diff --git a/server/src/wled_controller/api/routes/audio_sources.py b/server/src/wled_controller/api/routes/audio_sources.py
index 6f20a54..6fc5651 100644
--- a/server/src/wled_controller/api/routes/audio_sources.py
+++ b/server/src/wled_controller/api/routes/audio_sources.py
@@ -24,6 +24,7 @@ from wled_controller.storage.audio_source import AudioSource
 from wled_controller.storage.audio_source_store import AudioSourceStore
 from wled_controller.storage.color_strip_store import ColorStripStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -42,7 +43,7 @@ def _to_response(source: AudioSource) -> AudioSourceResponse:
         audio_source_id=getattr(source, "audio_source_id", None),
         channel=getattr(source, "channel", None),
         description=source.description,
-        tags=getattr(source, 'tags', []),
+        tags=source.tags,
         created_at=source.created_at,
         updated_at=source.updated_at,
     )
@@ -85,6 +86,9 @@ async def create_audio_source(
         )
         fire_entity_event("audio_source", "created", source.id)
         return _to_response(source)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -125,6 +129,9 @@ async def update_audio_source(
         )
         fire_entity_event("audio_source", "updated", source_id)
         return _to_response(source)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -148,6 +155,9 @@ async def delete_audio_source(
 
         store.delete_source(source_id)
         fire_entity_event("audio_source", "deleted", source_id)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
diff --git a/server/src/wled_controller/api/routes/audio_templates.py b/server/src/wled_controller/api/routes/audio_templates.py
index 98f72f0..f42ab4b 100644
--- a/server/src/wled_controller/api/routes/audio_templates.py
+++ b/server/src/wled_controller/api/routes/audio_templates.py
@@ -19,6 +19,7 @@ from wled_controller.core.audio.factory import AudioEngineRegistry
 from wled_controller.storage.audio_template_store import AudioTemplateStore
 from wled_controller.storage.audio_source_store import AudioSourceStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -38,7 +39,7 @@ async def list_audio_templates(
         responses = [
             AudioTemplateResponse(
                 id=t.id, name=t.name, engine_type=t.engine_type,
-                engine_config=t.engine_config, tags=getattr(t, 'tags', []),
+                engine_config=t.engine_config, tags=t.tags,
                 created_at=t.created_at,
                 updated_at=t.updated_at, description=t.description,
             )
@@ -66,10 +67,13 @@ async def create_audio_template(
         fire_entity_event("audio_template", "created", template.id)
         return AudioTemplateResponse(
             id=template.id, name=template.name, engine_type=template.engine_type,
-            engine_config=template.engine_config, tags=getattr(template, 'tags', []),
+            engine_config=template.engine_config, tags=template.tags,
             created_at=template.created_at,
             updated_at=template.updated_at, description=template.description,
         )
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -90,7 +94,7 @@ async def get_audio_template(
         raise HTTPException(status_code=404, detail=f"Audio template {template_id} not found")
     return AudioTemplateResponse(
         id=t.id, name=t.name, engine_type=t.engine_type,
-        engine_config=t.engine_config, tags=getattr(t, 'tags', []),
+        engine_config=t.engine_config, tags=t.tags,
         created_at=t.created_at,
         updated_at=t.updated_at, description=t.description,
     )
@@ -113,10 +117,13 @@ async def update_audio_template(
         fire_entity_event("audio_template", "updated", template_id)
         return AudioTemplateResponse(
             id=t.id, name=t.name, engine_type=t.engine_type,
-            engine_config=t.engine_config, tags=getattr(t, 'tags', []),
+            engine_config=t.engine_config, tags=t.tags,
             created_at=t.created_at,
             updated_at=t.updated_at, description=t.description,
         )
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -137,6 +144,9 @@ async def delete_audio_template(
         fire_entity_event("audio_template", "deleted", template_id)
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
diff --git a/server/src/wled_controller/api/routes/automations.py b/server/src/wled_controller/api/routes/automations.py
index 6552504..c9bfcac 100644
--- a/server/src/wled_controller/api/routes/automations.py
+++ b/server/src/wled_controller/api/routes/automations.py
@@ -33,6 +33,7 @@ from wled_controller.storage.automation import (
 from wled_controller.storage.automation_store import AutomationStore
 from wled_controller.storage.scene_preset_store import ScenePresetStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 router = APIRouter()
@@ -113,7 +114,7 @@ def _automation_to_response(automation, engine: AutomationEngine, request: Reque
         is_active=state["is_active"],
         last_activated_at=state.get("last_activated_at"),
         last_deactivated_at=state.get("last_deactivated_at"),
-        tags=getattr(automation, 'tags', []),
+        tags=automation.tags,
         created_at=automation.created_at,
         updated_at=automation.updated_at,
     )
@@ -163,6 +164,9 @@ async def create_automation(
 
     try:
         conditions = [_condition_from_schema(c) for c in data.conditions]
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -249,6 +253,9 @@ async def update_automation(
     if data.conditions is not None:
         try:
             conditions = [_condition_from_schema(c) for c in data.conditions]
+        except EntityNotFoundError as e:
+            raise HTTPException(status_code=404, detail=str(e))
+
         except ValueError as e:
             raise HTTPException(status_code=400, detail=str(e))
 
diff --git a/server/src/wled_controller/api/routes/color_strip_processing.py b/server/src/wled_controller/api/routes/color_strip_processing.py
index 9165d64..d74de07 100644
--- a/server/src/wled_controller/api/routes/color_strip_processing.py
+++ b/server/src/wled_controller/api/routes/color_strip_processing.py
@@ -28,6 +28,7 @@ from wled_controller.storage.color_strip_processing_template_store import ColorS
 from wled_controller.storage.color_strip_store import ColorStripStore
 from wled_controller.storage import DeviceStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -43,7 +44,7 @@ def _cspt_to_response(t) -> ColorStripProcessingTemplateResponse:
         created_at=t.created_at,
         updated_at=t.updated_at,
         description=t.description,
-        tags=getattr(t, 'tags', []),
+        tags=t.tags,
     )
 
 
@@ -79,6 +80,9 @@ async def create_cspt(
         )
         fire_entity_event("cspt", "created", template.id)
         return _cspt_to_response(template)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -119,6 +123,9 @@ async def update_cspt(
         )
         fire_entity_event("cspt", "updated", template_id)
         return _cspt_to_response(template)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -148,6 +155,9 @@ async def delete_cspt(
         fire_entity_event("cspt", "deleted", template_id)
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
diff --git a/server/src/wled_controller/api/routes/color_strip_sources.py b/server/src/wled_controller/api/routes/color_strip_sources.py
index e73f724..57c3e02 100644
--- a/server/src/wled_controller/api/routes/color_strip_sources.py
+++ b/server/src/wled_controller/api/routes/color_strip_sources.py
@@ -42,6 +42,7 @@ from wled_controller.storage.picture_source import ProcessedPictureSource, Scree
 from wled_controller.storage.picture_source_store import PictureSourceStore
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 logger = get_logger(__name__)
 
 router = APIRouter()
@@ -154,6 +155,10 @@ async def create_color_strip_source(
         fire_entity_event("color_strip_source", "created", source.id)
         return _css_to_response(source)
 
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
diff --git a/server/src/wled_controller/api/routes/devices.py b/server/src/wled_controller/api/routes/devices.py
index 9d8f43e..c6e454d 100644
--- a/server/src/wled_controller/api/routes/devices.py
+++ b/server/src/wled_controller/api/routes/devices.py
@@ -30,6 +30,7 @@ from wled_controller.core.processing.processor_manager import ProcessorManager
 from wled_controller.storage import DeviceStore
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -51,7 +52,7 @@ def _device_to_response(device) -> DeviceResponse:
         rgbw=device.rgbw,
         zone_mode=device.zone_mode,
         capabilities=sorted(get_device_capabilities(device.device_type)),
-        tags=getattr(device, 'tags', []),
+        tags=device.tags,
         dmx_protocol=getattr(device, 'dmx_protocol', 'artnet'),
         dmx_start_universe=getattr(device, 'dmx_start_universe', 0),
         dmx_start_channel=getattr(device, 'dmx_start_channel', 1),
diff --git a/server/src/wled_controller/api/routes/output_targets.py b/server/src/wled_controller/api/routes/output_targets.py
index 66b7d76..e672766 100644
--- a/server/src/wled_controller/api/routes/output_targets.py
+++ b/server/src/wled_controller/api/routes/output_targets.py
@@ -59,6 +59,7 @@ from wled_controller.storage.key_colors_output_target import (
 )
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -106,7 +107,7 @@ def _target_to_response(target) -> OutputTargetResponse:
             adaptive_fps=target.adaptive_fps,
             protocol=target.protocol,
             description=target.description,
-            tags=getattr(target, 'tags', []),
+            tags=target.tags,
 
             created_at=target.created_at,
             updated_at=target.updated_at,
@@ -119,7 +120,7 @@ def _target_to_response(target) -> OutputTargetResponse:
             picture_source_id=target.picture_source_id,
             key_colors_settings=_kc_settings_to_schema(target.settings),
             description=target.description,
-            tags=getattr(target, 'tags', []),
+            tags=target.tags,
 
             created_at=target.created_at,
             updated_at=target.updated_at,
@@ -130,7 +131,7 @@ def _target_to_response(target) -> OutputTargetResponse:
             name=target.name,
             target_type=target.target_type,
             description=target.description,
-            tags=getattr(target, 'tags', []),
+            tags=target.tags,
 
             created_at=target.created_at,
             updated_at=target.updated_at,
@@ -188,6 +189,9 @@ async def create_target(
 
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -598,6 +602,9 @@ async def test_kc_target(
 
         try:
             chain = source_store.resolve_stream_chain(target.picture_source_id)
+        except EntityNotFoundError as e:
+            raise HTTPException(status_code=404, detail=str(e))
+
         except ValueError as e:
             raise HTTPException(status_code=400, detail=str(e))
 
@@ -735,6 +742,9 @@ async def test_kc_target(
 
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except RuntimeError as e:
diff --git a/server/src/wled_controller/api/routes/pattern_templates.py b/server/src/wled_controller/api/routes/pattern_templates.py
index 325f3bb..f6d3d23 100644
--- a/server/src/wled_controller/api/routes/pattern_templates.py
+++ b/server/src/wled_controller/api/routes/pattern_templates.py
@@ -19,6 +19,7 @@ from wled_controller.storage.key_colors_output_target import KeyColorRectangle
 from wled_controller.storage.pattern_template_store import PatternTemplateStore
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -37,7 +38,7 @@ def _pat_template_to_response(t) -> PatternTemplateResponse:
         created_at=t.created_at,
         updated_at=t.updated_at,
         description=t.description,
-        tags=getattr(t, 'tags', []),
+        tags=t.tags,
     )
 
 
@@ -76,6 +77,9 @@ async def create_pattern_template(
         )
         fire_entity_event("pattern_template", "created", template.id)
         return _pat_template_to_response(template)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -121,6 +125,9 @@ async def update_pattern_template(
         )
         fire_entity_event("pattern_template", "updated", template_id)
         return _pat_template_to_response(template)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -149,6 +156,9 @@ async def delete_pattern_template(
         fire_entity_event("pattern_template", "deleted", template_id)
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
diff --git a/server/src/wled_controller/api/routes/picture_sources.py b/server/src/wled_controller/api/routes/picture_sources.py
index 3d916ea..07f13bb 100644
--- a/server/src/wled_controller/api/routes/picture_sources.py
+++ b/server/src/wled_controller/api/routes/picture_sources.py
@@ -41,6 +41,7 @@ from wled_controller.storage.postprocessing_template_store import Postprocessing
 from wled_controller.storage.picture_source_store import PictureSourceStore
 from wled_controller.storage.picture_source import ScreenCapturePictureSource, StaticImagePictureSource, VideoCaptureSource
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -62,7 +63,7 @@ def _stream_to_response(s) -> PictureSourceResponse:
         created_at=s.created_at,
         updated_at=s.updated_at,
         description=s.description,
-        tags=getattr(s, 'tags', []),
+        tags=s.tags,
         # Video fields
         url=getattr(s, "url", None),
         loop=getattr(s, "loop", None),
@@ -228,6 +229,9 @@ async def create_picture_source(
         return _stream_to_response(stream)
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -280,6 +284,9 @@ async def update_picture_source(
         )
         fire_entity_event("picture_source", "updated", stream_id)
         return _stream_to_response(stream)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -309,6 +316,9 @@ async def delete_picture_source(
         fire_entity_event("picture_source", "deleted", stream_id)
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -383,6 +393,9 @@ async def test_picture_source(
         # Resolve stream chain
         try:
             chain = store.resolve_stream_chain(stream_id)
+        except EntityNotFoundError as e:
+            raise HTTPException(status_code=404, detail=str(e))
+
         except ValueError as e:
             raise HTTPException(status_code=400, detail=str(e))
 
@@ -541,6 +554,9 @@ async def test_picture_source(
 
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except RuntimeError as e:
diff --git a/server/src/wled_controller/api/routes/postprocessing.py b/server/src/wled_controller/api/routes/postprocessing.py
index 3a8695a..a956c0c 100644
--- a/server/src/wled_controller/api/routes/postprocessing.py
+++ b/server/src/wled_controller/api/routes/postprocessing.py
@@ -36,6 +36,7 @@ from wled_controller.storage.postprocessing_template_store import Postprocessing
 from wled_controller.storage.picture_source_store import PictureSourceStore
 from wled_controller.storage.picture_source import ScreenCapturePictureSource, StaticImagePictureSource
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -51,7 +52,7 @@ def _pp_template_to_response(t) -> PostprocessingTemplateResponse:
         created_at=t.created_at,
         updated_at=t.updated_at,
         description=t.description,
-        tags=getattr(t, 'tags', []),
+        tags=t.tags,
     )
 
 
@@ -61,13 +62,9 @@ async def list_pp_templates(
     store: PostprocessingTemplateStore = Depends(get_pp_template_store),
 ):
     """List all postprocessing templates."""
-    try:
-        templates = store.get_all_templates()
-        responses = [_pp_template_to_response(t) for t in templates]
-        return PostprocessingTemplateListResponse(templates=responses, count=len(responses))
-    except Exception as e:
-        logger.error(f"Failed to list postprocessing templates: {e}")
-        raise HTTPException(status_code=500, detail=str(e))
+    templates = store.get_all_templates()
+    responses = [_pp_template_to_response(t) for t in templates]
+    return PostprocessingTemplateListResponse(templates=responses, count=len(responses))
 
