Zhenzhen_video_extend

Video models hand you five seconds and call it a day. Comfly_video_extend is the ComfyUI node that pushes a Kling-generated clip a few seconds further, continuing naturally from the last frame instead of starting over. It's part of the Comfly pack's Kling group, which means it runs entirely through the ai.comfly.chat relay under your API key - no local model, billed per extension.

The mechanism is simple in the best way: you hand it a video_id (the task id from a Kling generation on the relay) and a prompt, it POSTs to the relay's /kling/v1/videos/video-extend endpoint, then polls every couple of seconds until the extension is done. Out comes a new VIDEO object plus a fresh video_id you can chain into another extension.

Inputs

• video_id - the task id from a prior Kling video generation. This is a STRING input marked as force-input, so wire it from another node's task_id output or paste it in.
• prompt - what should happen in the extension. Keep it in the same spirit as the original shot ("camera continues, she looks up") so the model has somewhere to go.
• api_key - optional, as everywhere in this pack.

Outputs

video is a ComfyUI VIDEO object - plug it straight into the built-in Save Video node and the README is explicit that this is the intended path. video_id is the new task id for chaining another extension. response is the JSON status blob, which is also where errors land (task_status, task_status_msg).

Install

Same pack, same drill:

cd ComfyUI/custom_nodes
git clone https://github.com/ainewsto/Comfyui_Comfly

or ComfyUI Manager → search "Comfyui_Comfly" → install → restart. API key from ai.comfly.chat in the api_key field.

Where it gets fiddly

The README's Kling notes matter here: Kling's video extension historically only supported the v1.0 model - check which model produced your video_id before you chain an extension, or you'll get a task that fails with a model mismatch buried in response. Extensions are also incremental and billed per call, so the sane pattern is: generate → extend → extend the extension, rather than one long request. And like every node in this pack, it's dead in the water if the relay is down - there's no local fallback. It's a simple, honest node for a simple job: a few more seconds of Kling footage without leaving ComfyUI.