test(workout): prove skipped exercise recovery

Cover skip-and-undo as a recoverable workout mistake so the product recovery surface is guarded alongside invalid input, edit-last-set, host failures, and replay failures.

req: examples/001

req: local/001

req: local/004

examples/workout/src/lib.rs

@@ -1137,6 +1137,39 @@ mod tests {
         assert_eq!(app.with_workout(|state| state.plan[0].kg), 24.0);
     }
 
+    #[test]
+    fn skipped_exercise_recovers_through_undo() {
+        // req: examples/001 req: local/001 req: local/004
+        let app = AppState::demo();
+
+        let skipped = run(|()| skip_exercise(app.clone()), ());
+        assert!(contains_payload_text(&skipped, "skipped Goblet squat"));
+        assert!(contains_payload_text(&skipped, "Next: Push-up set 1/2"));
+        assert_eq!(
+            app.with_workout(|state| (
+                state.events.len(),
+                state.projection.current_exercise,
+                state.projection.phase.clone(),
+            )),
+            (1, 1, WorkoutPhase::Ready)
+        );
+
+        let undone = run(|()| undo_last_action(app.clone()), ());
+        assert!(contains_payload_text(
+            &undone,
+            "Undid: skipped Goblet squat"
+        ));
+        assert!(contains_payload_text(&undone, "Next: Goblet squat set 1/3"));
+        assert_eq!(
+            app.with_workout(|state| (
+                state.events.len(),
+                state.projection.current_exercise,
+                state.projection.phase.clone(),
+            )),
+            (0, 0, WorkoutPhase::Ready)
+        );
+    }
+
     #[test]
     fn undo_recovers_last_session_action() {
         // req: examples/001 req: local/001 req: local/004