test(gateway): unify discord mock via shared conftest; drop duplicated mock in model_picker test

The cherry-picked model_picker test installed its own discord mock at
module-import time via a local _ensure_discord_mock(), overwriting
sys.modules['discord'] with a mock that lacked attributes other
gateway tests needed (Intents.default(), File, app_commands.Choice).
On pytest-xdist workers that collected test_discord_model_picker.py
first, the shared mock in tests/gateway/conftest.py got clobbered and
downstream tests failed with AttributeError / TypeError against
missing mock attrs. Classic sys.modules cross-test pollution (see
xdist-cross-test-pollution skill).

Fix:
- Extend the canonical _ensure_discord_mock() in tests/gateway/conftest.py
  to cover everything the model_picker test needs: real View/Select/
  Button/SelectOption classes (not MagicMock sentinels), an Embed
  class that preserves title/description/color kwargs for assertion,
  and Color.greyple.
- Strip the duplicated mock-setup block from test_discord_model_picker.py
  and rely on the shared mock that conftest installs at collection
  time.

Regression check:
  scripts/run_tests.sh tests/gateway/ tests/hermes_cli/ -k 'discord or model or copilot or provider' -o 'addopts='
  1291 passed (was 1288 passed + 3 xdist-ordered failures before this commit).

tests/gateway/conftest.py

@@ -88,11 +88,63 @@ def _ensure_discord_mock() -> None:
     discord_mod.Thread = type("Thread", (), {})
     discord_mod.ForumChannel = type("ForumChannel", (), {})
     discord_mod.Interaction = object
-    discord_mod.Embed = MagicMock
+    discord_mod.Message = type("Message", (), {})
+
+    # Embed: accept the kwargs production code / tests use
+    # (title, description, color). MagicMock auto-attributes work too,
+    # but some tests construct and inspect .title/.description directly.
+    class _FakeEmbed:
+        def __init__(self, *, title=None, description=None, color=None, **_):
+            self.title = title
+            self.description = description
+            self.color = color
+    discord_mod.Embed = _FakeEmbed
+
+    # ui.View / ui.Select / ui.Button: real classes (not MagicMock) so
+    # tests that subclass ModelPickerView / iterate .children / clear
+    # items work.
+    class _FakeView:
+        def __init__(self, timeout=None):
+            self.timeout = timeout
+            self.children = []
+        def add_item(self, item):
+            self.children.append(item)
+        def clear_items(self):
+            self.children.clear()
+
+    class _FakeSelect:
+        def __init__(self, *, placeholder=None, options=None, custom_id=None, **_):
+            self.placeholder = placeholder
+            self.options = options or []
+            self.custom_id = custom_id
+            self.callback = None
+            self.disabled = False
+
+    class _FakeButton:
+        def __init__(self, *, label=None, style=None, custom_id=None, emoji=None,
+                     url=None, disabled=False, row=None, sku_id=None, **_):
+            self.label = label
+            self.style = style
+            self.custom_id = custom_id
+            self.emoji = emoji
+            self.url = url
+            self.disabled = disabled
+            self.row = row
+            self.sku_id = sku_id
+            self.callback = None
+
+    class _FakeSelectOption:
+        def __init__(self, *, label=None, value=None, description=None, **_):
+            self.label = label
+            self.value = value
+            self.description = description
+    discord_mod.SelectOption = _FakeSelectOption
+
     discord_mod.ui = SimpleNamespace(
-        View=object,
+        View=_FakeView,
+        Select=_FakeSelect,
+        Button=_FakeButton,
         button=lambda *a, **k: (lambda fn: fn),
-        Button=object,
     )
     discord_mod.ButtonStyle = SimpleNamespace(
         success=1, primary=2, secondary=2, danger=3,
@@ -100,7 +152,7 @@ def _ensure_discord_mock() -> None:
     )
     discord_mod.Color = SimpleNamespace(
         orange=lambda: 1, green=lambda: 2, blue=lambda: 3,
-        red=lambda: 4, purple=lambda: 5,
+        red=lambda: 4, purple=lambda: 5, greyple=lambda: 6,
     )
 
     # app_commands — needed by _register_slash_commands auto-registration

tests/gateway/test_discord_model_picker.py

@@ -1,118 +1,16 @@
-"""Regression tests for the Discord /model picker."""
+"""Regression tests for the Discord /model picker.
 
