Restore motion threshold defaults

Treat nil, zero, and negative pixel-change thresholds as the historical default of 150, removing the disabled-motion behavior and adding configuration tests.

machinery/src/computervision/main.go

@@ -24,17 +24,12 @@ func ProcessMotion(motionCursor *packets.QueueCursor, configuration *models.Conf
 	var motionRectangle models.MotionRectangle
 	var motionRectangles []models.MotionRectangle
 
-	// Resolve the motion sensitivity (pixel-change threshold):
-	//   nil (unset) -> default 150
-	//   0           -> motion detection DISABLED (temporary off switch from the UI)
-	//   > 0         -> trigger when the number of changed pixels exceeds it
+	// Resolve the motion sensitivity (pixel-change threshold). Nil, zero, and
+	// negative values use the historical default so older configurations keep
+	// recording after an upgrade.
 	pixelThreshold := 150
-	motionDisabled := false
-	if config.Capture.PixelChangeThreshold != nil {
+	if config.Capture.PixelChangeThreshold != nil && *config.Capture.PixelChangeThreshold > 0 {
 		pixelThreshold = *config.Capture.PixelChangeThreshold
-		if pixelThreshold <= 0 {
-			motionDisabled = true
-		}
 	}
 	// In motion mode we always run detection. In CONTINUOUS mode recording is
 	// 24/7 so motion detection is normally skipped, BUT if a motion region is
@@ -45,11 +40,7 @@ func ProcessMotion(motionCursor *packets.QueueCursor, configuration *models.Conf
 	continuousMode := config.Capture.Continuous == "true"
 	hasMotionRegion := config.Region != nil && len(config.Region.Polygon) > 0
 
-	if motionDisabled {
-
-		log.Log.Warning("computervision.main.ProcessMotion(): motion detection is DISABLED because pixelChangeThreshold is set to 0 or less (nil/unset would default to 150). If motion detection is expected to be running, set capture.pixelChangeThreshold to a positive value (150 recommended) or AGENT_CAPTURE_PIXEL_CHANGE, then restart/update the agent.")
-
-	} else if continuousMode && !hasMotionRegion {
+	if continuousMode && !hasMotionRegion {
 
 		log.Log.Info("computervision.main.ProcessMotion(): continuous recording enabled and no motion region configured, so no motion detection required.")
 
@@ -236,9 +227,9 @@ func ProcessMotion(motionCursor *packets.QueueCursor, configuration *models.Conf
 													// a reference square of sqrt(threshold) px (in this MOTION
 													// frame's pixel space) so the user can visually gauge how
 													// large a moving object must be before it is detected.
-												"pixelChangeThreshold": pixelThreshold,
+													"pixelChangeThreshold": pixelThreshold,
+												},
 											},
-										},
 										}
 										payload, err := models.PackageMQTTMessage(configuration, message)
 										if err == nil {

machinery/src/config/main.go

@@ -651,13 +651,12 @@ func applyAgentEnvVars(configuration *models.Configuration, prefix string, apply
 		}
 	}
 
-	// Motion sensitivity: nil/unset must still resolve to the default (150), not
-	// be left nil. An explicit 0 (temporary "disable motion detection" switch
-	// from the UI) is a real, non-nil value and must NOT be touched here. Only
-	// applied for the effective configuration (applyDefaults), not for the
-	// separate global/custom views, so a missing value in one layer can still be
-	// inherited from the other instead of being masked by this default.
-	if applyDefaults && configuration.Config.Capture.PixelChangeThreshold == nil {
+	// Motion sensitivity historically used 0 to mean "use the default". Preserve
+	// that behaviour for configurations created before this field became a
+	// pointer, and also recover invalid negative values. Only apply this to the
+	// effective configuration so missing values can still be inherited between
+	// the separate global and custom layers.
+	if applyDefaults && (configuration.Config.Capture.PixelChangeThreshold == nil || *configuration.Config.Capture.PixelChangeThreshold <= 0) {
 		defaultPixelChangeThreshold := 150
 		configuration.Config.Capture.PixelChangeThreshold = &defaultPixelChangeThreshold
 	}

machinery/src/config/main_test.go

@@ -0,0 +1,40 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/kerberos-io/agent/machinery/src/models"
+)
+
+func TestApplyAgentEnvVarsPixelChangeThresholdDefault(t *testing.T) {
+	tests := []struct {
+		name      string
+		threshold *int
+		want      int
+	}{
+		{name: "missing", want: 150},
+		{name: "legacy zero", threshold: intPointer(0), want: 150},
+		{name: "negative", threshold: intPointer(-1), want: 150},
+		{name: "positive", threshold: intPointer(275), want: 275},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			configuration := &models.Configuration{}
+			configuration.Config.Capture.PixelChangeThreshold = test.threshold
+
+			applyAgentEnvVars(configuration, "TEST_", true)
+
+			if configuration.Config.Capture.PixelChangeThreshold == nil {
+				t.Fatal("PixelChangeThreshold is nil after applying defaults")
+			}
+			if got := *configuration.Config.Capture.PixelChangeThreshold; got != test.want {
+				t.Fatalf("PixelChangeThreshold = %d, want %d", got, test.want)
+			}
+		})
+	}
+}
+
+func intPointer(value int) *int {
+	return &value
+}