diff --git a/tests/test_safety_plan_chat_header.py b/tests/test_safety_plan_chat_header.py
new file mode 100644
index 0000000..8d1e42f
--- /dev/null
+++ b/tests/test_safety_plan_chat_header.py
@@ -0,0 +1,19 @@
+from pathlib import Path
+
+INDEX = Path("index.html")
+
+
+def test_chat_header_has_persistent_safety_plan_button():
+    html = INDEX.read_text()
+    assert 'id="chat-header"' in html
+    assert 'id="chat-safety-plan-btn"' in html
+    assert 'aria-label="Open My Safety Plan from chat header"' in html
+    assert 'My Safety Plan' in html
+
+
+def test_chat_header_button_opens_existing_safety_plan_modal():
+    html = INDEX.read_text()
+    assert "var chatSafetyPlanBtn = document.getElementById('chat-safety-plan-btn');" in html
+    assert "chatSafetyPlanBtn.addEventListener('click'" in html
+    assert "safetyPlanModal.classList.add('active');" in html
+    assert "_activateSafetyPlanFocusTrap(chatSafetyPlanBtn);" in html