From d9b8f65d7cc563ce8fb57f6b3695e264caa3dc03 Mon Sep 17 00:00:00 2001
From: Marco Arnulfo <marcoarnulfo1@gmail.com>
Date: Mon, 12 Oct 2026 13:23:06 +0200
Subject: [PATCH] Render Queue: the failure toast says why the render failed
 (#568)

---
 crates/engine/src/render_queue.rs | 13 ++++++++++---
 crates/engine/src/rq_tests.rs     | 26 +++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/crates/engine/src/render_queue.rs b/crates/engine/src/render_queue.rs
index aae05a38..56754e7c 100644
--- a/crates/engine/src/render_queue.rs
+++ b/crates/engine/src/render_queue.rs
@@ -610,10 +610,17 @@ impl Session {
                 let _ = t.join();
             }
             let st = job.shared.snapshot();
-            let failed = updates.iter().filter(|u| matches!(u, ItemUpdate::Finished { status: RenderStatus::Failed(_), .. })).count();
+            let failures: Vec<&str> = updates
+                .iter()
+                .filter_map(|u| if let ItemUpdate::Finished { status: RenderStatus::Failed(e), .. } = u { Some(e.as_str()) } else { None })
+                .collect();
+            let failed = failures.len();
             let stopped = updates.iter().any(|u| matches!(u, ItemUpdate::Finished { status: RenderStatus::UserStopped, .. }));
-            let msg = if failed > 0 {
-                format!("Render finished with {failed} failed item(s)")
+            // The reason is otherwise only in the Status column's tooltip (#568).
+            let msg = if let [only] = failures.as_slice() {
+                format!("Render finished with 1 failed item(s): {only}")
+            } else if let Some(first) = failures.first() {
+                format!("Render finished with {failed} failed item(s), first: {first}")
             } else if stopped {
                 "Render stopped".to_string()
             } else {
diff --git a/crates/engine/src/rq_tests.rs b/crates/engine/src/rq_tests.rs
index 88c7a6e8..81a18722 100644
--- a/crates/engine/src/rq_tests.rs
+++ b/crates/engine/src/rq_tests.rs
@@ -87,7 +87,9 @@ fn add_configure_render() {
     assert_eq!(std::path::Path::new(q[0].last_output.as_deref().unwrap()), std::path::PathBuf::from(crate::tests_stubs::tmp_out("rq/out.mov")));
     assert_eq!(q[1].status, RenderStatus::Failed("boom".into()));
     assert_eq!(q[2].status.label(), "Unqueued");
-    assert!(s.drain_events().iter().any(|e| matches!(e, Event::Toast { error: true, .. })));
+    let events = s.drain_events();
+    let toast = events.iter().find_map(|e| if let Event::Toast { message, error: true } = e { Some(message.as_str()) } else { None });
+    assert_eq!(toast, Some("Render finished with 1 failed item(s): boom"), "the toast says why (#568)");
     // Reorder, duplicate, remove, undo.
     s.execute("renderQueue.move", json!({"item": b["item"], "to": 1})).unwrap();
     assert_eq!(s.project.render_queue[0].id, b["item"].as_u64().unwrap());
@@ -114,6 +116,28 @@ fn persists_in_project_file() {
     assert!(effectcraft_project::Project::from_json(&old).unwrap().render_queue.is_empty());
 }
 
+#[test]
+fn failure_toast_names_the_first_reason() {
+    struct Failing;
+    impl Exporter for Failing {
+        fn formats(&self) -> Vec<OutputFormat> {
+            OutputFormat::ALL.to_vec()
+        }
+        fn export(&self, job: &ExportJob, _: &mut dyn FnMut(u64, u64) -> bool) -> Result<ExportResult, String> {
+            let name = std::path::Path::new(job.path).file_name().unwrap().to_string_lossy().into_owned();
+            Err(format!("cannot write {name}"))
+        }
+    }
+    let mut s = demo();
+    s.exporter = Some(Arc::new(Failing));
+    s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests_stubs::tmp_out("rq/first.gif")})).unwrap();
+    s.execute("renderQueue.add", json!({"format": "gif", "output": crate::tests_stubs::tmp_out("rq/second.gif")})).unwrap();
+    s.execute("renderQueue.render", json!({})).unwrap();
+    let events = s.drain_events();
+    let toast = events.iter().find_map(|e| if let Event::Toast { message, error: true } = e { Some(message.as_str()) } else { None });
+    assert_eq!(toast, Some("Render finished with 2 failed item(s), first: cannot write first.gif"));
+}
+
 #[test]
 fn background_render_and_stop() {
     struct Slow;