 
 @router.post("/api/v1/postprocessing-templates", response_model=PostprocessingTemplateResponse, tags=["Postprocessing Templates"], status_code=201)
@@ -87,6 +84,9 @@ async def create_pp_template(
         )
         fire_entity_event("pp_template", "created", template.id)
         return _pp_template_to_response(template)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -127,6 +127,9 @@ async def update_pp_template(
         )
         fire_entity_event("pp_template", "updated", template_id)
         return _pp_template_to_response(template)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -156,6 +159,9 @@ async def delete_pp_template(
         fire_entity_event("pp_template", "deleted", template_id)
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -184,6 +190,9 @@ async def test_pp_template(
         # Resolve source stream chain to get the raw stream
         try:
             chain = stream_store.resolve_stream_chain(test_request.source_stream_id)
+        except EntityNotFoundError as e:
+            raise HTTPException(status_code=404, detail=str(e))
+
         except ValueError as e:
             raise HTTPException(status_code=400, detail=str(e))
 
@@ -327,6 +336,9 @@ async def test_pp_template(
 
     except HTTPException:
         raise
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
diff --git a/server/src/wled_controller/api/routes/scene_presets.py b/server/src/wled_controller/api/routes/scene_presets.py
index 2bf3ee9..fda2543 100644
--- a/server/src/wled_controller/api/routes/scene_presets.py
+++ b/server/src/wled_controller/api/routes/scene_presets.py
@@ -28,6 +28,7 @@ from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.storage.scene_preset import ScenePreset
 from wled_controller.storage.scene_preset_store import ScenePresetStore
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 router = APIRouter()
@@ -46,7 +47,7 @@ def _preset_to_response(preset: ScenePreset) -> ScenePresetResponse:
             "fps": t.fps,
         } for t in preset.targets],
         order=preset.order,
-        tags=getattr(preset, 'tags', []),
+        tags=preset.tags,
         created_at=preset.created_at,
         updated_at=preset.updated_at,
     )
@@ -85,6 +86,9 @@ async def create_scene_preset(
 
     try:
         preset = store.create_preset(preset)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
diff --git a/server/src/wled_controller/api/routes/sync_clocks.py b/server/src/wled_controller/api/routes/sync_clocks.py
index 1fb2aa3..6992849 100644
--- a/server/src/wled_controller/api/routes/sync_clocks.py
+++ b/server/src/wled_controller/api/routes/sync_clocks.py
@@ -20,6 +20,7 @@ from wled_controller.storage.sync_clock_store import SyncClockStore
 from wled_controller.storage.color_strip_store import ColorStripStore
 from wled_controller.core.processing.sync_clock_manager import SyncClockManager
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -34,7 +35,7 @@ def _to_response(clock: SyncClock, manager: SyncClockManager) -> SyncClockRespon
         name=clock.name,
         speed=rt.speed if rt else clock.speed,
         description=clock.description,
-        tags=getattr(clock, 'tags', []),
+        tags=clock.tags,
         is_running=rt.is_running if rt else True,
         elapsed_time=rt.get_time() if rt else 0.0,
         created_at=clock.created_at,
@@ -73,6 +74,9 @@ async def create_sync_clock(
         )
         fire_entity_event("sync_clock", "created", clock.id)
         return _to_response(clock, manager)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -114,6 +118,9 @@ async def update_sync_clock(
             manager.update_speed(clock_id, clock.speed)
         fire_entity_event("sync_clock", "updated", clock_id)
         return _to_response(clock, manager)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -137,6 +144,9 @@ async def delete_sync_clock(
         manager.release_all_for(clock_id)
         store.delete_clock(clock_id)
         fire_entity_event("sync_clock", "deleted", clock_id)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
diff --git a/server/src/wled_controller/api/routes/system.py b/server/src/wled_controller/api/routes/system.py
index bc7e8da..fd082e7 100644
--- a/server/src/wled_controller/api/routes/system.py
+++ b/server/src/wled_controller/api/routes/system.py
@@ -68,6 +68,7 @@ psutil.cpu_percent(interval=None)
 
 # GPU monitoring (initialized once in utils.gpu, shared with metrics_history)
 from wled_controller.utils.gpu import nvml_available as _nvml_available, nvml as _nvml, nvml_handle as _nvml_handle
+from wled_controller.storage.base_store import EntityNotFoundError
 
 
 def _get_cpu_name() -> str | None:
@@ -96,8 +97,8 @@ def _get_cpu_name() -> str | None:
                 .decode()
                 .strip()
             )
-    except Exception:
-        pass
+    except Exception as e:
+        logger.warning("CPU name detection failed: %s", e)
     return platform.processor() or None
 
 
@@ -157,7 +158,7 @@ async def list_all_tags(_: AuthRequired):
         items = fn() if fn else None
         if items:
             for item in items:
-                all_tags.update(getattr(item, 'tags', []))
+                all_tags.update(item.tags)
     return {"tags": sorted(all_tags)}
 
 
@@ -205,6 +206,10 @@ async def get_displays(
             count=len(displays),
         )
 
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -265,8 +270,8 @@ def get_system_performance(_: AuthRequired):
                 memory_total_mb=round(mem_info.total / 1024 / 1024, 1),
                 temperature_c=float(temp),
             )
-        except Exception:
-            pass
+        except Exception as e:
+            logger.debug("NVML query failed: %s", e)
 
     return PerformanceResponse(
         cpu_name=_cpu_name,
diff --git a/server/src/wled_controller/api/routes/templates.py b/server/src/wled_controller/api/routes/templates.py
index a417b8b..ea88c3c 100644
--- a/server/src/wled_controller/api/routes/templates.py
+++ b/server/src/wled_controller/api/routes/templates.py
@@ -41,6 +41,7 @@ from wled_controller.storage.template_store import TemplateStore
 from wled_controller.storage.picture_source_store import PictureSourceStore
 from wled_controller.storage.picture_source import ScreenCapturePictureSource
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -64,7 +65,7 @@ async def list_templates(
                 name=t.name,
                 engine_type=t.engine_type,
                 engine_config=t.engine_config,
-                tags=getattr(t, 'tags', []),
+                tags=t.tags,
                 created_at=t.created_at,
                 updated_at=t.updated_at,
                 description=t.description,
@@ -104,12 +105,16 @@ async def create_template(
             name=template.name,
             engine_type=template.engine_type,
             engine_config=template.engine_config,
-            tags=getattr(template, 'tags', []),
+            tags=template.tags,
             created_at=template.created_at,
             updated_at=template.updated_at,
             description=template.description,
         )
 
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -134,7 +139,7 @@ async def get_template(
         name=template.name,
         engine_type=template.engine_type,
         engine_config=template.engine_config,
-        tags=getattr(template, 'tags', []),
+        tags=template.tags,
         created_at=template.created_at,
         updated_at=template.updated_at,
         description=template.description,
@@ -165,12 +170,16 @@ async def update_template(
             name=template.name,
             engine_type=template.engine_type,
             engine_config=template.engine_config,
-            tags=getattr(template, 'tags', []),
+            tags=template.tags,
             created_at=template.created_at,
             updated_at=template.updated_at,
             description=template.description,
         )
 
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -210,6 +219,9 @@ async def delete_template(
 
     except HTTPException:
         raise  # Re-raise HTTP exceptions as-is
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except Exception as e:
@@ -359,6 +371,10 @@ def test_template(
             ),
         )
 
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
     except RuntimeError as e:
diff --git a/server/src/wled_controller/api/routes/value_sources.py b/server/src/wled_controller/api/routes/value_sources.py
index 758574d..547fa1d 100644
--- a/server/src/wled_controller/api/routes/value_sources.py
+++ b/server/src/wled_controller/api/routes/value_sources.py
@@ -23,6 +23,7 @@ from wled_controller.storage.value_source_store import ValueSourceStore
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.core.processing.processor_manager import ProcessorManager
 from wled_controller.utils import get_logger
+from wled_controller.storage.base_store import EntityNotFoundError
 
 logger = get_logger(__name__)
 
@@ -105,6 +106,9 @@ async def create_value_source(
         )
         fire_entity_event("value_source", "created", source.id)
         return _to_response(source)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -158,6 +162,9 @@ async def update_value_source(
         pm.update_value_source(source_id)
         fire_entity_event("value_source", "updated", source_id)
         return _to_response(source)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
@@ -182,6 +189,9 @@ async def delete_value_source(
 
         store.delete_source(source_id)
         fire_entity_event("value_source", "deleted", source_id)
+    except EntityNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+
     except ValueError as e:
         raise HTTPException(status_code=400, detail=str(e))
 
diff --git a/server/src/wled_controller/config.py b/server/src/wled_controller/config.py
index 155cbe1..c1f1f41 100644
--- a/server/src/wled_controller/config.py
+++ b/server/src/wled_controller/config.py
@@ -93,7 +93,7 @@ class Config(BaseSettings):
         if not config_path.exists():
             raise FileNotFoundError(f"Configuration file not found: {config_path}")
 
-        with open(config_path, "r") as f:
+        with open(config_path, "r", encoding="utf-8") as f:
             config_data = yaml.safe_load(f)
 
         return cls(**config_data)
diff --git a/server/src/wled_controller/core/automations/automation_engine.py b/server/src/wled_controller/core/automations/automation_engine.py
index b11819f..b6ad77d 100644
--- a/server/src/wled_controller/core/automations/automation_engine.py
+++ b/server/src/wled_controller/core/automations/automation_engine.py
@@ -398,8 +398,8 @@ class AutomationEngine:
                 "automation_id": automation_id,
                 "action": action,
             })
-        except Exception:
-            pass
+        except Exception as e:
+            logger.error("Automation action failed: %s", e, exc_info=True)
 
     # ===== Public query methods (used by API) =====
 
diff --git a/server/src/wled_controller/core/devices/adalight_client.py b/server/src/wled_controller/core/devices/adalight_client.py
index 2eade9d..a1b5723 100644
--- a/server/src/wled_controller/core/devices/adalight_client.py
+++ b/server/src/wled_controller/core/devices/adalight_client.py
@@ -168,9 +168,7 @@ class AdalightClient(LEDClient):
         else:
             arr = np.array(pixels, dtype=np.uint16)
 
-        if brightness < 255:
-            arr = arr * brightness // 255
-
+        # Note: brightness already applied by processor loop (_cached_brightness)
         np.clip(arr, 0, 255, out=arr)
         rgb_bytes = arr.astype(np.uint8).tobytes()
         return self._header + rgb_bytes
diff --git a/server/src/wled_controller/core/devices/ambiled_client.py b/server/src/wled_controller/core/devices/ambiled_client.py
index 343dd10..b63f975 100644
--- a/server/src/wled_controller/core/devices/ambiled_client.py
+++ b/server/src/wled_controller/core/devices/ambiled_client.py
@@ -40,9 +40,7 @@ class AmbiLEDClient(AdalightClient):
         else:
             arr = np.array(pixels, dtype=np.uint16)
 
-        if brightness < 255:
-            arr = arr * brightness // 255
-
+        # Note: brightness already applied by processor loop (_cached_brightness)
         # Clamp to 0–250: values >250 are command bytes in AmbiLED protocol
         np.clip(arr, 0, 250, out=arr)
         rgb_bytes = arr.astype(np.uint8).tobytes()
diff --git a/server/src/wled_controller/core/devices/chroma_client.py b/server/src/wled_controller/core/devices/chroma_client.py
index f6f02c4..c2327de 100644
--- a/server/src/wled_controller/core/devices/chroma_client.py
+++ b/server/src/wled_controller/core/devices/chroma_client.py
@@ -145,7 +145,7 @@ class ChromaClient(LEDClient):
         else:
             pixel_arr = np.array(pixels, dtype=np.uint8)
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
         device_info = CHROMA_DEVICES.get(self._chroma_device_type)
         if not device_info:
             return False
@@ -156,10 +156,7 @@ class ChromaClient(LEDClient):
         # Chroma uses BGR packed as 0x00BBGGRR integers
         colors = []
         for i in range(n):
-            r, g, b = pixel_arr[i]
-            r = int(r * bri_scale)
-            g = int(g * bri_scale)
-            b = int(b * bri_scale)
+            r, g, b = int(pixel_arr[i][0]), int(pixel_arr[i][1]), int(pixel_arr[i][2])
             colors.append(r | (g << 8) | (b << 16))
 
         # Pad to max_leds if needed
diff --git a/server/src/wled_controller/core/devices/espnow_client.py b/server/src/wled_controller/core/devices/espnow_client.py
index 4077c80..b798585 100644
--- a/server/src/wled_controller/core/devices/espnow_client.py
+++ b/server/src/wled_controller/core/devices/espnow_client.py
@@ -115,7 +115,8 @@ class ESPNowClient(LEDClient):
         else:
             pixel_bytes = bytes(c for rgb in pixels for c in rgb)
 
-        frame = _build_frame(self._peer_mac, pixel_bytes, brightness)
+        # Note: brightness already applied by processor loop; pass 255 to firmware
+        frame = _build_frame(self._peer_mac, pixel_bytes, 255)
         try:
             self._serial.write(frame)
         except Exception as e:
diff --git a/server/src/wled_controller/core/devices/gamesense_client.py b/server/src/wled_controller/core/devices/gamesense_client.py
index 491d100..9e8ee64 100644
--- a/server/src/wled_controller/core/devices/gamesense_client.py
+++ b/server/src/wled_controller/core/devices/gamesense_client.py
@@ -187,7 +187,7 @@ class GameSenseClient(LEDClient):
         else:
             pixel_arr = np.array(pixels, dtype=np.uint8)
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         # Use average color for single-zone devices, or first N for multi-zone
         if len(pixel_arr) == 0:
@@ -195,9 +195,9 @@ class GameSenseClient(LEDClient):
 
         # Compute average color for the zone
         avg = pixel_arr.mean(axis=0)
-        r = int(avg[0] * bri_scale)
-        g = int(avg[1] * bri_scale)
-        b = int(avg[2] * bri_scale)
+        r = int(avg[0])
+        g = int(avg[1])
+        b = int(avg[2])
 
         event_data = {
             "game": GAME_NAME,
diff --git a/server/src/wled_controller/core/devices/hue_client.py b/server/src/wled_controller/core/devices/hue_client.py
index d5d33f2..4320d87 100644
--- a/server/src/wled_controller/core/devices/hue_client.py
+++ b/server/src/wled_controller/core/devices/hue_client.py
@@ -46,13 +46,13 @@ def _build_entertainment_frame(
     header[15] = 0x00  # reserved
 
     # Light data
-    bri_scale = brightness / 255.0
+    # Note: brightness already applied by processor loop (_cached_brightness)
     data = bytearray()
     for idx, (r, g, b) in enumerate(lights):
         light_id = idx  # 0-based light index in entertainment group
-        r16 = int(r * bri_scale * 257)  # scale 0-255 to 0-65535
-        g16 = int(g * bri_scale * 257)
-        b16 = int(b * bri_scale * 257)
+        r16 = int(r * 257)  # scale 0-255 to 0-65535
+        g16 = int(g * 257)
+        b16 = int(b * 257)
         data += struct.pack(">BHHH", light_id, r16, g16, b16)
 
     return bytes(header) + bytes(data)
diff --git a/server/src/wled_controller/core/devices/openrgb_client.py b/server/src/wled_controller/core/devices/openrgb_client.py
index cd8f2c1..e6c9db6 100644
--- a/server/src/wled_controller/core/devices/openrgb_client.py
+++ b/server/src/wled_controller/core/devices/openrgb_client.py
@@ -302,9 +302,7 @@ class OpenRGBLEDClient(LEDClient):
                 return
         self._last_sent_pixels = pixel_array.copy()
 
-        # Apply brightness scaling after dedup
-        if brightness < 255:
-            pixel_array = (pixel_array.astype(np.uint16) * brightness >> 8).astype(np.uint8)
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         # Separate mode: resample full pixel array independently per zone
         if self._zone_mode == "separate" and len(self._target_zones) > 1:
diff --git a/server/src/wled_controller/core/devices/spi_client.py b/server/src/wled_controller/core/devices/spi_client.py
index 3029295..3a4762c 100644
--- a/server/src/wled_controller/core/devices/spi_client.py
+++ b/server/src/wled_controller/core/devices/spi_client.py
@@ -162,7 +162,7 @@ class SPIClient(LEDClient):
         if not self._connected:
             return
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         if isinstance(pixels, np.ndarray):
             pixel_arr = pixels
@@ -176,7 +176,7 @@ class SPIClient(LEDClient):
             except ImportError:
                 return
 
-            self._strip.setBrightness(brightness)
+            self._strip.setBrightness(255)
             for i in range(min(len(pixel_arr), self._led_count)):
                 r, g, b = pixel_arr[i]
                 self._strip.setPixelColor(i, Color(int(r), int(g), int(b)))
@@ -185,7 +185,7 @@ class SPIClient(LEDClient):
         elif self._spi:
             # SPI bitbang path: convert RGB to WS2812 wire format
             # Each bit is encoded as 3 SPI bits: 1=110, 0=100
-            scaled = (pixel_arr[:self._led_count].astype(np.float32) * bri_scale).astype(np.uint8)
+            scaled = pixel_arr[:self._led_count]
             # GRB order for WS2812
             grb = scaled[:, [1, 0, 2]]
             raw_bytes = grb.tobytes()
diff --git a/server/src/wled_controller/core/devices/usbhid_client.py b/server/src/wled_controller/core/devices/usbhid_client.py
index f847899..7fd7574 100644
--- a/server/src/wled_controller/core/devices/usbhid_client.py
+++ b/server/src/wled_controller/core/devices/usbhid_client.py
@@ -100,7 +100,7 @@ class USBHIDClient(LEDClient):
         else:
             pixel_list = list(pixels)
 
-        bri_scale = brightness / 255.0
+        # Note: brightness already applied by processor loop (_cached_brightness)
 
         # Build HID reports — split across multiple reports if needed
         # Each report: [REPORT_ID][CMD][OFFSET_LO][OFFSET_HI][COUNT][R G B R G B ...]
@@ -119,9 +119,9 @@ class USBHIDClient(LEDClient):
 
             for i, (r, g, b) in enumerate(chunk):
                 base = 5 + i * 3
-                report[base] = int(r * bri_scale)
-                report[base + 1] = int(g * bri_scale)
-                report[base + 2] = int(b * bri_scale)
+                report[base] = int(r)
+                report[base + 1] = int(g)
+                report[base + 2] = int(b)
 
             reports.append(bytes(report))
             offset += len(chunk)
diff --git a/server/src/wled_controller/core/devices/wled_client.py b/server/src/wled_controller/core/devices/wled_client.py
index 1aa8d9c..e091240 100644
--- a/server/src/wled_controller/core/devices/wled_client.py
+++ b/server/src/wled_controller/core/devices/wled_client.py
@@ -378,9 +378,7 @@ class WLEDClient(LEDClient):
             True if successful
         """
         try:
-            if brightness < 255:
-                pixels = (pixels.astype(np.uint16) * brightness >> 8).astype(np.uint8)
-
+            # Note: brightness already applied by processor loop (_cached_brightness)
             logger.debug(f"Sending {len(pixels)} LEDs via DDP")
             self._ddp_client.send_pixels_numpy(pixels)
             logger.debug(f"Successfully sent pixel colors via DDP")
@@ -419,7 +417,7 @@ class WLEDClient(LEDClient):
             # Build WLED JSON state
             payload = {
                 "on": True,
-                "bri": int(brightness),
+                "bri": 255,  # brightness already applied by processor loop
                 "seg": [
                     {
                         "id": segment_id,
@@ -461,9 +459,7 @@ class WLEDClient(LEDClient):
         else:
             pixel_array = np.array(pixels, dtype=np.uint8)
 
-        if brightness < 255:
-            pixel_array = (pixel_array.astype(np.uint16) * brightness >> 8).astype(np.uint8)
-
+        # Note: brightness already applied by processor loop (_cached_brightness)
         self._ddp_client.send_pixels_numpy(pixel_array)
 
     # ===== LEDClient abstraction methods =====
diff --git a/server/src/wled_controller/core/processing/api_input_stream.py b/server/src/wled_controller/core/processing/api_input_stream.py
index 1b43c6e..9db157a 100644
--- a/server/src/wled_controller/core/processing/api_input_stream.py
+++ b/server/src/wled_controller/core/processing/api_input_stream.py
@@ -92,7 +92,11 @@ class ApiInputColorStripStream(ColorStripStream):
             if n > self._led_count:
                 self._ensure_capacity(n)
             if n == self._led_count:
-                self._colors = colors.astype(np.uint8)
+                if self._colors.shape == colors.shape:
+                    np.copyto(self._colors, colors, casting='unsafe')
+                else:
+                    self._colors = np.empty((n, 3), dtype=np.uint8)
+                    np.copyto(self._colors, colors, casting='unsafe')
             elif n < self._led_count:
                 # Zero-pad to led_count
                 padded = np.zeros((self._led_count, 3), dtype=np.uint8)
diff --git a/server/src/wled_controller/core/processing/composite_stream.py b/server/src/wled_controller/core/processing/composite_stream.py
index ff61ef0..f73ca6b 100644
--- a/server/src/wled_controller/core/processing/composite_stream.py
+++ b/server/src/wled_controller/core/processing/composite_stream.py
@@ -48,12 +48,22 @@ class CompositeColorStripStream(ColorStripStream):
         self._latest_colors: Optional[np.ndarray] = None
         self._latest_layer_colors: Optional[List[np.ndarray]] = None
         self._colors_lock = threading.Lock()
+        self._need_layer_snapshots: bool = False  # set True when get_layer_colors() is called
 
         # layer_index -> (source_id, consumer_id, stream)
         self._sub_streams: Dict[int, tuple] = {}
         # layer_index -> (vs_id, value_stream)
         self._brightness_streams: Dict[int, tuple] = {}
         self._sub_lock = threading.Lock()  # guards _sub_streams and _brightness_streams
+        self._sub_streams_version: int = 0  # bumped when _sub_streams changes
+        self._sub_snapshot_version: int = -1  # version of cached snapshot
+        self._sub_snapshot_cache: Dict[int, tuple] = {}  # cached dict(self._sub_streams)
+
+        # Pre-resolved blend methods: blend_mode_str -> bound method
+        self._blend_methods = {
+            k: getattr(self, v) for k, v in self._BLEND_DISPATCH.items()
+        }
+        self._default_blend_method = self._blend_normal
 
         # Pre-allocated scratch (rebuilt when LED count changes)
         self._pool_n = 0
@@ -111,6 +121,7 @@ class CompositeColorStripStream(ColorStripStream):
 
     def get_layer_colors(self) -> Optional[List[np.ndarray]]:
         """Return per-layer color snapshots (after resize/brightness, before blending)."""
+        self._need_layer_snapshots = True
         with self._colors_lock:
             return self._latest_layer_colors
 
@@ -165,6 +176,7 @@ class CompositeColorStripStream(ColorStripStream):
     # ── Sub-stream lifecycle ────────────────────────────────────
 
     def _acquire_sub_streams(self) -> None:
+        self._sub_streams_version += 1
         for i, layer in enumerate(self._layers):
             if not layer.get("enabled", True):
                 continue
@@ -193,6 +205,7 @@ class CompositeColorStripStream(ColorStripStream):
                     )
 
     def _release_sub_streams(self) -> None:
+        self._sub_streams_version += 1
         for _idx, (src_id, consumer_id, _stream) in list(self._sub_streams.items()):
             try:
                 self._css_manager.release(src_id, consumer_id)
@@ -356,7 +369,10 @@ class CompositeColorStripStream(ColorStripStream):
                     layer_snapshots: List[np.ndarray] = []
 
                     with self._sub_lock:
-                        sub_snapshot = dict(self._sub_streams)
+                        if self._sub_streams_version != self._sub_snapshot_version:
+                            self._sub_snapshot_cache = dict(self._sub_streams)
+                            self._sub_snapshot_version = self._sub_streams_version
+                        sub_snapshot = self._sub_snapshot_cache
 
                     for i, layer in enumerate(self._layers):
                         if not layer.get("enabled", True):
@@ -412,7 +428,8 @@ class CompositeColorStripStream(ColorStripStream):
                                 colors = (colors.astype(np.uint16) * int(bri * 256) >> 8).astype(np.uint8)
 
                         # Snapshot layer colors before blending (copy — may alias shared buf)
-                        layer_snapshots.append(colors.copy())
+                        if self._need_layer_snapshots:
+                            layer_snapshots.append(colors.copy())
 
                         opacity = layer.get("opacity", 1.0)
                         blend_mode = layer.get("blend_mode", _BLEND_NORMAL)
@@ -425,11 +442,11 @@ class CompositeColorStripStream(ColorStripStream):
                                 result_buf[:] = colors
                             else:
                                 result_buf[:] = 0
-                                blend_fn = getattr(self, self._BLEND_DISPATCH.get(blend_mode, "_blend_normal"))
+                                blend_fn = self._blend_methods.get(blend_mode, self._default_blend_method)
                                 blend_fn(result_buf, colors, alpha, result_buf)
                             has_result = True
                         else:
-                            blend_fn = getattr(self, self._BLEND_DISPATCH.get(blend_mode, "_blend_normal"))
+                            blend_fn = self._blend_methods.get(blend_mode, self._default_blend_method)
                             blend_fn(result_buf, colors, alpha, result_buf)
 
                     if has_result:
diff --git a/server/src/wled_controller/core/processing/metrics_history.py b/server/src/wled_controller/core/processing/metrics_history.py
index 3cf5fa8..25df874 100644
--- a/server/src/wled_controller/core/processing/metrics_history.py
+++ b/server/src/wled_controller/core/processing/metrics_history.py
@@ -91,7 +91,8 @@ class MetricsHistory:
         # Per-target metrics from processor states
         try:
             all_states = self._manager.get_all_target_states()
-        except Exception:
+        except Exception as e:
+            logger.error("Failed to get target states: %s", e)
             all_states = {}
 
         now = datetime.now(timezone.utc).isoformat()
diff --git a/server/src/wled_controller/core/processing/target_processor.py b/server/src/wled_controller/core/processing/target_processor.py
index 40d6dea..6c3fcde 100644
--- a/server/src/wled_controller/core/processing/target_processor.py
+++ b/server/src/wled_controller/core/processing/target_processor.py
@@ -43,6 +43,7 @@ class ProcessingMetrics:
     errors_count: int = 0
     last_error: Optional[str] = None
     last_update: Optional[datetime] = None
+    last_update_mono: float = 0.0  # monotonic timestamp for hot-path; lazily converted to last_update on read
     start_time: Optional[datetime] = None
     fps_actual: float = 0.0
     fps_potential: float = 0.0
diff --git a/server/src/wled_controller/core/processing/value_stream.py b/server/src/wled_controller/core/processing/value_stream.py
index 7d0467b..e681e61 100644
--- a/server/src/wled_controller/core/processing/value_stream.py
+++ b/server/src/wled_controller/core/processing/value_stream.py
@@ -22,6 +22,7 @@ from __future__ import annotations
 
 import math
 import time
+from abc import ABC, abstractmethod
 from datetime import datetime
 from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
 
@@ -43,12 +44,13 @@ logger = get_logger(__name__)
 # Base class
 # ---------------------------------------------------------------------------
 
-class ValueStream:
+class ValueStream(ABC):
     """Abstract base for runtime value streams."""
 
