BlehFixGuiderPreviewing

If you're generating with LTX and previews are just broken or missing entirely, this is the node the README says you need - not a nice-to-have, a requirement, stated in exactly those terms: "You absolutely need to pass your guider through this for LTX (2.0, 2.3, 2.3 wide) previews to work."

Here's why it's necessary. This node wraps a GUIDER - the object that drives sampling in ComfyUI's newer guider-based workflow style - so that bleh's previewer gets an explicit hint about the shape of the latent it's looking at. Most models don't need this; the previewer can figure out latent shapes on its own. LTX is the exception, because it uses nested tensors that the previewer can't introspect without help.

Route your GUIDER through this node before it reaches your sampler. The output is the same guider, functionally unchanged for sampling purposes, just now carrying the shape hint bleh's previewer reads.

Inputs: guider (required GUIDER), fps_override (default 0, meaning disabled, range 0-9999 - lets you override the frame rate used when animating previews, useful if you're generating video at a non-default FPS and notice your animated previews playing back at the wrong speed; this applies regardless of which video model you're using, not just LTX). There's also an optional prefer_previewer (default default), and this is the setting worth paying closest attention to if you're specifically on LTX 2.3: the README explains there's no way for the previewer's internal logic to tell LTX 2.0's latent format apart from 2.3's on its own, so you have to tell it explicitly - set this to ltxav23 for standard LTX 2.3, or ltxav23wide for the wide variant. The author notes he's personally been using the wide previewer, which he says gives better quality at the cost of somewhat higher resource use. One thing worth knowing about this option specifically: the README calls out that it sets global state, so it applies pack-wide rather than being scoped to just this node's corner of your graph.

Output is a GUIDER.

Where this fits in an LTX graph specifically: LTX workflows built around the newer SamplerCustomAdvanced/guider style already produce a GUIDER object somewhere before sampling - this node just needs to sit in that wire, between wherever the guider gets built (typically a CFGGuider or similar) and the sampler that consumes it. It's a small, one-node insertion rather than a restructuring of the graph.

Install is the standard route for the pack - ComfyUI Manager, or a manual git clone https://github.com/blepping/ComfyUI-bleh into custom_nodes plus a restart. This node only supplies the shape hint; the previewer feature itself still needs to be enabled and configured through blehconfig.yaml the normal way.

If you've wired this node in and previews on LTX 2.3 are still garbled or missing, prefer_previewer is the first thing to check - the default setting genuinely can't distinguish 2.3 from 2.0 on its own, which is the entire reason this option exists in the first place. Getting that one setting wrong looks identical, from the outside, to the node not being wired in at all.