diff --git a/internal/router/scenarios.go b/internal/router/scenarios.go
index d65c29e..126162d 100644
--- a/internal/router/scenarios.go
+++ b/internal/router/scenarios.go
@@ -185,20 +185,18 @@ func latestUserMessages(messages []MessageContent) []MessageContent {
 	return nil
 }
 
-// hasComplexPattern looks for complex operations that need more capable models.
-// This includes tool-based operations (executing functions, writing/editing files, etc.)
+// hasComplexPattern looks for truly complex or architectural operations that need
+// the most capable models.  It is intentionally narrow: common coding/debugging
+// tasks ("build", "debug", "create file", "bash") are NOT complex, because they
+// appear constantly in tool results and ordinary conversation and would otherwise
+// route every turn to the complex model.
 func hasComplexPattern(messages []MessageContent) bool {
 	complexKeywords := []string{
-		// Architectural
+		// Architectural / large-scale design
 		"architect", "architecture", "refactor", "redesign",
 		"complex", "difficult", "challenging",
 		"optimize", "performance", "efficiency",
 		"design pattern", "best practice",
-		"bug", "debug", "error", "exception", "stack trace",
-		// Tool-related keywords indicate complex operations
-		"execute", "run command", "bash", "shell",
-		"implement", "build", "create", "add feature",
-		"write to", "edit file", "create file",
 	}
 
 	for _, msg := range messages {
diff --git a/internal/router/scenarios_test.go b/internal/router/scenarios_test.go
index 9021df6..0f24ff4 100644
--- a/internal/router/scenarios_test.go
+++ b/internal/router/scenarios_test.go
@@ -195,15 +195,17 @@ func TestDetectScenario_LatestTextVisualIntentWithoutNewImageStaysNonVision(t *t
 	}
 }
 
-func TestDetectScenario_DebugWithoutVisualIntentStaysTextComplex(t *testing.T) {
+func TestDetectScenario_DebugWithoutVisualIntentStaysTextDefault(t *testing.T) {
+	// "debug" was removed from complexKeywords because tool_result content
+	// constantly contains it, routing every turn to complex by accident.
 	messages := []MessageContent{
 		{Role: "user", Content: "Cosa vedi?", HasImage: true, ImageHashes: []string{"img1"}},
 		{Role: "assistant", Content: "Vedo una schermata."},
 		{Role: "user", Content: "debug questo codice", HasImage: false},
 	}
 	result := DetectScenario(messages, 100, mockConfig())
-	if result.Scenario != ScenarioComplex {
-		t.Errorf("Expected ScenarioComplex, got %s", result.Scenario)
+	if result.Scenario != ScenarioDefault {
+		t.Errorf("Expected ScenarioDefault (debug is no longer a complex trigger), got %s", result.Scenario)
 	}
 }
 
@@ -230,8 +232,10 @@ func TestDetectScenario_VisionLongContextTakesPriorityOverVisionComplex(t *testi
 }
 
 func TestRouteForStreaming_VisionComplexKeepsVisionComplexScenario(t *testing.T) {
+	// "bug" was removed from complexKeywords; use a retained architectural
+	// keyword ("refactor") to exercise the vision_complex path.
 	messages := []MessageContent{
-		{Role: "user", Content: "Find the bug in this screenshot", HasImage: true},
+		{Role: "user", Content: "Refactor the code shown in this screenshot", HasImage: true},
 	}
 	result := RouteForStreaming(messages, 100, mockConfig())
 	if result.Scenario != ScenarioVisionComplex {