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/entity_stublib.py

@@ -11,6 +11,8 @@ import enum
 import sys
 import types
 
+import voluptuous_mirror
+
 ENTITIES_STUB_NAMES = (
     "voluptuous",
     "homeassistant",
@@ -115,9 +117,9 @@ def install() -> 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: the faithful mirror keeps schema defaults visible — a bare-key
+    # stub cannot tell a schema WITH a default from one without.
+    voluptuous_mirror.install(vol)
     sys.modules["voluptuous"] = vol
 
     ha = types.ModuleType("homeassistant")
@@ -148,12 +150,16 @@ def install() -> None:
             # t32 F2 (audited helper): recording no-op at hub scope
             pass
 
-        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):

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()

tests/voluptuous_mirror.py

@@ -0,0 +1,89 @@
+"""A voluptuous mirror faithful enough to SEE a dropped schema default.
+
+The test environment never installs voluptuous (the config-flow tests import
+``config_flow`` against import-only stubs), so the harness has to model the two
+behaviours the flow schemas depend on:
+
+* ``Optional(field, default=value)`` / ``Required(field, default=value)`` carry
+  that default on the KEY object;
+* keys compare by FIELD NAME only — real ``voluptuous.Marker`` implements
+  ``__hash__ = hash(self.schema)`` and ``__eq__`` on class + schema. A later
+  re-declaration of the same field therefore keeps the FIRST key object, so a
+  default added by a second declaration is silently dropped.
+
+That second property is exactly how the t33 F-A discovery-prefill bug hid from
+the suite: the old stubs reduced every key to its bare string, so a schema
+whose host key carried no default looked identical to one that carried the
+discovered address. ``TestVoluptuousMirrorContract`` in
+``tests/test_config_flow_ux.py`` pins both properties so the harness itself
+cannot regress into blindness.
+"""
+
+from __future__ import annotations
+
+UNDEFINED = object()
+"""Sentinel for "this key declares no default" (real ``voluptuous.UNDEFINED``)."""
+
+
+class Marker:
+    """Stand-in for ``voluptuous.Marker`` (the ``Required``/``Optional`` base)."""
+
+    def __init__(self, schema, default=UNDEFINED):
+        self.schema = schema
+        self.default = default
+
+    def __hash__(self):
+        # real Marker hashes the field name only
+        return hash(self.schema)
+
+    def __eq__(self, other):
+        # real Marker compares class + field name, never the default
+        return type(other) is type(self) and other.schema == self.schema
+
+    def __repr__(self):
+        return f"<{type(self).__name__} {self.schema!r} default={self.default!r}>"
+
+
+class Required(Marker):
+    """Stand-in for ``voluptuous.Required``."""
+
+
+class Optional(Marker):
+    """Stand-in for ``voluptuous.Optional``."""
+
+
+def install(vol) -> None:
+    """Wire the mirror onto a stub ``voluptuous`` module object."""
+    vol.UNDEFINED = UNDEFINED
+    vol.Marker = Marker
+    vol.Required = Required
+    vol.Optional = Optional
+    vol.Schema = lambda schema: schema
+
+
+def defaults_by_key(schema_dict) -> dict:
+    """``{field: default}`` for a schema declared with mirror keys."""
+    return {key.schema: key.default for key in declared_keys(schema_dict)}
+
+
+def declared_keys(schema_dict) -> list:
+    """The schema's marker keys, in declaration order.
+
+    Raises on a non-marker key: a bare string key means the harness (or the
+    code under test) lost the KEY structure this mirror exists to check.
+    Test-harness bookkeeping keys (``__suggested__`` and friends) are skipped.
+    """
+    keys = []
+    for key in schema_dict:
+        if isinstance(key, Marker):
+            keys.append(key)
+            continue
+        if isinstance(key, str) and key.startswith("__"):
+            continue
+        raise AssertionError(f"schema key {key!r} is not a voluptuous marker")
+    return keys
+
+
+def declared_fields(schema_dict) -> list:
+    """The field names of a schema, in declaration order."""
+    return [key.schema for key in declared_keys(schema_dict)]