diff --git a/internal/tui/components/chat/messages/renderer.go b/internal/tui/components/chat/messages/renderer.go
index 11bb9f923456b6d16566d06951757e6be6ecbbf1..6bf3fbc3fa0c4fe6a6ba44d930bf3418696ea1d3 100644
--- a/internal/tui/components/chat/messages/renderer.go
+++ b/internal/tui/components/chat/messages/renderer.go
@@ -793,7 +793,10 @@ func escapeLine(t *styles.Theme, text string) string {
 		n     int
 		w     int
 	)
-	faint := t.S().Muted.Faint(true)
+	var faint lipgloss.Style
+	if t != nil {
+		faint = t.S().Muted.Faint(true)
+	}
 	for len(text) > 0 {
 		seq, w, n, state = ansi.DecodeSequence(text, state, nil)
 		if w > 0 {
diff --git a/internal/tui/components/chat/messages/renderer_test.go b/internal/tui/components/chat/messages/renderer_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..cc20ed711aa16ab1bd2ab8f462cd9ee33e58b005
--- /dev/null
+++ b/internal/tui/components/chat/messages/renderer_test.go
@@ -0,0 +1,52 @@
+package messages
+
+import (
+	"testing"
+)
+
+func TestEscapeContent(t *testing.T) {
+	cases := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "nothing to escape",
+			input:    "Hello, World!",
+			expected: "Hello, World!",
+		},
+		{
+			name:     "escape csi sequences",
+			input:    "\x1b[31mRed Text\x1b[0m",
+			expected: "\\x1b[31mRed Text\\x1b[0m",
+		},
+		{
+			name:     "escape control characters",
+			input:    "Hello\x00World\x7f!",
+			expected: "Hello\\x00World\\x7f!",
+		},
+		{
+			name:     "escape csi sequences with control characters",
+			input:    "\x1b[31mHello\x00World\x7f!\x1b[0m",
+			expected: "\\x1b[31mHello\\x00World\\x7f!\\x1b[0m",
+		},
+		{
+			name:     "just unicode",
+			input:    "こんにちは", // "Hello" in Japanese
+			expected: "こんにちは",
+		},
+		{
+			name:     "unicode with csi sequences and control characters",
+			input:    "\x1b[31mこんにちは\x00World\x7f!\x1b[0m",
+			expected: "\\x1b[31mこんにちは\\x00World\\x7f!\\x1b[0m",
+		},
+	}
+	for i, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			result := escapeContent(nil, c.input)
+			if result != c.expected {
+				t.Errorf("case %d, expected %q, got %q", i+1, c.expected, result)
+			}
+		})
+	}
+}