A fill aimed entirely outside its object is an error, and the test says so

TestFillRegionOutsideObjectPlantsNothing pinned the old silent success;
the #127 review asked for the error, and the agent is the caller it helps.

Co-Authored-By: Claude Fable 5 <[email protected]>

internal/service/ops_test.go

@@ -212,10 +212,13 @@ func TestFillRegionRejectsNonFiniteRegion(t *testing.T) {
 	}
 }
 
-// TestFillRegionOutsideObjectPlantsNothing covers a region that misses the object
+// TestFillRegionOutsideObjectIsRefused covers a region that misses the object
-// entirely. clampTo inverts such a region rather than emptying it, and an
+// entirely. clampTo inverts such a region rather than emptying it; it used to
-// inverted region must plant nothing — not one plop at some point off the bed.
+// plant nothing and report success, which read as "done" to a caller that had
-func TestFillRegionOutsideObjectPlantsNothing(t *testing.T) {
+// aimed at the wrong coordinates — the agent, mixing up the garden frame and
+// the bed's local one. Now it is an error, and still never one plop at some
+// point off the bed.
+func TestFillRegionOutsideObjectIsRefused(t *testing.T) {
 	ctx := context.Background()
 	s := newTestService(t, openConfig())
 	owner := seedUser(t, s, "[email protected]")
@@ -225,12 +228,15 @@ func TestFillRegionOutsideObjectPlantsNothing(t *testing.T) {
 
 	// Wholly east of the bed: clampTo gives MinX=500, MaxX=50.
 	created, err := s.FillRegion(ctx, owner, bed.ID, rect(500, -50, 600, 50), plant.ID, nil, FillClump, nil)
-	if err != nil {
+	if !errors.Is(err, domain.ErrInvalidInput) {
-		t.Fatalf("FillRegion: %v", err)
+		t.Errorf("FillRegion outside the bed: err = %v, want ErrInvalidInput", err)
 	}
 	if len(created) != 0 {
 		t.Errorf("filled %d plops for a region outside the bed, want 0: %+v", len(created), created)
 	}
+	if full, _ := s.GardenFull(ctx, owner, g.ID, nil); len(full.Plantings) != 0 {
+		t.Errorf("the bed holds %d plops after a refused fill", len(full.Plantings))
+	}
 }
 
 // seedFillBed makes a plantable bed of the given size centered in a big garden.