-from types import ModuleType, SimpleNamespace
-from unittest.mock import AsyncMock, MagicMock
-import sys
+Uses the shared discord mock from tests/gateway/conftest.py (installed
+at collection time via _ensure_discord_mock()). Previously this file
+installed its own mock at module-import time and clobbered sys.modules,
+breaking other gateway tests under pytest-xdist.
+"""
+
+from types import SimpleNamespace
+from unittest.mock import AsyncMock
 
 import pytest
 
-
-def _ensure_discord_mock():
-    existing = sys.modules.get("discord")
-    if isinstance(existing, ModuleType) and getattr(existing, "__file__", None):
-        return
-
-    class _FakeView:
-        def __init__(self, timeout=None):
-            self.timeout = timeout
-            self.children = []
-
-        def add_item(self, item):
-            self.children.append(item)
-
-        def clear_items(self):
-            self.children.clear()
-
-    class _FakeSelect:
-        def __init__(self, *, placeholder, options, custom_id):
-            self.placeholder = placeholder
-            self.options = options
-            self.custom_id = custom_id
-            self.callback = None
-            self.disabled = False
-
-    class _FakeButton:
-        def __init__(self, *, label, style, custom_id=None, emoji=None, url=None, disabled=False, row=None, sku_id=None):
-            self.label = label
-            self.style = style
-            self.custom_id = custom_id
-            self.emoji = emoji
-            self.url = url
-            self.disabled = disabled
-            self.row = row
-            self.sku_id = sku_id
-            self.callback = None
-
-    class _FakeSelectOption:
-        def __init__(self, *, label, value, description=None):
-            self.label = label
-            self.value = value
-            self.description = description
-
-    class _FakeEmbed:
-        def __init__(self, *, title, description, color):
-            self.title = title
-            self.description = description
-            self.color = color
-
-    class _FakeColor:
-        @staticmethod
-        def green():
-            return "green"
-
-        @staticmethod
-        def blue():
-            return "blue"
-
-        @staticmethod
-        def red():
-            return "red"
-
-        @staticmethod
-        def greyple():
-            return "greyple"
-
-    class _FakeButtonStyle:
-        green = "green"
-        grey = "grey"
-        red = "red"
-        blurple = "blurple"
-
-    discord_mod = sys.modules.get("discord") or MagicMock()
-    discord_mod.Intents.default.return_value = MagicMock()
-    discord_mod.DMChannel = type("DMChannel", (), {})
-    discord_mod.Thread = type("Thread", (), {})
-    discord_mod.ForumChannel = type("ForumChannel", (), {})
-    discord_mod.Interaction = object
-    discord_mod.Message = type("Message", (), {})
-    discord_mod.SelectOption = _FakeSelectOption
-    discord_mod.Embed = _FakeEmbed
-    discord_mod.Color = _FakeColor
-    discord_mod.ButtonStyle = _FakeButtonStyle
-    discord_mod.app_commands = getattr(
-        discord_mod,
-        "app_commands",
-        SimpleNamespace(describe=lambda **kwargs: (lambda fn: fn)),
-    )
-    discord_mod.ui = SimpleNamespace(
-        View=_FakeView,
-        Select=_FakeSelect,
-        Button=_FakeButton,
-        button=lambda **kwargs: (lambda fn: fn),
-    )
-
-    ext_mod = MagicMock()
-    commands_mod = MagicMock()
-    commands_mod.Bot = MagicMock
-    ext_mod.commands = commands_mod
-
-    sys.modules["discord"] = discord_mod
-    sys.modules.setdefault("discord.ext", ext_mod)
-    sys.modules.setdefault("discord.ext.commands", commands_mod)
-
-
-_ensure_discord_mock()
-
 from gateway.platforms.discord import ModelPickerView
 
 
@@ -135,7 +33,12 @@ async def test_model_picker_clears_controls_before_running_switch_callback():
         )
 
     async def edit_original_response(**kwargs):
-        events.append(("final-edit", kwargs["embed"].title, kwargs["embed"].description, kwargs["view"]))
+        events.append((
+            "final-edit",
+            kwargs["embed"].title,
+            kwargs["embed"].description,
+            kwargs["view"],
+        ))
 
     view = ModelPickerView(
         providers=[