[planner] early exit if rotation doesn't match

masque/builder/planner/planner.py

@@ -857,6 +857,22 @@ class Solver:
             return False
         return self.request.out_ptype is None or ptypes_compatible(end_port.ptype, self.request.out_ptype)
 
+    def rotation_matches_request(self, steps: Sequence[SelectedPrimitive]) -> bool:
+        """
+        Return true when a sequence can produce the requested output rotation.
+
+        Primitive parameters do not affect the rotation contract, so
+        rotation-impossible candidates can be rejected before parameter solving.
+        """
+        angle = 0.0
+        for step in steps:
+            step_rotation = step.out_port.rotation
+            if step_rotation is None:
+                raise BuildError('Primitive endpoints must have rotation')
+            angle += float(step_rotation) + pi
+        rotation_delta = ((angle - pi) - self.request.out_rotation) % (2 * pi)
+        return is_close(rotation_delta, 0) or is_close(rotation_delta, 2 * pi)
+
     def finalize(self, steps: Sequence[SelectedPrimitive]) -> Candidate:
         """
         Try all small solve sets for one raw sequence and return the first match.
@@ -874,6 +890,8 @@ class Solver:
                 raise BuildError(f'{self.request.route_name} route requires a jog constraint')
             constraints.append(('y', float(self.request.jog)))
         route_constraints = tuple(constraints)
+        if not self.rotation_matches_request(steps):
+            raise BuildError(f'{self.request.route_name} composed primitive route is unsupported')
         adjustable = self.adjustable_indices(steps)
         solve_sets: list[tuple[int, ...]] = [()]
         max_solve = min(len(route_constraints), len(adjustable))