fix(config_flow): F-A/F-A2/F-D — the discovered host and the 5555 port ride the schema KEY defaults (t33)

F-A (HIGH): _user_schema_dict re-declared vol.Optional(CONF_ADB_HOST) /
CONF_PROTOCOL_HOST inside `if "host" in defaults:` — a no-op, because
voluptuous keys compare by field name and the first (defaultless) key object
survives. The discovered address therefore never reached the form, and the
user submitted a blank host. The host keys are now declared WITH default=host
(_host_field_key), so a discovery-driven user step arrives pre-filled.

F-A2: a discovery-driven user step says the address is known
("{discovery_note}Discovered Shield at <host> — its address is already filled
in below. ") through description_placeholders, and the no_state_source
re-render keeps the prefill instead of rebuilding a blank schema.

F-D: the ADB port is declared with default=DEFAULT_ADB_PORT (5555), and a YAML
seed's port hint is carried into the form instead of being flattened to 5555.
The seed host now feeds _seed_host (same prefill, no discovery claim).

Reproduce-through-test: tests/voluptuous_mirror.py mirrors the real
voluptuous.Marker key contract (hash/eq by field name, default=UNDEFINED when
omitted), because voluptuous is not installed in either CI variant and the old
bare-key stubs could not tell a schema WITH a default from one without. The
pre-t33 discovery assertion only checked the stored attribute and stayed green
while the form rendered blank; it now reads the schema keys and fails on the
pre-fix code (8 tests reproduced red locally).

Verified: uvx --with pytest-asyncio pytest tests -q → 242 passed, 1 skipped;
uvx ruff check custom_components tests → clean.

tests/test_standalone_setup.py

@@ -15,6 +15,7 @@ from types import SimpleNamespace
 from unittest import mock
 
 import pytest
+import voluptuous_mirror as vol_mirror
 from conftest import _SHIELD_DIR, _load_module
 from nsh.const import (
     CONF_ADB_ENABLED,
@@ -54,9 +55,10 @@ def _install_stubs() -> None:
         return
 
     vol = types.ModuleType("voluptuous")
-    vol.Required = lambda key, default=None: key
-    vol.Optional = lambda key, default=None: key
-    vol.Schema = lambda schema: schema
+    # t33 F-A: a faithful mirror — the default stays ON the key, so a schema
+    # whose host default was dropped FAILS here instead of looking identical
+    # to one that carries it (the old bare-key stub hid exactly that bug).
+    vol_mirror.install(vol)
     sys.modules["voluptuous"] = vol
 
     ha = types.ModuleType("homeassistant")
@@ -71,12 +73,16 @@ def _install_stubs() -> None:
             kwargs.pop("domain", None)
             super().__init_subclass__(**kwargs)
 
-        def async_show_form(self, *, step_id, data_schema=None, errors=None):
+        def async_show_form(
+            self, *, step_id, data_schema=None, errors=None,
+            description_placeholders=None,
+        ):
             return {
                 "type": "form",
                 "step_id": step_id,
                 "errors": dict(errors or {}),
                 "data_schema": data_schema,
+                "description_placeholders": dict(description_placeholders or {}),
             }
 
         def async_create_entry(self, *, title, data, options=None):
@@ -942,6 +948,11 @@ class TestZeroconfDiscovery:
         )
 
     async def test_discovery_prefills_the_user_step(self, tmp_path):
+        """t33 F-A: the discovered host is the DEFAULT OF THE SCHEMA KEYS.
+
+        The old check (the attribute was stored) stayed green while the
+        rendered form was blank — this one reads the schema itself.
+        """
         module = _form_module()
         flow = module.NvidiaShieldConfigFlow()
         flow.hass = FakeHass(str(tmp_path))
@@ -950,9 +961,13 @@ class TestZeroconfDiscovery:
 
         assert result["type"] == "form"
         assert result["step_id"] == "user"
-        # pre-fill landed: the discovered host is recorded for the schema
         assert flow._discovered_host == "192.168.1.50"
-        assert result["data_schema"] is not None
+        defaults = vol_mirror.defaults_by_key(result["data_schema"])
+        assert defaults[CONF_ADB_HOST] == "192.168.1.50"
+        assert defaults[CONF_PROTOCOL_HOST] == "192.168.1.50"
+        # ...and a discovery-driven form says the address is already known
+        note = result["description_placeholders"]["discovery_note"]
+        assert "Discovered Shield at 192.168.1.50" in note
 
     async def test_discovery_without_address_aborts(self, tmp_path):
         module = _form_module()