feat(video): support first-last-frame for Wan 2.2 I2V

The I2V path forwards a last-frame image to the pipeline when one is supplied and the loaded pipeline accepts it, turning the run into first-last-frame interpolation. supports_last_frame() gates on the pipeline taking a last_image argument and not running expand_timesteps, which conditions on the first frame only, so a model that cannot use a last frame logs a warning instead of silently ignoring it.

modules/video_models/video_run.py

@@ -67,7 +67,13 @@ def generate(*args, **kwargs):
         if init_image is None:
             return video_utils.queue_err('No input image provided. Please upload or select an image.')
         p.task_args['image'] = images.resize_image(resize_mode=2, im=init_image, width=p.width, height=p.height, upscaler_name=None, output_type='pil')
-        log.debug(f'Video: op=I2V init={init_image} resized={p.task_args["image"]}')
+        if last_image is not None and video_utils.supports_last_frame(shared.sd_model):
+            p.task_args['last_image'] = images.resize_image(resize_mode=2, im=last_image, width=p.width, height=p.height, upscaler_name=None, output_type='pil')
+            log.debug(f'Video: op=FLF2V init={init_image} last={last_image} resized={p.task_args["image"]}')
+        elif last_image is not None:
+            log.warning(f'Video: op=I2V model="{model}" last frame not supported, ignoring')
+        else:
+            log.debug(f'Video: op=I2V init={init_image} resized={p.task_args["image"]}')
     elif 'FLF2V' in model:
         if init_image is None:
             return video_utils.queue_err('No input image provided. Please upload or select an image.')

modules/video_models/video_utils.py

@@ -1,6 +1,7 @@
 import os
 import sys
 import time
+import inspect
 from PIL import Image
 from installer import install
 from modules import shared, sd_models, timer, errors, devices
@@ -19,6 +20,18 @@ def get_url(url):
     return f'<a href="{url}" target="_blank" rel="noopener noreferrer" class="video-model-link">{url}</a><br><br>' if url else '<br><br>'
 
 
+def supports_last_frame(model):
+    # last-frame (FLF2V) conditioning needs a pipeline whose __call__ accepts `last_image`.
+    # wan 2.2 5b accepts the arg but masks timesteps from the first frame only, so it drops the last frame.
+    try:
+        params = list(inspect.signature(type(model).__call__, follow_wrapped=True).parameters)
+    except (ValueError, TypeError):
+        return False
+    if 'last_image' not in params:
+        return False
+    return not getattr(getattr(model, 'config', None), 'expand_timesteps', False)
+
+
 def check_av():
     install('av')
     try: