fix(stt): check selected provider (not any) + plugin support

PR review feedback:
- Replace _has_any_command_stt_provider() with selected-provider
  check via _resolve_command_stt_provider_config()
- Add _check_plugin_stt_provider() for plugin-registered backends
- Add tests: selected command, unrelated command (should NOT pass),
  and plugin provider path

tests/tools/test_voice_mode.py

@@ -500,6 +500,56 @@ class TestCheckVoiceRequirements:
         assert result["stt_available"] is False
         assert "STT provider: MISSING" in result["details"]
 
+    def test_command_stt_provider_selected(self, monkeypatch):
+        """Catch-all branch fires for a selected command provider (not any provider)."""
+        monkeypatch.setattr("tools.voice_mode._audio_available", lambda: True)
+        monkeypatch.setattr("tools.voice_mode.detect_audio_environment",
+                            lambda: {"available": True, "warnings": []})
+        monkeypatch.setattr("tools.transcription_tools._get_provider", lambda cfg: "my-custom-stt")
+        monkeypatch.setattr("tools.transcription_tools._resolve_command_stt_provider_config",
+                            lambda p, c: {"command": "whisper_cpp"} if p == "my-custom-stt" else None)
+
+        from tools.voice_mode import check_voice_requirements
+
+        result = check_voice_requirements()
+        assert result["available"] is True
+        assert result["stt_available"] is True
+        assert "STT provider: OK (command: my-custom-stt)" in result["details"]
+
+    def test_unrelated_command_provider_not_confused(self, monkeypatch):
+        """Unrelated command provider does NOT make a different selected provider appear OK."""
+        monkeypatch.setattr("tools.voice_mode._audio_available", lambda: True)
+        monkeypatch.setattr("tools.voice_mode.detect_audio_environment",
+                            lambda: {"available": True, "warnings": []})
+        monkeypatch.setattr("tools.transcription_tools._get_provider", lambda cfg: "none")
+        monkeypatch.setattr("tools.transcription_tools._resolve_command_stt_provider_config",
+                            lambda p, c: {"command": "whisper_cpp"} if p == "my-custom-stt" else None)
+
+        from tools.voice_mode import check_voice_requirements
+
+        result = check_voice_requirements()
+        assert result["available"] is False
+        assert result["stt_available"] is False
+        assert "STT provider: MISSING" in result["details"]
+
+    def test_plugin_stt_provider(self, monkeypatch):
+        """Plugin STT provider is recognized."""
+        monkeypatch.setattr("tools.voice_mode._audio_available", lambda: True)
+        monkeypatch.setattr("tools.voice_mode.detect_audio_environment",
+                            lambda: {"available": True, "warnings": []})
+        monkeypatch.setattr("tools.transcription_tools._get_provider", lambda cfg: "my-plugin-stt")
+        monkeypatch.setattr("tools.transcription_tools._resolve_command_stt_provider_config",
+                            lambda p, c: None)
+        monkeypatch.setattr("tools.voice_mode._check_plugin_stt_provider",
+                            lambda p: p == "my-plugin-stt")
+
+        from tools.voice_mode import check_voice_requirements
+
+        result = check_voice_requirements()
+        assert result["available"] is True
+        assert result["stt_available"] is True
+        assert "STT provider: OK (plugin: my-plugin-stt)" in result["details"]
+
 
 # ============================================================================
 # AudioRecorder

tools/voice_mode.py

@@ -1269,6 +1269,17 @@ def listen_for_speech(
 # ============================================================================
 # Requirements check
 # ============================================================================
+def _check_plugin_stt_provider(provider: str) -> bool:
+    """Return True when *provider* is backed by a registered TranscriptionProvider plugin."""
+    if not provider:
+        return False
+    try:
+        from agent.transcription_registry import get_provider
+        return get_provider(provider.lower().strip()) is not None
+    except ImportError:
+        return False
+
+
 def check_voice_requirements() -> Dict[str, Any]:
     """Check if all voice mode requirements are met.
 
@@ -1277,7 +1288,7 @@ def check_voice_requirements() -> Dict[str, Any]:
         ``missing_packages``, and ``details``.
     """
     # Determine STT provider availability
-    from tools.transcription_tools import _get_provider, _has_any_command_stt_provider, _load_stt_config, is_stt_enabled
+    from tools.transcription_tools import _get_provider, _load_stt_config, _resolve_command_stt_provider_config, is_stt_enabled
     stt_config = _load_stt_config()
     stt_enabled = is_stt_enabled(stt_config)
     stt_provider = _get_provider(stt_config)
@@ -1319,8 +1330,10 @@ def check_voice_requirements() -> Dict[str, Any]:
         details_parts.append("STT provider: OK (xAI Grok STT)")
     elif stt_provider == "elevenlabs":
         details_parts.append("STT provider: OK (ElevenLabs Scribe)")
-    elif _has_any_command_stt_provider(stt_config):
-        details_parts.append(f"STT provider: OK ({stt_provider})")
+    elif _resolve_command_stt_provider_config(stt_provider, stt_config):
+        details_parts.append(f"STT provider: OK (command: {stt_provider})")
+    elif _check_plugin_stt_provider(stt_provider):
+        details_parts.append(f"STT provider: OK (plugin: {stt_provider})")
     else:
         details_parts.append(
             "STT provider: MISSING (uv pip install faster-whisper — "