fix(config_flow): F2 — MAC-less zeroconf discovery calls the audited _async_handle_discovery_without_unique_id helper and guards against a same-host duplicate prefill, so re-discovery can't stack entries; the import guard reads entries via the base _async_current_entries helper; TestMacLessDiscoveryF2 pins helper call + one-entry outcome (t32)

tests/test_standalone_setup.py

@@ -95,6 +95,12 @@ def _install_stubs() -> None:
         def _async_current_entries(self):
             return _zc_holder.entries
 
+        # t32 F2: the audited helper for uniqueness-less discovery — a
+        # recording no-op here; the flow's own host guard does the stacking
+        # prevention the acceptance pins.
+        def _async_handle_discovery_without_unique_id(self):
+            _zc_holder.discovery_without_unique_id_calls += 1
+
     class OptionsFlow:
         def async_show_form(self, *, step_id, data_schema=None, errors=None):
             return {
@@ -128,7 +134,7 @@ def _install_stubs() -> None:
 
     # Shared holder so tests can swap the current-entry list through the
     # module object (the stub closure reads this same object).
-    _zc_holder = types.SimpleNamespace(entries=[])
+    _zc_holder = types.SimpleNamespace(entries=[], discovery_without_unique_id_calls=0)
     sys.modules[__name__]._zc_holder = _zc_holder
 
     class AbortIfConfiguredError(Exception):
@@ -835,6 +841,50 @@ class TestIpChangeSelfHealF1:
             assert factory() is None
 
 
+class TestMacLessDiscoveryF2:
+    """t32 F2 (rider): MAC-less zeroconf discovery records the
+    uniqueness-less discovery and can't stack a duplicate prefill."""
+
+    def _discovery(self, host="192.168.1.50", props=None):
+        return SimpleNamespace(
+            ip_address=host, host=host, properties=props or {}
+        )
+
+    async def test_mac_less_records_the_helper(self, tmp_path):
+        module = _form_module()
+        flow = module.NvidiaShieldConfigFlow()
+        flow.hass = FakeHass(str(tmp_path))
+        sys.modules[__name__]._zc_holder.discovery_without_unique_id_calls = 0
+
+        result = await flow.async_step_zeroconf(self._discovery())
+
+        assert result["type"] == "form"  # prefill still offered once
+        assert (
+            sys.modules[__name__]._zc_holder.discovery_without_unique_id_calls
+            == 1
+        )
+
+    async def test_mac_less_rediscovery_does_not_stack(self, tmp_path):
+        """A second MAC-less discovery of an already-configured host
+        aborts — one-entry outcome."""
+        module = _form_module()
+        flow = module.NvidiaShieldConfigFlow()
+        flow.hass = FakeHass(str(tmp_path))
+        entry = SimpleNamespace(
+            entry_id="e1",
+            unique_id=None,  # MAC-less entry
+            options={CONF_PROTOCOL_HOST: "192.168.1.50"},
+            title="Shield",
+        )
+        sys.modules[__name__]._zc_holder.entries[:] = [entry]
+
+        result = await flow.async_step_zeroconf(self._discovery())
+
+        assert result == {"type": "abort", "reason": "already_configured"}
+        # the entries list is untouched: one-entry outcome
+        assert len(sys.modules[__name__]._zc_holder.entries) == 1
+
+
 class TestZeroconfDiscovery:
     """P4-1a: _androidtvremote2._tcp discovery → pre-filled user step."""