diff --git a/cmd/sidekick-tui/tui_test.go b/cmd/sidekick-tui/tui_test.go
index a4dd884..8e75480 100644
--- a/cmd/sidekick-tui/tui_test.go
+++ b/cmd/sidekick-tui/tui_test.go
@@ -6,6 +6,7 @@ import (
 
   "github.com/charmbracelet/bubbles/viewport"
   tea "github.com/charmbracelet/bubbletea"
+  "sidekick"
 )
 
 // Since sidekick-tui/main.go uses global variables and is a tea.Model,
@@ -87,3 +88,48 @@ func TestMessageWrapping(t *testing.T) {
     t.Errorf("expected long message to be wrapped, but no newline found in viewport")
   }
 }
+
+func TestHistoryNavigation(t *testing.T) {
+  m := initialModel()
+  m.ready = true
+  m.history = append(m.history, sidekick.Message{Role: sidekick.MessageRoleUser, Content: "First"})
+  m.history = append(m.history, sidekick.Message{Role: sidekick.MessageRoleAssistant, Content: "AI Response"})
+  m.history = append(m.history, sidekick.Message{Role: sidekick.MessageRoleUser, Content: "Second"})
+
+  // Test UP from empty draft
+  m2, _ := m.Update(tea.KeyMsg{Type: tea.KeyUp})
+  tm2 := m2.(model)
+  if tm2.textarea.Value() != "Second" {
+    t.Errorf("expected 'Second', got '%s'", tm2.textarea.Value())
+  }
+  if tm2.historyIndex != 1 {
+    t.Errorf("expected historyIndex 1, got %d", tm2.historyIndex)
+  }
+
+  // Test UP again
+  m3, _ := tm2.Update(tea.KeyMsg{Type: tea.KeyUp})
+  tm3 := m3.(model)
+  if tm3.textarea.Value() != "First" {
+    t.Errorf("expected 'First', got '%s'", tm3.textarea.Value())
+  }
+  if tm3.historyIndex != 0 {
+    t.Errorf("expected historyIndex 0, got %d", tm3.historyIndex)
+  }
+
+  // Test DOWN
+  m4, _ := tm3.Update(tea.KeyMsg{Type: tea.KeyDown})
+  tm4 := m4.(model)
+  if tm4.textarea.Value() != "Second" {
+    t.Errorf("expected 'Second', got '%s'", tm4.textarea.Value())
+  }
+
+  // Test DOWN to draft
+  m5, _ := tm4.Update(tea.KeyMsg{Type: tea.KeyDown})
+  tm5 := m5.(model)
+  if tm5.textarea.Value() != "" {
+    t.Errorf("expected empty draft, got '%s'", tm5.textarea.Value())
+  }
+  if tm5.historyIndex != -1 {
+    t.Error("expected historyIndex to reset to -1")
+  }
+}