SDWebUIRequestPayloadExtend

SDWebUI_Request_PayloadExtend (shown as SDWebUIRequestPayloadExtend) is the overflow bin for the A1111 txt2img request. The base SDWebUI_Request_Payload node covers the everyday settings; this one carries everything else the AUTOMATIC1111 API accepts but you only touch on special occasions - hires fix, the refiner, seed variation, extra networks, scripts, and a shelf of sampler-adjacent parameters like s_churn and eta.

Honest framing up front: this is the thinnest node in the pack, and for a reason you should hear before you go looking for it. As shipped (v1.0.2), the SDWebUI_Request node's function only reads its payload and backend_url inputs - it never merges in a TXT2IMGRequestExtend payload. So this node's output is a well-formed object you can inspect, but the request node doesn't consume it yet. Connecting it can throw a TypeError about an unexpected argument, or the data just gets ignored, depending on your ComfyUI version. It reads as a half-built feature waiting for the next release. Keep that in mind and treat it as experimental.

What it builds

The node constructs a TXT2IMGRequestExtend - a subclass of the same BaseRequest the base payload uses, but with the advanced A1111 txt2img fields appended. You'll recognize the field names from the A1111 API docs:

• enable_hr with hr_scale, hr_upscaler, hr_second_pass_steps, hr_prompt, hr_negative_prompt, and the resize options - the hires fix block. Flipping enable_hr is the switch that actually does something.
• refiner_checkpoint / refiner_switch_at - the SDXL refiner handoff.
• subseed / subseed_strength - A1111's variation seed.
• restore_faces, tiling, do_not_save_samples / do_not_save_grid, disable_extra_networks.
• script_name / script_args / alwayson_scripts / styles - hooks for A1111 extensions and saved prompt styles, which is where a lot of people would actually want this node to shine.
• A batch of Karras-adjacent parameters (s_min_uncond, s_churn, s_tmax, s_tmin, s_noise, eta) - these only matter if you know what you're doing with them, and if you do, you're probably better off doing this in ComfyUI natively.

Outputs are payload (a TXT2IMGRequestExtend) and payload_dict (DICT) for inspection.

Install

Identical to the rest of the pack:

cd ComfyUI/custom_nodes
git clone https://github.com/DiaoDaiaChan/ComfyUI_API_Request

or grab it via ComfyUI Manager, then restart. No model downloads, no heavy dependencies.

The short version

If you're trying to do hires fix or a refiner pass against an A1111 backend, right now you're better off building those into the base payload's fields or handling them in ComfyUI itself, because this node's output isn't actually wired into the request yet. Watch the pack's repo for a release that wires payload_extend into SDWebUI_Request - when that lands, this becomes the useful node it's clearly meant to be.