Verify deterministic movement from observations

Co-authored-by: codegirl007 <codegirl-007@users.noreply.github.com>

agentbox/internal/agent/deterministic_test.go

@@ -1,7 +1,11 @@
 package agent
 
 import (
+	"bytes"
 	"context"
+	"image"
+	"image/color"
+	"image/png"
 	"testing"
 
 	"agentbox/internal/environment"
@@ -19,7 +23,13 @@ func TestDeterministicSequence(t *testing.T) {
 		{"", true},
 	}
 	for index, expected := range want {
-		decision, err := controller.NextAction(context.Background(), "", nil, Observation{})
+		x := 20
+		if index >= 2 {
+			x = 140
+		}
+		decision, err := controller.NextAction(context.Background(), "", nil, Observation{
+			Screenshot: screenshotWithSquare(t, x),
+		})
 		if err != nil {
 			t.Fatalf("step %d: %v", index, err)
 		}
@@ -31,3 +41,35 @@ func TestDeterministicSequence(t *testing.T) {
 		}
 	}
 }
+
+func TestDeterministicRejectsMissingMovement(t *testing.T) {
+	controller := &Deterministic{}
+	for step := 0; step < 2; step++ {
+		if _, err := controller.NextAction(context.Background(), "", nil, Observation{
+			Screenshot: screenshotWithSquare(t, 20),
+		}); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if _, err := controller.NextAction(context.Background(), "", nil, Observation{
+		Screenshot: screenshotWithSquare(t, 20),
+	}); err == nil {
+		t.Fatal("movement verification error = nil")
+	}
+}
+
+func screenshotWithSquare(t *testing.T, startX int) []byte {
+	t.Helper()
+	img := image.NewRGBA(image.Rect(0, 0, 240, 100))
+	green := color.RGBA{G: 255, B: 102, A: 255}
+	for y := 20; y < 60; y++ {
+		for x := startX; x < startX+40; x++ {
+			img.Set(x, y, green)
+		}
+	}
+	var output bytes.Buffer
+	if err := png.Encode(&output, img); err != nil {
+		t.Fatal(err)
+	}
+	return output.Bytes()
+}