#1743: check final storage overflow destinations for queued outputs

crates/engine/src/render_queue.rs

@@ -59,7 +59,8 @@ pub trait Exporter: Send + Sync {
     fn formats(&self) -> Vec<OutputFormat>;
     /// Whether Skip Existing Files preserves sequence frames written by earlier items. Exporters
     /// without an existence check (such as memory sinks) must keep the conservative default.
-    fn supports_skip_existing(&self) -> bool {
+    /// The check must cover the final destination for these settings, including any overflow.
+    fn supports_skip_existing(&self, _settings: &effectcraft_project::render_queue::RenderSettings) -> bool {
         false
     }
     /// Render and write one item (blocking). `progress(done, total)` returns `false` to cancel;
@@ -500,7 +501,7 @@ impl Session {
         let refused = self.check_outputs(&items);
         // Two outputs of this job on one file: the render would replace its own output, so it is
         // refused before anything is written (the items refused above take no part).
-        if let Some(refusal) = crate::output_guard::duplicate_refusal(&self.duplicate_outputs(&items, &refused)) {
+        if let Some(refusal) = crate::output_guard::duplicate_refusal(&self.duplicate_outputs(&items, &refused)?) {
             return Err(refusal);
         }
         items.retain(|modules| modules.first().is_none_or(|(it, _)| !refused.iter().any(|r| r.item == it.id)));