diff --git a/internal/ui/model.go b/internal/ui/model.go
index a9a870d4..0aff9862 100644
--- a/internal/ui/model.go
+++ b/internal/ui/model.go
@@ -1208,53 +1208,7 @@ func (m *AppModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.modelSelector = nil
 		m.state = stateInput
 		if m.setModel != nil {
-			previousModel := m.providerName + "/" + m.modelName
-
-			// Check if thinking level needs adjustment for the new model.
-			// Some models (e.g., OpenAI gpt-5.4) don't support "minimal" and require "none".
-			if m.thinkingLevel != "" && m.thinkingLevel != "off" {
-				parts := strings.SplitN(msg.ModelString, "/", 2)
-				if len(parts) == 2 {
-					modelName := parts[1]
-					currentLevel := models.ParseThinkingLevel(m.thinkingLevel)
-					if !models.IsValidThinkingLevelForModel(currentLevel, modelName) {
-						fallback := models.SuggestThinkingLevelFallback(currentLevel, modelName)
-						if fallback != models.ThinkingOff {
-							m.printSystemMessage(fmt.Sprintf(
-								"Note: Model %s doesn't support '%s' thinking level. Adjusted to '%s'.",
-								modelName, currentLevel, fallback,
-							))
-							m.thinkingLevel = string(fallback)
-							if m.setThinkingLevel != nil {
-								_ = m.setThinkingLevel(string(fallback))
-							}
-							go func() { _ = prefs.SaveThinkingLevelPreference(string(fallback)) }()
-						}
-					}
-				}
-			}
-
-			if err := m.setModel(msg.ModelString); err != nil {
-				m.printSystemMessage(fmt.Sprintf("Failed to switch model: %v", err))
-			} else {
-				// Update display state directly — we cannot use
-				// NotifyModelChanged (prog.Send) from inside Update()
-				// without deadlocking BubbleTea.
-				parts := strings.SplitN(msg.ModelString, "/", 2)
-				if len(parts) == 2 {
-					m.providerName = parts[0]
-					m.modelName = parts[1]
-				}
-				m.printSystemMessage(fmt.Sprintf("Switched to %s", msg.ModelString))
-				// Persist model selection for next launch.
-				go func() { _ = prefs.SaveModelPreference(msg.ModelString) }()
-				if m.emitModelChange != nil {
-					emit := m.emitModelChange
-					newModel := msg.ModelString
-					prev := previousModel
-					go emit(newModel, prev, "user")
-				}
-			}
+			m.switchModel(msg.ModelString)
 		}
 		return m, tea.Batch(cmds...)
 
@@ -4211,11 +4165,31 @@ func (m *AppModel) handleModelCommand(args string) tea.Cmd {
 		return nil
 	}
 
+	// Direct model switch with the provided model string.
+	m.switchModel(args)
+	return nil
+}
+
+// switchModel performs a direct model switch, shared by the model selector
+// overlay and the /model slash command: it adjusts the thinking level when
+// the new model doesn't support the current one, calls the setModel
+// callback, updates display state, persists preferences, and emits the
+// ModelChange extension event.
+//
+// Display state is updated directly — we cannot use NotifyModelChanged
+// (prog.Send) from inside Update() without deadlocking BubbleTea.
+func (m *AppModel) switchModel(modelString string) {
+	if m.setModel == nil {
+		m.printSystemMessage("Model switching is not available.")
+		return
+	}
+
+	previousModel := m.providerName + "/" + m.modelName
+
 	// Check if thinking level needs adjustment for the new model.
 	// Some models (e.g., OpenAI gpt-5.4) don't support "minimal" and require "none".
 	if m.thinkingLevel != "" && m.thinkingLevel != "off" {
-		parts := strings.SplitN(args, "/", 2)
-		if len(parts) == 2 {
+		if parts := strings.SplitN(modelString, "/", 2); len(parts) == 2 {
 			modelName := parts[1]
 			currentLevel := models.ParseThinkingLevel(m.thinkingLevel)
 			if !models.IsValidThinkingLevelForModel(currentLevel, modelName) {
@@ -4235,32 +4209,26 @@ func (m *AppModel) handleModelCommand(args string) tea.Cmd {
 		}
 	}
 
-	// Direct model switch with the provided model string.
-	previousModel := m.providerName + "/" + m.modelName
-	if err := m.setModel(args); err != nil {
+	if err := m.setModel(modelString); err != nil {
 		m.printSystemMessage(fmt.Sprintf("Failed to switch model: %v", err))
-		return nil
+		return
 	}
 
 	// Update display state directly (cannot use prog.Send from Update).
-	parts := strings.SplitN(args, "/", 2)
-	if len(parts) == 2 {
+	if parts := strings.SplitN(modelString, "/", 2); len(parts) == 2 {
 		m.providerName = parts[0]
 		m.modelName = parts[1]
 	}
 
-	if m.emitModelChange != nil {
-		emit := m.emitModelChange
-		prev := previousModel
-		newModel := args
-		go emit(newModel, prev, "user")
-	}
+	m.printSystemMessage(fmt.Sprintf("Switched to %s", modelString))
 
 	// Persist model selection for next launch.
-	go func() { _ = prefs.SaveModelPreference(args) }()
+	go func() { _ = prefs.SaveModelPreference(modelString) }()
 
-	m.printSystemMessage(fmt.Sprintf("Switched to %s", args))
-	return nil
+	if m.emitModelChange != nil {
+		emit := m.emitModelChange
+		go emit(modelString, previousModel, "user")
+	}
 }
 
 // --------------------------------------------------------------------------