+    @abstractmethod
     def get_value(self) -> float:
         """Return current scalar value (0.0–1.0)."""
-        return 1.0
+        ...
 
     def start(self) -> None:
         """Acquire resources (if any)."""
diff --git a/server/src/wled_controller/core/processing/wled_target_processor.py b/server/src/wled_controller/core/processing/wled_target_processor.py
index 6f4b729..3aca515 100644
--- a/server/src/wled_controller/core/processing/wled_target_processor.py
+++ b/server/src/wled_controller/core/processing/wled_target_processor.py
@@ -382,6 +382,14 @@ class WledTargetProcessor(TargetProcessor):
         else:
             total_ms = None
 
+        # Lazily convert monotonic timestamp to UTC datetime for API
+        last_update = metrics.last_update
+        if metrics.last_update_mono > 0:
+            elapsed = time.monotonic() - metrics.last_update_mono
+            last_update = datetime.now(timezone.utc) if elapsed < 1.0 else datetime.fromtimestamp(
+                time.time() - elapsed, tz=timezone.utc
+            )
+
         return {
             "target_id": self._target_id,
             "device_id": self._device_id,
@@ -405,7 +413,7 @@ class WledTargetProcessor(TargetProcessor):
             "display_index": self._resolved_display_index,
             "overlay_active": self._overlay_active,
             "needs_keepalive": self._needs_keepalive,
-            "last_update": metrics.last_update,
+            "last_update": last_update,
             "errors": [metrics.last_error] if metrics.last_error else [],
             "device_streaming_reachable": self._device_reachable if self._is_running else None,
             "fps_effective": self._effective_fps if self._is_running else None,
@@ -419,6 +427,14 @@ class WledTargetProcessor(TargetProcessor):
         if metrics.start_time and self._is_running:
             uptime_seconds = (datetime.now(timezone.utc) - metrics.start_time).total_seconds()
 
+        # Lazily convert monotonic timestamp to UTC datetime for API
+        last_update = metrics.last_update
+        if metrics.last_update_mono > 0:
+            elapsed = time.monotonic() - metrics.last_update_mono
+            last_update = datetime.now(timezone.utc) if elapsed < 1.0 else datetime.fromtimestamp(
+                time.time() - elapsed, tz=timezone.utc
+            )
+
         return {
             "target_id": self._target_id,
             "device_id": self._device_id,
@@ -429,7 +445,7 @@ class WledTargetProcessor(TargetProcessor):
             "frames_processed": metrics.frames_processed,
             "errors_count": metrics.errors_count,
             "last_error": metrics.last_error,
-            "last_update": metrics.last_update,
+            "last_update": last_update,
         }
 
     # ----- Overlay -----
@@ -578,7 +594,8 @@ class WledTargetProcessor(TargetProcessor):
         keepalive_interval = self._keepalive_interval
 
         fps_samples: collections.deque = collections.deque(maxlen=10)
-        send_timestamps: collections.deque = collections.deque()
+        _fps_sum = 0.0
+        send_timestamps: collections.deque = collections.deque(maxlen=target_fps + 10)
         last_send_time = 0.0
         _last_preview_broadcast = 0.0
         prev_frame_time_stamp = time.perf_counter()
@@ -728,7 +745,7 @@ class WledTargetProcessor(TargetProcessor):
                         has_any_frame = False
 
                     _diag_device_info_age += 1
-                    if _diag_device_info is None or _diag_device_info_age >= 30:
+                    if _diag_device_info is None or _diag_device_info_age >= 300:
                         _diag_device_info = self._ctx.get_device_info(self._device_id)
                         _diag_device_info_age = 0
                     device_info = _diag_device_info
@@ -822,8 +839,6 @@ class WledTargetProcessor(TargetProcessor):
                                 send_timestamps.append(now)
                                 self._metrics.frames_keepalive += 1
                             self._metrics.frames_skipped += 1
-                            while send_timestamps and send_timestamps[0] < loop_start - 1.0:
-                                send_timestamps.popleft()
                             self._metrics.fps_current = len(send_timestamps)
                             await asyncio.sleep(SKIP_REPOLL)
                             continue
@@ -849,8 +864,6 @@ class WledTargetProcessor(TargetProcessor):
                                     await self._broadcast_led_preview(send_colors, cur_brightness)
                                     _last_preview_broadcast = now
                             self._metrics.frames_skipped += 1
-                            while send_timestamps and send_timestamps[0] < now - 1.0:
-                                send_timestamps.popleft()
                             self._metrics.fps_current = len(send_timestamps)
                             is_animated = stream.is_animated
                             repoll = SKIP_REPOLL if is_animated else frame_time
@@ -888,7 +901,7 @@ class WledTargetProcessor(TargetProcessor):
 
                         self._metrics.timing_send_ms = send_ms
                         self._metrics.frames_processed += 1
-                        self._metrics.last_update = datetime.now(timezone.utc)
+                        self._metrics.last_update_mono = time.monotonic()
 
                         if self._metrics.frames_processed <= 3 or self._metrics.frames_processed % 100 == 0:
                             logger.info(
@@ -900,14 +913,16 @@ class WledTargetProcessor(TargetProcessor):
                         interval = now - prev_frame_time_stamp
                         prev_frame_time_stamp = now
                         if self._metrics.frames_processed > 1:
-                            fps_samples.append(1.0 / interval if interval > 0 else 0)
-                            self._metrics.fps_actual = sum(fps_samples) / len(fps_samples)
+                            new_fps = 1.0 / interval if interval > 0 else 0
+                            if len(fps_samples) == fps_samples.maxlen:
+                                _fps_sum -= fps_samples[0]
+                            fps_samples.append(new_fps)
+                            _fps_sum += new_fps
+                            self._metrics.fps_actual = _fps_sum / len(fps_samples)
 
                         processing_time = now - loop_start
                         self._metrics.fps_potential = 1.0 / processing_time if processing_time > 0 else 0
 
-                        while send_timestamps and send_timestamps[0] < now - 1.0:
-                            send_timestamps.popleft()
                         self._metrics.fps_current = len(send_timestamps)
 
                     except Exception as e:
diff --git a/server/src/wled_controller/storage/audio_template_store.py b/server/src/wled_controller/storage/audio_template_store.py
index 817b32c..d605d39 100644
--- a/server/src/wled_controller/storage/audio_template_store.py
+++ b/server/src/wled_controller/storage/audio_template_store.py
@@ -2,7 +2,7 @@
 
 import uuid
 from datetime import datetime, timezone
-from typing import Dict, List, Optional
+from typing import Any, Dict, List, Optional
 
 from wled_controller.core.audio.factory import AudioEngineRegistry
 from wled_controller.storage.audio_template import AudioCaptureTemplate
@@ -73,7 +73,7 @@ class AudioTemplateStore(BaseJsonStore[AudioCaptureTemplate]):
         self,
         name: str,
         engine_type: str,
-        engine_config: Dict[str, any],
+        engine_config: Dict[str, Any],
         description: Optional[str] = None,
         tags: Optional[List[str]] = None,
     ) -> AudioCaptureTemplate:
@@ -102,7 +102,7 @@ class AudioTemplateStore(BaseJsonStore[AudioCaptureTemplate]):
         template_id: str,
         name: Optional[str] = None,
         engine_type: Optional[str] = None,
-        engine_config: Optional[Dict[str, any]] = None,
+        engine_config: Optional[Dict[str, Any]] = None,
         description: Optional[str] = None,
         tags: Optional[List[str]] = None,
     ) -> AudioCaptureTemplate:
diff --git a/server/src/wled_controller/storage/base_store.py b/server/src/wled_controller/storage/base_store.py
index 2aa9743..9d4e51a 100644
--- a/server/src/wled_controller/storage/base_store.py
+++ b/server/src/wled_controller/storage/base_store.py
@@ -3,7 +3,7 @@
 import json
 import threading
 from pathlib import Path
-from typing import Callable, Dict, Generic, List, TypeVar
+from typing import Callable, ClassVar, Dict, Generic, List, TypeVar
 
 from wled_controller.utils import atomic_write_json, get_logger
 
@@ -11,6 +11,11 @@ T = TypeVar("T")
 logger = get_logger(__name__)
 
 
+class EntityNotFoundError(ValueError):
+    """Raised when an entity is not found in the store."""
+    pass
+
+
 class BaseJsonStore(Generic[T]):
     """JSON-file-backed entity store with common CRUD helpers.
 
