feat: split frame strength into high/low noise strength per frame

Each frame path now has two strength fields instead of one:
'start frame high strength', 'start frame low strength' (and same
for middle/end). Migration splits old single 'X frame strength' into
both new keys using the same value.

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

api_routes.py

@@ -96,9 +96,12 @@ def _get_data(name: str, file_name: str, seq: int = Query(default=1)) -> dict[st
     result = dict(match)
     # Inject strength defaults if not yet saved to JSON
     for key, default in (
-        ("start frame strength", 1.0),
-        ("middle frame strength", 1.0),
-        ("end frame strength", 1.0),
+        ("start frame high strength", 1.0),
+        ("start frame low strength", 1.0),
+        ("middle frame high strength", 1.0),
+        ("middle frame low strength", 1.0),
+        ("end frame high strength", 1.0),
+        ("end frame low strength", 1.0),
     ):
         result.setdefault(key, default)
     # Computed stem names from frame paths
@@ -133,7 +136,11 @@ def _get_keys(name: str, file_name: str, seq: int = Query(default=1)) -> dict[st
         else:
             types.append("STRING")
     # Injected defaults — always present even if not yet saved to JSON
-    for key in ("start frame strength", "middle frame strength", "end frame strength"):
+    for key in (
+        "start frame high strength", "start frame low strength",
+        "middle frame high strength", "middle frame low strength",
+        "end frame high strength", "end frame low strength",
+    ):
         if key not in match:
             keys.append(key)
             types.append("FLOAT")

tab_batch_ng.py

@@ -317,9 +317,9 @@ def render_batch_processor(state: AppState):
         'seed', 'camera', KEY_SEQUENCE_NUMBER,
         'frame_to_skip', 'logic index', 'transition', 'vace_length',
         'input_a_frames', 'input_b_frames', 'reference switch', 'vace schedule',
-        'start frame path', 'start frame strength',
-        'middle frame path', 'middle frame strength',
-        'end frame path', 'end frame strength',
+        'start frame path', 'start frame high strength', 'start frame low strength',
+        'middle frame path', 'middle frame high strength', 'middle frame low strength',
+        'end frame path', 'end frame high strength', 'end frame low strength',
         'video file path',
     }
     standard_keys.update(lora_keys)
@@ -560,10 +560,10 @@ def _render_sequence_card(i, seq, batch_list, data, file_path, state,
 
                 # --- Frame paths (start / middle / end) ---
                 logic_val = int(seq.get('logic index', 0))
-                for bit, img_label, img_key, str_key in [
-                    (0, 'Start Frame', 'start frame path', 'start frame strength'),
-                    (1, 'Middle Frame', 'middle frame path', 'middle frame strength'),
-                    (2, 'End Frame', 'end frame path', 'end frame strength'),
+                for bit, img_label, img_key, hi_key, lo_key in [
+                    (0, 'Start Frame', 'start frame path', 'start frame high strength', 'start frame low strength'),
+                    (1, 'Middle Frame', 'middle frame path', 'middle frame high strength', 'middle frame low strength'),
+                    (2, 'End Frame', 'end frame path', 'end frame high strength', 'end frame low strength'),
                 ]:
                     ui.label(img_label).classes('text-caption text-weight-bold q-mt-sm')
                     with ui.row().classes('w-full items-center no-wrap q-mt-xs'):
@@ -581,11 +581,13 @@ def _render_sequence_card(i, seq, batch_list, data, file_path, state,
                                 f'style="width:36px;height:36px;object-fit:cover;'
                                 f'border-radius:4px;cursor:pointer;flex-shrink:0">'
                             ).on('click', img_dlg.open)
-                        str_inp = dict_number('Strength', seq, str_key, default=1.0,
-                                              step=0.05, format='%.2f').style(
-                            'width:80px').props('outlined dense')
                         sw = ui.switch(value=bool((logic_val >> bit) & 1))
                         frame_switches.append(sw)
+                    with ui.row().classes('w-full no-wrap q-mt-xs q-gutter-xs'):
+                        dict_number('High', seq, hi_key, default=1.0,
+                                    step=0.05, format='%.2f').classes('col').props('outlined dense')
+                        dict_number('Low', seq, lo_key, default=1.0,
+                                    step=0.05, format='%.2f').classes('col').props('outlined dense')
 
             with splitter.after:
                 # Mode

utils.py

@@ -44,11 +44,14 @@ DEFAULTS = {
     "reference switch": 1,
     "video file path": "",
     "start frame path": "",
-    "start frame strength": 1.0,
+    "start frame high strength": 1.0,
+    "start frame low strength": 1.0,
     "middle frame path": "",
-    "middle frame strength": 1.0,
+    "middle frame high strength": 1.0,
+    "middle frame low strength": 1.0,
     "end frame path": "",
-    "end frame strength": 1.0,
+    "end frame high strength": 1.0,
+    "end frame low strength": 1.0,
 
     # --- LoRAs (name as STRING, strength as FLOAT) ---
     "lora 1 high": "",
@@ -173,6 +176,13 @@ def _migrate_key_renames(data: dict) -> None:
             item['end frame path'] = item.pop('flf image path')
         if 'reference image path' in item and 'start frame path' not in item:
             item['start frame path'] = item.pop('reference image path')
+        # Split old single strength into high+low
+        for prefix in ('start frame', 'middle frame', 'end frame'):
+            old_key = f'{prefix} strength'
+            if old_key in item:
+                val = item.pop(old_key)
+                item.setdefault(f'{prefix} high strength', val)
+                item.setdefault(f'{prefix} low strength', val)
 
 
 def _migrate_lora_keys(data: dict) -> None: