Encapsulate target-type dispatch via polymorphism (Phase 1)

Replace isinstance checks with polymorphic methods on PictureTarget
hierarchy: register_with_manager, sync_with_manager, update_fields,
and has_picture_source property.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/storage/key_colors_picture_target.py

@@ -74,6 +74,34 @@ class KeyColorsPictureTarget(PictureTarget):
     picture_source_id: str = ""
     settings: KeyColorsSettings = field(default_factory=KeyColorsSettings)
 
+    def register_with_manager(self, manager) -> None:
+        """Register this KC target with the processor manager."""
+        manager.add_kc_target(
+            target_id=self.id,
+            picture_source_id=self.picture_source_id,
+            settings=self.settings,
+        )
+
+    def sync_with_manager(self, manager, *, settings_changed: bool, source_changed: bool, device_changed: bool) -> None:
+        """Push changed fields to the processor manager."""
+        if settings_changed:
+            manager.update_target_settings(self.id, self.settings)
+        if source_changed:
+            manager.update_target_source(self.id, self.picture_source_id)
+
+    def update_fields(self, *, name=None, device_id=None, picture_source_id=None,
+                      settings=None, key_colors_settings=None, description=None) -> None:
+        """Apply mutable field updates for KC targets."""
+        super().update_fields(name=name, description=description)
+        if picture_source_id is not None:
+            self.picture_source_id = picture_source_id
+        if key_colors_settings is not None:
+            self.settings = key_colors_settings
+
+    @property
+    def has_picture_source(self) -> bool:
+        return True
+
     def to_dict(self) -> dict:
         d = super().to_dict()
         d["picture_source_id"] = self.picture_source_id

server/src/wled_controller/storage/picture_target.py

@@ -16,6 +16,27 @@ class PictureTarget:
     updated_at: datetime
     description: Optional[str] = None
 
+    def register_with_manager(self, manager) -> None:
+        """Register this target with the processor manager. Subclasses override."""
+        pass
+
+    def sync_with_manager(self, manager, *, settings_changed: bool, source_changed: bool, device_changed: bool) -> None:
+        """Push changed fields to a running processor. Subclasses override."""
+        pass
+
+    def update_fields(self, *, name=None, device_id=None, picture_source_id=None,
+                      settings=None, key_colors_settings=None, description=None) -> None:
+        """Apply mutable field updates. Base handles common fields; subclasses handle type-specific ones."""
+        if name is not None:
+            self.name = name
+        if description is not None:
+            self.description = description
+
+    @property
+    def has_picture_source(self) -> bool:
+        """Whether this target type uses a picture source."""
+        return False
+
     def to_dict(self) -> dict:
         """Convert to dictionary."""
         return {

server/src/wled_controller/storage/picture_target_store.py

@@ -190,24 +190,15 @@ class PictureTargetStore:
             for other in self._targets.values():
                 if other.id != target_id and other.name == name:
                     raise ValueError(f"Picture target with name '{name}' already exists")
-            target.name = name
 
-        if description is not None:
-            target.description = description
-
-        if isinstance(target, WledPictureTarget):
-            if device_id is not None:
-                target.device_id = device_id
-            if picture_source_id is not None:
-                target.picture_source_id = picture_source_id
-            if settings is not None:
-                target.settings = settings
-
-        if isinstance(target, KeyColorsPictureTarget):
-            if picture_source_id is not None:
-                target.picture_source_id = picture_source_id
-            if key_colors_settings is not None:
-                target.settings = key_colors_settings
+        target.update_fields(
+            name=name,
+            device_id=device_id,
+            picture_source_id=picture_source_id,
+            settings=settings,
+            key_colors_settings=key_colors_settings,
+            description=description,
+        )
 
         target.updated_at = datetime.utcnow()
         self._save()
@@ -239,7 +230,7 @@ class PictureTargetStore:
     def is_referenced_by_source(self, source_id: str) -> bool:
         """Check if any target references a picture source."""
         for target in self._targets.values():
-            if isinstance(target, (WledPictureTarget, KeyColorsPictureTarget)) and target.picture_source_id == source_id:
+            if target.has_picture_source and target.picture_source_id == source_id:
                 return True
         return False
 

server/src/wled_controller/storage/wled_picture_target.py

@@ -16,6 +16,40 @@ class WledPictureTarget(PictureTarget):
     picture_source_id: str = ""
     settings: ProcessingSettings = field(default_factory=ProcessingSettings)
 
+    def register_with_manager(self, manager) -> None:
+        """Register this WLED target with the processor manager."""
+        if self.device_id:
+            manager.add_target(
+                target_id=self.id,
+                device_id=self.device_id,
+                settings=self.settings,
+                picture_source_id=self.picture_source_id,
+            )
+
+    def sync_with_manager(self, manager, *, settings_changed: bool, source_changed: bool, device_changed: bool) -> None:
+        """Push changed fields to the processor manager."""
+        if settings_changed:
+            manager.update_target_settings(self.id, self.settings)
+        if source_changed:
+            manager.update_target_source(self.id, self.picture_source_id)
+        if device_changed:
+            manager.update_target_device(self.id, self.device_id)
+
+    def update_fields(self, *, name=None, device_id=None, picture_source_id=None,
+                      settings=None, key_colors_settings=None, description=None) -> None:
+        """Apply mutable field updates for WLED targets."""
+        super().update_fields(name=name, description=description)
+        if device_id is not None:
+            self.device_id = device_id
+        if picture_source_id is not None:
+            self.picture_source_id = picture_source_id
+        if settings is not None:
+            self.settings = settings
+
+    @property
+    def has_picture_source(self) -> bool:
+        return True
+
     def to_dict(self) -> dict:
         """Convert to dictionary."""
         d = super().to_dict()