diff --git a/phone_agent/actions/handler.py b/phone_agent/actions/handler.py
index 0bef1c3a2..d7932b4cc 100644
--- a/phone_agent/actions/handler.py
+++ b/phone_agent/actions/handler.py
@@ -223,10 +223,22 @@ def _handle_long_press(self, action: dict, width: int, height: int) -> ActionRes
 
     def _handle_wait(self, action: dict, width: int, height: int) -> ActionResult:
         """Handle wait action."""
-        duration_str = action.get("duration", "1 seconds")
+        duration_raw = action.get("duration", "1 seconds")
         try:
-            duration = float(duration_str.replace("seconds", "").strip())
-        except ValueError:
+            # The model normally emits a string such as "3 seconds", but some
+            # models (or non-standard prompts) return a bare int/float instead.
+            # Calling ``.replace`` on a number raises ``AttributeError``, which
+            # the previous ``except ValueError`` did not catch, so the wait
+            # silently failed. Handle both forms explicitly.
+            if isinstance(duration_raw, (int, float)):
+                duration = float(duration_raw)
+            else:
+                duration = float(str(duration_raw).replace("seconds", "").strip())
+        except (ValueError, TypeError):
+            duration = 1.0
+
+        # ``time.sleep`` raises ``ValueError`` for negative values, so clamp.
+        if duration < 0:
             duration = 1.0
 
         time.sleep(duration)
diff --git a/tests/test_wait_action.py b/tests/test_wait_action.py
new file mode 100644
index 000000000..251acd2c6
--- /dev/null
+++ b/tests/test_wait_action.py
@@ -0,0 +1,77 @@
+"""Unit tests for the ``Wait`` action handler.
+
+These tests exercise ``ActionHandler._handle_wait`` via the public ``execute``
+entry point. They are pure and deterministic — ``time.sleep`` is patched so no
+real time is spent and no device or network access is required.
+"""
+
+from unittest.mock import patch
+
+from phone_agent.actions.handler import ActionHandler
+
+
+def _wait_action(**kwargs):
+    action = {"_metadata": "do", "action": "Wait"}
+    action.update(kwargs)
+    return action
+
+
+class TestHandleWait:
+    """Tests for ``ActionHandler._handle_wait`` robustness."""
+
+    def test_string_duration_with_unit(self):
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(duration="3 seconds"), 1080, 1920)
+        assert result.success is True
+        assert result.should_finish is False
+        sleep.assert_called_once_with(3.0)
+
+    def test_string_duration_without_unit(self):
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(duration="2"), 1080, 1920)
+        assert result.success is True
+        sleep.assert_called_once_with(2.0)
+
+    def test_default_duration_when_missing(self):
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(), 1080, 1920)
+        assert result.success is True
+        sleep.assert_called_once_with(1.0)
+
+    def test_integer_duration_does_not_crash(self):
+        """A bare int duration must not raise AttributeError.
+
+        Previously ``int.replace`` raised ``AttributeError`` which the
+        ``except ValueError`` clause did not catch, so the wait silently
+        failed with ``success=False``.
+        """
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(duration=3), 1080, 1920)
+        assert result.success is True
+        sleep.assert_called_once_with(3.0)
+
+    def test_float_duration(self):
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(duration=1.5), 1080, 1920)
+        assert result.success is True
+        sleep.assert_called_once_with(1.5)
+
+    def test_unparseable_duration_falls_back(self):
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(duration="soon"), 1080, 1920)
+        assert result.success is True
+        sleep.assert_called_once_with(1.0)
+
+    def test_negative_duration_is_clamped(self):
+        """A negative duration must be clamped so time.sleep does not raise."""
+        handler = ActionHandler()
+        with patch("phone_agent.actions.handler.time.sleep") as sleep:
+            result = handler.execute(_wait_action(duration="-5 seconds"), 1080, 1920)
+        assert result.success is True
+        sleep.assert_called_once_with(1.0)