Work area: an edit never clamps with crossed bounds (#605 follow-up)

A project saved with an inverted work area, or a comp shorter than a
frame, made Tick::clamp panic on the next start or end edit.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01QiAJeFttZp83Fh7YuzAR5f

crates/engine/src/commands/comp.rs

@@ -182,10 +182,11 @@ fn work_area(s: &mut Session, p: &Value) -> Result<Value> {
             _ => {}
         }
         if let Some(b) = begin {
-            c.work_area.0 = b.clamp(Tick::ZERO, c.duration - fd);
+            // min/max, not clamp: the bounds cross on a comp shorter than a frame or an inverted area.
+            c.work_area.0 = b.min(c.duration - fd).max(Tick::ZERO);
         }
         if let Some(e) = end {
-            c.work_area.1 = e.clamp(c.work_area.0 + fd, c.duration);
+            c.work_area.1 = e.max(c.work_area.0 + fd).min(c.duration);
         }
         // A start on its own can land after the current end. Pull it back so the interval
         // still covers one frame, the same rule as `set: "begin"`.

crates/engine/src/tests_menu_cmds.rs

@@ -196,6 +196,7 @@ fn separated_position_follows_canvas_resize_and_crop() {
     placed(&separated, b, 1.0, 50.0, 30.0);
     assert_eq!(opaque_bounds(&separated, Tick::ZERO), (70, 70, 25, 25, 34, 34, 100));
     assert_eq!(opaque_bounds(&separated, Tick::from_seconds_f64(1.0)), (70, 70, 45, 25, 54, 34, 100));
+}
 
 /// Pixel-centre of the opaque samples, so a 10×10 solid centred on (11, 22) reports (11, 22).
 fn opaque_centroid(s: &Session) -> (f64, f64, u32) {
@@ -399,6 +400,19 @@ fn lift_and_extract_work_area() {
     assert!((spans[1].0 - 2.0).abs() < 1e-6 && (spans[1].1 - 8.0).abs() < 1e-6, "{spans:?}");
 }
 
+/// A project saved with an inverted work area (by an older build) is edited without a panic:
+/// `clamp` with crossed bounds would abort.
+#[test]
+fn an_inverted_saved_work_area_takes_an_end_edit() {
+    let mut s = comp();
+    let cid = s.active_comp_id().unwrap();
+    std::sync::Arc::make_mut(&mut s.project).comp_mut(cid).unwrap().work_area = (Tick::from_seconds_f64(9.0), Tick::from_seconds_f64(2.0));
+    s.execute("comp.workArea", json!({"end": 1.0})).unwrap();
+    s.execute("comp.workArea", json!({"start": 50.0})).unwrap();
+    let c = s.active_comp().unwrap();
+    assert!(c.work_area.0 >= Tick::ZERO && c.work_area.0 + c.frame_duration() <= c.work_area.1 && c.work_area.1 <= c.duration);
+}
+
 #[test]
 fn work_area_stays_ordered_when_the_start_passes_the_end() {
     let ordered = |s: &Session| {