fix: persist clean voice transcripts and /voice off state

- keep CLI voice prefixes API-local while storing the original user text
- persist explicit gateway off state and restore adapter auto-TTS suppression on restart
- add regression coverage for both behaviors

tests/gateway/test_voice_command.py

@@ -3,12 +3,53 @@
 import json
 import os
 import queue
+import sys
 import threading
 import time
 import pytest
 from types import SimpleNamespace
 from unittest.mock import AsyncMock, MagicMock, patch
 
+
+def _ensure_discord_mock():
+    """Install a lightweight discord mock when discord.py isn't available."""
+    if "discord" in sys.modules and hasattr(sys.modules["discord"], "__file__"):
+        return
+
+    discord_mod = MagicMock()
+    discord_mod.Intents.default.return_value = MagicMock()
+    discord_mod.Client = MagicMock
+    discord_mod.File = MagicMock
+    discord_mod.DMChannel = type("DMChannel", (), {})
+    discord_mod.Thread = type("Thread", (), {})
+    discord_mod.ForumChannel = type("ForumChannel", (), {})
+    discord_mod.ui = SimpleNamespace(View=object, button=lambda *a, **k: (lambda fn: fn), Button=object)
+    discord_mod.ButtonStyle = SimpleNamespace(success=1, primary=2, danger=3, green=1, blurple=2, red=3)
+    discord_mod.Color = SimpleNamespace(orange=lambda: 1, green=lambda: 2, blue=lambda: 3, red=lambda: 4)
+    discord_mod.Interaction = object
+    discord_mod.Embed = MagicMock
+    discord_mod.app_commands = SimpleNamespace(
+        describe=lambda **kwargs: (lambda fn: fn),
+        choices=lambda **kwargs: (lambda fn: fn),
+        Choice=lambda **kwargs: SimpleNamespace(**kwargs),
+    )
+    discord_mod.opus = SimpleNamespace(is_loaded=lambda: True, load_opus=lambda *_args, **_kwargs: None)
+    discord_mod.FFmpegPCMAudio = MagicMock
+    discord_mod.PCMVolumeTransformer = MagicMock
+    discord_mod.http = SimpleNamespace(Route=MagicMock)
+
+    ext_mod = MagicMock()
+    commands_mod = MagicMock()
+    commands_mod.Bot = MagicMock
+    ext_mod.commands = commands_mod
+
+    sys.modules.setdefault("discord", discord_mod)
+    sys.modules.setdefault("discord.ext", ext_mod)
+    sys.modules.setdefault("discord.ext.commands", commands_mod)
+
+
+_ensure_discord_mock()
+
 from gateway.platforms.base import MessageEvent, MessageType, SessionSource
 
 
@@ -65,7 +106,7 @@ class TestHandleVoiceCommand:
         event = _make_event("/voice off")
         result = await runner._handle_voice_command(event)
         assert "disabled" in result.lower()
-        assert "123" not in runner._voice_mode
+        assert runner._voice_mode["123"] == "off"
 
     @pytest.mark.asyncio
     async def test_voice_tts(self, runner):
@@ -100,7 +141,7 @@ class TestHandleVoiceCommand:
         event = _make_event("/voice")
         result = await runner._handle_voice_command(event)
         assert "disabled" in result.lower()
-        assert "123" not in runner._voice_mode
+        assert runner._voice_mode["123"] == "off"
 
     @pytest.mark.asyncio
     async def test_persistence_saved(self, runner):
@@ -116,6 +157,33 @@ class TestHandleVoiceCommand:
         loaded = runner._load_voice_modes()
         assert loaded == {"456": "all"}
 
+    @pytest.mark.asyncio
+    async def test_persistence_saved_for_off(self, runner):
+        event = _make_event("/voice off")
+        await runner._handle_voice_command(event)
+        data = json.loads(runner._VOICE_MODE_PATH.read_text())
+        assert data["123"] == "off"
+
+    def test_sync_voice_mode_state_to_adapter_restores_off_chats(self, runner):
+        runner._voice_mode = {"123": "off", "456": "all"}
+        adapter = SimpleNamespace(_auto_tts_disabled_chats=set())
+
+        runner._sync_voice_mode_state_to_adapter(adapter)
+
+        assert adapter._auto_tts_disabled_chats == {"123"}
+
+    def test_restart_restores_voice_off_state(self, runner, tmp_path):
+        runner._VOICE_MODE_PATH.write_text(json.dumps({"123": "off"}))
+
+        restored_runner = _make_runner(tmp_path)
+        restored_runner._voice_mode = restored_runner._load_voice_modes()
+        adapter = SimpleNamespace(_auto_tts_disabled_chats=set())
+
+        restored_runner._sync_voice_mode_state_to_adapter(adapter)
+
+        assert restored_runner._voice_mode["123"] == "off"
+        assert adapter._auto_tts_disabled_chats == {"123"}
+
     @pytest.mark.asyncio
     async def test_per_chat_isolation(self, runner):
         e1 = _make_event("/voice on", chat_id="aaa")
@@ -693,7 +761,7 @@ class TestVoiceChannelCommands:
         runner._voice_mode["123"] = "all"
         result = await runner._handle_voice_channel_leave(event)
         assert "left" in result.lower()
-        assert "123" not in runner._voice_mode
+        assert runner._voice_mode["123"] == "off"
         mock_adapter.leave_voice_channel.assert_called_once_with(111)
 
     # -- _handle_voice_channel_input --
@@ -1163,7 +1231,7 @@ class TestLeaveExceptionHandling:
 
         result = await runner._handle_voice_channel_leave(event)
         assert "left" in result.lower()
-        assert "123" not in runner._voice_mode
+        assert runner._voice_mode["123"] == "off"
         assert mock_adapter._voice_input_callback is None
 
     @pytest.mark.asyncio
@@ -1626,8 +1694,8 @@ class TestVoiceTimeoutCleansRunnerState:
 
         runner._handle_voice_timeout_cleanup("999")
 
-        assert "999" not in runner._voice_mode, \
-            "voice_mode must be removed after timeout cleanup"
+        assert runner._voice_mode["999"] == "off", \
+            "voice_mode must persist explicit off state after timeout cleanup"
 
     @pytest.mark.asyncio
     async def test_timeout_without_callback_does_not_crash(self, adapter):