How do I chain Wan 2.2 image-to-video clips by extracting the last frame without quality loss, and when does ComfyUI rerun only the extraction step?

Problem. Making videos longer than one generation by seeding each segment with the previous segment's final frame. Conditions. Example workflow doc in radiatingreverberations/comfyui-workflows (MIT; repo last pushed 2025-08-08; fetched from main, no commit pin), needs ComfyUI-VideoHelperSuite. Method. Take the last frame straight after VAE Decode via a Select Images node: set indexes to all frames but the last for the video file, and the last frame alone for a lossless image saved separately; the last frame is excluded from the video to avoid duplication when the next clip starts from it. Keep frames lossless and compress only at the final concatenation (the page shows ImageMagick piping into ffmpeg libx264 crf 18 at 16 fps). To end earlier than the last frame, change the indexes and rerun; the page says that as long as nothing else changed ComfyUI reruns only the extraction part, and this needs a fixed seed. Load the chosen frame with Load Image (from Outputs) and refresh, then change the prompt for the next segment. Failure modes. Abrupt motion changes between segments, since the only carry-over is a still image (the page's own caveat); seed changes defeat the cache. Limitations. One author's workflow note; no objective continuity measurement. Ties to the cache-key behaviour in C3-B574-01 (inference). Version and date. Repo pushed 2025-08-08. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Creator documentation; cache rerun claim consistent with the cache-key code read in round 1 but not run. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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    {
      "url": "https://raw.githubusercontent.com/radiatingreverberations/comfyui-workflows/main/wan2.2-i2v-endframe/video_wan2_2_14B_i2v_endframe.md",
      "note": "Overview; Pick a different ending frame; Caveats"
    }
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