@@ -23,17 +28,19 @@ class BaseJsonStore(Generic[T]):
     - ``_json_key``:     root key in JSON file (e.g. ``"sync_clocks"``)
     - ``_entity_name``:  human label for errors (e.g. ``"Sync clock"``)
     - ``_version``:      schema version string (default ``"1.0.0"``)
+    - ``_legacy_json_keys``: fallback root keys for migration (default ``[]``)
     """
 
     _json_key: str
     _entity_name: str
     _version: str = "1.0.0"
+    _legacy_json_keys: ClassVar[List[str]] = []
 
     def __init__(self, file_path: str, deserializer: Callable[[dict], T]):
         self.file_path = Path(file_path)
         self._items: Dict[str, T] = {}
         self._deserializer = deserializer
-        self._lock = threading.Lock()
+        self._lock = threading.RLock()
         self._load()
 
     # ── I/O ────────────────────────────────────────────────────────
@@ -47,7 +54,15 @@ class BaseJsonStore(Generic[T]):
             with open(self.file_path, "r", encoding="utf-8") as f:
                 data = json.load(f)
 
+            # Try primary key, then legacy keys for migration
             items_data = data.get(self._json_key, {})
+            if not items_data:
+                for legacy_key in self._legacy_json_keys:
+                    items_data = data.get(legacy_key, {})
+                    if items_data:
+                        logger.info(f"Migrating {self._entity_name} from legacy key '{legacy_key}'")
+                        break
+
             loaded = 0
             for item_id, item_dict in items_data.items():
                 try:
@@ -76,6 +91,7 @@ class BaseJsonStore(Generic[T]):
         Note: This is synchronous blocking I/O. When called from async route
         handlers, it briefly blocks the event loop (typically < 5ms for small
         stores). Acceptable for user-initiated CRUD; not suitable for hot loops.
+        Callers must hold ``self._lock``.
         """
         try:
             data = {
@@ -93,30 +109,33 @@ class BaseJsonStore(Generic[T]):
     # ── Common CRUD ────────────────────────────────────────────────
 
     def get_all(self) -> List[T]:
-        return list(self._items.values())
+        with self._lock:
+            return list(self._items.values())
 
     def get(self, item_id: str) -> T:
-        if item_id not in self._items:
-            raise ValueError(f"{self._entity_name} not found: {item_id}")
-        return self._items[item_id]
+        with self._lock:
+            if item_id not in self._items:
+                raise EntityNotFoundError(f"{self._entity_name} not found: {item_id}")
+            return self._items[item_id]
 
     def delete(self, item_id: str) -> None:
-        if item_id not in self._items:
-            raise ValueError(f"{self._entity_name} not found: {item_id}")
-        del self._items[item_id]
-        self._save()
+        with self._lock:
+            if item_id not in self._items:
+                raise EntityNotFoundError(f"{self._entity_name} not found: {item_id}")
+            del self._items[item_id]
+            self._save()
         logger.info(f"Deleted {self._entity_name}: {item_id}")
 
     def count(self) -> int:
-        return len(self._items)
+        with self._lock:
+            return len(self._items)
 
     # ── Helpers ────────────────────────────────────────────────────
 
     def _check_name_unique(self, name: str, exclude_id: str = None) -> None:
         """Raise ValueError if *name* is empty or already taken.
 
-        Callers should hold ``self._lock`` when calling this + mutating
-        ``_items`` to prevent race conditions between concurrent requests.
+        Must be called while holding ``self._lock``.
         """
         if not name or not name.strip():
             raise ValueError("Name is required")
diff --git a/server/src/wled_controller/storage/output_target_store.py b/server/src/wled_controller/storage/output_target_store.py
index b7b7f75..82d894f 100644
--- a/server/src/wled_controller/storage/output_target_store.py
+++ b/server/src/wled_controller/storage/output_target_store.py
@@ -24,35 +24,11 @@ class OutputTargetStore(BaseJsonStore[OutputTarget]):
 
     _json_key = "output_targets"
     _entity_name = "Output target"
+    _legacy_json_keys = ["picture_targets"]
 
     def __init__(self, file_path: str):
         super().__init__(file_path, OutputTarget.from_dict)
 
-    def _load(self) -> None:
-        """Override to support legacy 'picture_targets' JSON key."""
-        import json as _json
-        from pathlib import Path
-        if not self.file_path.exists():
-            logger.info(f"{self._entity_name} store file not found — starting empty")
-            return
-        try:
-            with open(self.file_path, "r", encoding="utf-8") as f:
-                data = _json.load(f)
-            targets_data = data.get("output_targets") or data.get("picture_targets", {})
-            loaded = 0
-            for target_id, target_dict in targets_data.items():
-                try:
-                    self._items[target_id] = self._deserializer(target_dict)
-                    loaded += 1
-                except Exception as e:
-                    logger.error(f"Failed to load {self._entity_name} {target_id}: {e}", exc_info=True)
-            if loaded > 0:
-                logger.info(f"Loaded {loaded} {self._json_key} from storage")
-        except Exception as e:
-            logger.error(f"Failed to load {self._json_key} from {self.file_path}: {e}")
-            raise
-        logger.info(f"{self._entity_name} store initialized with {len(self._items)} items")
-
     # Backward-compatible aliases
     get_all_targets = BaseJsonStore.get_all
     get_target = BaseJsonStore.get
diff --git a/server/src/wled_controller/storage/template_store.py b/server/src/wled_controller/storage/template_store.py
index b0e8449..602ef64 100644
--- a/server/src/wled_controller/storage/template_store.py
+++ b/server/src/wled_controller/storage/template_store.py
@@ -2,7 +2,7 @@
 
 import uuid
 from datetime import datetime, timezone
-from typing import Dict, List, Optional
+from typing import Any, Dict, List, Optional
 
 from wled_controller.core.capture_engines.factory import EngineRegistry
 from wled_controller.storage.base_store import BaseJsonStore
@@ -65,7 +65,7 @@ class TemplateStore(BaseJsonStore[CaptureTemplate]):
         self,
         name: str,
         engine_type: str,
-        engine_config: Dict[str, any],
+        engine_config: Dict[str, Any],
         description: Optional[str] = None,
         tags: Optional[List[str]] = None,
     ) -> CaptureTemplate:
@@ -95,7 +95,7 @@ class TemplateStore(BaseJsonStore[CaptureTemplate]):
         template_id: str,
         name: Optional[str] = None,
         engine_type: Optional[str] = None,
-        engine_config: Optional[Dict[str, any]] = None,
+        engine_config: Optional[Dict[str, Any]] = None,
         description: Optional[str] = None,
         tags: Optional[List[str]] = None,
     ) -> CaptureTemplate: