fix: add macOS Homebrew Opus fallback and fix shutdown dict iteration

- Add Homebrew library path fallback when ctypes.util.find_library fails
  on macOS (Apple Silicon + Intel paths, guarded by platform check)
- Fix RuntimeError in gateway stop() by iterating over dict copy
- Update Opus tests to verify find_library-first + conditional fallback

gateway/platforms/discord.py

@@ -409,6 +409,19 @@ class DiscordAdapter(BasePlatformAdapter):
         if not discord.opus.is_loaded():
             import ctypes.util
             opus_path = ctypes.util.find_library("opus")
+            # ctypes.util.find_library fails on macOS with Homebrew-installed libs,
+            # so fall back to known Homebrew paths if needed.
+            if not opus_path:
+                import sys
+                _homebrew_paths = (
+                    "/opt/homebrew/lib/libopus.dylib",  # Apple Silicon
+                    "/usr/local/lib/libopus.dylib",     # Intel Mac
+                )
+                if sys.platform == "darwin":
+                    for _hp in _homebrew_paths:
+                        if os.path.isfile(_hp):
+                            opus_path = _hp
+                            break
             if opus_path:
                 try:
                     discord.opus.load_opus(opus_path)

gateway/run.py

@@ -754,7 +754,7 @@ class GatewayRunner:
         logger.info("Stopping gateway...")
         self._running = False
         
-        for platform, adapter in self.adapters.items():
+        for platform, adapter in list(self.adapters.items()):
             try:
                 await adapter.disconnect()
                 logger.info("✓ %s disconnected", platform.value)

tests/gateway/test_discord_opus.py

@@ -4,22 +4,31 @@ import inspect
 
 
 class TestOpusFindLibrary:
-    """Opus loading must use ctypes.util.find_library, not hardcoded paths."""
+    """Opus loading must try ctypes.util.find_library first, with platform fallback."""
 
-    def test_no_hardcoded_opus_path(self):
-        from gateway.platforms.discord import DiscordAdapter
-        source = inspect.getsource(DiscordAdapter.connect)
-        assert "/opt/homebrew" not in source, \
-            "Opus loading must not use hardcoded /opt/homebrew path"
-        assert "libopus.so.0" not in source, \
-            "Opus loading must not use hardcoded libopus.so.0 path"
-
-    def test_uses_find_library(self):
+    def test_uses_find_library_first(self):
+        """find_library must be the primary lookup strategy."""
         from gateway.platforms.discord import DiscordAdapter
         source = inspect.getsource(DiscordAdapter.connect)
         assert "find_library" in source, \
             "Opus loading must use ctypes.util.find_library"
 
+    def test_homebrew_fallback_is_conditional(self):
+        """Homebrew paths must only be tried when find_library returns None."""
+        from gateway.platforms.discord import DiscordAdapter
+        source = inspect.getsource(DiscordAdapter.connect)
+        # Homebrew fallback must exist
+        assert "/opt/homebrew" in source or "homebrew" in source, \
+            "Opus loading should have macOS Homebrew fallback"
+        # find_library must appear BEFORE any Homebrew path
+        fl_idx = source.index("find_library")
+        hb_idx = source.index("/opt/homebrew")
+        assert fl_idx < hb_idx, \
+            "find_library must be tried before Homebrew fallback paths"
+        # Fallback must be guarded by platform check
+        assert "sys.platform" in source or "darwin" in source, \
+            "Homebrew fallback must be guarded by macOS platform check"
+
     def test_opus_decode_error_logged(self):
         """Opus decode failure must log the error, not silently return."""
         from gateway.platforms.discord import VoiceReceiver