Add 'available' command to list all effect types

- Add _cmd_available() method to list all registered effect types
- Discover plugins and query registry to get complete list
- Add 'available' to help text and command processing
- Update help description for 'effects' command to clarify it shows current pipeline

engine/effects/plugins/repl.py

@@ -249,6 +249,8 @@ class ReplEffect(EffectPlugin):
                 self._cmd_param(cmd_args, ctx)
             elif cmd_name == "pipeline":
                 self._cmd_pipeline(ctx)
+            elif cmd_name == "available":
+                self._cmd_available(ctx)
             elif cmd_name == "add_stage":
                 self._cmd_add_stage(cmd_args)
             elif cmd_name == "remove_stage":
@@ -273,7 +275,8 @@ class ReplEffect(EffectPlugin):
         self.state.output_buffer.append("Available commands:")
         self.state.output_buffer.append("  help - Show this help")
         self.state.output_buffer.append("  status - Show pipeline status")
-        self.state.output_buffer.append("  effects - List all effects")
+        self.state.output_buffer.append("  effects - List effects in current pipeline")
+        self.state.output_buffer.append("  available - List all available effect types")
         self.state.output_buffer.append("  effect <name> <on|off> - Toggle effect")
         self.state.output_buffer.append(
             "  param <effect> <param> <value> - Set parameter"
@@ -318,6 +321,26 @@ class ReplEffect(EffectPlugin):
         else:
             self.state.output_buffer.append("No context available")
 
+    def _cmd_available(self, ctx: EffectContext | None):
+        """List all available effect types."""
+        try:
+            from engine.effects import get_registry
+            from engine.effects.plugins import discover_plugins
+
+            # Discover plugins if not already done
+            discover_plugins()
+            registry = get_registry()
+            all_effects = registry.list_all()
+
+            if all_effects:
+                self.state.output_buffer.append("Available effect types:")
+                for name in sorted(all_effects.keys()):
+                    self.state.output_buffer.append(f"  - {name}")
+            else:
+                self.state.output_buffer.append("No effects registered")
+        except Exception as e:
+            self.state.output_buffer.append(f"Error listing effects: {e}")
+
     def _cmd_effect(self, args: list[str], ctx: EffectContext | None):
         """Toggle effect on/off."""
         if len(args) < 2: