track: PaneTrack, error: &str) {
         let mut changes: Vec<(&str, Option<String>)> = Vec::new();
         let mut change = |name: &'static str, written: &str, value: String| {
             if written != value {
@@ -483,6 +501,7 @@ impl Watcher {
         }
         change("@agent_state", &pane.written_state, track.status().label().to_string());
         change("@dingger_since", &pane.written_since, track.since.map(|s| s.to_string()).unwrap_or_default());
+        change("@dingger_error", &pane.written_error, error.to_string());
         change("@agent", &pane.written_agent, pane.agent.map(detect_core::agent_label).unwrap_or("").to_string());
         let name = crate::names::display_name(pane.agent, &pane.pane_title, &pane.cwd, host_name())
             .unwrap_or_default();
@@ -544,16 +563,22 @@ impl Watcher {
         }
     }
 
-    fn notify(&self, pane: &tmux::Pane, kind: NotificationKind) {
+    fn notify(&self, pane: &tmux::Pane, kind: NotificationKind, error: &str) {
         // herdr: a blocked pane plays the alert even when the user is looking
-        // at it; a finished pane stays silent when they already are.
+        // at it; a finished (or failed) pane stays silent when they already
+        // are.
         let watching = pane.attended;
-        if matches!(kind, NotificationKind::Finished) && watching {
+        if matches!(kind, NotificationKind::Finished | NotificationKind::Failed) && watching {
             return;
         }
         let agent = pane.agent.map(detect_core::agent_label).unwrap_or("agent");
         if self.notifications && !watching {
-            send_notification(agent, &kind, &format!("{} ({agent})", pane.display_target));
+            let mut context = format!("{} ({agent})", pane.display_target);
+            if matches!(kind, NotificationKind::Failed) && !error.is_empty() {
+                context.push_str(": ");
+                context.push_str(error);
+            }
+            send_notification(agent, &kind, &context);
         }
         // A low agent makes no sound; it still notifies and waits in line.
         if self.sounds && importance_of(pane) != Importance::Low {